Organic selection: Proximate environmental effects on the evolution of morphology and behaviour

Organic selection (the Baldwin Effect) by which an environmentally elicited phenotypic adaptation comes under genotypic control following selection was proposed independently in 1896 by the psychologists James Baldwin and Conwy Lloyd Morgan and by the paleontologist Henry Fairfield Osborn. Modified forms of organic selection were proposed as autonomization by Schmalhausen in 1938, as genetic assimilation by Waddington in 1942, and as an explanation for evolution in changing environments or for speciation by Matsuda and West-Eberhard in the 1980s. Organic selection as a mechanism mediating proximate environmental effects on the evolution of morphology and behaviour is the topic of this essay. Discussion includes the context in which organic selection was proposed, Lamarckian or neo-lamarckian implications of organic selection, Waddington's experimental studies demonstrating the existence and efficacy of genetic assimilation, stabilizing selection and norms of reaction favoured by Schmalhausen, and Matsuda's search for a mechanism of organic selection in endocrine changes and in heterochrony.