On the difficulty in getting out of historical ruts: Waddington and an argument for behavioral epigenetics

In the early days of evolutionary theory, biologists studied development to discover phylogenetic connections among species through embryological similarities, and psychologists such as James Mark Baldwin and Sigmund Freud constructed theories that combined evolution with social, cognitive, and emotional development. But after the fall of Lamarckian and recapitulation theories, Mendelian population genetics focused on direct correlations between genes and adult characteristics to the exclusion of embryology and the ontogeny of phenotypes. Psychologists followed suit, and began to search for genes “for” psychological characteristics, a reductionist tendency that continues to this day. But C.H. Waddington's sophisticated theories of epigenesis provide a way to reintegrate development with genetics along with a more cohesive description of gene-environment linkages. This paper examines how history has canalized thought about genes in psychology, and provides examples of current research to show the way out of such conceptual ruts.

► Discussions of genetic effects in psychology often ignore developmental processes.
► This is a historical artifact of the separation of epigenesis from genetics.
► C. H. Waddington's concepts of epigenetic landscape and epigenome avoided the split.
► Studies show different reaction norms in attachment under varied rearing environments.
► Plastic canalized ontogenetic pathways should replace a nature-nurture dichotomy.