Devolution (biology)

In common parlance, "devolution", "de-evolution", or backward evolution is the notion that a species can change into a more "primitive" form. Biologically, it is a misnomer because evolution does not have a direction or motive. So, its reverse is not possible. So, in simple terms, devolution may be stated as a form of evolution where organisms evolve to be in simpler forms. It is associated with the idea that evolution is supposed to make species more advanced, and that some modern species have lost functions or complexity and seem to be degenerate forms of their ancestors. This view is rejected by modern evolutionary theory, in which adaptation arises from natural selection of forms best suited to the environment, and so can lead to loss of features when these features are costly to maintain. Thus for cave dwelling animals the loss of eyes arises because it is an advantage, not degeneracy.^[1]

The idea of devolution can arise from thinking that "evolution" requires some sort of purposeful direction towards "increasing complexity". Modern evolution theory accepts the possibility of decreasing complexity, as in vestigiality, in the course of evolutionary change,^[2] but earlier views that species are subject to "racial decay"or "drives to perfection" or "devolution" have been rejected.^[3] 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 mutations happen to give a better chance of successful reproduction in the environment they arise in, while the many disadvantageous mutations are lost.

Concepts underlying ideas of devolution

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 "lungs are better than gills", 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.^[2]

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.^[2]

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.^[2]

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 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.^[4] 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".^[5] 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.^[6]

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".^[7][8]

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.^[9]

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."^[10]

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".^[11][12] 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.^[13]

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.^[14] The entomologist William Morton Wheeler^[15] and the Lamarckian E.W. MacBride (1866-1940) also advocated degenerative evolution. According to Macbride invertebrates were actually degenerate vertebrates, his arguement was based on the idea that "crawling on the seabed was inherently less stimulating than swimming in open waters."^[16]

Dollo's law

Main article: 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 cetacea—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.

Degeneration theory

Johan Friedrich Blumenbach 1752 - 1840

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.^[17]

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.^[18]

According to Blumenbach there are five races all belonging to a single species: Caucasian, Mongolian, Ethiopian, American and Malay. Blumenbach however stated:

I have allotted the first place to the Caucasian because this stock displays the most beautiful race of men.^[19]

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.^[19]

Use of the term by proponents of creationism

According to Christian 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.^[20]

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",^[21] 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".^[22] 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:

Accordingly, by every just rule of comparison and analogy, we may well declare that if there is any blood relationship between man and the anthropoid apes, it is the latter which have degenerated from the former, instead of the former having developed from the latter. I do not say that this is the true solution of this enigma; but I do say that there is far more scientific evidence in favour of this hypothesis than there ever has been in favour of the long popular theory that man is a developed animal.^[23]

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:

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!^[24]

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 sinning 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.^[25]

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.^[26]

Young Earth creationist Joseph Mastropaolo,^[27] 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,^[28] "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)^[29] 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.^[30][31]

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.^[32]

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".^[33]

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".^[34][35]

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,^[36] 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^[37], Stickleback, Amblyopsidae and the Greta oto.^[38] Evolutionary biologists point out, however, that examples such as this are not evidence for devolution and the creationists have misunderstood the mechanisms of evolution.^[39]

Streamlining evolution

"Devolution", the verb "devolve" and the past participle "devolved" are all common terms in science fiction 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^{[citation needed]}. 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.

See also

• Degeneration
• Devo, a band whose name is a contraction of the term
• Dysgenics
• Evolution of complexity
• Great chain of being
• HeLa
• International Society for Krishna Consciousness views on evolution
• Ray Lankester, in particular the section Invertebrates and degeneration.
• Ulas family
• Yeridat ha-dorot

Notes and citations

1. ^ TalkOrigins Archive response to Creationist claims - Claim CB932: Evolution of degenerate forms
2. ^ ^{a b c d} Michael J. Dougherty. Is the human race evolving or devolving? Scientific American July 20, 1998.
3. ^ "Darwin's precursors and influences: Glossary". http://www.talkorigins.org/faqs/precursors/glossary.html. Retrieved 2010-01-18. 
4. ^ History, Humanity and Evolution: Essays for John C. Greene By James Richard Moore, p. 331
5. ^ Renovating Russia: the human sciences and the fate of liberal modernity, 1880-1930, Daniel Beer, 2008, p. 36
6. ^ Late Victorian Gothic tales, 2005, Roger Luckhurst, p. 20 Link
7. ^ Darwin's Screens: Evolutionary Aesthetics, Time and Sexual Display in the Cinema By Barbara Creed, 2009, p. 8
8. ^ Nietzsche, biology, and metaphor, Gregory Moore, Friedrich Wilhelm Nietzsche, 2002, p. 117
9. ^ Life's splendid drama: evolutionary biology and the reconstruction of life's ancestry 1860-1940, Peter J. Bowler, 1996, p. 164
10. ^ The eclipse of Darwinism: anti-Darwinian evolution theories in the decades around 1990, Peter J. Bowler, 1992, p. 161
11. ^ Evolution: the history of an idea, Peter J. Bowler, 1989, p. 263
12. ^ The Encyclopædia britannica: a dictionary of arts, sciences, literature and general information, Volume 20, Hugh Chisholm, The Encyclopædia britannica company, 1911, p. 590
13. ^ Evolution: the history of an idea, Peter J. Bowler, 1989, p. 249
14. ^ The biology of hypogean fishes, Aldemaro Romero, Aldemaro Romero Díaz, 2001, p. 57
15. ^ Darwinian heresies, Abigail Lustig, Robert John Richards, Michael Ruse, 2004, p.11
16. ^ Life's splendid drama: evolutionary biology and the reconstruction of life's ancestry 1860-1940, Peter J. Bowler, 1996, p. 432
17. ^ Marvin Harris, The rise of anthropological theory: a history of theories of culture, 2001, p. 84.
18. ^ Marvin Harris, The rise of anthropological theory: a history of theories of culture, 2001, p. 84
19. ^ ^{a b} Emmanuel Chukwudi Eze, Race and the enlightenment: a reader, 1997, p. 79
20. ^ Aegyptopithecus the ‘Egyptian ape’ by Matthew Murdock Link
21. ^ Raymond Weschler (2005). "Inherit the Wind (Drama) ( 1960)" (PDF). ESLnotes.com – The English Learner Movie Guides. p. 10. http://www.eslnotes.com/movies/pdf/inherit-the-wind.pdf. Retrieved 2010-01-18. 
22. ^ Curator (1995). "The Scopes "Monkey Trial," or "A 1925 Media Circus"". Borndigital. http://www.borndigital.com/scopes.htm. Retrieved 2010-01-18. 
23. ^ George McReady Price, The Phantom of Organic Evolution, New York: New York: Fleming H. Revell, 1924, reprinted in Selected Works of George McCready Price, ed. Ronald L. Numbers, New York: Garland Publishing, 1995, ISBN 0-8153-1808-1. volume 7 of the series Creationism in Twentieth Century America. Chapter IX Section V, page 210-211 (pages 446-447 of reprint). Italics in original.
24. ^ Douglas Dewar, The Transformist Illusion. 2005 edition, p. 42
25. ^ Ken Ham, New Answer Book 2, Green Forest, AR: Master Books, 2008, p. 32
26. ^ Ken Ham, New Answer Book 2, Green Forest, AR: Master Books, 2008, p. 34
27. ^ Biology vs Evolution, Joseph Mastropaolo, Creation Research Society Quarterly 38: 151-158, 2001
28. ^ Biology Eliminates Evolution and Confirms Genesis (pdf) (google cache [1])
29. ^ Sanford, John C. (2005). Genetic Entropy & the Mystery of the Genome. Ivan Press. ISBN. 
30. ^ Sanford, J.C., Baumgardner, J., Gibson, P., Brewer, W., ReMine, W. (2007). Mendel's Accountant: a biologically realistic forward-time population genetics program. SCPE 8(2): 147-165. http://www.scpe.org.
31. ^ Sanford, J.C., Baumgardner, J., Gibson, P., Brewer, W., ReMine, W. (2007). Using computer simulation to understand mutation accumulation dynamics and genetic load. In Shi et al. (Eds.), ICCS 2007, Part II, LNCS 4488 (pp.386-392), Springer-Verlag, Berlin, Heidelberg.
32. ^ Lee Spetner, Not by Chance, Shattering the Modern Theory of Evolution, 1996, pp 131 - 138
33. ^ Redeeming culture: American religion in an age of science, James Burkhart Gilbert, 1997, p. 154
34. ^ Human evolution: a guide to the debates, Brian Regal, 2004, p. 223
35. ^ Creation, Devolution and wisdom teeth Online
36. ^ Cremo, Michael (2003). Human Devolution: A Vedic alternative to Darwin's theory. Bhaktivedanta Book Publishing. ISBN 0892133341. 
37. ^ ‘Vestigial’ Organs: What do they prove? by Dr Don Batten and Dr Jonathan Sarfati
38. ^ See examples cited by creationists Stickleback and Glasswing
39. ^ NSS Bulletin Vol. 47 No. 2 P. 86-88 Can Evolution Regress? Aldemaro Romero