Homininae
Encyclopedia
Homininae is a subfamily of Hominidae
, which includes humans, gorilla
s and chimpanzee
s, and some extinct relatives; it comprises all those hominids, such as Australopithecus
, that arose after the split from orangutans (Ponginae
). Our family tree, which has 3 main branches leading to chimpanzees, humans and gorillas, could be more coherent than previously thought. Today there are several species of chimpanzee and gorillas (see Taxonomy) but only one human species remains, although several sub-species of humans appeared about a million years ago and still existed 30,000 years ago. The proposed evolutionary tree makes sense also when one considers brain size: there is a constant increase in brain volume along the human line, whereas the brain size remains almost unchanged in the chimpanzee and gorilla lines. Bipedalism seems to be an early acquisition in Homininae, which was present in early Australopithecines; it evolved independently into knuckle-walking
in both chimpanzees and gorillas, and into efficient walking and running in modern humans. Evolution of family structure and sexuality is more complex and cannot be followed by paleontological studies of fossils. However physical characteristics and sexual dimorphism can provide some clues.
The subfamily Homininae can be further subdivided into the tribes Gorillini (gorillas) and Hominini
(bonobo
s, chimpanzees and humans). The early Late Miocene
Nakalipithecus nakayamai
, described in 2007, and perhaps also its contemporary Ouranopithecus, are basal members of this clade
, not assignable to either the gorilla or the chimpanzee-humans lineage. They suggest that the Homininae tribes diverged not earlier than about 8 million years ago (see Human evolutionary genetics
). A hominin is a member of the tribe Hominini, a hominine is a member of the subfamily Homininae, a hominid is a member of the family Hominidae, and a hominoid is a member of the superfamily Hominoidea.
Today, chimpanzees and gorillas live in tropical forests with acid soils where bones are hardly preserved as fossils. It is considered that no fossil chimpanzees or gorillas have been reported. However, four chimpanzee teeth, about 500 ky old have recently been discovered in the rift valley, where many fossils from the human lineage (hominins) have previously been found. This discovery shows that, at the time, some chimpanzees lived close to Homo (H. erectus
or H. rhodesiensis). It is likely that the same could be true for gorillas. For an history of Australopithecines and Homo
fossils (see List of human evolution fossils).
are a family of robust Australopithecines that lived from –2.7 to –1.2 mya. They have many similarities with gorillas. Paranthropus have gorilla-like cranial crests: the sagittal crest
is running at the top of the skull, the very strong jaw muscles (Temporalis muscle) go all the way up to attach on both sides of this crest. Paranthropus also have characteristic wide cheek bones (zygomatic arch
es) projecting forward of the nasal opening and marks along the skull from strong chewing muscles. In addition, large postcanine dentition, thick enamel, and robust mandibles indicate a diet of hard or tough foods. Today Gorilla
s show a strong sexual dimorphism: males reach an height of 180 cm and a weight of more than 200 kg, twice that of females (140 cm, 100 kg). Sexual dimorphism in Paranthropus was not as strong as in today gorillas, but Paranthropus were taller and heavier than other Australopithecines living at the same time, hence their name: Robustus, and showed a more pronounced sexual dimorphism. Between 2.7 million and 1.2 million years ago Paranthropus shared the earth with some early examples of the genus Homo, such as H. habilis and H. ergaster. As far back as 2.7 Mya P. aethiopicus co-existed with A. africanus
and A. afarensis.
It is widely believed that the Paranthropus lineage died out, leaving no descendants. Although these many similarities between Paranthropus and gorillas were noted in the original papers describing Paranthropus discoveries, the logical conclusion that they could be gorilla ancestors was not proposed.
, the common ancestor of humans and chimpanzees had as many pre-human traits as chimpanzee-like traits. An australopithecine
4 million years old (such as Ardipithecus ramidus 4.4 mya) is close to the last common ancestor (5-6 mya); it is thus difficult to place in a precise chimpanzee or human lineage because the two diverged not long before. Some of the most recent Paranthropus fossils are 1 million years old, about one tenth the time since the purported time of divergence of humans and gorillas (7-9 mya). Many of the Paranthropus traits are very much like those of gorillas. In contrast, it is more difficult to place 3- or 4-million-year-old australopithecine
fossils in the chimp or human lineages. Most A. africanus
fossils seem to be in the human lineage, whereas those of A. afarensis are in the chimp lineage, probably with the exception of "Selam
" (3.3 mya), which has been placed in A. afarensis, but has more Homo traits than "Lucy
" (3.2 mya), for instance, and might better be placed in A. africanus
. According to Adrienne Zihlman, Bonobo body proportions closely resemble those of Australopithecus. The recent discovery of Australopithecus sediba
is remarkable. As shown on the figure (Prof. Lee R. Berger
) the body proportions of A. sediba are similar to those of "Lucy"; A. sediba could possibly be considered as a late form of A. afarensis.
Mainstream views on Australopithecines evolution can be found in the "human evolution
" page, but similar conclusions, suggesting Paranthropus as ancestors of gorilla, have been reached by at least two other biologists, independently: the author of the "Paranthropus aethiopicus" page of the "Online Biology Dictionary" and Richard Dawkins in his book "The Ancestor's Tale
". According to this theory, chimps and bonobos
are descended from Australopithecus
gracile type species while gorillas are descended from Paranthropus robustus
P. boisei or P. aethiopicus. These apes may have once been bipedal, but then lost this ability when they were forced back into an arboreal habitat, presumably by those australopithecines who eventually became us. In short, the ancestors of chimpanzees and gorillas are A. afarensis and Paranthropus
, respectively.
Subfamily Homininae
) as the ancestors of modern humans progressed along the timeline of human evolution
, starting from about 600 cm3 in Homo habilis
up to 1500 cm3 in Homo sapiens neanderthalensis, whereas the brain size along the chimpanzee and gorilla lines remained almost unchanged (see figure). Thus, in general there is a good correlation between brain volume and intelligence
. However, modern Homo sapiens have a brain volume slightly smaller (1250 cm3) than Neanderthals, women have a brain slightly smaller than men and the Flores hominids (Homo floresiensis
), nicknamed hobbits, had a cranial capacity of about 380 cm3 (considered small for a chimpanzee), about a third of the Homo erectus
average. It is proposed that they evolved from H. erectus as a case of insular dwarfism. In spite of their smaller brain, there is evidence that H. floresiensis used fire and made stone tools at least as sophisticated as those of their proposed ancestors H. erectus. In this case, it seems that for intelligence, the structure of the brain is more important than its size. "As large as you need and as small as you can" to summarize the opposite evolutionary constraints on human brain size.
and menopause
in women both also occur in a few other primates however, but are uncommon in other species. Having sex in private also distinguishes us from Bonobos, Chimpanzees and Gorillas. Testis and Penis size are related to family structure: monogamy
or promiscuity
, or harem
, in humans, chimpanzees or gorillas, respectively. The levels of sexual dimorphism
are generally seen as a marker of sexual selection
. Studies have suggested that the earliest homininae were dimorphic and that this lessened over the course of the evolution of the genus Homo, correlating with humans becoming more monogamous, whereas gorillas, who live in harems, show a large degree of sexual dimorphism (see Paranthropus
). Concealed (or "hidden") ovulation means that the phase of fertility is not detectable in women, whereas chimpanzees advertise ovulation via an obvious swelling of the genitals. Women can be partly aware of their ovulation along the menstrual phases, but men are essentially unable to detect ovulation in women. Most primates have semi-concealed ovulation, thus one can think that the common ancestor had semi-concealed ovulation, that was inherited by gorillas, and that later evolved in concealed ovulation in humans and advertised ovulation in chimpanzees. Menopause also occurs in rhesus monkeys, and possibly in chimpanzees, but does not in gorillas and is quite uncommon in other primates (and other mammal groups). Menopause contributes to an increased longevity
of women.
and early Paranthropus
may have been bipedal, but then lost this ability when they were forced back into an arboreal habitat, presumably by early Homo. Very early homininae such as Ardipithecus ramidus may have possessed an arboreal type of bipedalism that later independently evolved towards knuckle-walking
in chimpanzees and gorillas and towards efficient walking and running in modern humans (see figure). It is also proposed that one cause of Neanderthal extinction could have been a less efficient running than Cro-Magnon
.
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 ....
, which includes humans, 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 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, and some extinct relatives; it comprises all those hominids, such as Australopithecus
Australopithecus
Australopithecus is a genus of hominids that is now extinct. From the evidence gathered by palaeontologists and archaeologists, it appears that the Australopithecus genus evolved in eastern Africa around 4 million years ago before spreading throughout the continent and eventually becoming extinct...
, that arose after the split from orangutans (Ponginae
Ponginae
Ponginae is a subfamily in the hominidae family. It contains a number of genera, all but one extinct:*Pongo *†Gigantopithecus*†Sivapithecus*†Lufengpithecus*†Ankarapithecus*†Ouranopithecus*†Griphopithecus...
). Our family tree, which has 3 main branches leading to chimpanzees, humans and gorillas, could be more coherent than previously thought. Today there are several species of chimpanzee and gorillas (see Taxonomy) but only one human species remains, although several sub-species of humans appeared about a million years ago and still existed 30,000 years ago. The proposed evolutionary tree makes sense also when one considers brain size: there is a constant increase in brain volume along the human line, whereas the brain size remains almost unchanged in the chimpanzee and gorilla lines. Bipedalism seems to be an early acquisition in Homininae, which was present in early Australopithecines; it evolved independently into knuckle-walking
Knuckle-walking
Knuckle-walking is a form of quadrupedal walking in which the forelimbs hold the fingers in a partially flexed posture that allows body weight to press down on the ground through the knuckles....
in both chimpanzees and gorillas, and into efficient walking and running in modern humans. Evolution of family structure and sexuality is more complex and cannot be followed by paleontological studies of fossils. However physical characteristics and sexual dimorphism can provide some clues.
History of name and discoveries
Until 1980, the family Hominidae contained only humans, with the great apes in the family Pongidae. Discoveries led to a revision of classification, with the great apes (now Ponginae) and humans (Homininae) united in Hominidae. Further discoveries indicated that gorillas and chimpanzees are more closely related to humans than they are to orangutans, hence their current placement in Homininae.The subfamily Homininae can be further subdivided into the tribes Gorillini (gorillas) and Hominini
Hominini
Hominini is the tribe of Homininae that comprises Homo, and the two species of the genus Pan , their ancestors, and the extinct lineages of their common ancestor . Members of the tribe are called hominins...
(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, chimpanzees and humans). The early Late Miocene
Late Miocene
The Late Miocene is a sub-epoch of the Miocene Epoch made up of two stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch....
Nakalipithecus nakayamai
Nakalipithecus nakayamai
Nakalipithecus nakayamai is a prehistoric great ape species that lived in today's Kenya region early in the Late Miocene, 10 million years ago . It is the type species of the new genus Nakalipithecus...
, described in 2007, and perhaps also its contemporary Ouranopithecus, are basal members of this 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...
, not assignable to either the gorilla or the chimpanzee-humans lineage. They suggest that the Homininae tribes diverged not earlier than about 8 million years ago (see Human evolutionary genetics
Human evolutionary genetics
Human evolutionary genetics studies how one human genome differs from the other, the evolutionary past that gave rise to it, and its current effects. Differences between genomes have anthropological, medical and forensic implications and applications...
). A hominin is a member of the tribe Hominini, a hominine is a member of the subfamily Homininae, a hominid is a member of the family Hominidae, and a hominoid is a member of the superfamily Hominoidea.
Today, chimpanzees and gorillas live in tropical forests with acid soils where bones are hardly preserved as fossils. It is considered that no fossil chimpanzees or gorillas have been reported. However, four chimpanzee teeth, about 500 ky old have recently been discovered in the rift valley, where many fossils from the human lineage (hominins) have previously been found. This discovery shows that, at the time, some chimpanzees lived close to Homo (H. erectus
H. erectus
H. erectus may refer to:* Homo erectus, an extinct hominid species* Hippocampus erectus, a seahorse species from the Western Atlantic-See also:* H. erecta * Erectus...
or H. rhodesiensis). It is likely that the same could be true for gorillas. For an history of Australopithecines and Homo
Homo
Homo may refer to:*the Greek prefix ὅμο-, meaning "the same"*the Latin for man, human being*Homo, the taxonomical genus including modern humans...
fossils (see List of human evolution fossils).
Paranthropus and gorillas
ParanthropusParanthropus
The robust australopithecines, members of the extinct hominin genus Paranthropus , were bipedal hominids that probably descended from the gracile australopithecine hominids...
are a family of robust Australopithecines that lived from –2.7 to –1.2 mya. They have many similarities with gorillas. Paranthropus have gorilla-like cranial crests: the sagittal crest
Sagittal crest
A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull of many mammalian and reptilian skulls, among others....
is running at the top of the skull, the very strong jaw muscles (Temporalis muscle) go all the way up to attach on both sides of this crest. Paranthropus also have characteristic wide cheek bones (zygomatic arch
Zygomatic arch
The zygomatic arch or cheek bone is formed by the zygomatic process of temporal bone and the temporal process of the zygomatic bone , the two being united by an oblique suture; the tendon of the Temporalis passes medial to the arch to gain insertion into the coronoid process...
es) projecting forward of the nasal opening and marks along the skull from strong chewing muscles. In addition, large postcanine dentition, thick enamel, and robust mandibles indicate a diet of hard or tough foods. Today 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 show a strong sexual dimorphism: males reach an height of 180 cm and a weight of more than 200 kg, twice that of females (140 cm, 100 kg). Sexual dimorphism in Paranthropus was not as strong as in today gorillas, but Paranthropus were taller and heavier than other Australopithecines living at the same time, hence their name: Robustus, and showed a more pronounced sexual dimorphism. Between 2.7 million and 1.2 million years ago Paranthropus shared the earth with some early examples of the genus Homo, such as H. habilis and H. ergaster. As far back as 2.7 Mya P. aethiopicus co-existed with A. africanus
A. africanus
A. africanus is an abbreviation of a species name. In binomial nomenclature the name of a species is always the name of the genus to which the species belongs, followed by the species name . In A. africanus the genus name has been abbreviated to A. and the species has been spelled out in full...
and A. afarensis.
It is widely believed that the Paranthropus lineage died out, leaving no descendants. Although these many similarities between Paranthropus and gorillas were noted in the original papers describing Paranthropus discoveries, the logical conclusion that they could be gorilla ancestors was not proposed.
Evolution
It is commonly believed that the australopithecines are more closely related to humans than to African apes. This view is hardly compatible with the biomolecular data which place the Homo/Pan split at the beginning of the australopithecine period. Nothing in the fossil hominid morphology precludes the possibility that some australopithecines were ancestral to gorillas or chimpanzees and others to humans. Based on human evolutionary geneticsHuman evolutionary genetics
Human evolutionary genetics studies how one human genome differs from the other, the evolutionary past that gave rise to it, and its current effects. Differences between genomes have anthropological, medical and forensic implications and applications...
, the common ancestor of humans and chimpanzees had as many pre-human traits as chimpanzee-like traits. An australopithecine
Australopithecine
The term australopithecine refers generally to any species in the related genera Australopithecus or Paranthropus. These species occurred in the Plio-Pleistocene era, and were bipedal and dentally similar to humans, but with a brain size not much larger than modern apes, lacking the...
4 million years old (such as Ardipithecus ramidus 4.4 mya) is close to the last common ancestor (5-6 mya); it is thus difficult to place in a precise chimpanzee or human lineage because the two diverged not long before. Some of the most recent Paranthropus fossils are 1 million years old, about one tenth the time since the purported time of divergence of humans and gorillas (7-9 mya). Many of the Paranthropus traits are very much like those of gorillas. In contrast, it is more difficult to place 3- or 4-million-year-old australopithecine
Australopithecine
The term australopithecine refers generally to any species in the related genera Australopithecus or Paranthropus. These species occurred in the Plio-Pleistocene era, and were bipedal and dentally similar to humans, but with a brain size not much larger than modern apes, lacking the...
fossils in the chimp or human lineages. Most A. africanus
A. africanus
A. africanus is an abbreviation of a species name. In binomial nomenclature the name of a species is always the name of the genus to which the species belongs, followed by the species name . In A. africanus the genus name has been abbreviated to A. and the species has been spelled out in full...
fossils seem to be in the human lineage, whereas those of A. afarensis are in the chimp lineage, probably with the exception of "Selam
Selam (Australopithecus)
Selam is the fossilized skull and other skeletal remains of a 3-year-old Australopithecus afarensis female whose bones were first found in Dikika, Ethiopia in 2000 and recovered over the following years. She is often nicknamed Lucy's baby. The remains have been dated at 3.3 mya, approximately...
" (3.3 mya), which has been placed in A. afarensis, but has more Homo traits than "Lucy
Lucy (Australopithecus)
Lucy is the common name of AL 288-1, several hundred pieces of bone representing about 40% of the skeleton of an individual Australopithecus afarensis. The specimen was discovered in 1974 at Hadar in the Awash Valley of Ethiopia's Afar Depression. Lucy is estimated to have lived 3.2 million years...
" (3.2 mya), for instance, and might better be placed in A. africanus
A. africanus
A. africanus is an abbreviation of a species name. In binomial nomenclature the name of a species is always the name of the genus to which the species belongs, followed by the species name . In A. africanus the genus name has been abbreviated to A. and the species has been spelled out in full...
. According to Adrienne Zihlman, Bonobo body proportions closely resemble those of Australopithecus. The recent discovery of Australopithecus sediba
Australopithecus sediba
Australopithecus sediba is a species of Australopithecus of the early Pleistocene, identified based on fossil remains dated to about 2 million years ago....
is remarkable. As shown on the figure (Prof. Lee R. Berger
Lee R. Berger
Lee Rogers Berger is a paleoanthropologist, physical anthropologist and archeologist and is best known for his discovery of Australopithecus sediba and his work on Australopithecus africanus body proportions and the Taung Bird of Prey Hypothesis.-Background:Berger was born in Shawnee Mission,...
) the body proportions of A. sediba are similar to those of "Lucy"; A. sediba could possibly be considered as a late form of A. afarensis.
Mainstream views on Australopithecines evolution can be found in the "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...
" page, but similar conclusions, suggesting Paranthropus as ancestors of gorilla, have been reached by at least two other biologists, independently: the author of the "Paranthropus aethiopicus" page of the "Online Biology Dictionary" and Richard Dawkins in his book "The Ancestor's Tale
The Ancestor's Tale
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 humans backwards through evolutionary history, meeting humanity's cousins as they converge on common ancestors...
". According to this theory, chimps and bonobos
Bonobos
Bonobos is a dub band from Osaka, Japan. They formed in August of 2001. Their current lineup includes; Chunho Sai , Yasuyuki Sasaki , Natsuko Morimoto , Bondo Tsuji and Izumi Matsui...
are descended from Australopithecus
Australopithecus
Australopithecus is a genus of hominids that is now extinct. From the evidence gathered by palaeontologists and archaeologists, it appears that the Australopithecus genus evolved in eastern Africa around 4 million years ago before spreading throughout the continent and eventually becoming extinct...
gracile type species while gorillas are descended from Paranthropus robustus
Paranthropus robustus
Paranthropus robustus was originally discovered in Southern Africa in 1938. The development of P. robustus, namely in cranial features, seemed to be aimed in the direction of a "heavy-chewing complex"...
P. boisei or P. aethiopicus. These apes may have once been bipedal, but then lost this ability when they were forced back into an arboreal habitat, presumably by those australopithecines who eventually became us. In short, the ancestors of chimpanzees and gorillas are A. afarensis and Paranthropus
Paranthropus
The robust australopithecines, members of the extinct hominin genus Paranthropus , were bipedal hominids that probably descended from the gracile australopithecine hominids...
, respectively.
Taxonomic classification
- Tribe Gorillini
- Genus GorillaGorillaGorillas 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...
- Western GorillaWestern GorillaThe western gorilla is a great ape and the most populous species of the genus Gorilla.-Taxonomy:Nearly all of the individuals of this taxon belong to the western lowland gorilla subspecies whose population is approximately 95,000 individuals...
, (Gorilla gorilla)- Western Lowland GorillaWestern Lowland GorillaThe western lowland gorilla is a subspecies of the western gorilla that lives in montane, primary, and secondary forests and lowland swamps in Angola, Cameroon, Central African Republic, Congo, Democratic Republic of the Congo, Equatorial Guinea and Gabon. It is the gorilla usually found in zoos...
, (Gorilla gorilla gorilla) - Cross River GorillaCross River GorillaThe Cross River gorilla is a subspecies of the western gorilla that can be found on the border between Nigeria and Cameroon, in both tropical and subtropical moist broadleaf forests which are also home to the Nigeria-Cameroon Chimpanzee, another subspecies of great ape...
, (Gorilla gorilla diehli)
- Western Lowland Gorilla
- Eastern GorillaEastern GorillaThe eastern gorilla is a species of the genus Gorilla and the largest living primate. At present, the species is subdivided into two subspecies. The eastern lowland gorilla is the most populous, at about 5,000 individuals. The mountain gorilla has only about 700 individuals...
, (Gorilla beringei)- Mountain GorillaMountain GorillaThe Mountain Gorilla is one of the two subspecies of the Eastern Gorilla. There are two populations. One is found in the Virunga volcanic mountains of Central Africa, within three National Parks: Mgahinga, in south-west Uganda; Volcanoes, in north-west Rwanda; and Virunga in the eastern Democratic...
, (Gorilla beringei beringei) - Eastern Lowland GorillaEastern Lowland GorillaThe Eastern Lowland Gorilla is a subspecies of Eastern Gorilla that is now only found in the forests of eastern Democratic Republic of the Congo...
, (Gorilla beringei graueri)
- Mountain Gorilla
- Western Gorilla
- Genus Gorilla
- Tribe HomininiHomininiHominini is the tribe of Homininae that comprises Homo, and the two species of the genus Pan , their ancestors, and the extinct lineages of their common ancestor . Members of the tribe are called hominins...
- Genus Pan
- Common ChimpanzeeCommon ChimpanzeeThe common chimpanzee , also known as the robust chimpanzee, is a great ape. Colloquially, the common chimpanzee is often called the chimpanzee , though technically this term refers to both species in the genus Pan: the common chimpanzee and the closely related bonobo, formerly called the pygmy...
, (Pan troglodytes)- Central ChimpanzeeCentral ChimpanzeeThe central chimpanzee or Tschego is a subspecies of the common chimpanzee...
, (Pan troglodytes troglodytes) - West African Chimpanzee, (Pan troglodytes verus)
- Nigeria-Cameroon ChimpanzeeNigeria-Cameroon ChimpanzeeThe Nigeria-Cameroon chimpanzee is a subspecies of the common chimpanzee which inhabits the rainforests along the border of Nigeria and Cameroon. Male Nigeria-Cameroon chimpanzees can weigh as much as 70 kilos with a body length of up to 1.2 metres...
, (Pan troglodytes ellioti) - Eastern ChimpanzeeEastern ChimpanzeeThe eastern chimpanzee is a subspecies of the common chimpanzee. It occurs in the Central African Republic, the Sudan, the Democratic Republic of the Congo, Uganda, Rwanda, Burundi, and Tanzania....
, (Pan troglodytes schweinfurthii)
- Central Chimpanzee
- BonoboBonoboThe 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...
(Pygmy Chimpanzee), (Pan paniscus)
- Common Chimpanzee
- Genus HomoHomo (genus)Homo is the genus that includes modern humans and species closely related to them. The genus is estimated to be about 2.3 to 2.4 million years old, evolving from australopithecine ancestors with the appearance of Homo habilis....
- HumanHumanHumans are the only living species in the Homo genus...
, (Homo sapiens)- Con synchronisms, (Homo sapiens species)
- Human
- Genus Pan
Brain size evolution
There has been a gradual increase in brain volume (brain sizeBrain size
Brain size is one aspect of animal anatomy and evolution. Both overall brain size and the size of substructures have been analysed, and the question of links between size and functioning - particularly intelligence - has often proved controversial...
) as the ancestors of modern humans progressed along the timeline of human evolution
Timeline of human evolution
The 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...
, starting from about 600 cm3 in 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...
up to 1500 cm3 in Homo sapiens neanderthalensis, whereas the brain size along the chimpanzee and gorilla lines remained almost unchanged (see figure). Thus, in general there is a good correlation between brain volume and intelligence
Intelligence
Intelligence has been defined in different ways, including the abilities for abstract thought, understanding, communication, reasoning, learning, planning, emotional intelligence and problem solving....
. However, modern Homo sapiens have a brain volume slightly smaller (1250 cm3) than Neanderthals, women have a brain slightly smaller than men and the Flores hominids (Homo floresiensis
Homo floresiensis
Homo floresiensis is a possible species, now extinct, in the genus Homo. The remains were discovered in 2003 on the island of Flores in Indonesia. Partial skeletons of nine individuals have been recovered, including one complete cranium...
), nicknamed hobbits, had a cranial capacity of about 380 cm3 (considered small for a chimpanzee), about a third of the Homo erectus
Homo erectus
Homo erectus is an extinct species of hominid that lived from the end of the Pliocene epoch to the later Pleistocene, about . The species originated in Africa and spread as far as India, China and Java. There is still disagreement on the subject of the classification, ancestry, and progeny of H...
average. It is proposed that they evolved from H. erectus as a case of insular dwarfism. In spite of their smaller brain, there is evidence that H. floresiensis used fire and made stone tools at least as sophisticated as those of their proposed ancestors H. erectus. In this case, it seems that for intelligence, the structure of the brain is more important than its size. "As large as you need and as small as you can" to summarize the opposite evolutionary constraints on human brain size.
Evolution of family structure and sexuality
Sexuality is related to family structure and partly shapes it. The involvement of fathers in education is quite unique to our species, at least when compared to other Homininae. Concealed ovulationConcealed ovulation
Concealed ovulation or hidden estrus is the lack of distinctive signaling that the adult female of a species is "in heat". These signals may include swelling and redness of the genitalia in baboons and bonobos Pan paniscus, pheromone release in the feline family, etc...
and menopause
Menopause
Menopause is a term used to describe the permanent cessation of the primary functions of the human ovaries: the ripening and release of ova and the release of hormones that cause both the creation of the uterine lining and the subsequent shedding of the uterine lining...
in women both also occur in a few other primates however, but are uncommon in other species. Having sex in private also distinguishes us from Bonobos, Chimpanzees and Gorillas. Testis and Penis size are related to family structure: monogamy
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...
or promiscuity
Promiscuity
In humans, promiscuity refers to less discriminating casual sex with many sexual partners. The term carries a moral or religious judgement and is viewed in the context of the mainstream social ideal for sexual activity to take place within exclusive committed relationships...
, or harem
Harem
Harem refers to the sphere of women in what is usually a polygynous household and their enclosed quarters which are forbidden to men...
, in humans, chimpanzees or gorillas, respectively. The levels of 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:...
are generally seen as a marker 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...
. Studies have suggested that the earliest homininae were dimorphic and that this lessened over the course of the evolution of the genus Homo, correlating with humans becoming more monogamous, whereas gorillas, who live in harems, show a large degree of sexual dimorphism (see Paranthropus
Paranthropus
The robust australopithecines, members of the extinct hominin genus Paranthropus , were bipedal hominids that probably descended from the gracile australopithecine hominids...
). Concealed (or "hidden") ovulation means that the phase of fertility is not detectable in women, whereas chimpanzees advertise ovulation via an obvious swelling of the genitals. Women can be partly aware of their ovulation along the menstrual phases, but men are essentially unable to detect ovulation in women. Most primates have semi-concealed ovulation, thus one can think that the common ancestor had semi-concealed ovulation, that was inherited by gorillas, and that later evolved in concealed ovulation in humans and advertised ovulation in chimpanzees. Menopause also occurs in rhesus monkeys, and possibly in chimpanzees, but does not in gorillas and is quite uncommon in other primates (and other mammal groups). Menopause contributes to an increased longevity
Longevity
The word "longevity" is sometimes used as a synonym for "life expectancy" in demography or known as "long life", especially when it concerns someone or something lasting longer than expected ....
of women.
Evolution of bipedalism
Recent studies of Ardipithecus ramidus (4.4 million years old) and Orrorin (6 million years old) suggest bipedalism, it is thus possible that bipedalism evolved very early in homininae and was reduced in chimpanzee and gorilla when they became more specialized. AustralopithecusAustralopithecus
Australopithecus is a genus of hominids that is now extinct. From the evidence gathered by palaeontologists and archaeologists, it appears that the Australopithecus genus evolved in eastern Africa around 4 million years ago before spreading throughout the continent and eventually becoming extinct...
and early Paranthropus
Paranthropus
The robust australopithecines, members of the extinct hominin genus Paranthropus , were bipedal hominids that probably descended from the gracile australopithecine hominids...
may have been bipedal, but then lost this ability when they were forced back into an arboreal habitat, presumably by early Homo. Very early homininae such as Ardipithecus ramidus may have possessed an arboreal type of bipedalism that later independently evolved towards knuckle-walking
Knuckle-walking
Knuckle-walking is a form of quadrupedal walking in which the forelimbs hold the fingers in a partially flexed posture that allows body weight to press down on the ground through the knuckles....
in chimpanzees and gorillas and towards efficient walking and running in modern humans (see figure). It is also proposed that one cause of Neanderthal extinction could have been a less efficient running than Cro-Magnon
Cro-Magnon
The Cro-Magnon were the first early modern humans of the European Upper Paleolithic. The earliest known remains of Cro-Magnon-like humans are radiometrically dated to 35,000 years before present....
.
Prominent researchers
- Zeresenay AlemsegedZeresenay AlemsegedDr. Zeresenay Alemseged is an Ethiopian paleoanthropologist and Chair of the Anthropology Department] at the California Academy of Sciences in San Francisco, USA...
, an Ethiopian paleoanthropologist living in San Francisco and expert on human evolution; discovered Selam. - Lee R. BergerLee R. BergerLee Rogers Berger is a paleoanthropologist, physical anthropologist and archeologist and is best known for his discovery of Australopithecus sediba and his work on Australopithecus africanus body proportions and the Taung Bird of Prey Hypothesis.-Background:Berger was born in Shawnee Mission,...
, an American paleoanthropologist working in South Africa; discovered fossils of large mammals including homininae, A. sediba. - Robert BroomRobert BroomProfessor Robert Broom was a Scottish South African doctor and paleontologist. He qualified as a medical practitioner in 1895 and received his DSc in 1905 from the University of Glasgow...
, a Scottish physician and palaeontologist whose work in South Africa led to the discovery of ParanthropusParanthropusThe robust australopithecines, members of the extinct hominin genus Paranthropus , were bipedal hominids that probably descended from the gracile australopithecine hominids...
and of "Mrs. PlesMrs. PlesMrs. Ples is the popular nickname for the most complete skull of an Australopithecus africanus specimen ever found in South Africa. Many fossils of this species, which are considered to be the distant relatives of all humankind, have been found in the Sterkfontein area, in what has been designated...
". - Michel BrunetMichel BrunetMichel Brunet may refer to:* Michel Brunet , Canadian historian* Michel Brunet , French paleontologist* Michel Brunet , Canadian skater...
, a French paleoanthropologist and professor, discovered Toumaï in Chad. - Yves CoppensYves CoppensYves Coppens is a French anthropologist. He graduated from the University of Rennes. He has studied ancient hominids and has had multiple published works on this topic, and has also produced a film....
, a French paleontologist, discovered the first Paranthropus (P. aethiopicus) and LucyLucy (Australopithecus)Lucy is the common name of AL 288-1, several hundred pieces of bone representing about 40% of the skeleton of an individual Australopithecus afarensis. The specimen was discovered in 1974 at Hadar in the Awash Valley of Ethiopia's Afar Depression. Lucy is estimated to have lived 3.2 million years...
. - Raymond DartRaymond DartRaymond Arthur Dart was an Australian anatomist and anthropologist, best known for his involvement in the 1924 discovery of the first fossil ever found of Australopithecus africanus, an extinct hominid closely related to humans, at Taung in the North of South Africa in the province...
, an Australian palaeoanthropologist, discovered the Taung ChildTaung ChildThe Taung Child — or Taung Baby — is the fossilized skull of a young Australopithecus africanus individual. It was discovered in 1924 by quarrymen working for the Northern Lime Company in Taung, South Africa...
in South Africa, the first Australopithecus africanusAustralopithecus africanusAustralopithecus africanus was an early hominid, an australopithecine, who lived between 2–3 million years ago in the Pliocene. In common with the older Australopithecus afarensis, A. africanus was slenderly built, or gracile, and was thought to have been a direct ancestor of modern humans. Fossil...
. - Charles DarwinCharles DarwinCharles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
, the British naturalist who documented with considerable evidence that species originate through evolutionary changes. - Richard DawkinsRichard DawkinsClinton Richard Dawkins, FRS, FRSL , known as Richard Dawkins, is a British ethologist, evolutionary biologist and author...
, a British geneticist, researcher and writer on a wide range of topics involving evolution. - Donald JohansonDonald JohansonDonald Carl Johanson is an American paleoanthropologist. Along with Maurice Taieb, and Yves Coppens he is known for the discovery of the skeleton of the female hominid australopithecine known as "Lucy", in the Afar Triangle region of Hadar, Ethiopia.-Early years:Johanson was born in Chicago,...
, an American paleontologist, with many discoveries including LucyLucy (Australopithecus)Lucy is the common name of AL 288-1, several hundred pieces of bone representing about 40% of the skeleton of an individual Australopithecus afarensis. The specimen was discovered in 1974 at Hadar in the Awash Valley of Ethiopia's Afar Depression. Lucy is estimated to have lived 3.2 million years...
, the emblematic Australopithecus afarensisAustralopithecus afarensisAustralopithecus afarensis is an extinct hominid that lived between 3.9 and 2.9 million years ago. A. afarensis was slenderly built, like the younger Australopithecus africanus. It is thought that A...
. - Louis LeakeyLouis LeakeyLouis Seymour Bazett Leakey was a British archaeologist and naturalist whose work was important in establishing human evolutionary development in Africa. He also played a major role in creating organizations for future research in Africa and for protecting wildlife there...
, an African archaeologist and naturalist whose work was important in establishing homininae evolution in Africa. - Mary LeakeyMary LeakeyMary Leakey was a British archaeologist and anthropologist, who discovered the first skull of a fossil ape on Rusinga Island and also a noted robust Australopithecine called Zinjanthropus at Olduvai. For much of her career she worked together with her husband, Louis Leakey, in Olduvai Gorge,...
, a British archaeologist and anthropologist whose discoveries in Africa include several Australopithecines and the Laetoli footprints. - Svante PääboSvante PääboSvante Pääbo is a Swedish biologist specializing in evolutionary genetics. He was born in 1955 in Stockholm to Sune Bergström, who shared the Nobel Prize in Physiology or Medicine with Bengt I. Samuelsson and John R. Vane in 1982, and his mother, Estonian Karin Pääbo.He earned his PhD from Uppsala...
, a Swedish biologist specializing in evolutionary genetics, leader of the sequencing of the NeanderthalNeanderthalThe Neanderthal is an extinct member of the Homo genus known from Pleistocene specimens found in Europe and parts of western and central Asia...
and Denisovan genomes. - Brigitte Senut, a French paleoanthropologist and professor, with many discoveries including Orrorin.
- Sarah Tishkoff, an American geneticist whose recent work has greatly improved our understanding of African evolutionary genetics
- Philip V. Tobias, a South African palaeoanthropologist, one of the world's leading authorities on the evolution of humankind.
- Erik TrinkausErik TrinkausErik Trinkaus, PhD, is a prominent paleoanthropologist and expert on Neanderthal biology and human evolution. Trinkaus researches the evolution of the species Homo sapiens and recent human diversity, focusing on the paleoanthropology and emergence of late archaic and early modern humans, and the...
, a prominent American paleoanthropologist and expert on NeanderthalNeanderthalThe Neanderthal is an extinct member of the Homo genus known from Pleistocene specimens found in Europe and parts of western and central Asia...
biology and human evolution. - Adrienne Zihlman, an American anthropologist, professor at UCSC, working on primate anatomy and on the role of females in evolution.
See also
- Human evolutionHuman evolutionHuman 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...
- Human evolutionary geneticsHuman evolutionary geneticsHuman evolutionary genetics studies how one human genome differs from the other, the evolutionary past that gave rise to it, and its current effects. Differences between genomes have anthropological, medical and forensic implications and applications...
- List of human evolution fossils
- Pan prior
- The Third Chimpanzee
Citations
- "Human Evolutionary Genetics" Jobling M.A., Hurles M., Tyler Smith C. 2004, Garland Science, New York