As I was talking with Horst Schneider earlier this afternoon, I nonchalantly guessed that at least ninety percent of human behavior could be understood by the study of other primates, such as chimpanzees, orangutans, and gorillas. We were talking about our friends and acquaintances, it goes without saying. Ever since our talk several hours ago, I have been wondering about my wild guess. Have I overshot? If so, by how much? But the more I think about it, and the more carefully I look at people milling around me, the more I am convinced that I have undershot. And by a wide margin.