User:Jaspergeli/Atavism
From Wikipedia, the free encyclopedia
In biology, an atavism is a modification of a biological structure whereby an ancestral trait reappears after having been lost through the evolutionary change in previous generations. Atavisms can occur in several ways; one of which is when genes for previously existing phenotypic features are preserved in DNA, and these become expressed through a mutation that either knocks out the overriding genes for the new traits or makes the old traits override the new one. A number of traits can vary as a result of shortening of the fetal development of a trait (neoteny) or by prolongation of the same. In such a case, a shift in the time a trait is allowed to develop before it is fixed can bring forth an ancestral phenotype. Atavisms are often seen as evidence of evolution.
In social sciences, atavisms describe a cultural tendency of reversion. For example, people in the modern era reverting to the ways of thinking and acting in a former time. The word atavism is derived from the Latin atavus—a great-great-great-grandfather or, more generally, an ancestor.