The Ancestor's Tale
Encyclopedia
The Ancestor's Tale is a 2004 popular science
book
by Richard Dawkins
, with contributions from Dawkins' research assistant Yan Wong. It follows the path of human
s backwards through evolution
ary history, meeting humanity's cousins as they converge on common ancestors. The book was nominated for the 2005 Aventis Prize for Science Books.
The narrative is structured as a pilgrimage
, with all modern animals following their own path through history to the origin of life. Humans meet their evolutionary cousins at rendezvous points along the way, the points at which the lineage diverged. At each point Dawkins attempts to infer, from molecular and fossil
evidence, the probable form of the most recent common ancestor
and describes the modern animals that join humanity's growing travelling party. This structure is inspired by Geoffrey Chaucer
's The Canterbury Tales
.
The pilgrimage visits a total of 40 "rendezvous points" from rendezvous zero, the most recent common ancestor of all of humanity, to rendezvous 39, eubacteria, the ancestor of all surviving organisms. Though Dawkins is confident of the essential shape of this phylogenetic taxonomy
, he enters caveats on a small number of branch points where a compelling weight of evidence had not been assembled at the time of writing.
At each rendezvous point, Dawkins recounts interesting tales concerning the cousin animals which are about to join the band of pilgrims. Every newly recruited species
, genus
or family
has its own peculiar features, often ones that are relevant to human anatomy or otherwise interesting for humans. For instance, Dawkins discusses why the axolotl
never needs to grow up, how new species
come about, how hard it is to classify animals, and why our fish
-like ancestors moved to the land. These peculiar features are studied and analyzed using a newly introduced tool or method from evolutionary biology, carefully woven into a tale to illustrate how the Darwinian theory of evolution
explains all diversity in nature.
Even though the book is best read sequentially, every chapter can also be read independently as a self-contained tale with an emphasis on a particular aspect of modern biology. As a whole, the book elaborates on all major topics in evolution.
Dawkins also tells personal stories about his childhood and time at university
. He talks with fondness about a tiny bushbaby
he kept as a child in Malawi
(Nyasaland). He described his surprise when he learned that the closest living relatives to the hippos
are the whales.
The book was produced in two hardback versions: a British one with extensive colour illustrations (by Weidenfeld & Nicolson), and an American one with a reduced number of black-and-white illustrations (by Houghton Mifflin). Paperback versions and an abridged audio version (narrated by Dawkins and his wife Lalla Ward
) have also been published.
The book is dedicated to Dawkins' friend and mentor, population geneticist
John Maynard Smith
, who died shortly before the book went to press.
at each rendezvous point. At each rendezvous point, we meet the concestor of ourselves and the listed species or collection of species. This does not mean that the concestor was much like those creatures; after the "rendezvous", our fellow "pilgrims" have had as much time to evolve and change as we have. Only creatures alive at the time of the book's writing join us at each rendezvous point. Except for a few special cases, numerous extinct species and families such as the dinosaur
s are excluded from the pilgrimage.
In what Dawkins calls the "Great Historic Rendezvous", he describes the significantly important event of endosymbiosis
, which results in the beginnings of eukaryotic cells. In his estimates, this occurred in two or three steps, roughly two billion years ago. Firstly, bacteria, perhaps related to Rickettsia
, entered proto-protozoan cells. For one reason or another, the bacteria were not digested and did not kill the cell. The cell offered protection to the bacteria, and the bacteria provided energy to the cell, resulting in a mutualistic symbiotic relationship
. This is the speculated origin of mitochondria
. Subsequently, photosynthetic bacteria (thought to be related to cyanobacteria) entered some, but not all, of these mitochondria-containing cells. These ancient bacteria evolved to become chloroplast
s, and the cells became the Plant
and Algal
lineages. Meanwhile, the cells which this second endosymbiotic relationship did not occur in went on to form the Kingdoms Fungi
and Animal
ia, as well as various Protozoa
.
Chloroplasts and mitochondria have their own genome
s, and they replicate independent of the cell in which they live. Dawkins acknowledges how the endosymbiotic theory proposed by Lynn Margulis
is now virtually universally accepted.
Popular science
Popular science, sometimes called literature of science, is interpretation of science intended for a general audience. While science journalism focuses on recent scientific developments, popular science is broad-ranging, often written by scientists as well as journalists, and is presented in many...
book
Book
A book is a set or collection of written, printed, illustrated, or blank sheets, made of hot lava, paper, parchment, or other materials, usually fastened together to hinge at one side. A single sheet within a book is called a leaf or leaflet, and each side of a leaf is called a page...
by Richard Dawkins
Richard Dawkins
Clinton Richard Dawkins, FRS, FRSL , known as Richard Dawkins, is a British ethologist, evolutionary biologist and author...
, with contributions from Dawkins' research assistant Yan Wong. It follows the path of human
Human
Humans are the only living species in the Homo genus...
s backwards through evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
ary history, meeting humanity's cousins as they converge on common ancestors. The book was nominated for the 2005 Aventis Prize for Science Books.
Synopsis
Pilgrimage
A pilgrimage is a journey or search of great moral or spiritual significance. Typically, it is a journey to a shrine or other location of importance to a person's beliefs and faith...
, with all modern animals following their own path through history to the origin of life. Humans meet their evolutionary cousins at rendezvous points along the way, the points at which the lineage diverged. At each point Dawkins attempts to infer, from molecular and fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
evidence, the probable form of the most recent common ancestor
Most recent common ancestor
In genetics, the most recent common ancestor of any set of organisms is the most recent individual from which all organisms in the group are directly descended...
and describes the modern animals that join humanity's growing travelling party. This structure is inspired by Geoffrey Chaucer
Geoffrey Chaucer
Geoffrey Chaucer , known as the Father of English literature, is widely considered the greatest English poet of the Middle Ages and was the first poet to have been buried in Poet's Corner of Westminster Abbey...
's The Canterbury Tales
The Canterbury Tales
The Canterbury Tales is a collection of stories written in Middle English by Geoffrey Chaucer at the end of the 14th century. The tales are told as part of a story-telling contest by a group of pilgrims as they travel together on a journey from Southwark to the shrine of Saint Thomas Becket at...
.
The pilgrimage visits a total of 40 "rendezvous points" from rendezvous zero, the most recent common ancestor of all of humanity, to rendezvous 39, eubacteria, the ancestor of all surviving organisms. Though Dawkins is confident of the essential shape of this phylogenetic taxonomy
Phylogenetic tree
A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics...
, he enters caveats on a small number of branch points where a compelling weight of evidence had not been assembled at the time of writing.
At each rendezvous point, Dawkins recounts interesting tales concerning the cousin animals which are about to join the band of pilgrims. Every newly recruited species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
or family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
has its own peculiar features, often ones that are relevant to human anatomy or otherwise interesting for humans. For instance, Dawkins discusses why the axolotl
Axolotl
The axolotl , Ambystoma mexicanum, is a neotenic salamander, closely related to the Tiger Salamander. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled. It is also called ajolote...
never needs to grow up, how new species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
come about, how hard it is to classify animals, and why our fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
-like ancestors moved to the land. These peculiar features are studied and analyzed using a newly introduced tool or method from evolutionary biology, carefully woven into a tale to illustrate how the Darwinian theory of evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
explains all diversity in nature.
Dawkins also tells personal stories about his childhood and time at university
University
A university is an institution of higher education and research, which grants academic degrees in a variety of subjects. A university is an organisation that provides both undergraduate education and postgraduate education...
. He talks with fondness about a tiny bushbaby
Galago
Galagos , also known as bushbabies, bush babies or nagapies , are small, nocturnal primates native to continental Africa, and make up the family Galagidae...
he kept as a child in Malawi
Malawi
The Republic of Malawi is a landlocked country in southeast Africa that was formerly known as Nyasaland. It is bordered by Zambia to the northwest, Tanzania to the northeast, and Mozambique on the east, south and west. The country is separated from Tanzania and Mozambique by Lake Malawi. Its size...
(Nyasaland). He described his surprise when he learned that the closest living relatives to the hippos
Hippopotamus
The hippopotamus , or hippo, from the ancient Greek for "river horse" , is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae After the elephant and rhinoceros, the hippopotamus is the third largest land mammal and the heaviest...
are the whales.
The book was produced in two hardback versions: a British one with extensive colour illustrations (by Weidenfeld & Nicolson), and an American one with a reduced number of black-and-white illustrations (by Houghton Mifflin). Paperback versions and an abridged audio version (narrated by Dawkins and his wife Lalla Ward
Lalla Ward
Sarah Ward known as Lalla Ward, is an English actor, author and illustrator. As an actor, she is known for playing the part of Romana in the BBC science fiction television series Doctor Who. She is married to evolutionary biologist Richard Dawkins.-Early career:Ward's stage name, "Lalla", comes...
) have also been published.
The book is dedicated to Dawkins' friend and mentor, population geneticist
Population genetics
Population genetics is the study of allele frequency distribution and change under the influence of the four main evolutionary processes: natural selection, genetic drift, mutation and gene flow. It also takes into account the factors of recombination, population subdivision and population...
John Maynard Smith
John Maynard Smith
John Maynard Smith,His surname was Maynard Smith, not Smith, nor was it hyphenated. F.R.S. was a British theoretical evolutionary biologist and geneticist. Originally an aeronautical engineer during the Second World War, he took a second degree in genetics under the well-known biologist J.B.S....
, who died shortly before the book went to press.
List of rendezvous points
Dawkins uses the term concestor—coined by Nicky Warren—for the most recent common ancestorMost recent common ancestor
In genetics, the most recent common ancestor of any set of organisms is the most recent individual from which all organisms in the group are directly descended...
at each rendezvous point. At each rendezvous point, we meet the concestor of ourselves and the listed species or collection of species. This does not mean that the concestor was much like those creatures; after the "rendezvous", our fellow "pilgrims" have had as much time to evolve and change as we have. Only creatures alive at the time of the book's writing join us at each rendezvous point. Except for a few special cases, numerous extinct species and families such as the dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s are excluded from the pilgrimage.
Prologue
| rendezvous point | Time | Significant event | Story |
|---|---|---|---|
| n/a | 0.01 mya | Neolithic Revolution Neolithic Revolution The Neolithic Revolution was the first agricultural revolution. It was the transition from hunting and gathering to agriculture and settlement. Archaeological data indicates that various forms of plants and animal domestication evolved independently in 6 separate locations worldwide circa... |
The Farmer's Tale describes the Neolithic Revolution Neolithic Revolution The Neolithic Revolution was the first agricultural revolution. It was the transition from hunting and gathering to agriculture and settlement. Archaeological data indicates that various forms of plants and animal domestication evolved independently in 6 separate locations worldwide circa... |
| n/a | 0.04 mya | Great Leap Forward | The Cro-Magnon's Tale describes the Great Leap Forward. |
Primates
| rendezvous point | Time | Joining party | Story |
|---|---|---|---|
| 0 | All Humankind | The Tasmanian's Tale illustrates the identical ancestors point Identical ancestors point In genetic genealogy, the identical ancestors point is that point in a given population's past where each individual then alive turned out to be either the ancestor of every individual alive now, or to have no living descendants at all... starting from which all living people trace exactly the same set of ancestors back in time. |
|
| Eve's Tale touches upon coalescent theory Coalescent theory In genetics, coalescent theory is a retrospective model of population genetics. It attempts to trace all alleles of a gene shared by all members of a population to a single ancestral copy, known as the most recent common ancestor... , Mitochondrial Eve Mitochondrial Eve In the field of human genetics, Mitochondrial Eve refers to the matrilineal "MRCA" . In other words, she was the woman from whom all living humans today descend, on their mother's side, and through the mothers of those mothers and so on, back until all lines converge on one person... , Y-chromosomal Adam Y-chromosomal Adam In human genetics, Y-chromosomal Adam is the theoretical most recent common ancestor from whom all living people are descended patrilineally . Many studies report that Y-chromosomal Adam lived as early as around 142,000 years ago and possibly as recently as 60,000 years ago... and polymorphism Polymorphism (biology) Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph... . The story ends with a speculation that the ABO blood group system ABO blood group system The ABO blood group system is the most important blood type system in human blood transfusion. The associated anti-A antibodies and anti-B antibodies are usually IgM antibodies, which are usually produced in the first years of life by sensitization to environmental substances such as food,... in humans and chimps are examples of trans-specific polymorphism; a type-B human may actually be more closely related to type-B chimp than type-B human is related to type-A human, from the perspective of the gene Gene A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains... s (or allele Allele An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation... s) responsible for the antigens. |
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| The Ergast Homo ergaster Homo ergaster is an extinct chronospecies of Homo that lived in eastern and southern Africa during the early Pleistocene, about 2.5–1.7 million years ago.There is still disagreement on the subject of the classification, ancestry, and progeny of H... 's Tale recounts how a mutated Mutation In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic... form of the FOXP2 FOXP2 Forkhead box protein P2 also known as FOXP2 is a protein that in humans is encoded by the FOXP2 gene, located on human chromosome 7 . FOXP2 orthologs have also been identified in all mammals for which complete genome data are available... gene could have allowed Homo ergaster to acquire language. |
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| The Handyman's Tale explains how Homo habilis Homo habilis Homo habilis is a species of the genus Homo, which lived from approximately at the beginning of the Pleistocene period. The discovery and description of this species is credited to both Mary and Louis Leakey, who found fossils in Tanzania, East Africa, between 1962 and 1964. Homo habilis Homo... acquired high 'brain to body mass ratio Brain to body mass ratio Brain-to-body mass ratio, also known as the brain to body weight ratio, is the ratio of brain weight to body weight, which is hypothesised to be a rough estimate of the intelligence of an animal. A more complex measurement, encephalization quotient, takes into account allometric effects of widely... ', at the same time introducing logarithmic scale Logarithmic scale A logarithmic scale is a scale of measurement using the logarithm of a physical quantity instead of the quantity itself.A simple example is a chart whose vertical axis increments are labeled 1, 10, 100, 1000, instead of 1, 2, 3, 4... and scatterplot Scatterplot A scatter plot or scattergraph is a type of mathematical diagram using Cartesian coordinates to display values for two variables for a set of data.... as tools for scientific studies. |
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| Little Foot Little Foot "Little Foot" is the nickname given to an extraordinarily complete fossil hominin skeleton found in 1994–1998 in the cave system of Sterkfontein, South Africa.- Discovery :... 's Tale examines how hominid first learned to walk on two legs. |
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| 1 | 6 mya | Chimpanzee Chimpanzee Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:... s (Pan) |
Human pilgrims join their evolutionary cousins, chimpanzees and bonobo Bonobo The bonobo , Pan paniscus, previously called the pygmy chimpanzee and less often, the dwarf or gracile chimpanzee, is a great ape and one of the two species making up the genus Pan. The other species in genus Pan is Pan troglodytes, or the common chimpanzee... s. |
| 2 | 7 mya | Gorilla Gorilla Gorillas are the largest extant species of primates. They are ground-dwelling, predominantly herbivorous apes that inhabit the forests of central Africa. Gorillas are divided into two species and either four or five subspecies... s (Gorilla) |
The Gorilla Gorilla Gorillas are the largest extant species of primates. They are ground-dwelling, predominantly herbivorous apes that inhabit the forests of central Africa. Gorillas are divided into two species and either four or five subspecies... 's Tale considers human's changing attitude towards the great apes Hominidae The Hominidae or include them .), as the term is used here, form a taxonomic family, including four extant genera: chimpanzees , gorillas , humans , and orangutans .... , ending with a discussion on racism Racism Racism is the belief that inherent different traits in human racial groups justify discrimination. In the modern English language, the term "racism" is used predominantly as a pejorative epithet. It is applied especially to the practice or advocacy of racial discrimination of a pernicious nature... , speciesism Speciesism Speciesism is the assigning of different values or rights to beings on the basis of their species membership. The term was created by British psychologist Richard D... and the Great Ape Project Great Ape Project The Great Ape Project , founded in 1994, is an international organization of primatologists, anthropologists, ethicists, and other experts who advocate a United Nations Declaration of the Rights of Great Apes that would confer basic legal rights on non-human great apes: chimpanzees, bonobos,... . |
| 3 | 14 mya | Orangutan Orangutan Orangutans are the only exclusively Asian genus of extant great ape. The largest living arboreal animals, they have proportionally longer arms than the other, more terrestrial, great apes. They are among the most intelligent primates and use a variety of sophisticated tools, also making sleeping... s (Pongo) |
The Orangutan Orangutan Orangutans are the only exclusively Asian genus of extant great ape. The largest living arboreal animals, they have proportionally longer arms than the other, more terrestrial, great apes. They are among the most intelligent primates and use a variety of sophisticated tools, also making sleeping... 's Tale introduces the principle of parsimony and its use in construction of family tree (cladogram Cladistics Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade... ) of species. Orangutan is the last of the great apes Hominidae The Hominidae or include them .), as the term is used here, form a taxonomic family, including four extant genera: chimpanzees , gorillas , humans , and orangutans .... to join the pilgrimage. |
| 4 | 18 mya | Gibbon Gibbon Gibbons are apes in the family Hylobatidae . The family is divided into four genera based on their diploid chromosome number: Hylobates , Hoolock , Nomascus , and Symphalangus . The extinct Bunopithecus sericus is a gibbon or gibbon-like ape which, until recently, was thought to be closely related... s (Hylobatidae) |
The Gibbon Gibbon Gibbons are apes in the family Hylobatidae . The family is divided into four genera based on their diploid chromosome number: Hylobates , Hoolock , Nomascus , and Symphalangus . The extinct Bunopithecus sericus is a gibbon or gibbon-like ape which, until recently, was thought to be closely related... 's Tale further elaborates on neighbor-joining Neighbor-joining In bioinformatics, neighbor joining is a bottom-up clustering method for the creation of phenetic trees , created by Naruya Saitou and Masatoshi Nei... , parsimony and textual criticism Textual criticism Textual criticism is a branch of literary criticism that is concerned with the identification and removal of transcription errors in the texts of manuscripts... techniques used to construct cladograms. When simple principle of parsimony proves inadequate to handle 'long branch attraction Long branch attraction Long branch attraction is a phenomenon in phylogenetic analyses when rapidly evolving lineages are inferred to be closely related, regardless of their true evolutionary relationships. For example, in DNA sequence-based analyses, the problem arises when sequences from two lineages evolve rapidly... ' problems caused by convergence Convergent evolution Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are... and reversion, the phylogenetic tree Phylogenetic tree A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics... (phylogram) and computational phylogenetic methods Computational phylogenetics Computational phylogenetics is the application of computational algorithms, methods and programs to phylogenetic analyses. The goal is to assemble a phylogenetic tree representing a hypothesis about the evolutionary ancestry of a set of genes, species, or other taxa... such as maximum likelihood Maximum likelihood In statistics, maximum-likelihood estimation is a method of estimating the parameters of a statistical model. When applied to a data set and given a statistical model, maximum-likelihood estimation provides estimates for the model's parameters.... analysis are introduced. The tale ends with yet another example of trans-specific polymorphism: sexual dimorphism Sexual dimorphism Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:... ; the sex-determining Sex-determination system A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. Most sexual organisms have two sexes. In many cases, sex determination is genetic: males and females have different alleles or even different genes that specify their sexual... SRY SRY SRY is a sex-determining gene on the Y chromosome in the therians .This intronless gene encodes a transcription factor that is a member of the SOX gene family of DNA-binding proteins... has never been in female bodies long since gibbons and humans diverged. This serves to highlight the fact that different phylogenetic trees can be created by tracing different sets of genes Coalescent theory In genetics, coalescent theory is a retrospective model of population genetics. It attempts to trace all alleles of a gene shared by all members of a population to a single ancestral copy, known as the most recent common ancestor... ; the one mainstream 'species tree' is nothing more than a summary of multitude of gene trees, a 'majority vote' among gene trees. Gibbon is the last ape Ape Apes are Old World anthropoid mammals, more specifically a clade of tailless catarrhine primates, belonging to the biological superfamily Hominoidea. The apes are native to Africa and South-east Asia, although in relatively recent times humans have spread all over the world... to join the pilgrimage. |
| 5 | 25 mya | Old World Monkeys (Cercopithecidae) | Old World monkeys, being in the same Catarrhini Catarrhini Catarrhini is one of the two subdivisions of the higher primates . It contains the Old World monkeys and the apes, which in turn are further divided into the lesser apes or gibbons and the great apes, consisting of the orangutans, gorillas, chimpanzees, bonobos, and humans... clade Clade A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological... as apes, are closer cousins to apes than to New World monkeys. Old World monkeys are sometimes called the 'tailed apes'. |
| 6 | 40 mya | New World Monkeys (Platyrrhini) | The Howler Monkey Howler monkey Howler monkeys are among the largest of the New World monkeys. Fifteen species are currently recognised. Previously classified in the family Cebidae, they are now placed in the family Atelidae. These monkeys are native to South and Central American forests... 's Tale calls attention to the critical role of gene duplication Gene duplication Gene duplication is any duplication of a region of DNA that contains a gene; it may occur as an error in homologous recombination, a retrotransposition event, or duplication of an entire chromosome.The second copy of the gene is often free from selective pressure — that is, mutations of it have no... in evolution. While our remote vertebrate Vertebrate Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds... ancestors possessed trichromatic vision, our nocturnal, warm-blooded Warm-blooded The term warm-blooded is a colloquial term to describe animal species which have a relatively higher blood temperature, and maintain thermal homeostasis primarily through internal metabolic processes... , mammal Mammal Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young... ian ancestors lost one of three cones Cone cell Cone cells, or cones, are photoreceptor cells in the retina of the eye that are responsible for color vision; they function best in relatively bright light, as opposed to rod cells that work better in dim light. If the retina is exposed to an intense visual stimulus, a negative afterimage will be... in the retina Retina The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical... at the time of dinosaur Dinosaur Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of... s. This is why fish Fish Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups... , reptile Reptile Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors... s and bird Bird Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from... s are trichromatic while all mammals with the exception of apes and New World monkeys are strictly handicapped dichromats. Because color vision Color vision Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths of the light they reflect, emit, or transmit... is of paramount importance to diurnal Diurnal animal Diurnality is a plant or animal behavior characterized by activity during the day and sleeping at night.-In animals:Animals that are not diurnal might be nocturnal or crepuscular . Many animal species are diurnal, including many mammals, insects, reptiles and birds... animals that eat ripe fruits, apes and New World monkeys regained tri-color vision independently via chromosomal translocation Chromosomal translocation In genetics, a chromosome translocation is a chromosome abnormality caused by rearrangement of parts between nonhomologous chromosomes. A gene fusion may be created when the translocation joins two otherwise separated genes, the occurrence of which is common in cancer. It is detected on... . In apes, trichromacy resulted from true duplication of the opsin Opsin Opsins are a group of light-sensitive 35–55 kDa membrane-bound G protein-coupled receptors of the retinylidene protein family found in photoreceptor cells of the retina. Five classical groups of opsins are involved in vision, mediating the conversion of a photon of light into an electrochemical... gene. New World monkeys first achieved trichromacy in its female population by producing two alleles (green and red) for the same locus Locus (genetics) In the fields of genetics and genetic computation, a locus is the specific location of a gene or DNA sequence on a chromosome. A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map... for the opsin gene on the X-chromosome, an example of polymorphism Polymorphism (biology) Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph... . Its males, with only one copy of the X-chromosome, remained dichromats with either a green or a red opsin, an example of heterozygote advantage Heterozygote advantage A heterozygote advantage describes the case in which the heterozygote genotype has a higher relative fitness than either the homozygote dominant or homozygote recessive genotype. The specific case of heterozygote advantage is due to a single locus known as overdominance... . Howler monkeys, a type of New World monkey, took this one step further and achieved trichromacy for both sexes when its X-chromosome gained two loci Locus (genetics) In the fields of genetics and genetic computation, a locus is the specific location of a gene or DNA sequence on a chromosome. A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map... to house both the green allele and the red allele. New World monkeys are the last simian Simian The simians are the "higher primates" familiar to most people: the Old World monkeys and apes, including humans, , and the New World monkeys or platyrrhines. Simians tend to be larger than the "lower primates" or prosimians.- Classification and evolution :The simians are split into three groups... s (also known as 'higher primate Primate A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment... s' or anthropoids Simian The simians are the "higher primates" familiar to most people: the Old World monkeys and apes, including humans, , and the New World monkeys or platyrrhines. Simians tend to be larger than the "lower primates" or prosimians.- Classification and evolution :The simians are split into three groups... ) to join the pilgrimage. |
| 7 | 58 mya | Tarsier Tarsier Tarsiers are haplorrhine primates of the genus Tarsius, a genus in the family Tarsiidae, which is itself the lone extant family within the infraorder Tarsiiformes... s (Tarsius) |
Tarsier is the last haplorrhine Haplorrhini The haplorhines, the "dry-nosed" primates , are members of the Haplorhini clade: the prosimian tarsiers and the anthropoids... to join the pilgrimage. A nocturnal animals, the tarsier has two enormous eyes each as large as its brain. Unlike other nocturnal mammals, however, tarsier eyes do not contain tapetum lucidum Tapetum lucidum The tapetum lucidum is a layer of tissue in the eye of many vertebrate animals.... which reflects light from the back of the eye for a second exposure on the retina Retina The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical... to maximize light capture. From this we can infer that the common ancestor of all haplorrhine must have been a diurnal animal Diurnal animal Diurnality is a plant or animal behavior characterized by activity during the day and sleeping at night.-In animals:Animals that are not diurnal might be nocturnal or crepuscular . Many animal species are diurnal, including many mammals, insects, reptiles and birds... which shed the tapetum lucidum to eliminate blurry images caused by reflected light. When the tarsier became a nocturnal animal, it enlarged its eyes to compensate for the lack of tapetum lucidum. |
| 8 | 63 mya | Lemur Lemur Lemurs are a clade of strepsirrhine primates endemic to the island of Madagascar. They are named after the lemures of Roman mythology due to the ghostly vocalizations, reflective eyes, and the nocturnal habits of some species... s, Bushbabies Galago Galagos , also known as bushbabies, bush babies or nagapies , are small, nocturnal primates native to continental Africa, and make up the family Galagidae... and their kin (Strepsirrhini) |
The pilgrimage meets with the rest of the prosimian Prosimian Prosimians are a grouping of mammals defined as being primates, but not monkeys or apes. They include, among others, lemurs, bushbabies, and tarsiers. They are considered to have characteristics that are more primitive than those of monkeys and apes. Prosimians are the only primates native to... cousins: the lemur Lemur Lemurs are a clade of strepsirrhine primates endemic to the island of Madagascar. They are named after the lemures of Roman mythology due to the ghostly vocalizations, reflective eyes, and the nocturnal habits of some species... s, potto Potto The potto is a strepsirrhine primate from the Lorisidae family. It is the only species in genus Perodicticus... s, bushbabies Galago Galagos , also known as bushbabies, bush babies or nagapies , are small, nocturnal primates native to continental Africa, and make up the family Galagidae... , and loris Loris Loris is the common name for the strepsirrhine primates of the subfamily Lorisinae in family Lorisidae. Loris is one genus in this subfamily and includes the slender lorises, while Nycticebus is the genus for the slow lorises.... es. The Aye-Aye Aye-aye The aye-aye is a lemur, a strepsirrhine primate native to Madagascar that combines rodent-like teeth and a special thin middle finger to fill the same ecological niche as a woodpecker... 's Tale showcases the strange lemur Lemur Lemurs are a clade of strepsirrhine primates endemic to the island of Madagascar. They are named after the lemures of Roman mythology due to the ghostly vocalizations, reflective eyes, and the nocturnal habits of some species... s which are only found on the island of Madagascar Madagascar The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa... . Madagascar was originally part of the Gondwana Gondwana In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,... supercontinent Supercontinent In geology, a supercontinent is a landmass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia qualifies as a supercontinent today.-History:... which included present Africa Africa Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area... continent Continent A continent is one of several very large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents—they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia.Plate tectonics is... and Indian subcontinent Indian subcontinent The Indian subcontinent, also Indian Subcontinent, Indo-Pak Subcontinent or South Asian Subcontinent is a region of the Asian continent on the Indian tectonic plate from the Hindu Kush or Hindu Koh, Himalayas and including the Kuen Lun and Karakoram ranges, forming a land mass which extends... . Gondwana broke off into drifting blocks of land, some of which became Africa, India and Madagascar. As an estranged island, Madagascar became a speciation Speciation Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages... hotbed. For instance a small founding population Founder effect In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It was first fully outlined by Ernst Mayr in 1942, using existing theoretical work by those such as Sewall... of strepsirrhine Strepsirrhini The clade Strepsirrhini is one of the two suborders of primates. Madagascar's only non-human primates are strepsirrhines, and others can be found in southeast Asia and Africa... primates (possibly rafted in from neighboring continent) flourished and diversified into all niches of the ecosystem Ecosystem An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight.... , in the absence of monkeys. The story reminds us how Madagascar, with a land mass Land mass Land mass refers to the total area of a country or geographical region . The Earth's total land mass is which is about 29.2% of its total surface. Water covers approximately 70.8% of the Earth's surface, mostly in the form of oceans.... 1/1000 of Earth Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets... 's total land area, ends up housing unique species that account for 4% of all species of animals and plants. Lemurs and their kin are the last of the primate Primate A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment... s to join the pilgrimage. |
Non-primate mammals
| rendezvous point | Time | Joining party | Story |
|---|---|---|---|
| 9 | 70 mya | Colugos and Tree Shrews Treeshrew The treeshrews are small mammals native to the tropical forests of Southeast Asia. They make up the families Tupaiidae, the treeshrews, and Ptilocercidae, the pen-tailed treeshrews, and the entire order Scandentia. There are 20 species in 5 genera... (Dermoptera and Scandentia) |
The Cretaceous–Tertiary extinction event occurred at 65 million years ago, due to both large scale volcanic Volcano 2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15... activities in the Deccan traps Deccan Traps The Deccan Traps are a large igneous province located on the Deccan Plateau of west-central India and one of the largest volcanic features on Earth. They consist of multiple layers of solidified flood basalt that together are more than thick and cover an area of and a volume of... over a period of time, and the final asteroid Asteroid Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones... impact event Impact event An impact event is the collision of a large meteorite, asteroid, comet, or other celestial object with the Earth or another planet. Throughout recorded history, hundreds of minor impact events have been reported, with some occurrences causing deaths, injuries, property damage or other significant... which created the Chicxulub Crater Chicxulub Crater The Chicxulub crater is an ancient impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named... . The sudden temperature change and sunlight reduction caused massive disruptions to Earth's ecosystem. As a result, all dinosaur Dinosaur Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of... s except the bird Bird Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from... s, as well as numerous other species went extinct. The disappearance of dinosaurs made it possible for many different species of shrew Shrew A shrew or shrew mouse is a small molelike mammal classified in the order Soricomorpha. True shrews are also not to be confused with West Indies shrews, treeshrews, otter shrews, or elephant shrews, which belong to different families or orders.Although its external appearance is generally that of... -like, nocturnal insectivore Insectivore An insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures. An alternate term is entomophage, which also refers to the human practice of eating insects.... s to evolve into hippos Hippopotamus The hippopotamus , or hippo, from the ancient Greek for "river horse" , is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae After the elephant and rhinoceros, the hippopotamus is the third largest land mammal and the heaviest... , lion Lion The lion is one of the four big cats in the genus Panthera, and a member of the family Felidae. With some males exceeding 250 kg in weight, it is the second-largest living cat after the tiger... s, elephant Elephant Elephants are large land mammals in two extant genera of the family Elephantidae: Elephas and Loxodonta, with the third genus Mammuthus extinct... s, etc. to fill the new ecological voids, an example of evolutionary radiation Evolutionary radiation An evolutionary radiation is an increase in taxonomic diversity or morphological disparity, due to adaptive change or the opening of ecospace. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment,... . One of these shrew-like creatures was the concestor of the current pilgrimage party and the new joiners, the colugos and tree shrews. |
| The tree shrews resemble the squirrel Squirrel Squirrels belong to a large family of small or medium-sized rodents called the Sciuridae. The family includes tree squirrels, ground squirrels, chipmunks, marmots , flying squirrels, and prairie dogs. Squirrels are indigenous to the Americas, Eurasia, and Africa and have been introduced to Australia... s. The colugos resemble flying squirrel Flying squirrel Flying squirrels, scientifically known as Pteromyini or Petauristini, are a tribe of 44 species of squirrels .- Description :... s. In both cases, the resemblance is only superficial, due to convergence Convergent evolution Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are... ; the squirrels are rodent Rodent Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing.... s and will meet us further down the pilgrimage. At the present, scientists are not yet sure about the exact relationships among the tree shrews, the colugos and us. Dawkins provisionally accepts the view that they join forces first, before meeting the pilgrimage party. This would place our concestor 9 at a time before K–T boundary K–T boundary The K–T boundary is a geological signature, usually a thin band, dated to 65.5 ± 0.3 Ma ago. K is the traditional abbreviation for the Cretaceous period, and T is the abbreviation for the Tertiary period... which marked the extinction of the dinosaurs. The Colugo's Tale warns us that even though the general structure of the family tree is sound, some of the details could change as more evidences become known. |
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| 10 | 75 mya | Rodent Rodent Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing.... s and Rabbitkind Lagomorpha The lagomorphs are the members of the taxonomic order Lagomorpha, of which there are two living families, the Leporidae , and the Ochotonidae... (Glires) |
Rodent Rodent Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing.... s comprise the largest number of species in mammal Mammal Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young... ia, more than 40 percent of all mammalian species. Members include rat Rat Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus... s, mice Mouse A mouse is a small mammal belonging to the order of rodents. The best known mouse species is the common house mouse . It is also a popular pet. In some places, certain kinds of field mice are also common. This rodent is eaten by large birds such as hawks and eagles... , lemming Lemming Lemmings are small rodents, usually found in or near the Arctic, in tundra biomes. They are subniveal animals, and together with voles and muskrats, they make up the subfamily Arvicolinae , which forms part of the largest mammal radiation by far, the superfamily Muroidea, which also includes rats,... s, beaver Beaver The beaver is a primarily nocturnal, large, semi-aquatic rodent. Castor includes two extant species, North American Beaver and Eurasian Beaver . Beavers are known for building dams, canals, and lodges . They are the second-largest rodent in the world... s, squirrel Squirrel Squirrels belong to a large family of small or medium-sized rodents called the Sciuridae. The family includes tree squirrels, ground squirrels, chipmunks, marmots , flying squirrels, and prairie dogs. Squirrels are indigenous to the Americas, Eurasia, and Africa and have been introduced to Australia... s, etc. The Mouse's Tale explains how mammals possess similar and relatively small genome Genome In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA.... s in the order of 30,000 gene Gene A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains... s, yet each animal exhibits distinct features and surprising complexities. Dawkins debunks the popular description of genome as blueprint Blueprint A blueprint is a type of paper-based reproduction usually of a technical drawing, documenting an architecture or an engineering design. More generally, the term "blueprint" has come to be used to refer to any detailed plan.... s which give rise to the misconception that the more complex the animal, the more complex the blueprint ought to be. Instead, genes in a genome should be thought of as word Word In language, a word is the smallest free form that may be uttered in isolation with semantic or pragmatic content . This contrasts with a morpheme, which is the smallest unit of meaning but will not necessarily stand on its own... s or sentences Sentence (linguistics) In the field of linguistics, a sentence is an expression in natural language, and often defined to indicate a grammatical unit consisting of one or more words that generally bear minimal syntactic relation to the words that precede or follow it... in a language Language Language may refer either to the specifically human capacity for acquiring and using complex systems of communication, or to a specific instance of such a system of complex communication... , and embryonic development Embryogenesis Embryogenesis is the process by which the embryo is formed and develops, until it develops into a fetus.Embryogenesis starts with the fertilization of the ovum by sperm. The fertilized ovum is referred to as a zygote... over time is akin to 'order' of words and sentences in a book. While the number of genes are limited, the endless number of 'orders' by which similar genes in mice and humans are deployed during embryonic development can generate astonishing complexity and distinguish a mouse from a man. |
| The Beaver's Tale revisits the key insights that Dawkins contributed to the field of evolution in his book The Extended Phenotype The Extended Phenotype The Extended Phenotype is a biological concept introduced by Richard Dawkins in a 1982 book with the same title. The main idea is that phenotype should not be limited to biological processes such as protein biosynthesis or tissue growth, but extended to include all effects that a gene has on its... . A beaver's body is known as a phenotype Phenotype A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior... , an external and visible manifestation of the internal and hidden genotype Genotype The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration... . In the same way the beaver body Organism In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise... is regarded as an expression of its genes, beaver dams or beaver lake Lake A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,... s can be considered 'extended phenotypes' of the same beaver genes. Better beaver genes make better beaver bodies, beaver dams and beaver lakes. In other words, beaver genes are selected not only by the fitness of beaver bodies, but also by the effectiveness of beaver dams and beaver lakes they produce. |
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| 11 | 85 mya | Laurasiatheres Laurasiatheria Laurasiatheria is a large group of placental mammals believed to have originated on the northern supercontinent of Laurasia. It includes shrews, hedgehogs, pangolins, bats, whales, most hoofed mammals, and carnivorans, among others.... (Laurasiatheria) |
An extremely diverse group of animals join the pilgrimage, including Carnivora Carnivora The diverse order Carnivora |Latin]] carō "flesh", + vorāre "to devour") includes over 260 species of placental mammals. Its members are formally referred to as carnivorans, while the word "carnivore" can refer to any meat-eating animal... (dog Dog The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in... s, cat Cat The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests... s, bear Bear Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern... s and seals Pinniped Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped... ), Perissodactyla (horse Horse The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today... s, tapir Tapir A Tapir is a large browsing mammal, similar in shape to a pig, with a short, prehensile snout. Tapirs inhabit jungle and forest regions of South America, Central America, and Southeast Asia. There are four species of Tapirs: the Brazilian Tapir, the Malayan Tapir, Baird's Tapir and the Mountain... s and rhinos Rhinoceros Rhinoceros , also known as rhino, is a group of five extant species of odd-toed ungulates in the family Rhinocerotidae. Two of these species are native to Africa and three to southern Asia.... ), Cetartiodactyla Cetartiodactyla Cetartiodactyla is the clade in which whales and even-toed ungulates have currently been placed. The term was coined by merging the name for the two orders, Cetacea and Artiodactyla, into a single word. The term Cetartiodactyla reflects the idea that whales evolved within the artiodactyls... (deer Deer Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year... , cattle Cattle Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius... , pig Pig A pig is any of the animals in the genus Sus, within the Suidae family of even-toed ungulates. Pigs include the domestic pig, its ancestor the wild boar, and several other wild relatives... s and hippos Hippopotamus The hippopotamus , or hippo, from the ancient Greek for "river horse" , is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae After the elephant and rhinoceros, the hippopotamus is the third largest land mammal and the heaviest... ), Chiroptera (bat Bat Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,... s), Insectivora Insectivora The order Insectivora is a now-abandoned biological grouping within the class of mammals... (moles Mole (animal) Moles are small cylindrical mammals adapted to a subterranean lifestyle. They have velvety fur; tiny or invisible ears and eyes; and short, powerful limbs with large paws oriented for digging. The term is especially and most properly used for the true moles, those of the Talpidae family in the... and shrew Shrew A shrew or shrew mouse is a small molelike mammal classified in the order Soricomorpha. True shrews are also not to be confused with West Indies shrews, treeshrews, otter shrews, or elephant shrews, which belong to different families or orders.Although its external appearance is generally that of... s), etc. Some of them fly Flight Flight is the process by which an object moves either through an atmosphere or beyond it by generating lift or propulsive thrust, or aerostatically using buoyancy, or by simple ballistic movement.... , others swim, and yet many of them gallop. Half of them are predators Predation In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption... which hunt the other half of the group. The only thing they share in common is that they join up with one another before the group joins us to meet concestor 11. This group of animals belong to the Laurasiatheria Laurasiatheria Laurasiatheria is a large group of placental mammals believed to have originated on the northern supercontinent of Laurasia. It includes shrews, hedgehogs, pangolins, bats, whales, most hoofed mammals, and carnivorans, among others.... clade as all of them originated from the supercontinent Supercontinent In geology, a supercontinent is a landmass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia qualifies as a supercontinent today.-History:... of Laurasia Laurasia In paleogeography, Laurasia was the northernmost of two supercontinents that formed part of the Pangaea supercontinent from approximately... . |
| The Hippo Hippopotamus The hippopotamus , or hippo, from the ancient Greek for "river horse" , is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae After the elephant and rhinoceros, the hippopotamus is the third largest land mammal and the heaviest... 's Tale is really the whale Whale Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga... 's tale. All cetacea Cetacea The order Cetacea includes the marine mammals commonly known as whales, dolphins, and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal", was more general. It comes from Ancient Greek , meaning "whale" or "any huge fish or sea... ns, including whales, dolphins and porpoises, are descendants of land-living mammals of the Artiodactyl order Order (biology) In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family... (even-toed ungulate animals). Both cetaceans and artiodactyl are now classified under the super-order Cetartiodactyla Cetartiodactyla Cetartiodactyla is the clade in which whales and even-toed ungulates have currently been placed. The term was coined by merging the name for the two orders, Cetacea and Artiodactyla, into a single word. The term Cetartiodactyla reflects the idea that whales evolved within the artiodactyls... which includes both whales and hippos Hippopotamus The hippopotamus , or hippo, from the ancient Greek for "river horse" , is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae After the elephant and rhinoceros, the hippopotamus is the third largest land mammal and the heaviest... . In fact, whales are the closest living relatives of hippos; they evolved from a common ancestor Most recent common ancestor In genetics, the most recent common ancestor of any set of organisms is the most recent individual from which all organisms in the group are directly descended... at around 54 million years ago. This story illustrates how a species can flip into evolutionary overdrive when it enters into a new environment, while its closest relatives remain unchanged for long time in their static environment. |
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| The Seal Pinniped Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped... 's Tale illustrates how a sex ratio Sex ratio Sex ratio is the ratio of males to females in a population. The primary sex ratio is the ratio at the time of conception, secondary sex ratio is the ratio at time of birth, and tertiary sex ratio is the ratio of mature organisms.... of 50:50 (males to females) is found in most sexually reproducing Sexual reproduction Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the... animals from both monogamous Monogamy Monogamy /Gr. μονός+γάμος - one+marriage/ a form of marriage in which an individual has only one spouse at any one time. In current usage monogamy often refers to having one sexual partner irrespective of marriage or reproduction... and polygamous Polygamy Polygamy is a marriage which includes more than two partners... species. In a harem-based (polygynous Polygyny Polygyny is a form of marriage in which a man has two or more wives at the same time. In countries where the practice is illegal, the man is referred to as a bigamist or a polygamist... ) system such as that of elephant seal Elephant seal Elephant seals are large, oceangoing seals in the genus Mirounga. There are two species: the northern elephant seal and the southern elephant seal . Both were hunted to the brink of extinction by the end of the 19th century, but numbers have since recovered... s where 4 percent of males account for 88 percent of all copulations, the actual sex ratio of 50:50 seems to produce an excess of males who consume resources but end up leaving no offsprings. This puzzle is solved by the concept of Fisher's principle Fisher's principle Fisher's principle explains why the sex ratio of most species is approximately 1:1. It was famously outlined by Ronald Fisher in his 1930 book The Genetical Theory of Natural Selection . Nevertheless, A. W. F. Edwards has remarked that it is "probably the most celebrated argument in evolutionary... (named 'parental expenditure') proposed by R.A. Fisher Ronald Fisher Sir Ronald Aylmer Fisher FRS was an English statistician, evolutionary biologist, eugenicist and geneticist. Among other things, Fisher is well known for his contributions to statistics by creating Fisher's exact test and Fisher's equation... . This led to further work by Robert Trivers Robert Trivers Robert L. Trivers is an American evolutionary biologist and sociobiologist and Professor of Anthropology and Biological Sciences at Rutgers University. Trivers is most noted for proposing the theories of reciprocal altruism , parental investment , facultative sex ratio determination , and... on parental investment Parental investment In evolutionary biology, parental investment is any parental expenditure that benefits one offspring at a cost to parents' ability to invest in other components of fitness... to elucidate sexual selection Sexual selection Sexual selection, a concept introduced by Charles Darwin in his 1859 book On the Origin of Species, is a significant element of his theory of natural selection... . More importantly, the elephant seal typifies sexual dimorphism Sexual dimorphism Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:... , as a bull elephant seal can grow to be three times the size of a cow seal, thanks to sex-limited genes Sex-limited genes Sex-limited genes are genes which are present in both sexes of sexually reproducing species but turned on in only one sex. In other words, sex-limited genes cause the two sexes to show different traits or phenotypes. An example of sex-limited genes are genes which instructs male elephant seal to... which exist in both male and female bodies, but remain turned off in females. The degree of sexual dimorphism is correlated with the harem size, which allows us to draw inferences about our immediate human ancestors: they were probably mildly polygynous. |
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| 12 | 95 mya | Xenarthra Xenarthra The superorder Xenarthra is a group of placental mammals , existent today only in the Americas and represented by anteaters, tree sloths, and armadillos. The origins of the order can be traced back as far as the Paleogene in South America... ns (Xenarthra) |
The Armadillo Armadillo Armadillos are New World placental mammals, known for having a leathery armor shell. Dasypodidae is the only surviving family in the order Cingulata, part of the superorder Xenarthra along with the anteaters and sloths. The word armadillo is Spanish for "little armored one"... 's Tale reminds us of the aye-aye Aye-aye The aye-aye is a lemur, a strepsirrhine primate native to Madagascar that combines rodent-like teeth and a special thin middle finger to fill the same ecological niche as a woodpecker... 's tale, except that instead of Madagascar Madagascar The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa... , the speciation Speciation Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages... hotbed is the continent of South America South America South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east... . This continent broke off from Gondwana Gondwana In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,... in Early Cretaceous Cretaceous The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the... period, then joined North America North America North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas... which broke off from Laurasia Laurasia In paleogeography, Laurasia was the northernmost of two supercontinents that formed part of the Pangaea supercontinent from approximately... . During its long period of isolation, South America was host to marsupial Marsupial Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central... s which flourished and took up all carnivorous Carnivore A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging... niches Ecological niche In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food... . The placental mammals Eutheria Eutheria is a group of mammals consisting of placental mammals plus all extinct mammals that are more closely related to living placentals than to living marsupials . They are distinguished from noneutherians by various features of the feet, ankles, jaws and teeth... (including armadillo) and now-extinct ungulate Meridiungulata Meridiungulata is an extinct clade with the rank of cohort or super-order, containing the South-American ungulates: Pyrotheria , Astrapotheria, Notoungulata and Litopterna... s evolved to fill the rest of the ecosystem. When South America joined North America during the Great American Interchange Great American Interchange The Great American Interchange was an important paleozoogeographic event in which land and freshwater fauna migrated from North America via Central America to South America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor and bridged the formerly separated continents... at 3 million years ago, animals and plants cross the Isthmus of Panama Isthmus of Panama The Isthmus of Panama, also historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country of Panama and the Panama Canal... in both directions, introducing new species to new land and driving some local species to extinction. Jaguar Jaguar The jaguar is a big cat, a feline in the Panthera genus, and is the only Panthera species found in the Americas. The jaguar is the third-largest feline after the tiger and the lion, and the largest in the Western Hemisphere. The jaguar's present range extends from Southern United States and Mexico... s and other carnivorous Carnivora The diverse order Carnivora |Latin]] carō "flesh", + vorāre "to devour") includes over 260 species of placental mammals. Its members are formally referred to as carnivorans, while the word "carnivore" can refer to any meat-eating animal... placental mammals were introduced to South America, while armadillos migrated to North America. |
| 13 | 105 mya | Afrotheres Afrotheria Afrotheria is a clade of mammals, the living members of which belong to groups from Africa or of African origin: golden moles, sengis , tenrecs, aardvarks, hyraxes, elephants and sea cows. The common ancestry of these animals was not recognized until the late 1990s... (Afrotheria) |
The pilgrimage party is joined by the last of the placental mammals Eutheria Eutheria is a group of mammals consisting of placental mammals plus all extinct mammals that are more closely related to living placentals than to living marsupials . They are distinguished from noneutherians by various features of the feet, ankles, jaws and teeth... : elephant Elephant Elephants are large land mammals in two extant genera of the family Elephantidae: Elephas and Loxodonta, with the third genus Mammuthus extinct... s, elephant shrew Elephant shrew Elephant shrews or jumping shrews are small insectivorous mammals native to Africa, belonging to the family Macroscelididae, in the order Macroscelidea... s, dugong Dugong The dugong is a large marine mammal which, together with the manatees, is one of four living species of the order Sirenia. It is the only living representative of the once-diverse family Dugongidae; its closest modern relative, Steller's sea cow , was hunted to extinction in the 18th century... s, manatee Manatee Manatees are large, fully aquatic, mostly herbivorous marine mammals sometimes known as sea cows... s, hyrax Hyrax A hyrax is any of four species of fairly small, thickset, herbivorous mammals in the order Hyracoidea. The rock hyrax Procavia capensis, the yellow-spotted rock hyrax Heterohyrax brucei, the western tree hyrax Dendrohyrax dorsalis, and the southern tree hyrax, Dendrohyrax arboreus live in Africa... es, aardvark Aardvark The aardvark is a medium-sized, burrowing, nocturnal mammal native to Africa... s, etc. They all hail from Africa, as hinted by the name of their clade Clade A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological... , Afrotheria Afrotheria Afrotheria is a clade of mammals, the living members of which belong to groups from Africa or of African origin: golden moles, sengis , tenrecs, aardvarks, hyraxes, elephants and sea cows. The common ancestry of these animals was not recognized until the late 1990s... . The concestor we greet at this point, as well as those we met earlier at rendezvous 12 and 11, all look like insectivorous Insectivore An insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures. An alternate term is entomophage, which also refers to the human practice of eating insects.... shrew Shrew A shrew or shrew mouse is a small molelike mammal classified in the order Soricomorpha. True shrews are also not to be confused with West Indies shrews, treeshrews, otter shrews, or elephant shrews, which belong to different families or orders.Although its external appearance is generally that of... s. |
| 14 | 140 mya | Marsupial Marsupial Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central... s (Metatheria) |
The entire band of placental mammals meet up with the other great group of mammals, the marsupial Marsupial Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central... s. Even though present-day marsupials are mostly found in Australia Australia Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area... and New Guinea New Guinea New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago... , they originally flourished and diversified for a period of time in South America South America South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east... . Evidence points to the migration of a single species of opossum Didelphimorphia Opossums make up the largest order of marsupials in the Western Hemisphere, including 103 or more species in 19 genera. They are also commonly called possums, though that term technically refers to Australian fauna of the suborder Phalangeriformes. The Virginia opossum was the first animal to be... -like marsupial from South America to Australia before 55 million years ago, when it was still possible to make the journey through Antarctica before Australia pulled Continental drift Continental drift is the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912... too far away from Gondwana Gondwana In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,... . Once settled in the isolated Australia, the founding Founder effect In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It was first fully outlined by Ernst Mayr in 1942, using existing theoretical work by those such as Sewall... marsupials quickly evolved into distinct species and, for the next 40 million years, took up the entire range of 'trades' previously occupied by dinosaur Dinosaur Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of... s, in the absence of any placental mammals. |
| The Marsupial Mole Marsupial mole Marsupial moles is a family of marsupials of the order Notoryctemorphia, consisting of only two extant species:* Notoryctes typhlops * Notoryctes caurinus ... 's Tale again highlights the wonders that convergent evolution Convergent evolution Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are... can create. Despite great evolutionary distance Genetic distance Genetic distance refers to the genetic divergence between species or between populations within a species. It is measured by a variety of parameters. Smaller genetic distances indicate a close genetic relationship whereas large genetic distances indicate a more distant genetic relationship... between marsupial moles in Australia and the golden mole Golden mole Golden moles are small, insectivorous burrowing mammals native to southern Africa. They form the family Chrysochloridae, and are taxonomically distinct from the true moles which they resemble due to convergence... s in Africa, they are remarkably similar in terms of phenotype Phenotype A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior... s, with the exception that the marsupial moles sport a pouch Pouch (marsupial) The pouch is a distinguishing feature of female marsupials ; the name marsupial is derived from the Latin marsupium, meaning "pouch". Marsupials give birth to a live but relatively undeveloped fetus called a joey. When the joey is born it crawls from inside the mother to the pouch... as all marsupials do. There are also marsupial mice (Dasyuridae Dasyuridae Dasyuridae is a family of marsupials native to Australia and New Guinea, including 61 species divided into 15 genera. Many are small and mouse-like, giving them the misnomer marsupial mice, but the group also includes the cat-sized quolls, as well as the Tasmanian Devil... ), marsupial flying squirrels (Sugar Glider Sugar Glider The sugar glider is a small gliding possum originating from the marsupial family.The sugar glider is native to eastern and northern mainland Australia and is also native to New Guinea and the Bismarck Archipelago.- Habitat :Sugar gliders can be found all throughout the northern and eastern parts of... ) and marsupial wolf (Thylacine Thylacine The thylacine or ,also ;binomial name: Thylacinus cynocephalus, Greek for "dog-headed pouched one") was the largest known carnivorous marsupial of modern times. It is commonly known as the Tasmanian tiger or the Tasmanian wolf... ), not to mention the equivalent of antelope Antelope Antelope is a term referring to many even-toed ungulate species indigenous to various regions in Africa and Eurasia. Antelopes comprise a miscellaneous group within the family Bovidae, encompassing those old-world species that are neither cattle, sheep, buffalo, bison, nor goats... s and gazelle Gazelle A gazelle is any of many antelope species in the genus Gazella, or formerly considered to belong to it. Six species are included in two genera, Eudorcas and Nanger, which were formerly considered subgenera... s, the kangaroo Kangaroo A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country... s and wallabies Wallaby A wallaby is any of about thirty species of macropod . It is an informal designation generally used for any macropod that is smaller than a kangaroo or wallaroo that has not been given some other name.-Overview:... which despite great differences in shape, cover the same range of diet and way of life as their African counterparts. |
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| 15 | 180 mya | Monotreme Monotreme Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals... s (Monotremata) |
The monotreme Monotreme Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals... s are the last of the mammals to join us, and we meet a concestor for the first time in the then-contiguous supercontinent of Pangea. The monotremes consititutes only a few genera: Platypus Platypus The platypus is a semi-aquatic mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young... , Short-beaked Echidna Short-beaked Echidna The short-beaked echidna , also known as the spiny anteater because of its diet of ants and termites, is one of four living species of echidna and the only member of the genus Tachyglossus... and Long-beaked echidna Long-beaked echidna The long-beaked echidnas make up one of the two genera of echidnas, spiny monotremes that lives in New Guinea. There are three living species and two extinct species in this genus... . They are mammals and have typical mammalian features such as warm-blooded Warm-blooded The term warm-blooded is a colloquial term to describe animal species which have a relatively higher blood temperature, and maintain thermal homeostasis primarily through internal metabolic processes... ness, hair Hair Hair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class.... and milk Milk Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to the baby and can reduce the risk of many... production. But they resemble reptile Reptile Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors... s and bird Bird Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from... s in their possession of the cloaca Cloaca In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species... and their egg Egg (biology) An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing... -laying mode of reproduction. |
| The Duckbill Platypus The platypus is a semi-aquatic mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young... 's Tale warns us about the fallacy of labeling a half-mammal and half-reptile animal such as the duckbill platypus as primitive Primitive (biology) Primitive in the sense most relevant to phylogenetics means resembling the first living things and in particular resembling them in the simple nature of their anatomy and behaviour... . The platypus has exactly the same time to evolve as the rest of mammals, even if it does resemble our concestor 15 on the surface. In fact, it has evolved a highly developed form of electroreception Electroreception Electroreception is the biological ability to perceive natural electrical stimuli. It has been observed only in aquatic or amphibious animals, since water is a much better conductor than air. Electroreception is used in electrolocation and for electrocommunication.- Overview :Electroreception is... served by 40,000 electric sensors, and 60,000 mechanical push rods Mechanoreceptor A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. There are four main types in the glabrous skin of humans: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and Ruffini corpuscles... , both on its large bill to aid it in search of crustacean Crustacean Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span... s in the mud. In human, the brain dedicates disproportionally large amount of cells to the two hands as illustrated by the Penfield brain map, or Penfield homunculus Cortical homunculus A cortical homunculus is a pictorial representation of the anatomical divisions of the primary motor cortex and the primary somatosensory cortex , i.e., the portion of the human brain directly responsible for the movement and exchange of sense and motor information of the rest of the body.There... . When the same somatotopic map is drawn for platypus brain, the bill is served by equally prominent percentage of the brain. |
Non-mammal chordates
| rendezvous point | Time | Joining party | Story |
|---|---|---|---|
| 16 | 310 mya | Sauropsids (Sauropsida) | The pilgrims are about to join their reptile Reptile Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors... cousins, after marching for 130 million unbroken years from the last mammal concestor 15 who looks like a shrew Shrew A shrew or shrew mouse is a small molelike mammal classified in the order Soricomorpha. True shrews are also not to be confused with West Indies shrews, treeshrews, otter shrews, or elephant shrews, which belong to different families or orders.Although its external appearance is generally that of... to the reptile concestor 16 who looks like a lizard Lizard Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains... . In these 130 million years, mammal-like reptiles flourished, even before dinosaur Dinosaur Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of... s roamed the Earth. But like the 99 percent of all species that ever existed, all branches of mammal-like reptiles are now extinct, so they cannot join us in our pilgrimage. |
| The term reptile Reptile Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors... is not a true clade Clade A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological... name, as it fails to include bird Bird Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from... s which share a common ancestry. The terms reptile and fish are known as grades Paraphyly A group of taxa is said to be paraphyletic if the group consists of all the descendants of a hypothetical closest common ancestor minus one or more monophyletic groups of descendants... which only make sense scientifically when used in the now-discredited theory of progressive evolution (Orthogenesis). Progressive evolution proposes that species evolve independently, in a parallel, progressive direction from fish grade through amphibian grade via reptile grade towards mammal grade. From a cladistic Cladistics Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade... point of view, turtle Turtle Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield... s, lizard Lizard Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains... s, snake Snake Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales... s, crocodile Crocodile A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e... s, dinosaur Dinosaur Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of... s and bird Bird Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from... s are all members of the clade Sauropsids which is what Dawkins adapts instead of the term reptile. Dinosaurs, unfortunately as extinct species, cannot join us. But their only surviving descendants, the birds, take their place in the pilgrimage. |
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| The Galapagos Finch Darwin's finches Darwin's finches are a group of 14 or 15 species of passerine birds. It is still not clear which bird family they belong to, but they are not related to the true finches. They were first collected by Charles Darwin on the Galápagos Islands during the second voyage of the Beagle... 's Tale addresses a surprising question: why does not evolution go much faster than it does? Studies on Galapagos finches show that the Medium Ground-finch Medium Ground-finch The Medium Ground Finch is a species of bird in the Emberizidae family. It is endemic to the Galapagos Islands. Its natural habitats are subtropical or tropical dry forests and subtropical or tropical dry shrubland... (Geospiza fortis) could grow to be as large as the Large Ground-finch Large Ground-finch The Large Ground Finch is a species of bird. One of Darwin's finches, it is now placed in the family Thraupidae and was formerly in the Emberizidae. It is endemic to the Galapagos Islands, and is found in the arid zone of most of the archipelago, though it is absent from the southeastern islands... (Geospiza magnirostris), if 23 consecutive drought Drought A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region... years put pressure on birds to grow larger beak Beak The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young... s to better handle bigger and tougher seeds. But such extreme evolutionary speed is not observed in nature, given the geological time Geologic time scale The geologic time scale provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth... life has had on Earth. This is mostly because the rate of evolution follows major trends over geological timescale, while short-term pressures tend to cancel out one another. |
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| The Peacock Peafowl Peafowl are two Asiatic species of flying birds in the genus Pavo of the pheasant family, Phasianidae, best known for the male's extravagant eye-spotted tail, which it displays as part of courtship. The male is called a peacock, the female a peahen, and the offspring peachicks. The adult female... 's Tale is the quintessential illustration of sexual selection Sexual selection Sexual selection, a concept introduced by Charles Darwin in his 1859 book On the Origin of Species, is a significant element of his theory of natural selection... ; the peacock's tail is the ultimate example of non-utilitarian phenotype which appears to be an anomaly in natural selection Natural selection Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution.... , as it is a hindrance to peacock's survival Survival of the fittest "Survival of the fittest" is a phrase originating in evolutionary theory, as an alternative description of Natural selection. The phrase is today commonly used in contexts that are incompatible with the original meaning as intended by its first two proponents: British polymath philosopher Herbert... in its natural habitat. These arbitrary spurts of evolution can be explained by sexual selection, a special case of natural selection. The runaway explosion Chain reaction A chain reaction is a sequence of reactions where a reactive product or by-product causes additional reactions to take place. In a chain reaction, positive feedback leads to a self-amplifying chain of events.... of the extravagant tail is created by lockstep dimorphic selections Sexual dimorphism Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:... of male's genes for pretty tails and of female's genes for preferring such tails. The preference for pretty tails, in turns, is rooted in their use by males as tokens of underlying fitness Fitness (biology) Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment... ; an advertisement of health Health Health is the level of functional or metabolic efficiency of a living being. In humans, it is the general condition of a person's mind, body and spirit, usually meaning to be free from illness, injury or pain... . Sexual selection often complements other natural selection forces, and helps explain why human Human Humans are the only living species in the Homo genus... became bipedal to free the two hands for tool Tool A tool is a device that can be used to produce an item or achieve a task, but that is not consumed in the process. Informally the word is also used to describe a procedure or process with a specific purpose. Tools that are used in particular fields or activities may have different designations such... making and wielding, attained a larger brain Human brain The human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion... with artistic abilities Hominid intelligence The evolution of human intelligence refers to a set of theories that attempt to explain how human intelligence has evolved. These theories are closely tied to the evolution of the human brain and to the emergence of human language.... , and shed body hair Hair Hair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class.... to advertise lack of ectoparasites Parasitism Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites... during the course of human evolution Human evolution Human evolution refers to the evolutionary history of the genus Homo, including the emergence of Homo sapiens as a distinct species and as a unique category of hominids and mammals... . |
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| The Dodo Dodo The dodo was a flightless bird endemic to the Indian Ocean island of Mauritius. Related to pigeons and doves, it stood about a meter tall, weighing about , living on fruit, and nesting on the ground.... 's Tale illustrates how evolution optimizes genes for the present environment, how it has no foresight, and how it marches blindly The Blind Watchmaker The Blind Watchmaker: Why the Evidence of Evolution Reveals a Universe without Design is a 1986 book by Richard Dawkins in which he presents an explanation of, and argument for, the theory of evolution by means of natural selection. He also presents arguments to refute certain criticisms made on... sometimes to the detriment of the species. The dodo, originally a flying Bird flight Flight is the main mode of locomotion used by most of the world's bird species. Flight assists birds while feeding, breeding and avoiding predators.... pigeon related to the Rodrigues Solitaire Rodrigues Solitaire The Rodrigues Solitaire was a flightless member of the pigeon order endemic to Rodrigues, Mauritius. It was a close relative of the Dodo.-Discovery:... , reached the remote island of Mauritius Mauritius Mauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar... and shed its flying powers due to the lack of competition and natural predator Predation In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption... s to become a Flightless bird Flightless bird Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin... . The reallocation of resources away from building of massive breast muscle Muscle Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to... s for flying allowed the dodo to flourish, but ultimately lead to their extinction when European sailors and their carnivorous pets finally arrived. |
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| The Elephant Bird Elephant bird Elephant birds are an extinct family of flightless birds found only on the island of Madagascar and comprising the genera Aepyornis and Mullerornis.-Description:... 's Tale demonstrates how enigmatic distributions of genetically close Genetic distance Genetic distance refers to the genetic divergence between species or between populations within a species. It is measured by a variety of parameters. Smaller genetic distances indicate a close genetic relationship whereas large genetic distances indicate a more distant genetic relationship... species in completely separate continents can be explained and corroborated by evidences of continental drift Continental drift Continental drift is the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912... and seafloor spreading Seafloor spreading Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. Seafloor spreading helps explain continental drift in the theory of plate tectonics.... . The tale recounts the diaspora of a large group of flightless Flightless bird Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin... ratite birds Ratite A ratite is any of a diverse group of large, flightless birds of Gondwanan origin, most of them now extinct. Unlike other flightless birds, the ratites have no keel on their sternum—hence the name from the Latin ratis... from the then unbroken Gondwana Gondwana In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,... ; Moa Moa The moa were eleven species of flightless birds endemic to New Zealand. The two largest species, Dinornis robustus and Dinornis novaezelandiae, reached about in height with neck outstretched, and weighed about .... ended up in New Zealand New Zealand New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga... , rhea Rhea (bird) The rheas are ratites in the genus Rhea, native to South America. There are two existing species: the Greater or American Rhea and the Lesser or Darwin's Rhea. The genus name was given in 1752 by Paul Möhring and adopted as the English common name. Möhring's reason for choosing this name, from the... in South America South America South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east... , emu Emu The Emu Dromaius novaehollandiae) is the largest bird native to Australia and the only extant member of the genus Dromaius. It is the second-largest extant bird in the world by height, after its ratite relative, the ostrich. There are three subspecies of Emus in Australia... in Australia Australia Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area... , cassowary Cassowary The cassowaries are ratites, very large flightless birds in the genus Casuarius native to the tropical forests of New Guinea, nearby islands and northeastern Australia. There are three extant species recognized today... in New Guinea New Guinea New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago... , kiwi Kiwi Kiwi are flightless birds endemic to New Zealand, in the genus Apteryx and family Apterygidae.At around the size of a domestic chicken, kiwi are by far the smallest living ratites and lay the largest egg in relation to their body size of any species of bird in the world... in New Zealand New Zealand New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga... by island hopping Island hopping Island hopping is a term that refers to the means of crossing an ocean by a series of shorter journeys between islands, as opposed to a single journey directly across the ocean to the destination.- Forms :... , and ostrich Ostrich The Ostrich is one or two species of large flightless birds native to Africa, the only living member of the genus Struthio. Some analyses indicate that the Somali Ostrich may be better considered a full species apart from the Common Ostrich, but most taxonomists consider it to be a... in Africa Africa Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area... by way of Asia and Europe. Radioactive dating Radiometric dating Radiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates... of and magnetic striping studies on continuously formed crust Crust (geology) In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle... around rift Rift In geology, a rift or chasm is a place where the Earth's crust and lithosphere are being pulled apart and is an example of extensional tectonics.... s such as the Mid-Atlantic Ridge Mid-Atlantic Ridge The Mid-Atlantic Ridge is a mid-ocean ridge, a divergent tectonic plate boundary located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. It separates the Eurasian Plate and North American Plate in the North Atlantic, and the African Plate from the South... allow Paleobiogeographers Biogeography Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area... to piece back a coherent story of these birds' dispersion based on both phylogenetic tree Phylogenetic tree A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics... and plate tectonics Plate tectonics Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere... . |
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| 17 | 340 mya | Amphibian Amphibian Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods... s (Amphibia) |
Mammals and reptiles (the amniote Amniote The amniotes are a group of tetrapods that have a terrestrially adapted egg. They include synapsids and sauropsids , as well as their fossil ancestors. Amniote embryos, whether laid as eggs or carried by the female, are protected and aided by several extensive membranes... s) join the amphibian Amphibian Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods... s to meet the ancestor of all land vertebrates with four feet, the tetrapod Tetrapod Tetrapods are vertebrate animals having four limbs. Amphibians, reptiles, birds and mammals are all tetrapods; even snakes and other limbless reptiles and amphibians are tetrapods by descent. The earliest tetrapods evolved from the lobe-finned fishes in the Devonian... . Amphibians include frog Frog Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail... s, toad Toad A toad is any of a number of species of amphibians in the order Anura characterized by dry, leathery skin , short legs, and snoat-like parotoid glands... s, salamander Salamander Salamander is a common name of approximately 500 species of amphibians. They are typically characterized by a superficially lizard-like appearance, with their slender bodies, short noses, and long tails. All known fossils and extinct species fall under the order Caudata, while sometimes the extant... s, newt Newt A newt is an aquatic amphibian of the family Salamandridae, although not all aquatic salamanders are considered newts. Newts are classified in the subfamily Pleurodelinae of the family Salamandridae, and are found in North America, Europe and Asia... s and caecilian Caecilian The caecilians are an order of amphibians that superficially resemble earthworms or snakes. They mostly live hidden in the ground, making them the least familiar order of amphibians. All extant caecilians and their closest fossil relatives are grouped as the clade Apoda. They are mostly... s. While amniotes either give live birth Live birth In human reproduction, a live birth occurs when a fetus, whatever its gestational age, exits the maternal body and subsequently shows any sign of life, such as voluntary movement, heartbeat, or pulsation of the umbilical cord, for however brief a time and regardless of whether the umbilical cord or... s or lay waterproof eggs, the amphibians retain the ancestral practice of laying eggs in water. Unlike the waterproof skin of amniotes, the amphibian skin allows body water to evaporate through it, restricting amphibians to land areas with access to fresh water Fresh Water Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve... . |
| The Salamander Salamander Salamander is a common name of approximately 500 species of amphibians. They are typically characterized by a superficially lizard-like appearance, with their slender bodies, short noses, and long tails. All known fossils and extinct species fall under the order Caudata, while sometimes the extant... 's Tale uses examples of ring species Ring species In biology, a ring species is a connected series of neighboring populations, each of which can interbreed with closely sited related populations, but for which there exist at least two "end" populations in the series, which are too distantly related to interbreed, though there is a potential gene... to illustrate how a continuous series of interbreeding animals in the spatial Space Space is the boundless, three-dimensional extent in which objects and events occur and have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum... dimension is conceptually equivalent to that in the time Time Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects.... dimension. The Ensatina Ensatina Ensatina eschscholtzii is a complex of plethodontid salamanders found in coniferous forests, oak woodland and chaparral from British Columbia, through Washington, Oregon, across California , all the way down to Baja California in Mexico.-As a ring species:The... salamanders in the Central Valley in California California California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area... form a continuous ring (actually a horseshoe Horseshoe A horseshoe, is a fabricated product, normally made of metal, although sometimes made partially or wholly of modern synthetic materials, designed to protect a horse's hoof from wear and tear. Shoes are attached on the palmar surface of the hooves, usually nailed through the insensitive hoof wall... shape) around the valley. Any two neighboring population of Ensatina around the horseshoe can interbreed, but the plain Ensatina eschscholtzii on the western end of the horseshoe cannot interbreed with the large blotched Ensatina klauberi on the eastern end. Larus Larus Larus is a large genus of gulls with worldwide distribution . Many of its species are abundant and well-known birds in their ranges... gulls form another ring species which starts at Herring Gull in Great Britain Great Britain Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles... and ends at Lesser Black-backed Gull Lesser Black-backed Gull The Lesser Black-backed Gull is a large gull that breeds on the Atlantic coasts of Europe. It is migratory, wintering from the British Isles south to West Africa... in north-western Europe Europe Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting... . Dawkins likens both ring species in space to the ring in time that unites human Human Humans are the only living species in the Homo genus... s and chimpanzee Chimpanzee Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:... s via generations of ancestors over 6 million years, with concestor 1 in the midpoint. |
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| The Narrowmouth's Tale shows how speciation Speciation Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages... may still continue via parapatric speciation Parapatric speciation Parapatry is a term from biogeography, referring to organisms whose ranges do not significantly overlap but are immediately adjacent to each other; they only occur together in the narrow contact zone, if at all. This geographical distribution is opposed to sympatry & allopatry or peripatry... , when two closely related toad species meet again after initial geographical isolation. Gastrophryne olivacea Gastrophryne olivacea The Great Plains Narrowmouth Toad is a species of microhylid frog. They are found throughout much of the south central United States from the state of Nebraska south through Texas, and into northern Mexico... (Great Plains narrowmouth toad) and Gastrophryne carolinensis Gastrophryne carolinensis The Eastern Narrowmouth Toad is a species of microhylid frog. It is a relatively small, toad-like amphibian found in damp, shady habitats. The species is highly fossorial, and feeds primarily on ants... (Eastern narrowmouth toad) are closely related and can interbreed when their habitats overlap. But reinforcement, a selection process which increases reproductive isolation Reproductive isolation The mechanisms of reproductive isolation or hybridization barriers are a collection of mechanisms, behaviors and physiological processes that prevent the members of two different species that cross or mate from producing offspring, or which ensure that any offspring that may be produced is not... via character displacement Character displacement Character displacement refers to the phenomenon where differences among similar species whose distributions overlap geographically are accentuated in regions where the species co-occur but are minimized or lost where the species’ distributions do not overlap. This pattern results from evolutionary... , causes both species to differentiate their mating calls from each other by shifting pitch and duration in opposite directions; the more the two populations overlap, the more distinct their mating calls become. |
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| The Axolotl Axolotl The axolotl , Ambystoma mexicanum, is a neotenic salamander, closely related to the Tiger Salamander. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled. It is also called ajolote... 's Tale is about metamorphosis Metamorphosis Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation... , a biological process Biological process A biological process is a process of a living organism. Biological processes are made up of any number of chemical reactions or other events that results in a transformation.... which turns juveniles Juvenile (organism) A juvenile is an individual organism that has not yet reached its adult form, sexual maturity or size. Juveniles sometimes look very different from the adult form, particularly in terms of their colour... or larva Larva A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle... e into drastically dissimilar adult Adult An adult is a human being or living organism that is of relatively mature age, typically associated with sexual maturity and the attainment of reproductive age.... forms for reproduction, and about pedomorphosis, another process which enables juveniles of some species to become sexually-mature Sexual maturity Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct... without ever developing into their usual adult forms. Species which undergo metamorphosis include butterflies, barnacle Barnacle A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile suspension feeders, and have... s and salamander Salamander Salamander is a common name of approximately 500 species of amphibians. They are typically characterized by a superficially lizard-like appearance, with their slender bodies, short noses, and long tails. All known fossils and extinct species fall under the order Caudata, while sometimes the extant... s. Species which exhibit neoteny Neoteny Neoteny , also called juvenilization , is one of the two ways by which paedomorphism can arise. Paedomorphism is the retention by adults of traits previously seen only in juveniles, and is a subject studied in the field of developmental biology. In neoteny, the physiological development of an... , a type of pedomorphosis, include human Human Humans are the only living species in the Homo genus... , ostrich Ostrich The Ostrich is one or two species of large flightless birds native to Africa, the only living member of the genus Struthio. Some analyses indicate that the Somali Ostrich may be better considered a full species apart from the Common Ostrich, but most taxonomists consider it to be a... , pekingese Pekingese The Pekingese, or "Peke" is an ancient breed of toy dog, originating in China. The breed was favored by the Chinese Imperial court, and its name refers to the city of Beijing where the Forbidden City resides... and axolotl Axolotl The axolotl , Ambystoma mexicanum, is a neotenic salamander, closely related to the Tiger Salamander. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled. It is also called ajolote... . A text book example of neoteny, the axolotl Axolotl The axolotl , Ambystoma mexicanum, is a neotenic salamander, closely related to the Tiger Salamander. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled. It is also called ajolote... s are members of the Tiger Salamander Tiger Salamander The Tiger Salamander is a species of Mole Salamander. The proper common name is the Eastern Tiger Salamander, to differentiate from other closely related species.-Description:... complex, yet they become sexually-mature in larva form, remaining aquatic and gilled External gills External gills are the gills of an animal, most typically an amphibian, that are exposed to the environment, rather than set inside the pharynx and covered by gill slits, as they are in most fishes. Instead, the respiratory organs are set on a frill of stalks protruding from the sides of an animals... . With a treatment of thyroxine Thyroxine Thyroxine, or 3,5,3',5'-tetraiodothyronine , a form of thyroid hormones, is the major hormone secreted by the follicular cells of the thyroid gland.-Synthesis and regulation:... , it is possible to induce an axolotl to develop into a salamander, demonstrating that axolotl genome still retains information on its lost adult form. On the other hand, newt Newt A newt is an aquatic amphibian of the family Salamandridae, although not all aquatic salamanders are considered newts. Newts are classified in the subfamily Pleurodelinae of the family Salamandridae, and are found in North America, Europe and Asia... , a type of salamander, first develops from tadpole Tadpole A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :... into land-based salamander, but later reverts back to its juvenile tadpole form, and returns to the water to reproduce. The axolotl's tale reminds us that paedomorphosis often allows species to break out of an evolutionary dead end by sudden changes. |
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| 18 | 417 mya | Lungfish Lungfish Lungfish are freshwater fish belonging to the Subclass Dipnoi. Lungfish are best known for retaining characteristics primitive within the Osteichthyes, including the ability to breathe air, and structures primitive within Sarcopterygii, including the presence of lobed fins with a well-developed... (Dipnoi) |
The Queensland lungfish Queensland Lungfish The Queensland lungfish, Neoceratodus forsteri is the sole surviving member of the family Ceratodontidae and order Ceratodontiformes. It is one of only six extant lungfish species in the world... (Australian lungfish) and Coelacanth Coelacanth Coelacanths are members of an order of fish that includes the oldest living lineage of Sarcopterygii known to date.... are two of the most famous living fossil Living fossil Living fossil is an informal term for any living species which appears similar to a species otherwise only known from fossils and which has no close living relatives, or a group of organisms which have long fossil records... s; they resemble ancient fossil Fossil Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past... s and unlike most species, seemingly refused to continue to evolve for the past 400 million years. The lungfish joins the pilgrimage to meet concestor 18, before the coelacanth joins at rendezvous point 19. Instead of looking like members from the pilgrimage, the lungfish actually resembles coelacanth and concestor 19, the lobe-finned fish Sarcopterygii Sarcopterygii The Sarcopterygii or lobe-finned fishes – sometimes considered synonymous with Crossopterygii constitute a clade of the bony fishes, though a strict classification would include the terrestrial vertebrates... . Despite their morphological Morphology (biology) In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features.... similarities, however, the lungfish and coelacanth are very different genetically Molecular genetics Molecular genetics is the field of biology and genetics that studies the structure and function of genes at a molecular level. The field studies how the genes are transferred from generation to generation. Molecular genetics employs the methods of genetics and molecular biology... , as expected of species which lived separately for more than 400 million years. Because genes do not stop evolving, the molecular DNA of these two species show greater evolutionary distance Genetic distance Genetic distance refers to the genetic divergence between species or between populations within a species. It is measured by a variety of parameters. Smaller genetic distances indicate a close genetic relationship whereas large genetic distances indicate a more distant genetic relationship... from each other than to DNA of the rest of the pilgrimage. The Lungfish's Tale reminds us that the rate of morphological changes is not always obviously correlated with that of genetic change. |
| 19 | 425 mya | Coelacanth Coelacanth Coelacanths are members of an order of fish that includes the oldest living lineage of Sarcopterygii known to date.... s (Latimeria) |
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| 20 | 440 mya | Ray-Finned Fish Actinopterygii The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize... (Actinopterygii) |
The current pilgrimage consisting of all descendants of lobe-finned fish Sarcopterygii The Sarcopterygii or lobe-finned fishes – sometimes considered synonymous with Crossopterygii constitute a clade of the bony fishes, though a strict classification would include the terrestrial vertebrates... is joined by the equally successful ray-finned fishes Actinopterygii The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize... which includes sturgeon Sturgeon Sturgeon is the common name used for some 26 species of fish in the family Acipenseridae, including the genera Acipenser, Huso, Scaphirhynchus and Pseudoscaphirhynchus. The term includes over 20 species commonly referred to as sturgeon and several closely related species that have distinct common... , paddlefish Paddlefish Paddlefish are primitive Chondrostean ray-finned fishes. The paddlefish can be distinguished by its large mouth and its elongated, spatula-like snout, called a rostrum, which is longer than the rest of the head... , eel Eel Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators... , herring Herring Herring is an oily fish of the genus Clupea, found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Three species of Clupea are recognized. The main taxa, the Atlantic herring and the Pacific herring may each be divided into subspecies... , carp Carp Carp are various species of oily freshwater fish of the family Cyprinidae, a very large group of fish native to Europe and Asia. The cypriniformes are traditionally grouped with the Characiformes, Siluriformes and Gymnotiformes to create the superorder Ostariophysi, since these groups have certain... , salmon Salmon Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true... , trout Trout Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water... , seahorse Seahorse Seahorses compose the fish genus Hippocampus within the family Syngnathidae, in order Syngnathiformes. Syngnathidae also includes the pipefishes. "Hippocampus" comes from the Ancient Greek hippos meaning "horse" and kampos meaning “sea monster”.There are nearly 50 species of seahorse... , cod Cod Cod is the common name for genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of... , etc. to meet concestor 19, the bony fish Osteichthyes Osteichthyes , also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species... . Of all ray-finned fishes, most belong to the large infraclass teleostei Teleostei Teleostei is one of three infraclasses in class Actinopterygii, the ray-finned fishes. This diverse group, which arose in the Triassic period, includes 20,000 extant species in about 40 orders; most living fishes are members of this group... . |
| Some teleost Teleostei Teleostei is one of three infraclasses in class Actinopterygii, the ray-finned fishes. This diverse group, which arose in the Triassic period, includes 20,000 extant species in about 40 orders; most living fishes are members of this group... fishes evolved unfishy shapes to cope with their chosen ecological niches. The leafy sea dragon Leafy sea dragon The leafy seadragon or Glauert's seadragon, Phycodurus eques, is a marine fish in the family Syngnathidae, which also includes the seahorses. It is the only member of the genus Phycodurus. It is found along the southern and western coasts of Australia. The name is derived from the appearance, with... , for instance, abandons the typical streamline fish shape which works so well for the majority of fishes. Instead, it adopts a leafy shape to hang motionless in kelp forest Kelp forest Kelp forests are underwater areas with a high density of kelp. They are recognized as one of the most productive and dynamic ecosystems on Earth. Smaller areas of anchored kelp are called kelp beds.... , pretending to be a piece of seaweed Seaweed Seaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae... . The razorfish Shrimpfish Shrimpfish, also called razorfish, are five small species of marine fish in the subfamily Centriscinae of the family Centriscidae... takes up an elongated, laterally compressed body, together with a long, flattened snout Snout The snout, or muzzle, is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw.-Terminology:The term "muzzle", used as a noun, can be ambiguous... . It swims in a head-down vertical stance, allowing it to hide amongst tall spines of a sea urchin Sea urchin Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull... . The snipe eel Snipe eel Snipe eels are a family, Nemichthyidae, of eels that consists of nine species in three genera. They are pelagic fishes, found in every ocean, mostly at depths of 300-600 m but sometimes as deep as 4000 m. Depending on the species, adults may reach 1-2 m in length, yet they weigh only 80-400 g... is ridiculously thin, while the gulper eel sports jaws which look disproportionally large for its body. Lastly, the ocean sunfish Ocean sunfish The ocean sunfish, Mola mola, or common mola, is the heaviest known bony fish in the world. It has an average adult weight of . The species is native to tropical and temperate waters around the globe. It resembles a fish head with a tail, and its main body is flattened laterally... resembles a huge, two-ton disc or millstone, as its Latin name, Mola mola, suggests. The Leafy Sea Dragon's Tale demonstrates how animal shapes are malleable, ever changing to meet the requirements of each animal's way of life. |
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| The Pike Esox Esox is a genus of freshwater fish, the only living genus in the family Esocidae — the esocids which were endemic to North America, Europe and Eurasia during the Paleogene through present.The type species is E. lucius, the northern pike... 's Tale highlights a special organ which gives teleost fishes superior buoyancy Buoyancy In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the... control, the swim bladder Gas bladder The swim bladder, gas bladder, fish maw or air bladder is an internal gas-filled organ that contributes to the ability of a fish to control its buoyancy, and thus to stay at the current water depth without having to waste energy in swimming... . Contrary to common assumptions, swim bladder is not a precursor to lung Lung The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart... s in human and other lobe-finned fishes. Instead, the bony fish ancestor possessed a primitive lung which was co-opted Exaptation Exaptation, cooption, and preadaptation are related terms referring to shifts in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another. Exaptations are common in both anatomy and behaviour... by teleost fishes for buoyancy control, and in some cases as ear drum for hearing Hearing (sense) Hearing is the ability to perceive sound by detecting vibrations through an organ such as the ear. It is one of the traditional five senses... . The teleost fishes rely on gill Gill A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist... s for breathing underwater. They repurposed the primitive lung, turning its ability to absorb from and release gas into the blood Blood Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells.... stream into a volume-changing mechanism, thus allowing teleost fishes to move vertically in a water column without the use of fins. |
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| The Mudskipper Mudskipper Mudskippers are members of the subfamily Oxudercinae , within the family Gobiidae . They are completely amphibious fish, fish that can use their pectoral fins to walk on land... 's Tale shows how animals rediscover long lost faculties and reenact ancient evolutionary events via completely different biological mechanisms. Having forgone air-breathing by repurposing the lung for buoyancy control, some teleost fishes, such as the Siamese fighting fish Siamese fighting fish The Siamese fighting fish , also known as the betta , is a popular species of freshwater aquarium fish. The name of the genus is derived from ikan bettah, taken from a local dialect of Malay... (Betta splendens), reinvent air-breathing by gulping air and locally oxygenerating Oxygenate Oxygenated chemical compounds contain oxygen as a part of their chemical structure. The term usually refers to oxygenated fuels. Oxygenates are usually employed as gasoline additives to reduce carbon monoxide that is created during the burning of the fuel.... water in the gill Gill A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist... chamber. The mudskipper Periophthalmus not only takes air into its moist gill chamber, but can also breathe through its skin. Both the gill chamber and the skin must be wet at all times, and this distinguishes the new type of air-breathing from breathing through lung Lung The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart... s. Re-equipped with air-breathing apparatus, the mudskipper emerges onto land, replaying ancient lobefin's conquest of the land. |
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| The rapid speciation of haplochromine Haplochromine The haplochromine cichlids are a tribe of cichlids in subfamily Pseudocrenilabrinae called Haplochromini. This group includes the type genus plus a number of closely related genera such as Aulonocara, Astatotilapia, and Chilotilapia. They are endemic to eastern and southern Africa... cichlid Cichlid Cichlids are fishes from the family Cichlidae in the order Perciformes. Cichlids are members of a group known as the Labroidei along with the wrasses , damselfish , and surfperches . This family is both large and diverse. At least 1,300 species have been scientifically described, making it one of... fishes endemic to Lake Victoria Lake Victoria Lake Victoria is one of the African Great Lakes. The lake was named for Queen Victoria of the United Kingdom, by John Hanning Speke, the first European to discover this lake.... , Lake Malawi Lake Malawi Lake Malawi , is an African Great Lake and the southernmost lake in the Great Rift Valley system of East Africa. This lake, the third largest in Africa and the eighth largest lake in the world, is located between Malawi, Mozambique, and Tanzania... and Lake Tanganyika Lake Tanganyika Lake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, after Lake Baikal in Siberia; it is also the world's longest freshwater lake... exemplifies adaptive radiation Adaptive radiation In evolutionary biology, adaptive radiation is the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage. Starting with a recent single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different... and species flock Species flock In evolutionary biology, a species flock is a diverse, primarily monophyletic, group of closely related species in an isolated area.A species flock may arise when a species penetrates a new geographical area and diversifies to occupy a variety of ecological niches; this process is known as... . The Cichlid's Tale recounts how, by constructing an "unrooted haplotype network" using phylogenetic analysis Computational phylogenetics Computational phylogenetics is the application of computational algorithms, methods and programs to phylogenetic analyses. The goal is to assemble a phylogenetic tree representing a hypothesis about the evolutionary ancestry of a set of genes, species, or other taxa... on mitochondrial DNA of living species from regional rivers and lakes, researchers were able to infer the time and the location of each major speciation event in the evolutionary history of these cichlids. The haplotype network differs from normal phylogenetic tree Phylogenetic tree A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics... in that each node represents a haplotype Haplotype A haplotype in genetics is a combination of alleles at adjacent locations on the chromosome that are transmitted together... , not a species, and the node size is determined by number of species in which the haplotype is found. By analyzing genetic relationships between haplotypes, relative prevalence of each haplotype, and locations where species currently live, it is possible to trace past waves of adaptive radiation originating from a small founding species, as rivers and lakes rose and fell in level. |
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| The Blind Cave Fish Mexican tetra The Mexican tetra or Blind Cave Fish is a freshwater fishof the characin family oforder Characiformes.... 's Tale illustrates how normal organs can degenerate into vestigial organs. Different populations of Mexican tetra Mexican tetra The Mexican tetra or Blind Cave Fish is a freshwater fishof the characin family oforder Characiformes.... (Astyanax mexicanus) have ventured into dark caves separately, and have separately evolved regressive traits such as white skin coloration and regressive or blind Blindness Blindness is the condition of lacking visual perception due to physiological or neurological factors.Various scales have been developed to describe the extent of vision loss and define blindness... eyes. This is partially explained by the opportunity cost Opportunity cost Opportunity cost is the cost of any activity measured in terms of the value of the best alternative that is not chosen . It is the sacrifice related to the second best choice available to someone, or group, who has picked among several mutually exclusive choices. The opportunity cost is also the... theory; resources wasted on building the eye in a pitch-black cave deprives the fish of other traits useful for such environment. But more importantly, without evolutionary pressure Evolutionary pressure Any cause that reduces reproductive success in a proportion of a population, potentially exerts evolutionary pressure or selection pressure. With sufficient pressure, inherited traits that mitigate its effects - even if they would be deleterious in other circumstances - can become widely spread... to weed out bad mutations on the multitude of genes which together build the eye, any random change is more likely to disrupt the dedicate process of building the eye than to enhance it. There is no need to revert precisely the sets of genes carefully shaped by millions of years of evolution to get back to a blind creature. In other words, there are many more random ways of building a blind fish than of building a sighted one. And this is the essence of the Dollo's Law Dollo's law Dollo's law of irreversibility is a hypothesis proposed in 1893 by French-born Belgian paleontologist Louis Dollo which states that evolution is not reversible... as Dawkins interprets it - that evolution cannot be precisely and exactly reversed. |
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| The Flounder Flounder The flounder is an ocean-dwelling flatfish species that is found in coastal lagoons and estuaries of the Northern Atlantic and Pacific Oceans.-Taxonomy:There are a number of geographical and taxonomical species to which flounder belong.*Western Atlantic... 's Tale is a tale of imperfection. The flounder's contorted head and eyes allow it to lie on its side on the ocean floor, but they betray the lack of an intelligent designer Intelligent designer An intelligent designer, also referred to as an intelligent agent, is the hypothetical willed and self-aware entity that the intelligent design movement argues had some role in the origin and/or development of life... . As expounded in The Blind Watchmaker The Blind Watchmaker The Blind Watchmaker: Why the Evidence of Evolution Reveals a Universe without Design is a 1986 book by Richard Dawkins in which he presents an explanation of, and argument for, the theory of evolution by means of natural selection. He also presents arguments to refute certain criticisms made on... and Climbing Mount Improbable Climbing Mount Improbable Climbing Mount Improbable is a 1996 popular science book by Richard Dawkins. The book is about probability and how it applies to the theory of evolution, and is specifically designed to debunk claims by creationists about the probability of naturalistic mechanisms like natural selection.The main... , evolution Evolution Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth... does not 'design' every creature anew on a drawing board. Instead, natural selection Natural selection Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution.... works without foresight and makes gradual improvements on existing body plans from generation to generation. Because each creature at every step of the process must remain fit Fitness (biology) Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment... for its environment, evolution cannot make sudden and drastic changes to build a better future organism at the expense of current generation. |
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| 21 | 460 mya | Shark Shark Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago.... s and Their Kin Chondrichthyes Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone... (Chondrichthyes) |
Cartilaginous fishes chondrichthyan including shark Shark Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago.... s, rays Batoidea Batoidea is a superorder of cartilaginous fish commonly known as rays and skates, containing more than 500 described species in thirteen families... and chimaera Chimaera Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, ratfish , spookfish , or rabbitfishes... s join the pilgrimage in the Middle Ordovician. The newcomers have no bones. Instead, they are supported by a cartilaginous skeleton that never ossifies Ossification Ossification is the process of laying down new bone material by cells called osteoblasts. It is synonymous with bone tissue formation... , in contrast to bony fishes. Their skin is covered in dermal denticles, tiny scale-like protrusions, from which teeth may have evolved. Interestingly, sharks lack a swim bladder for buoyancy, and instead rely on swimming constantly, retaining urea Urea Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group.... in their blood, and having large livers with plenty of oil to remain afloat. The Carcharocles megalodon from the Miocene Miocene The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene... is described as a predator more terrifying than the Great White Shark Great white shark The great white shark, scientific name Carcharodon carcharias, also known as the great white, white pointer, white shark, or white death, is a large lamniform shark found in coastal surface waters in all major oceans. It is known for its size, with the largest individuals known to have approached... , as it was three times the size. The strange Chimaera Chimaera Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, ratfish , spookfish , or rabbitfishes... has strange gill covers, has no dermal denticles, and swims using their pectoral fins. Dawkins explains that concestor 21 is ancestor to all gnathostomes, animals with lower jaws, a structure which evolved from the gill arches. |
| 22 | 530 mya | Lamprey Lamprey Lampreys are a family of jawless fish, whose adults are characterized by a toothed, funnel-like sucking mouth. Translated from an admixture of Latin and Greek, lamprey means stone lickers... s and Hagfish Hagfish Hagfish, the clade Myxini , are eel-shaped slime-producing marine animals . They are the only living animals that have a skull but not a vertebral column. Along with lampreys, hagfish are jawless and are living fossils whose next nearest relatives include all vertebrates... (Cyclostomata) |
Jawless and limbless fishes Agnatha Agnatha is a superclass of jawless fish in the phylum Chordata, subphylum Vertebrata. The group excludes all vertebrates with jaws, known as gnathostomes.... , the lamprey Lamprey Lampreys are a family of jawless fish, whose adults are characterized by a toothed, funnel-like sucking mouth. Translated from an admixture of Latin and Greek, lamprey means stone lickers... s and hagfish Hagfish Hagfish, the clade Myxini , are eel-shaped slime-producing marine animals . They are the only living animals that have a skull but not a vertebral column. Along with lampreys, hagfish are jawless and are living fossils whose next nearest relatives include all vertebrates... , join the pilgrimage to meet the concestor of all vertebrate Vertebrate Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds... s. The jawless fish and the concestor 22 are borderline vertebrates. Unlike the rest of vertebrates, they retain the notochord Notochord The notochord is a flexible, rod-shaped body found in embryos of all chordates. It is composed of cells derived from the mesoderm and defines the primitive axis of the embryo. In some chordates, it persists throughout life as the main axial support of the body, while in most vertebrates it becomes... , a stiffening cartilage rod running along the back of an animal, well into adulthood. In all other vertebrates, the vestigial notochord appears in the embryo briefly and is replaced by segmented, articulate backbones in adults. On the other hand, both the jawless fish and the jawed fish share characteristics common to all members of the phylum Chordata at some time in their life cycle, including the notochord Notochord The notochord is a flexible, rod-shaped body found in embryos of all chordates. It is composed of cells derived from the mesoderm and defines the primitive axis of the embryo. In some chordates, it persists throughout life as the main axial support of the body, while in most vertebrates it becomes... , pharyngeal slit Pharyngeal slit Pharyngeal slits are filter-feeding organs found in non-vertebrate chordates and hemichordates living in aquatic environments. These repeated segments are controlled by similar developmental mechanisms. Some hemichordate species can have as many as 200 gill slits... , and the post-anal tail Tail The tail is the section at the rear end of an animal's body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds... . |
| The Lamprey's Tale further develops the gene's eye view of ancestry and pedigree that earlier tales, The Eve's Tale and The Gibbon's Tale, alluded to. In human, four haemoglobin genes are known to be cousin genes of each other. An ancestor globin gene from an ancient vertebrate split Gene duplication Gene duplication is any duplication of a region of DNA that contains a gene; it may occur as an error in homologous recombination, a retrotransposition event, or duplication of an entire chromosome.The second copy of the gene is often free from selective pressure — that is, mutations of it have no... into two genes, alpha HBA1 Hemoglobin, alpha 1, also known as HBA1, is a human gene encoding the hemoglobin protein.-Interactions:Hemoglobin, alpha 1 has been shown to interact with HBB. Interactions between the N-terminal amino groups of the alpha-subunits and the C-terminal histidine of the β-subunits participate in ion... and beta HBB Beta globin Beta globin Beta globin (HBB, β-globinprotin that, along with alpha globin (HBA), makes up the most common form of hemoglobin in adult humans. The normal adult hemoglobin tetramer consists of two alpha chains and two beta chains.-Gene locus:... , which ended up in two different chromosomes and continued to evolve independently. Both alpha and beta further split into more independently evolving genes. All jawed fish show such alpha/beta split as predicated by evolution. However, lampreys and hagfish Hagfish Hagfish, the clade Myxini , are eel-shaped slime-producing marine animals . They are the only living animals that have a skull but not a vertebral column. Along with lampreys, hagfish are jawless and are living fossils whose next nearest relatives include all vertebrates... are ancient enough that they predate this gene split. In fact, jawless fishes, whenever investigated, do not possess split globin genes. As Dawkins explained in the chapter 'All Africa and her progenies' in his book River out of Eden River out of Eden River Out of Eden: A Darwinian View of Life is a 1995 popular science book by Richard Dawkins. The book is about Darwinian evolution and includes summaries of the topics covered in his earlier books, The Selfish Gene, The Extended Phenotype and The Blind Watchmaker. It is part of the Science... , there are two ways to trace ancestry: via animals and via individual genes. The two mechanisms produce very different results. Ancestry of animals form a family tree (more correctly, a graph Graph theory In mathematics and computer science, graph theory is the study of graphs, mathematical structures used to model pairwise relations between objects from a certain collection. A "graph" in this context refers to a collection of vertices or 'nodes' and a collection of edges that connect pairs of... because sexually reproducing Sexual reproduction Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the... animals may share female and male parents). On the other hand, Ancestry of an individual gene is always a single chain going back to the first self-replicating RNA RNA world hypothesis The RNA world hypothesis proposes that life based on ribonucleic acid pre-dates the current world of life based on deoxyribonucleic acid , RNA and proteins. RNA is able both to store genetic information, like DNA, and to catalyze chemical reactions, like an enzyme protein... , since a gene is either a faithful copy or a mutated form of its single parent gene. The Ancestor's Tale is written from an animal's perspective, following the family tree of human backward in time. But the book could have been written from the gene's point of view. Starting from any gene (e.g. the alpha haemoglobin), each gene gene duplication Gene duplication Gene duplication is any duplication of a region of DNA that contains a gene; it may occur as an error in homologous recombination, a retrotransposition event, or duplication of an entire chromosome.The second copy of the gene is often free from selective pressure — that is, mutations of it have no... event could become a rendezvous point where pilgrimage of genes join their cousin genes. |
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| 23 | 560 mya | Lancelet Lancelet The lancelets , also known as amphioxus, are the modern representatives of the subphylum Cephalochordata, formerly thought to be the sister group of the craniates. They are usually found buried in sand in shallow parts of temperate or tropical seas. In Asia, they are harvested commercially as food... s (Amphioxiformes) |
Lancelet Lancelet The lancelets , also known as amphioxus, are the modern representatives of the subphylum Cephalochordata, formerly thought to be the sister group of the craniates. They are usually found buried in sand in shallow parts of temperate or tropical seas. In Asia, they are harvested commercially as food... s are text book examples of a chordate. Equipped with a notochord, a nerve tube on the dorsal side and gill slits, they typify the phylum Chordata. But lancelets are not primitive Primitive (biology) Primitive in the sense most relevant to phylogenetics means resembling the first living things and in particular resembling them in the simple nature of their anatomy and behaviour... nor our remote ancestor. They are as modern as all other members in the pilgrimage. The Lancelet's Tale continues to develop the theme introduced in The Duckbill's Tale, that all living animals have had equal time to evolve since the first concestor, and that no living animal should be described as either lower or more primitive. Dawkins extends this concept to apply to fossil Fossil Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past... s as well. Even though it is tempting to label fossils as our remote ancestor, they are more accurately described as our distant cousins who have been frozen in time. |
| 24 | 565 mya | Sea Squirts Tunicate Tunicates, also known as urochordates, are members of the subphylum Tunicata, previously known as Urochordata, a group of underwater saclike filter feeders with incurrent and excurrent siphons that is classified within the phylum Chordata. While most tunicates live on the ocean floor, others such... (Urochordata) |
A Sea squirt resemble a sedentary bag of sea water anchored to a rock. It feeds on food particles strained from water. Anatomically, the sea squirt looks very different to the joining pilgrimage of all vertebrates and protochordates, that is, until its larvae are examined. The sea squirt larva Larva A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle... looks and swims like a tadpole. it possesses a notochord and a dorsal nerve tube, and moves by undulating its post-anal tail from side to side. Vertebrates may have branched off from ancient sea squirt larvae via neoteny Neoteny Neoteny , also called juvenilization , is one of the two ways by which paedomorphism can arise. Paedomorphism is the retention by adults of traits previously seen only in juveniles, and is a subject studied in the field of developmental biology. In neoteny, the physiological development of an... , in a process reminiscent of The Axolotl's Tale. But recent DNA analysis on larvacea Larvacea Larvaceans are solitary, free-swimming tunicates found throughout the world's oceans. Like most tunicates, appendicularians are filter feeders. Unlike other tunicates, appendicularians live in the pelagic zone, specifically in the upper sunlit portion of the ocean or sometimes deeper... favors Darwin's initial interpretation, that one branch of ancient tadpole-like protochordates evolved a new metamorphosis Metamorphosis Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation... stage to turn into sedentary sea squirts. |
Non-chordate animals
Note: From the lancelets onward, Dawkins only provides dates under duress stating that, "dating becomes so difficult and controversial that my courage fails me".| rendezvous point | Time | Joining party | Story |
|---|---|---|---|
| 25 | 570 mya | Ambulacraria Ambulacraria Ambulacraria is a clade of invertebrates which includes echinoderms, hemichordates, and Xenoturbellida; a member of this group is called an ambulacrarian... ns (Ambulacraria) |
This diverse group includes the echinoderm Echinoderm Echinoderms are a phylum of marine animals. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone.... s, along with some organisms labelled "worms" and even Xenoturbella Xenoturbella Xenoturbella is a genus of bilaterian animals; it contains two marine worm-like species. The first known species was discovered in 1915 by Sixten Bock but the first published description was only in 1949 by Einar Westblad... , which until recently could not be classified at all, but analysis of its genes finally established its position as a distant relative of the echinoderms. |
| 26 | 590 mya | Protostome Protostome Protostomia are a clade of animals. Together with the deuterostomes and a few smaller phyla, they make up the Bilateria, mostly comprising animals with bilateral symmetry and three germ layers... s (Protostomia) |
The current pilgrimage, known as deuterostomes, is joined by a much larger group of animals, the protostome Protostome Protostomia are a clade of animals. Together with the deuterostomes and a few smaller phyla, they make up the Bilateria, mostly comprising animals with bilateral symmetry and three germ layers... s, to meet the ancestor of almost all organisms in the kingdom Animalia, a worm. Just a single class in the joining sub-kingdom of protostomia, the Insect Insect Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae... a, represents three quarter of all animal species on Earth. The great divide between protostomes (meaning 'mouth first') and deuterostomes (meaning 'mouth second') was devised by comparative embryologist Embryology Embryology is a science which is about the development of an embryo from the fertilization of the ovum to the fetus stage... s based on the way animal embryos diverge after gastrulation Gastrulation Gastrulation is a phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a trilaminar structure known as the gastrula. These three germ layers are known as the ectoderm, mesoderm, and endoderm.Gastrulation takes place after cleavage... where the blastula Blastula The blastula is a hollow sphere of cells formed during an early stage of embryonic development in animals . The blastula is created when the zygote undergoes the cell division process known as cleavage. The blastula is preceded by the morula and is followed by the gastrula in the developmental... (a hollow ball of cells) indents to form a cup. In the sub-kingdom of protostomia, the indentation eventually becomes the mouth. In deuterostomia which includes humans, the indentation eventually becomes the anus; the mouth is formed later. An extremely large variety of animal phyla constitute protostomia, including annelid worms (e.g. garden earthworm Earthworm Earthworm is the common name for the largest members of Oligochaeta in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening posterior to the female pores, even though the internal male segments are anterior to the female... s), flatworm Flatworm The flatworms, known in scientific literature as Platyhelminthes or Plathelminthes are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrate animals... s (e.g. tapeworms and flukes Trematoda Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:... ), molluscs (e.g. snail Snail Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often... s, oyster Oyster The word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified.... s, ammonite Ammonite Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct... s and octopus Octopus The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms... es), and arthropod Arthropod An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others... s (e.g. insect Insect Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae... s, crustacean Crustacean Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span... s, spider Spider Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms... s and centipede Centipede Centipedes are arthropods belonging to the class Chilopoda of the subphylum Myriapoda. They are elongated metameric animals with one pair of legs per body segment. Despite the name, centipedes can have a varying number of legs from under 20 to over 300. Centipedes have an odd number of pairs of... s). Unlike the species Species In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are... , classes Class (biology) In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order... and genera Genus In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia... of animals from the pilgrimage prior to this rendezvous point, joining animals from different phyla Phylum In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division.... have no obvious relationship to one another based on traditional anatomy Anatomy Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy... . But modern molecular rangefinding has allowed molecular taxonomists to organize all phyla in the pilgrimage into a hierarchy, with the worm as the concestor of all animals in Bilateria Bilateria The bilateria are all animals having a bilateral symmetry, i.e. they have a front and a back end, as well as an upside and downside. Radially symmetrical animals like jellyfish have a topside and downside, but no front and back... who are bilaterally symmetrical, with left and right side, a dorsal and a ventral side, and a head and a tail end. |
| The Ragworm's Tale talks about the evolution of left-right symmetry in bilaterians. | |||
| The Brine Shrimp Brine shrimp Artemia is a genus of aquatic crustaceans known as brine shrimp. Artemia, the only genus in the family Artemiidae, has changed little externally since the Triassic period... 's Tale discusses the possibility of chordates having a back-swimming ancestor. |
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| The Leaf Cutter's Tale discusses town like ant societies Ant colony An ant colony is an underground lair where ants live, eat and mate. Colonies consist of a series of underground chambers, connected to each other and the surface of the earth by small tunnels. There are rooms for nurseries, food storage, and mating... and their agricultural use of fungi Ant-fungus mutualism Ant-fungus mutualism is a symbiosis seen in certain ant and fungal species, where ants actively cultivate fungus much like humans farm crops as a food source. In some species, the ants and fungi are dependent on each other for survival. The leafcutter ant is a well known example of this symbiosis... . |
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| The Grasshopper Grasshopper The grasshopper is an insect of the suborder Caelifera in the order Orthoptera. To distinguish it from bush crickets or katydids, it is sometimes referred to as the short-horned grasshopper... 's Tale talks about the futility of discriminating between races Racism Racism is the belief that inherent different traits in human racial groups justify discrimination. In the modern English language, the term "racism" is used predominantly as a pejorative epithet. It is applied especially to the practice or advocacy of racial discrimination of a pernicious nature... . |
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| The Fruit Fly Drosophila melanogaster Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W... 's Tale introduces Hox genes. |
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| The Rotifer Rotifer The rotifers make up a phylum of microscopic and near-microscopic pseudocoelomate animals. They were first described by Rev. John Harris in 1696, and other forms were described by Anton van Leeuwenhoek in 1703... 's Tale talks about the outstanding paradox of sexual Sexual reproduction Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the... and asexual Asexual reproduction Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without... reproduction. |
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| The Barnacle Barnacle A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile suspension feeders, and have... 's Tale talks about palaentology Paleontology Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments... and the deceptiveness of weird looking organisms. |
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| The Velvet Worm Velvet worm The velvet worms are a minor ecdysozoan phylum. These obscurely segmented organisms have tiny eyes, antennae, multiple pairs of legs and slime glands. They have variously been compared to worms with legs, caterpillars and slugs... 's Tale talks about the Cambrian explosion Cambrian explosion The Cambrian explosion or Cambrian radiation was the relatively rapid appearance, around , of most major phyla, as demonstrated in the fossil record, accompanied by major diversification of other organisms, including animals, phytoplankton, and calcimicrobes... . |
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| 27 | 630 mya | Acoelomorph Flatworms Acoelomorpha The Acoelomorpha are a disputed phylum of animals with planula-like features that were considered to belong to the phylum Platyhelminthes. In 2004 molecular studies demonstrated that they are a separate phylum, although their position in the tree of life is contentious; most researchers believe... (Acoelomorpha) |
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| 28 | 680 mya | Cnidaria Cnidaria Cnidaria is a phylum containing over 9,000 species of animals found exclusively in aquatic and mostly marine environments. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance,... ns (Cnidaria) |
The Jellyfish Jellyfish Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria... 's Tale |
| The Polypifer's Tale | |||
| 29 | 730 mya | Ctenophore Ctenophore The Ctenophora are a phylum of animals that live in marine waters worldwide. Their most distinctive feature is the "combs", groups of cilia that they use for swimming, and they are the largest animals that swim by means of cilia – adults of various species range from a few millimeters to in size... s (Ctenophora) |
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| 30 | 780 mya | Placozoans (Placozoa) | |
| 31 | 800 mya | Sponges (Porifera) | The Sponge's Tale |
Non-animal eukaryotes
| rendezvous point | Time | Joining party | Story |
|---|---|---|---|
| 32 | 900 mya | Choanoflagellate Choanoflagellate The choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals... s (Choanoflagellatea) |
The Choanoflagellate Choanoflagellate The choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals... 's Tale is about the evolution of multicellularity. Choanoflagellates are the closest living relatives of the multicellular animals, and can form temporary colonies from a free-living unicellular stage. Sponges have choanocytes, cells that resemble single-celled choanoflagellates, providing an indication about how multicellularity may have evolved. |
| 33 | (?) | DRIPs Mesomycetozoea The Mesomycetozoea are a small group of protists, mostly parasites of fish and other animals.-Significance:... (Mesomycetozoea) |
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| 34 | (?) | Fungi Fungus A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria... |
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| 35 | (?) | Amoebozoa Amoebozoa The Amoebozoa are a major group of amoeboid protozoa, including the majority that move by means ofinternal cytoplasmic flow. Their pseudopodia are characteristically blunt and finger-like,... ns (Amoebozoa) |
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| 36 | (?) | Plant Plant Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or... s Plantae |
The Cauliflower Cauliflower Cauliflower is one of several vegetables in the species Brassica oleracea, in the family Brassicaceae. It is an annual plant that reproduces by seed... 's Tale tells the story about how geometrical considerations of constructing the most efficient supply tube network in tissues dictate a scaling exponent of 3/4 for such different structures as a cauliflower and our brain. |
| The Redwood Cupressaceae The Cupressaceae or cypress family is a conifer family with worldwide distribution. The family includes 27 to 30 genera , which include the junipers and redwoods, with about 130-140 species in total. They are monoecious, subdioecious or dioecious trees and shrubs from 1-116 m tall... 's Tale introduces methods of dating historical artifacts and fossil Fossil Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past... s. |
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| 37 | (?) | Uncertain | The Mixotrich's Tale |
In what Dawkins calls the "Great Historic Rendezvous", he describes the significantly important event of endosymbiosis
Endosymbiotic theory
The endosymbiotic theory concerns the mitochondria, plastids , and possibly other organelles of eukaryotic cells. According to this theory, certain organelles originated as free-living bacteria that were taken inside another cell as endosymbionts...
, which results in the beginnings of eukaryotic cells. In his estimates, this occurred in two or three steps, roughly two billion years ago. Firstly, bacteria, perhaps related to Rickettsia
Rickettsia
Rickettsia is a genus of non-motile, Gram-negative, non-sporeforming, highly pleomorphic bacteria that can present as cocci , rods or thread-like . Being obligate intracellular parasites, the Rickettsia survival depends on entry, growth, and replication within the cytoplasm of eukaryotic host cells...
, entered proto-protozoan cells. For one reason or another, the bacteria were not digested and did not kill the cell. The cell offered protection to the bacteria, and the bacteria provided energy to the cell, resulting in a mutualistic symbiotic relationship
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
. This is the speculated origin of mitochondria
Mitochondrion
In cell biology, a mitochondrion is a membrane-enclosed organelle found in most eukaryotic cells. These organelles range from 0.5 to 1.0 micrometers in diameter...
. Subsequently, photosynthetic bacteria (thought to be related to cyanobacteria) entered some, but not all, of these mitochondria-containing cells. These ancient bacteria evolved to become chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
s, and the cells became the Plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
and Algal
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
lineages. Meanwhile, the cells which this second endosymbiotic relationship did not occur in went on to form the Kingdoms Fungi
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
and Animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
ia, as well as various Protozoa
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
.
Chloroplasts and mitochondria have their own genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
s, and they replicate independent of the cell in which they live. Dawkins acknowledges how the endosymbiotic theory proposed by Lynn Margulis
Lynn Margulis
Lynn Margulis was an American biologist and University Professor in the Department of Geosciences at the University of Massachusetts Amherst. She is best known for her theory on the origin of eukaryotic organelles, and her contributions to the endosymbiotic theory, which is now generally accepted...
is now virtually universally accepted.
Prokaryotes
| rendezvous point | Time | Joining party | Story |
|---|---|---|---|
| 38 | (?) | Archaea Archaea The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon... |
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| 39 | (?) | Eubacteria | The Rhizobium Rhizobia Rhizobia are soil bacteria that fix nitrogen after becoming established inside root nodules of legumes . Rhizobia require a plant host; they cannot independently fix nitrogen... s Tale |
| Taq Thermus aquaticus Thermus aquaticus is a species of bacterium that can tolerate high temperatures, one of several thermophilic bacteria that belong to the Deinococcus-Thermus group... 's Tale |
Editions
- (2004) US hardcover ISBN 0-618-00583-8
- (2004) UK hardcover ISBN 0297825038
- (2005) US paperback ISBN 061861916X
- (2005) UK paperback ISBN 0753819961
- (2005) UK Audio ISBN 0-7528-7321-0
Translations
- Czech translation: Příběh předka
- Dutch translation: Het verhaal van onze voorouders
- French translation: Il était une fois nos ancêtres
- German translation: Geschichten vom Ursprung des Lebens
- Hungarian translation: Az Ős meséje - Zarándoklat az élet hajnalához
- Italian translation: Il racconto dell'antenato
- Korean translation: 조상 이야기
- Portuguese translation: A grande história da evolução
- Spanish translation: El cuento del antepasado
- Turkish translation: Ataların hikâyesi
See also
- Evolutionary history of lifeEvolutionary history of lifeThe evolutionary history of life on Earth traces the processes by which living and fossil organisms have evolved since life on Earth first originated until the present day. Earth formed about 4.5 Ga and life appeared on its surface within one billion years...
- Phylogenetic treePhylogenetic treeA phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics...
- Timeline of evolutionTimeline of evolutionThis timeline of evolution of life outlines the major events in the development of life on planet Earth since it first originated until the present day. In biology, evolution is any change across successive generations in the heritable characteristics of biological populations...
- Timeline of human evolutionTimeline of human evolutionThe timeline of human evolution outlines the major events in the development of human species, and the evolution of humans' ancestors. It includes a brief explanation of some animals, species or genera, which are possible ancestors of Homo sapiens...