“There is no nature that exists devoid of nurture; there is no nurture that develops without nature. To say otherwise is like saying that the area of a field is determined by its length but not its width. Every behavior is the product of an instinct trained by experience.

The study of human beings remained resolutely unreformed by these ideas until a few years ago. Even now, most anthropologists and social scientists are firmly committed to the view that evolution has nothing to tell them. Human bodies are products of "culture," and human culture does not reflect human nature, but the reverse. This restricts social scientists to investigation only differences between cultures and between individuals--and to exaggerating them. Yet what is most interesting to me about human beings is the things that are the same, not what is different--things like grammatical language, hierarchy, romantic love, sexual jealousy, long-term bongs between the genders ("marriage", in a sense). These are trainable instincts peculiar to out species and are just as surely the products of evolution as eyes and thumbs.”