Behave: The Biology of Humans at Our Best and Worst

by Robert M. Sapolsky

and this is the most important idea in the book: when you explain a behavior with one of these disciplines, you are implicitly invoking all the disciplines—any given type of explanation is the end product of the influences that preceded it. It has to work this way. If you say, “The behavior occurred because of the release of neurochemical Y in the brain,” you are also saying, “The behavior occurred because the heavy secretion of hormone X this morning increased the levels of neurochemical Y.” You’re also saying, “The behavior occurred because the environment in which that person was raised made her brain more likely to release neurochemical Y in response to certain types of stimuli.” And you’re also saying, “. . . because of the gene that codes for the particular version of neurochemical Y.” And if you’ve so much as whispered the word “gene,” you’re also saying, “. . . and because of the millennia of factors that shaped the evolution of that particular gene.” And so on.