Sociobiology and evolutionary psychology are related fields, both of which claim that biology is the principal determinant in human affairs. Sociobiology was initially, and by some accounts is entirely, the study of the genetic bases of animal behavior. Sociobiologists regularly also attempt to explain human behavior. Sociobiology is, as the term suggests, the biology of animal and human society. Sociobiology preceded and developed into evolutionary psychology, which features mental dispositions more than genes as the evolutionary determinants. The relationship of the two disciplines is both congenial and contested.

Even more contested, by biologists, social scientists, and humanists alike, is how far either discipline succeeds. Edward O. Wilson, the founder of sociobiology, calls it a "new holism," even, with capitals, "the Modern Synthesis" (1975, pp. 7, 4). But critics see it as genetic reductionism. Evolutionary psychologists claim that humans have what Jerome H. Barkow, Leda Cosmides, and John Tooby call...