Devolution (fallacy)
Encyclopedia
In common parlance, "devolution", "de-evolution", or backward evolution is the notion that a species can change into a more "primitive" form. Biologically, the term is a misnomer for that concept because evolution has neither a teleological
direction nor a motive, so it is difficult to speak meaningfully of its "reverse" at all. In simple terms, anything resembling "devolution" in that sense amounts to evolution of organisms into simpler forms. That confusion is based on two conceptual errors: the idea that evolution
is supposed to make species more "advanced", as opposed to "primitive"; and the idea that some modern species that have lost functions or complexity accordingly must be degenerate forms of their ancestors. These ideas are meaningless in terms of modern evolutionary theory, which deals with genetic adaptation
of populations, as a result of natural selection
of forms best suited to their environment. Selection depends in essence, not on systematic teleological increase of complexity, but on increased effectiveness of exploitation of resources for increased reproductive success. That process commonly might lead to more elaborate features or complexity, but if the maintenance of complex features incurs costs greater than any advantages those features confer, selection tends to lead to their loss. Thus for cave dwelling animals the loss of eyes arises because it is an advantage; to refer to it as degeneracy is meaningless in Darwinistic terms, however repugnant such a loss might seem to humans who value their eyes.
towards "increasing complexity". Modern evolution theory accepts the possibility of decreasing complexity, as in vestigiality, in the course of evolutionary change, but earlier views that species are subject to "racial decay"or "drives to perfection" or "devolution" have been rejected. Early scientific theories of transmutation of species
such as Lamarckism
and orthogenesis
perceived species diversity as a result of a purposeful internal drive or tendency to form improved adaptations to the environment, but in the modern evolutionary synthesis
evolution through natural selection
comes about when random heritable mutation
s happen to give a better chance of successful reproduction in the environment they arise in, while the many disadvantageous mutations are lost.
Devolution presumes that there is somehow a preferred hierarchy of structure and function, and that evolution must mean "progress" to "more advanced" organisms. For example, it could be said that "feet are better than hooves
" or "lung
s are better than gill
s", so that change to the "less advanced" structure would be called "devolution". A modern biologist sees all such changes as evolution, since for the organisms possessing the changed structures, each is a useful adaptation to their circumstances. For example, hooves have advantages for running quickly on plains, which benefits horses, and feet have advantages in climbing trees, which ancestors of humans did.
The concept of devolution as regress from progress relates to the ancient idea that humans are the ultimate product or goal of evolution. This belief is related to anthropocentrism
, the idea that human existence is the point of all universal existence. Such thinking can lead on to the idea that species evolve because they "need to" in order to adapt to environmental changes. Biologists refer to this misconception as teleology
, the idea of intrinsic finality
that things are "supposed" to be and behave a certain way, and naturally tend to act that way to pursue their own good. From a biological viewpoint, when species evolve it is not a reaction to necessity, but rather that the population contains variations with traits that favour their natural selection
. This view is supported by the fossil record which demonstrates that roughly ninety-nine percent of all species that ever lived are now extinct.
People thinking in terms of devolution commonly assume that progress is shown by increasing complexity, but biologists studying the evolution of complexity
find evidence of many examples of decreasing complexity in the record of evolution. The lower jaw in fish, reptiles and mammals has seen a decrease in complexity, if measured by the number of bones. Ancestors of modern horses had several toes on each foot; modern horses have a single hooved toe. Modern humans may be evolving towards never having wisdom teeth, and already have lost the tail found in many other mammals - not to mention other vestigial structures, such as the vermiform appendix
or the nictitating membrane
.
A more rational version of the concept of devolution, a version that does not involve concepts of "primitive" or "advanced" organisms, is for most purposes academic. It is based on the observation that if certain genetic changes in a particular combination (sometimes in a particular sequence as well) are precisely reversed, one should get precise reversal of the evolutionary process, yielding an atavism
or "throwback", whether more or less complex than the ancestors where the process began. At a trivial level, where just one or a few mutations are involved, selection pressure in one direction can have one effect, which can be reversed by new patterns of selection when conditions change. That could be seen as reversed evolution, though the concept is of not much interest because it does not differ in any functional or effective way from any other adaptation to selection pressures. As the number of genetic changes rises however, one combinatorial effect is that it becomes vanishingly unlikely that the full course of adaptation can be reversed precisely. Also, if one of the original adaptations involved complete loss of a gene, one can neglect any probability of reversal. Accordingly, one might well expect reversal of peppered moth colour changes, but not reversal of the loss of limbs in snakes.
In 1857 the physician Bénédict Morel
influenced by Lamarckism
claimed that environmental factors such as taking drugs
or alcohol
would produce degeneration
in the offspring of those individuals, and would revert those offspring
to a primitive state. Morel a devout Catholic
had believed that mankind had started in perfection, contrasting modern humanity to the past, Morel claimed there had been "Morbid deviation from an original type". The theory of devolution, was later advocated by some biologists.
According to (Luckhurst, 2005):
One of the first biologists to suggest devolution was Ray Lankester
, he explored the possibility that evolution by natural selection
may in somecases lead to devolution, an example he studied was the regressions in the life cycle of sea squirts. Lankester discussed the idea of devolution in his book Degeneration: A Chapter in Darwinism (1880). He was a critic of progressive evolution, pointing out that higher forms existed in the past which have since degenerated into simpler forms. Lankester argued that "if it was possible to evolve, it was also possible to devolve, and that complex organisms could devolve into simpler forms or animals".
Anton Dohrn
also developed a theory of degenerative evolution based on his studies of vertebrates. According to Dohrn many chordates are degenerated because of their environmental conditions. Dohrn claimed cyclostomes such as lampreys are degenerate fish as there is no evidence their jawless state is an ancestral feature but is the product of environmental adaptation due to parasitism
. According to Dohrn if cyclotomes would devolve further then they would resemble something like an Amphioxus.
Peter J. Bowler
has written that devolution was taken seriously by proponents of orthogenesis
and others in the late 19th century who at this period of time firmly believed that there was a direction in evolution. Orthogenesis
was the belief that evolution travels in internally directed trends and levels. The paleontologist Alpheus Hyatt
discussed the concept of devolution in his work, Hyatt used the concept of racial senility as the mechanism of devolution. Bowler defines racial senility as "an evolutionary retreat back to a state resembling that from which it began."
Hyatt who studied the fossils of invertebrates believed that up to a point ammonoids developed by regular stages up until a specific level but would later due to unfavourable conditions descend back to a previous level, this according to Hyatt was a form of lamarckism as the degeneration was a direct response to external factors. To Hyatt after the level of degeneration the species would then become extinct, according to Hyatt there was a "phase of youth, a phase of maturity, a phase of senility or degeneration foreshadowing the extinction of a type". To Hyatt the devolution was predetermined by internal factors which organisms can neither control or reverse. This idea of all evolutionary branches eventually running out of energy and degenerating into extinction
was a pessimistic view of evolution
and was unpopular amongst many scientists of the time.
Carl H. Eigenmann
an ichthyologist wrote Cave vertebrates of America: a study in degenerative evolution (1909) in which he concluded that cave
evolution
was essentially degenerative. The entomologist William Morton Wheeler
and the Lamarckian E.W. MacBride (1866-1940) also advocated degenerative evolution. According to Macbride invertebrates were actually degenerate vertebrates, his argument was based on the idea that "crawling on the seabed was inherently less stimulating than swimming in open waters."
—whales, dolphins and porpoises which are evolved from formerly land-dwelling mammals—is an adaptation of the spinal column for propulsion in water. Unlike the tail of the mammal's marine ancestor, the Sarcopterygii
, and the other teleosts
, which move from side to side, the cetacean's tail moves up and down as it flexes its mammalian spine, but the function of the tail in providing propulsion is remarkably similar.
Johann Friedrich Blumenbach
and other monogenists
such as Georges-Louis Leclerc, Comte de Buffon
were believers in the "Degeneration theory" of racial origins the theory claims that races can degenerate into "primitive" forms. Blumenbach claimed that Adam and Eve
were white
and that other races came about by degeneration from environmental factors such as the sun and poor dieting. Buffon believed that the degeneration could be reversed if proper environmental control was taken and that all contemporary forms of man could revert to the original Caucasian race
.
Blumenbach claimed Negroid pigmentation arose because of the result of the heat of the tropical sun. The cold wind caused the tawny colour of the Eskimos and the Chinese
were fair skinned compared to the other Asian stocks because they kept mostly in towns protected from environmental factors.
According to Blumenbach there are five races all belonging to a single species: Caucasian
, Mongolian
, Ethiopian
, American
and Malay
. Blumenbach however stated:
According to Blumenbach the other races are supposed to have degenerated from the Caucasian ideal stock. Blumenbach denied that his "Degeneration theory" was racist, he also wrote three essays claiming non-white peoples are capable of excelling in arts and sciences in reaction against racialists of his time who believed they couldn't.
creationists, devolution is:
The term was used in the play Inherit the Wind
(a parable
that fictionalizes the 1925 Scopes "Monkey" Trial
), when the character of Matthew Brady (representative of William Jennings Bryan
) argued that "Ladies and gentleman, devolution is not a theory but a cold fact ... the ape devolved from man", mocking evolutionary theory by offering an alternative he considers just as plausible. During the Scopes Trial itself, a report in The New York Times
said "After flocking to view the monkeys, Dayton has decided that it was not man who evolved from the anthropoid, but the anthropoid which devolved from man; and it points now at the two chimpanzees and the "missing link" to prove the assertion". The suggestion of ape degenerating from "man" had already been brought up by the early young-earth creationist George McReady Price in a work published before the trial:
An early creationist to discuss devolution was the ornithologist Douglas Dewar
, writing about the subject of the fossil record for the carboniferous period Dewar wrote:
The Young Earth creationist Ken Ham
claims Adam and Eve
were made into a state of perfection, with perfect DNA
, no mistakes or mutations and that because of man sin
ning against God
in Genesis of the Bible
, that God cursed the ground and animals and sentenced man to die. Ham claims this is where mutations come from, and the incredible amount of genetic information that God had created at the beginning has been devolving ever since; according to Ham organisms in nature are losing genetic information.
Creationists like Ham claim that mutations lead to a loss of genetic information and this is evidence for devolution. Ken Ham for example has stated:
Young Earth creationist Joseph Mastropaolo, argues that "Change over time, 'definition one' of evolution, actually describes devolution to extinction, the exact opposite of evolution.... actual epidemiological data from human genetic disorders and fatal birth defects, identify 'natural selection,' the alleged 'primary mechanism' for evolution, as actually a mechanism for devolution to extinction, the exact opposite of evolution." and elsewhere, "Evolution is the development of an organism from its chemicals or primitive state to its present state. Devolution is the sequence toward greater simplicity or disappearance or degeneration."
John C. Sanford
a plant geneticist
and creationist has argued for devolution, he has written a book entitled Genetic Entropy & the Mystery of the Genome (2005) in which he claims that the genome
is deteriorating and therefore could not have evolved
in the way specified by the Modern evolutionary synthesis
. Sanford has published two peer reviewed papers modeling genetic entropy.
The creationist author Lee Spetner
is a critic of the role of mutations in the modern evolutionary synthesis
, he has argued in his book Not by Chance: Shattering the Modern Theory of Evolution that mutations cause devolution.
Peter Stoner
an old earth creationist claimed that the universe
was immensely old, writing on astronomy
he wrote that "every star is losing energy and mass", he claimed that the second law of thermodynamics
proves "cosmic devolution".
Brian Regal associates devolution with the work of dentist
and creationist Jack Cuozzo. Cuozzo in his book Buried Alive (1998) claims that Neanderthal
dentition
proves that the Neanderthals lived much longer than modern humans and that modern humans have devolved, according to Cuozzo "it seems as if human jaws are becoming smaller over time".
The concept of devolution is also found in the teachings of Hindu creationism. Michael Cremo
a member of ISKCON has authored a book titled Human Devolution: A Vedic alternative to Darwin's theory, published by ISKCON's Bhaktivedanta Book Publishing, Cremo suggests that Darwinian evolution should be replaced with "devolution" from the original unity with Brahman
.
Examples of devolution cited by creationists, include vestigial organs, Stickleback
, Amblyopsidae and the Greta oto
. Evolutionary biologists point out, however, that examples such as this are not evidence for devolution and the creationists have misunderstood the mechanisms of evolution
.
for changes over time in populations of living things that make them less complex and remove some of their former adaptations. The terminology used herein is nontechnical, but the phenomenon is a real but counter-intuitive one, more accurately known as streamlining evolution. Since the development and maintenance of a feature such as an organ or a metabolite
has an opportunity cost
, changes in the environment that reduce the utility of an adaptation may mean that a higher evolutionary fitness is achieved by no longer using the adaptation, thus better using resources. This requires a mutation that inactivates one or more genes, perhaps by a change to DNA methylation
or a methionine
codon. Streamlining evolution allows evolution to remove features no longer of much/any use, like scaffolding on a completed bridge.
However, "devolution" in practice typically refers to changes that occur from a problem no longer existing rather than superior solutions existing. For instance, of the several hundred known species of animal that live their entire lives in total darkness, most have non-functional eyes rather than no eyes. This is due, for instance, to deterioration of the optic nerve
. It occurs because mutations that prevent eye formation have low probability. However, several eyeless animal species, such as the Kauai cave wolf spider, who live in total darkness, and whose ancestry mostly had eyes, do exist. Together with gene duplication
, streamlining evolution makes evolution surprisingly able to produce radical changes, despite being limited to successive, slight modifications.
Teleology
A teleology is any philosophical account which holds that final causes exist in nature, meaning that design and purpose analogous to that found in human actions are inherent also in the rest of nature. The word comes from the Greek τέλος, telos; root: τελε-, "end, purpose...
direction nor a motive, so it is difficult to speak meaningfully of its "reverse" at all. In simple terms, anything resembling "devolution" in that sense amounts to evolution of organisms into simpler forms. That confusion is based on two conceptual errors: the idea that 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...
is supposed to make species more "advanced", as opposed to "primitive"; and the idea that some modern species that have lost functions or complexity accordingly must be degenerate forms of their ancestors. These ideas are meaningless in terms of modern evolutionary theory, which deals with genetic adaptation
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
of populations, as a result of 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....
of forms best suited to their environment. Selection depends in essence, not on systematic teleological increase of complexity, but on increased effectiveness of exploitation of resources for increased reproductive success. That process commonly might lead to more elaborate features or complexity, but if the maintenance of complex features incurs costs greater than any advantages those features confer, selection tends to lead to their loss. Thus for cave dwelling animals the loss of eyes arises because it is an advantage; to refer to it as degeneracy is meaningless in Darwinistic terms, however repugnant such a loss might seem to humans who value their eyes.
Concepts underlying ideas of devolution
The idea of devolution can arise from thinking that "evolution" requires some sort of purposeful directionTeleology
A teleology is any philosophical account which holds that final causes exist in nature, meaning that design and purpose analogous to that found in human actions are inherent also in the rest of nature. The word comes from the Greek τέλος, telos; root: τελε-, "end, purpose...
towards "increasing complexity". Modern evolution theory accepts the possibility of decreasing complexity, as in vestigiality, in the course of evolutionary change, but earlier views that species are subject to "racial decay"or "drives to perfection" or "devolution" have been rejected. Early scientific theories of transmutation of species
Transmutation of species
Transmutation of species was a term used by Jean Baptiste Lamarck in 1809 for his theory that described the altering of one species into another, and the term is often used to describe 19th century evolutionary ideas that preceded Charles Darwin's theory of natural selection...
such as Lamarckism
Lamarckism
Lamarckism is the idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring . It is named after the French biologist Jean-Baptiste Lamarck , who incorporated the action of soft inheritance into his evolutionary theories...
and orthogenesis
Orthogenesis
Orthogenesis, orthogenetic evolution, progressive evolution or autogenesis, is the hypothesis that life has an innate tendency to evolve in a unilinear fashion due to some internal or external "driving force". The hypothesis is based on essentialism and cosmic teleology and proposes an intrinsic...
perceived species diversity as a result of a purposeful internal drive or tendency to form improved adaptations to the environment, but in the modern evolutionary synthesis
Modern evolutionary synthesis
The modern evolutionary synthesis is a union of ideas from several biological specialties which provides a widely accepted account of evolution...
evolution through 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....
comes about when random heritable mutation
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...
s happen to give a better chance of successful reproduction in the environment they arise in, while the many disadvantageous mutations are lost.
Devolution presumes that there is somehow a preferred hierarchy of structure and function, and that evolution must mean "progress" to "more advanced" organisms. For example, it could be said that "feet are better than hooves
Hoof
A hoof , plural hooves or hoofs , is the tip of a toe of an ungulate mammal, strengthened by a thick horny covering. The hoof consists of a hard or rubbery sole, and a hard wall formed by a thick nail rolled around the tip of the toe. The weight of the animal is normally borne by both the sole...
" or "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 are better than 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", so that change to the "less advanced" structure would be called "devolution". A modern biologist sees all such changes as evolution, since for the organisms possessing the changed structures, each is a useful adaptation to their circumstances. For example, hooves have advantages for running quickly on plains, which benefits horses, and feet have advantages in climbing trees, which ancestors of humans did.
The concept of devolution as regress from progress relates to the ancient idea that humans are the ultimate product or goal of evolution. This belief is related to anthropocentrism
Anthropocentrism
Anthropocentrism describes the tendency for human beings to regard themselves as the central and most significant entities in the universe, or the assessment of reality through an exclusively human perspective....
, the idea that human existence is the point of all universal existence. Such thinking can lead on to the idea that species evolve because they "need to" in order to adapt to environmental changes. Biologists refer to this misconception as teleology
Teleology
A teleology is any philosophical account which holds that final causes exist in nature, meaning that design and purpose analogous to that found in human actions are inherent also in the rest of nature. The word comes from the Greek τέλος, telos; root: τελε-, "end, purpose...
, the idea of intrinsic finality
Intrinsic finality
Intrinsic finality is the idea that there is a natural good for all beings, and that all beings have a natural tendency to pursue their own good. It is an underlying principle of both teleology and moral objectivism...
that things are "supposed" to be and behave a certain way, and naturally tend to act that way to pursue their own good. From a biological viewpoint, when species evolve it is not a reaction to necessity, but rather that the population contains variations with traits that favour their 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....
. This view is supported by the fossil record which demonstrates that roughly ninety-nine percent of all species that ever lived are now extinct.
People thinking in terms of devolution commonly assume that progress is shown by increasing complexity, but biologists studying the evolution of complexity
Evolution of complexity
The evolution of biological complexity is an important outcome of the process of evolution. Evolution has produced some remarkably complex organisms - although the actual level of complexity is very hard to define or measure accurately in biology, with properties such as gene content, the number of...
find evidence of many examples of decreasing complexity in the record of evolution. The lower jaw in fish, reptiles and mammals has seen a decrease in complexity, if measured by the number of bones. Ancestors of modern horses had several toes on each foot; modern horses have a single hooved toe. Modern humans may be evolving towards never having wisdom teeth, and already have lost the tail found in many other mammals - not to mention other vestigial structures, such as the vermiform appendix
Vermiform appendix
The appendix is a blind-ended tube connected to the cecum , from which it develops embryologically. The cecum is a pouchlike structure of the colon...
or the nictitating membrane
Nictitating membrane
The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten it while maintaining visibility. Some reptiles, birds, and sharks have a full nictitating membrane; in many mammals, there is a small...
.
A more rational version of the concept of devolution, a version that does not involve concepts of "primitive" or "advanced" organisms, is for most purposes academic. It is based on the observation that if certain genetic changes in a particular combination (sometimes in a particular sequence as well) are precisely reversed, one should get precise reversal of the evolutionary process, yielding an atavism
Atavism
Atavism is the tendency to revert to ancestral type. In biology, an atavism is an evolutionary throwback, such as traits reappearing which had disappeared generations before. Atavisms can occur in several ways...
or "throwback", whether more or less complex than the ancestors where the process began. At a trivial level, where just one or a few mutations are involved, selection pressure in one direction can have one effect, which can be reversed by new patterns of selection when conditions change. That could be seen as reversed evolution, though the concept is of not much interest because it does not differ in any functional or effective way from any other adaptation to selection pressures. As the number of genetic changes rises however, one combinatorial effect is that it becomes vanishingly unlikely that the full course of adaptation can be reversed precisely. Also, if one of the original adaptations involved complete loss of a gene, one can neglect any probability of reversal. Accordingly, one might well expect reversal of peppered moth colour changes, but not reversal of the loss of limbs in snakes.
History of devolution
The concept of devolution or degenerative evolution was used by scientists in the 19th century, at this time it was believed by most biologists that evolution had some kind of direction.In 1857 the physician Bénédict Morel
Bénédict Morel
Bénédict Augustin Morel , was a French physician born in Vienna, Austria. He was an influential figure in the field of psychiatry during the mid-19th century....
influenced by Lamarckism
Lamarckism
Lamarckism is the idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring . It is named after the French biologist Jean-Baptiste Lamarck , who incorporated the action of soft inheritance into his evolutionary theories...
claimed that environmental factors such as taking drugs
DRUGS
Destroy Rebuild Until God Shows are an American post-hardcore band formed in 2010. They released their debut self-titled album on February 22, 2011.- Formation :...
or alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
would produce degeneration
Degeneration
The idea of degeneration had significant influence on science, art and politics from the 1850s to the 1950s. The social theory developed consequently from Charles Darwin's Theory of Evolution...
in the offspring of those individuals, and would revert those offspring
Offspring
In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...
to a primitive state. Morel a devout Catholic
Catholic
The word catholic comes from the Greek phrase , meaning "on the whole," "according to the whole" or "in general", and is a combination of the Greek words meaning "about" and meaning "whole"...
had believed that mankind had started in perfection, contrasting modern humanity to the past, Morel claimed there had been "Morbid deviation from an original type". The theory of devolution, was later advocated by some biologists.
According to (Luckhurst, 2005):
Darwin soothed readers that evolution was progressive, and directed towards human perfectibility. The next generation of biologists were less confident or consoling. Using Darwin's theory, and many rival biological accounts of development then in circulation, scientists suspected that it was just as possible to devolve, to slip back down the evolutionary scale to prior states of development.
One of the first biologists to suggest devolution was Ray Lankester
Ray Lankester
Sir E. Ray Lankester KCB, FRS was a British zoologist, born in London.An invertebrate zoologist and evolutionary biologist, he held chairs at University College London and Oxford University. He was the third Director of the Natural History Museum, and was awarded the Copley Medal of the Royal...
, he explored the possibility that evolution by 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....
may in somecases lead to devolution, an example he studied was the regressions in the life cycle of sea squirts. Lankester discussed the idea of devolution in his book Degeneration: A Chapter in Darwinism (1880). He was a critic of progressive evolution, pointing out that higher forms existed in the past which have since degenerated into simpler forms. Lankester argued that "if it was possible to evolve, it was also possible to devolve, and that complex organisms could devolve into simpler forms or animals".
Anton Dohrn
Anton Dohrn
Felix Anton Dohrn was a prominent German Darwinist and the founder and first director of the Stazione Zoologica, Naples, Italy.-Family history:...
also developed a theory of degenerative evolution based on his studies of vertebrates. According to Dohrn many chordates are degenerated because of their environmental conditions. Dohrn claimed cyclostomes such as lampreys are degenerate fish as there is no evidence their jawless state is an ancestral feature but is the product of environmental adaptation due to parasitism
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...
. According to Dohrn if cyclotomes would devolve further then they would resemble something like an Amphioxus.
Peter J. Bowler
Peter J. Bowler
Peter J. Bowler is a historian of biology who has written extensively on the history of evolutionary thought, the history of the environmental sciences, and on the history of genetics. His 1984 book, Evolution: The History of an Idea is a standard textbook on the history of evolution, and was...
has written that devolution was taken seriously by proponents of orthogenesis
Orthogenesis
Orthogenesis, orthogenetic evolution, progressive evolution or autogenesis, is the hypothesis that life has an innate tendency to evolve in a unilinear fashion due to some internal or external "driving force". The hypothesis is based on essentialism and cosmic teleology and proposes an intrinsic...
and others in the late 19th century who at this period of time firmly believed that there was a direction in evolution. Orthogenesis
Orthogenesis
Orthogenesis, orthogenetic evolution, progressive evolution or autogenesis, is the hypothesis that life has an innate tendency to evolve in a unilinear fashion due to some internal or external "driving force". The hypothesis is based on essentialism and cosmic teleology and proposes an intrinsic...
was the belief that evolution travels in internally directed trends and levels. The paleontologist Alpheus Hyatt
Alpheus Hyatt
Alpheus Hyatt was an American zoologist and palaeontologist.- Biography :Alpheus Hyatt II was born in Washington, D.C. to Alpheus Hyatt and Harriet Randolph Hyatt...
discussed the concept of devolution in his work, Hyatt used the concept of racial senility as the mechanism of devolution. Bowler defines racial senility as "an evolutionary retreat back to a state resembling that from which it began."
Hyatt who studied the fossils of invertebrates believed that up to a point ammonoids developed by regular stages up until a specific level but would later due to unfavourable conditions descend back to a previous level, this according to Hyatt was a form of lamarckism as the degeneration was a direct response to external factors. To Hyatt after the level of degeneration the species would then become extinct, according to Hyatt there was a "phase of youth, a phase of maturity, a phase of senility or degeneration foreshadowing the extinction of a type". To Hyatt the devolution was predetermined by internal factors which organisms can neither control or reverse. This idea of all evolutionary branches eventually running out of energy and degenerating into extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
was a pessimistic view 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...
and was unpopular amongst many scientists of the time.
Carl H. Eigenmann
Carl H. Eigenmann
Carl H. Eigenmann was an ichthyologist who, along with his wife Rosa Smith Eigenmann, described many of the fishes of North America and South America for the first time....
an ichthyologist wrote Cave vertebrates of America: a study in degenerative evolution (1909) in which he concluded that cave
Cave
A cave or cavern is a natural underground space large enough for a human to enter. The term applies to natural cavities some part of which is in total darkness. The word cave also includes smaller spaces like rock shelters, sea caves, and grottos.Speleology is the science of exploration and study...
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...
was essentially degenerative. The entomologist William Morton Wheeler
William Morton Wheeler
William Morton Wheeler, Ph.D. was an American entomologist, myrmecologist and Harvard professor.-Early life:...
and the Lamarckian E.W. MacBride (1866-1940) also advocated degenerative evolution. According to Macbride invertebrates were actually degenerate vertebrates, his argument was based on the idea that "crawling on the seabed was inherently less stimulating than swimming in open waters."
Dollo's law
Complex organs evolve in a lineage over many generations, and once lost they are unlikely to re-evolve. This observation is sometimes generalized to a hypothesis known as Dollo's law, which states that evolution is not reversible. This does not mean that similar engineering solutions cannot be found by natural selection. For instance the tail of the cetaceaCetacea
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...
—whales, dolphins and porpoises which are evolved from formerly land-dwelling mammals—is an adaptation of the spinal column for propulsion in water. Unlike the tail of the mammal's marine ancestor, the 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...
, and the other teleosts
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...
, which move from side to side, the cetacean's tail moves up and down as it flexes its mammalian spine, but the function of the tail in providing propulsion is remarkably similar.
Degeneration theory
Johann Friedrich Blumenbach
Johann Friedrich Blumenbach was a German physician, physiologist and anthropologist, one of the first to explore the study of mankind as an aspect of natural history, whose teachings in comparative anatomy were applied to classification of what he called human races, of which he determined...
and other monogenists
Polygenism
Polygenism is a theory of human origins positing that the human races are of different lineages . This is opposite to the idea of monogenism, which posits a single origin of humanity.- Origins :...
such as Georges-Louis Leclerc, Comte de Buffon
Georges-Louis Leclerc, Comte de Buffon
Georges-Louis Leclerc, Comte de Buffon was a French naturalist, mathematician, cosmologist, and encyclopedic author.His works influenced the next two generations of naturalists, including Jean-Baptiste Lamarck and Georges Cuvier...
were believers in the "Degeneration theory" of racial origins the theory claims that races can degenerate into "primitive" forms. Blumenbach claimed that Adam and Eve
Adam and Eve
Adam and Eve were, according to the Genesis creation narratives, the first human couple to inhabit Earth, created by YHWH, the God of the ancient Hebrews...
were white
Caucasian race
The term Caucasian race has been used to denote the general physical type of some or all of the populations of Europe, North Africa, the Horn of Africa, Western Asia , Central Asia and South Asia...
and that other races came about by degeneration from environmental factors such as the sun and poor dieting. Buffon believed that the degeneration could be reversed if proper environmental control was taken and that all contemporary forms of man could revert to the original Caucasian race
Caucasian race
The term Caucasian race has been used to denote the general physical type of some or all of the populations of Europe, North Africa, the Horn of Africa, Western Asia , Central Asia and South Asia...
.
Blumenbach claimed Negroid pigmentation arose because of the result of the heat of the tropical sun. The cold wind caused the tawny colour of the Eskimos and the Chinese
Chinese people
The term Chinese people may refer to any of the following:*People with Han Chinese ethnicity ....
were fair skinned compared to the other Asian stocks because they kept mostly in towns protected from environmental factors.
According to Blumenbach there are five races all belonging to a single species: Caucasian
Caucasian race
The term Caucasian race has been used to denote the general physical type of some or all of the populations of Europe, North Africa, the Horn of Africa, Western Asia , Central Asia and South Asia...
, Mongolian
Mongols
Mongols ) are a Central-East Asian ethnic group that lives mainly in the countries of Mongolia, China, and Russia. In China, ethnic Mongols can be found mainly in the central north region of China such as Inner Mongolia...
, Ethiopian
Ethiopian people
Ethiopian people or Ethnic Ethiopians are an ethnic group found in the horn of African country of Ethiopia.-Origins:Ethnic Ethiopians are one of the nearly 80 ethnic groups of the horn of Africa country and are found in every regional state of Ethiopia...
, American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and Malay
Malay race
The concept of a Malay race was proposed by the German scientist Johann Friedrich Blumenbach , and classified as the brown race. Since Blumenbach, many anthropologists have rejected his theory of five races, citing the enormous complexity of classifying races...
. Blumenbach however stated:
I have allotted the first place to the Caucasian because this stock displays the most beautiful race of men.
According to Blumenbach the other races are supposed to have degenerated from the Caucasian ideal stock. Blumenbach denied that his "Degeneration theory" was racist, he also wrote three essays claiming non-white peoples are capable of excelling in arts and sciences in reaction against racialists of his time who believed they couldn't.
Use of the term by proponents of creationism
According to ChristianChristian
A Christian is a person who adheres to Christianity, an Abrahamic, monotheistic religion based on the life and teachings of Jesus of Nazareth as recorded in the Canonical gospels and the letters of the New Testament...
creationists, devolution is:
A theory of origins based on scripture which begins with the ultimate complexity of all living things at the time of creation. This was followed by degeneration and the break down of all living things on the genetic level beginning at the Curse (Genesis 3) and continuing to this day with increased momentum.
The term was used in the play Inherit the Wind
Inherit the Wind (play)
Inherit the Wind is a play by Jerome Lawrence and Robert Edwin Lee. The play, which debuted in 1955, is a parable that fictionalizes the 1925 Scopes "Monkey" Trial as a means to discuss the then-contemporary McCarthy trials.-Background:...
(a parable
Parable
A parable is a succinct story, in prose or verse, which illustrates one or more instructive principles, or lessons, or a normative principle. It differs from a fable in that fables use animals, plants, inanimate objects, and forces of nature as characters, while parables generally feature human...
that fictionalizes the 1925 Scopes "Monkey" Trial
Scopes Trial
The Scopes Trial—formally known as The State of Tennessee v. John Thomas Scopes and informally known as the Scopes Monkey Trial—was a landmark American legal case in 1925 in which high school science teacher, John Scopes, was accused of violating Tennessee's Butler Act which made it unlawful to...
), when the character of Matthew Brady (representative of William Jennings Bryan
William Jennings Bryan
William Jennings Bryan was an American politician in the late-19th and early-20th centuries. He was a dominant force in the liberal wing of the Democratic Party, standing three times as its candidate for President of the United States...
) argued that "Ladies and gentleman, devolution is not a theory but a cold fact ... the ape devolved from man", mocking evolutionary theory by offering an alternative he considers just as plausible. During the Scopes Trial itself, a report in The New York Times
The New York Times
The New York Times is an American daily newspaper founded and continuously published in New York City since 1851. The New York Times has won 106 Pulitzer Prizes, the most of any news organization...
said "After flocking to view the monkeys, Dayton has decided that it was not man who evolved from the anthropoid, but the anthropoid which devolved from man; and it points now at the two chimpanzees and the "missing link" to prove the assertion". The suggestion of ape degenerating from "man" had already been brought up by the early young-earth creationist George McReady Price in a work published before the trial:
An early creationist to discuss devolution was the ornithologist Douglas Dewar
Douglas Dewar
Douglas Dewar was a barrister, British civil servant in India and an ornithologist. He wrote widely in newspapers such as The Madras Mail, Pioneer, Times of India and periodicals such as the Civil and Military Gazette and Bird Notes.-Biography:He particularly advanced field studies of birds and he...
, writing about the subject of the fossil record for the carboniferous period Dewar wrote:
A few of the carboniferous insects were larger than any now existing; one of the dragon-flies had a wing-span of 28 inches. This suggests devolution rather than evolution!
The Young Earth creationist Ken Ham
Ken Ham
Kenneth Alfred Ham is the Australian President/CEO of Answers in Genesis USA. He is a vocal advocate for a young Earth and a literal interpretation of the Book of Genesis, and his cross-country speaking tours and many books make him one of the better known young-Earth...
claims Adam and Eve
Adam and Eve
Adam and Eve were, according to the Genesis creation narratives, the first human couple to inhabit Earth, created by YHWH, the God of the ancient Hebrews...
were made into a state of perfection, with perfect DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
, no mistakes or mutations and that because of man sin
Sin
In religion, sin is the violation or deviation of an eternal divine law or standard. The term sin may also refer to the state of having committed such a violation. Christians believe the moral code of conduct is decreed by God In religion, sin (also called peccancy) is the violation or deviation...
ning against God
God
God is the English name given to a singular being in theistic and deistic religions who is either the sole deity in monotheism, or a single deity in polytheism....
in Genesis of the Bible
Bible
The Bible refers to any one of the collections of the primary religious texts of Judaism and Christianity. There is no common version of the Bible, as the individual books , their contents and their order vary among denominations...
, that God cursed the ground and animals and sentenced man to die. Ham claims this is where mutations come from, and the incredible amount of genetic information that God had created at the beginning has been devolving ever since; according to Ham organisms in nature are losing genetic information.
Creationists like Ham claim that mutations lead to a loss of genetic information and this is evidence for devolution. Ken Ham for example has stated:
Observations confirm that mutations overwhelmingly cause a loss of information, not a net gain, as evolution requires.
Young Earth creationist Joseph Mastropaolo, argues that "Change over time, 'definition one' of evolution, actually describes devolution to extinction, the exact opposite of evolution.... actual epidemiological data from human genetic disorders and fatal birth defects, identify 'natural selection,' the alleged 'primary mechanism' for evolution, as actually a mechanism for devolution to extinction, the exact opposite of evolution." and elsewhere, "Evolution is the development of an organism from its chemicals or primitive state to its present state. Devolution is the sequence toward greater simplicity or disappearance or degeneration."
John C. Sanford
John C. Sanford
-Academic career:Sanford graduated in 1976 from the University of Minnesota with a BSc in horticulture. He then went to the University of Wisconsin–Madison where he received an MSc in 1978 and a PhD in 1980 in plant breeding and genetics. Between 1980 and 1986 Sanford was an assistant professor at...
a plant geneticist
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
and creationist has argued for devolution, he has written a book entitled Genetic Entropy & the Mystery of the Genome (2005) in which he claims that the 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....
is deteriorating and therefore could not have evolved
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...
in the way specified by the Modern evolutionary synthesis
Modern evolutionary synthesis
The modern evolutionary synthesis is a union of ideas from several biological specialties which provides a widely accepted account of evolution...
. Sanford has published two peer reviewed papers modeling genetic entropy.
The creationist author Lee Spetner
Lee Spetner
Lee M. Spetner is an American physicist and author, known best for his critique of the modern evolutionary synthesis. In spite of his opposition to neo-Darwinism, Spetner accepts a form of non-random evolution outlined in his 1996 book "Not By Chance! Shattering the Modern Theory of...
is a critic of the role of mutations in the modern evolutionary synthesis
Modern evolutionary synthesis
The modern evolutionary synthesis is a union of ideas from several biological specialties which provides a widely accepted account of evolution...
, he has argued in his book Not by Chance: Shattering the Modern Theory of Evolution that mutations cause devolution.
Peter Stoner
Peter Stoner
Peter Stoner was Chairman of the Departments of Mathematics and Astronomy at Pasadena City College until 1953; Chairman of the science division, Westmont College, 1953–57; Professor Emeritus of Science, Westmont College; Professor Emeritus of Mathematics and Astronomy, Pasadena City College.Stoner...
an old earth creationist claimed that the universe
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...
was immensely old, writing on astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
he wrote that "every star is losing energy and mass", he claimed that the second law of thermodynamics
Second law of thermodynamics
The second law of thermodynamics is an expression of the tendency that over time, differences in temperature, pressure, and chemical potential equilibrate in an isolated physical system. From the state of thermodynamic equilibrium, the law deduced the principle of the increase of entropy and...
proves "cosmic devolution".
Brian Regal associates devolution with the work of dentist
Dentist
A dentist, also known as a 'dental surgeon', is a doctor that specializes in the diagnosis, prevention, and treatment of diseases and conditions of the oral cavity. The dentist's supporting team aides in providing oral health services...
and creationist Jack Cuozzo. Cuozzo in his book Buried Alive (1998) claims that Neanderthal
Neanderthal
The Neanderthal is an extinct member of the Homo genus known from Pleistocene specimens found in Europe and parts of western and central Asia...
dentition
Dentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...
proves that the Neanderthals lived much longer than modern humans and that modern humans have devolved, according to Cuozzo "it seems as if human jaws are becoming smaller over time".
The concept of devolution is also found in the teachings of Hindu creationism. Michael Cremo
Michael Cremo
Michael A. Cremo , also known as Drutakarma Dasa, is an American Hindu creationist whose work argues that modern humans have lived on the earth for billions of years...
a member of ISKCON has authored a book titled Human Devolution: A Vedic alternative to Darwin's theory, published by ISKCON's Bhaktivedanta Book Publishing, Cremo suggests that Darwinian evolution should be replaced with "devolution" from the original unity with Brahman
Brahman
In Hinduism, Brahman is the one supreme, universal Spirit that is the origin and support of the phenomenal universe. Brahman is sometimes referred to as the Absolute or Godhead which is the Divine Ground of all being...
.
Examples of devolution cited by creationists, include vestigial organs, Stickleback
Stickleback
The Gasterosteidae are a family of fish including the sticklebacks. FishBase currently recognises sixteen species in the family, grouped in five genera. However several of the species have a number of recognised subspecies, and the taxonomy of the family is thought to be in need of revision...
, Amblyopsidae and the Greta oto
Greta oto
The Glasswinged butterfly is a brush-footed butterfly, and is a member of the subfamily Danainae, tribe Ithomiini, subtribe Godyridina....
. Evolutionary biologists point out, however, that examples such as this are not evidence for devolution and the creationists have misunderstood the mechanisms 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...
.
Streamlining evolution
"Devolution", the verb "devolve" and the past participle "devolved" are all common terms in science fictionScience fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...
for changes over time in populations of living things that make them less complex and remove some of their former adaptations. The terminology used herein is nontechnical, but the phenomenon is a real but counter-intuitive one, more accurately known as streamlining evolution. Since the development and maintenance of a feature such as an organ or a metabolite
Metabolite
Metabolites are the intermediates and products of metabolism. The term metabolite is usually restricted to small molecules. A primary metabolite is directly involved in normal growth, development, and reproduction. Alcohol is an example of a primary metabolite produced in large-scale by industrial...
has an 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...
, changes in the environment that reduce the utility of an adaptation may mean that a higher evolutionary fitness is achieved by no longer using the adaptation, thus better using resources. This requires a mutation that inactivates one or more genes, perhaps by a change to DNA methylation
DNA methylation
DNA methylation is a biochemical process that is important for normal development in higher organisms. It involves the addition of a methyl group to the 5 position of the cytosine pyrimidine ring or the number 6 nitrogen of the adenine purine ring...
or a methionine
Methionine
Methionine is an α-amino acid with the chemical formula HO2CCHCH2CH2SCH3. This essential amino acid is classified as nonpolar. This amino-acid is coded by the codon AUG, also known as the initiation codon, since it indicates mRNA's coding region where translation into protein...
codon. Streamlining evolution allows evolution to remove features no longer of much/any use, like scaffolding on a completed bridge.
However, "devolution" in practice typically refers to changes that occur from a problem no longer existing rather than superior solutions existing. For instance, of the several hundred known species of animal that live their entire lives in total darkness, most have non-functional eyes rather than no eyes. This is due, for instance, to deterioration of the optic nerve
Optic nerve
The optic nerve, also called cranial nerve 2, transmits visual information from the retina to the brain. Derived from the embryonic retinal ganglion cell, a diverticulum located in the diencephalon, the optic nerve doesn't regenerate after transection.-Anatomy:The optic nerve is the second of...
. It occurs because mutations that prevent eye formation have low probability. However, several eyeless animal species, such as the Kauai cave wolf spider, who live in total darkness, and whose ancestry mostly had eyes, do exist. Together with 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...
, streamlining evolution makes evolution surprisingly able to produce radical changes, despite being limited to successive, slight modifications.
See also
- DegenerationDegenerationThe idea of degeneration had significant influence on science, art and politics from the 1850s to the 1950s. The social theory developed consequently from Charles Darwin's Theory of Evolution...
- DevoDevoDevo is an American band formed in 1973 consisting of members from Kent and Akron, Ohio. The classic line-up of the band includes two sets of brothers, the Mothersbaughs and the Casales . The band had a #14 Billboard chart hit in 1980 with the single "Whip It", and has maintained a cult...
, a band whose name is a contraction of the term - DysgenicsDysgenicsDysgenics is the study of factors producing the accumulation and perpetuation of defective or disadvantageous genes and traits in offspring of a particular population or species. Dysgenic mutations have been studied in animals such as the mouse and the fruit fly...
- Evolution of complexityEvolution of complexityThe evolution of biological complexity is an important outcome of the process of evolution. Evolution has produced some remarkably complex organisms - although the actual level of complexity is very hard to define or measure accurately in biology, with properties such as gene content, the number of...
- Great chain of beingGreat chain of beingThe great chain of being , is a Christian concept detailing a strict, religious hierarchical structure of all matter and life, believed to have been decreed by the Christian God.-Divisions:...
- HeLaHeLaA HeLa cell is a cell type in an immortal cell line used in scientific research. It is the oldest and most commonly used human cell line. The line was derived from cervical cancer cells taken on February 8, 1951 from Henrietta Lacks, a patient who eventually died of her cancer on October 4, 1951...
- International Society for Krishna Consciousness views on evolution
- Ray LankesterRay LankesterSir E. Ray Lankester KCB, FRS was a British zoologist, born in London.An invertebrate zoologist and evolutionary biologist, he held chairs at University College London and Oxford University. He was the third Director of the Natural History Museum, and was awarded the Copley Medal of the Royal...
, in particular the section Invertebrates and degeneration. - Ulas familyUlas familyThe Ulas family is a large Kurdish family of 19 from rural southern Turkey, five of whom walk on all fours with their feet and the palms of their hands in what is called a "bear crawl". Their quadrupedal gait has never been reported in anatomically intact adult humans. The gait is different from...
- Yeridat ha-dorotYeridat ha-dorotYeridat ha-dorot , meaning literally "the decline of the generations", or nitkatnu ha-dorot , meaning "the diminution of the generations", is a concept in classical Rabbinic Judaism and contemporary Orthodox Judaism expressing a belief of the intellectual inferiority of subsequent, and contemporary...