Devolution (biology) - Wikipedia, the free encyclopedia

Devolution (biology) - Wikipedia, the free encyclopedia: Devolution, de-evolution, or backward evolution is the notion that species can change into more "primitive" forms over time. In modern biology the term is redundant: evolutionary science deals with selection or adaptation that results in populations of organisms genetically different from their ancestral forms. The discipline makes no general distinction between changes leading to populations of forms less complex or more complex than their ancestors, and in such terms the concept of a primitive species cannot be defined consistently. Consequently, within the discipline such a word is rarely useful.

Current non-technical application of the concept of "devolution" is based largely on the fallacies that:

• in biology there is a preferred hierarchy of structure and function, and that
• evolution must mean "progress" to "more advanced" organisms with more complex structure and function.

Those errors in turn are related to two misconceptions: that:

• evolution is supposed to make species more "advanced", as opposed to "primitive"; and that
• modern species that have lost some of the functions or complexity of their ancestors must accordingly be degenerate forms. (Note however that degeneracy in this context has little to do with the current technical use of the term degeneracy in biology).

The term "devolution" and its associated concepts never were prominent in biology and now are at most of historical interest, except where they have been adopted by creationists.

The concept of devolution as regress from progress relates to the ancient ideas that either life came into being through special creation or that humans are the ultimate product or goal of evolution. The latter 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, in contrast, if 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 most of the tail found in many other mammals - not to mention other vestigial structures, such as the vermiform appendix or the nictitating membrane.

Degeneration theory

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 diet. 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:

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.