Evolution proposes and ontogeny disposes

Genes, the basic building blocks of evolution, are highly conserved. For ex ample, the mouse and human have approximately the same number of genes, and around 94% are identical in the two species. Since species differ on multi ple dimensions (e.g.. anatomy, physiology, and behavior), it follows that i dentical genes may subserve different functions in different species. Two r easons for this are gene-gene interaction and gene-environment interaction land it is the presence of these interactions which prevents one from makin g deterministic statements about genetics, thus rendering obsolete the natu re-nurture controversy). Behavioral examples of both types of interactions are presented, including studies showing that (1) the uterine environment e nhances later cognitive competence, (2) early postnatal experiences affect learning and emotionality and can extend into future generations, (3) mater nal behavior changes the offspring's later behavior and physiology, and (3) knocking out one gene results in an animal less competent in one learning process but more competent in a complementary learning process. (C) 2000 Ac ademic Press.