AMUNDSON, R.; Univ of Hawaii at Hilo: Evo-devo�s Hard Problem: Natural Selection

Three broad problems faced evo-devo during the 20th century, and two have been solved. The problems were 1) To find a level of description of evolutionary processes that also expressed ontogeny. Heterochrony and allometry were unsuccessful candidates. 2) The dominance of transmission genetics, and its uncomfortable relations with developmental biology (n�e embryology). The transmission genetic basis of the Evolutionary Synthesis served as a kind of buffer between evolution and development. 3) The methodological accusation that developmental evolutionary theorists were typological, while proper evolutionists were population thinkers. Even though this seemed the most rhetorical, it is the problem that persists. The first two were solved when developmental genetics matured in the 1990s. Developmental genetics replaced the developmentally recalcitrant tradition of transmission genetics, and (when understood phylogenetically) it covers the ontogeny/phylogeny divide. It may seem that the third problem is solved also: the accusations of �typological thinking� have abated. But this is only an illusion born of the prestige of developmental genetics. The accusations of typological thinking were heavily rhetorical and historically inaccurate, but they contained a kernel of truth. I argued in The Changing Role of the Embryo in Evolutionary Thought that certain basic concepts of evo-devo indeed seem to violate the principles of population thinking. This does not make them unscientific (contrary to earlier rhetoric), but it poses a problem for the unification of evo-devo with standard views of the operation of natural selection. I will discuss some informal attempts made by evo-devo-ists to solve the problem, and how these attempts fail. In conclusion I will summarize as succinctly as possible what remains of the old challenge: typological thinking is inconsistent with natural selection.