Devolution (Biology) (Paperback)

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In common parlance, "devolution," "de-evolution," or backward evolution is the notion that a species can change into a more "primitive" form. 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. 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, but earlier views that species are subject to "racial decay"or "drives to perfection" or "devolution" have been rejected.