A similar question was previously answered by Meredith F. Small, associate professor in the anthropology department at Cornell University.
This time we asked Michael J. Dougherty, assistant director and senior staff biologist at Biological Sciences Curriculum Study in Colorado Springs, Colo., to offer his opinion.
From a biological perspective, there is no such thing as devolution. All changes in the gene frequencies of populations--and quite often in the traits those genes influence--are by definition evolutionary changes. The notion that humans might regress or "devolve" presumes that there is a preferred hierarchy of structure and function--say, that legs with feet are better than legs with hooves or that breathing with lungs is better than breathing with gills. But for the organisms possessing those structures, each is a useful adaptation.
Nonetheless, many people evaluate nonhuman organisms according to human anatomy and physiology and mistakenly conclude that humans are the ultimate product, even goal, of evolution. That attitude probably stems from the tendency of humans to think anthropocentrically, but the scholarship of natural theology, which was prominent in 18th-and 19th-century England, codified it even before Lamarck defined biology in the modern sense. Unfortunately, anthropocentric thinking is at the root of many common misconceptions in biology.
Chief among these misconceptions is that species evolve or change because they need to change to adapt to shifting environmental demands; biologists refer to this fallacy as teleology. In fact, more than 99 percent of all species that ever lived are extinct, so clearly there is no requirement that species always adapt successfully. As the fossil record demonstrates, extinction is a perfectly natural--and indeed quite common--response to changing environmental conditions. When species do evolve, it is not out of need but rather because their populations contain organisms with variants of traits that offer a reproductive advantage in a changing environment.
Another misconception is that increasing complexity is the necessary outcome of evolution. In fact, decreasing complexity is common in the record of evolution. For example, the lower jaw in vertebrates shows decreasing complexity, as measured by the numbers of bones, from fish to reptiles to mammals. (Evolution adapted the extra jaw bones into ear bones.) Likewise, ancestral horses had several toes on each foot; modern horses have a single toe with a hoof.
Evolution, not devolution, selected for those adaptations.
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13 Comments
Add CommentI think you missed the main point of proponents of human devolution. Bone complexity is one thing, but a decrease in intelligence and ability to solve problems is a completely different issue. The fact that today's population so heavily relies on machines to do the majority of the work and "thinking" for them, has and will continue to have a large impact on the ability for the majority of the population to survive when things start to break down. This will result in an Asimov-style world where humans will devolve to the point where they will have to reinvent the wheel.
Reply | Report Abuse | Link to thisThere is no such thing as devolution!
Reply | Report Abuse | Link to thisA loss of eyes or skin pigment from living in caves is evolution.
The loss of digestives systems in parasitic worms because their food is already digested is evolution. In both cases the most fit organisms do not waste energy making structures they do not need.
Evolution is ALWAYS uphill, in a positive direction.
Intelligence, health, problem solving abilities, strength - these traits once offered a reproductive advantage ensuring that the same traits would be found in the next generation. Unfortunately, most intelligent people put off having children until later in life today, and then they have only one or two offspring. The least intelligent, least capable people on the planet start having children at 15 years of age and have a new baby every year or two for the rest of their reproductive lives. Furthermore, even though they may be too poor or too stupid to raise those children properly, society steps in and provides financial assistance. Today the reproductive advantage goes to the least intelligent, most irresponsible segment of society simply because they breed the most. It doesn't take a rocket scientist to figure out the consequences.
Reply | Report Abuse | Link to thisSpeaking in terms of "uphill" and "downhill" without specifying what those concretely mean is misleading. Moreover, evolution quite often involves "survival of the not-so-bad" and "survival of the just-plain-lucky".
Reply | Report Abuse | Link to thisWhile I certainly think that intelligence is a wonderful trait for human beings to have, I am not blessed with the omniscience to prove that it will lead to the reproductive (or even ethical) improvement of our species several million years from now. If one could ask an ancient hominid what trait he wished to increase in his species, it might well have been the ability to go longer without food rather than a larger capacity for logical reasoning.
Eugenics movements that aim to breed humans for a trait (besides the ethical problems with them) are ultimately shortsighted moves. Genetic diversity is the real key to the health of our species.
what if humans are devolving because of inbreeding.. i mean if in this society women change there last name to the mans that would mean that throughout the generations it could be that you and your spouse could have shared a common ancestor.. and it could slowly happen to every generation to come without knowing..
Reply | Report Abuse | Link to thisIn addition to what elizabettac123 said, a loss of natural selection also means that our collective dna will degrade over time due to a build up of negative mutations (harmful mutations are much more common than beneficial ones). Eugenics is the solution.
Reply | Report Abuse | Link to thisThis should branch to not only physical morphological variation/adaptation, but should consider neurological, physiology, epigenomic expression, and a close look at changes in major histone compatibility complex(s). Yes, an undergrad is looking for a project to work on!
Reply | Report Abuse | Link to thisI'm not sure if evolution is an uphill or downhill progression. What if it didn't have a directional value at all? Perhaps evolution can be best understood as either a constant or not. Either a species is "progressing" or it isn't. Projecting this perception to say, various segments of today's human race could we not say evolution is struggling to exist? First we need to look at geographical location. North Korea for example, is not evolving to their population's benefit. America and Australia, are not evolving for the benefit of our ecosystem. Europe evolves intellectually but outgrew her environment with too many close quarter competitors for resources resulting in a form of habitat loss. Muslim communities constantly evolve towards their survival with the method of overwhelmingly increasing their population while other communities are decreasing their population regrowth due to contraception, career progression, personal desires and the "new age" view toward life. If you haven't ever understood the term "survival of the fittest" or "natural selection" simply observe what's occurring across the globe today through scientific eyes. Devolution exists friends, it is simply evolution in the state of dormancy.
Reply | Report Abuse | Link to thisInbred devolution is a certainty in some situations.
Reply | Report Abuse | Link to thisWhen a genetically diverse population of domestic rabbits was released to invade a new area of Port Coquitlam, British Columbia, all the rabbits that remained in the population after some time were black rabbits some of which showed fur loss from inbreeding. Anyone looking at that population of rabbits assumed that there had been only a small number of rabbits released, or perhaps there had been a population bottleneck. The assumptions are false.
Also, in human beings, there is genetic homozygosity within races known from DNA sampling. This means that all human races are inbred. The most populous races have the least diversity; similar hair, eye, and skin colour, for instance. Which means that the problem gets worse and not better as overpopulation continues.
The population genetics model I have come up with to explain this phenomenon simply includes the fact that individuals that have the most children reacquire the genetics to have the most children (after marrying "out") by inbreeding. I have found no prior population genetics model which does this so either I have discovered or rediscovered a new principle in evolutionary science.
Nor do genetic algorithms I have studied include this principle. To mathematically model it is necessary to suppose, in gist, that N genes are needed for a male to have N children, which must match N female genes (same or different).
I am sure this model goes inbred, random matings or otherwise, but the story is not over there. The inbred overpopulator acquires the traits for outnumbering and stifling genetic disimilarities in the population. Mass exclusion, harrassment, lies, misperception, rioting, assault, war.... are the consequence.
Finally I figured out the answer: Yes.
Reply | Report Abuse | Link to thisThe Evidence: http://www.youtube.com/watch?v=bUJjr5GRxCo&feature=share
Friggin schvartzm!
Reply | Report Abuse | Link to thisIts interesting how fast and loose the term evolution can be used. Is it really honest to say that any change, even degenerative change is evidence of macro evolution simply because even degeneration can technically be considered change, therefore evolution? Shouldn't evolution go from simple to more complex, or at least be able to explain where or how the already complex parent population came to exist in the first place? Lets either extend the neo Darwinian/modern synthesis, or admit its severe limitations as an explanatory mechanism in being able to quantify macro change. The modern synthesis is severely out of date and no longer modern but antiquated.
Reply | Report Abuse | Link to thisI completely agree with you, almost five years later.
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