On Human Nature

I recently finished reading On Human Nature by Edward O. Wilson. The premise of this book is that natural selection has shaped human nature. This is a premise I already agree with. It has come up in other reading I have done. The importance of this book is that it one of the first books on the subject, and perhaps the first to focus on it in depth. Wilson applies this idea to better understanding aggression, sex, altruism, and religion. I should read it again sometime, because I can't recall enough of it to say much in detail here. Some details I remember: The Aztecs practices human sacrifice and cannibalism, because they had a low population of big game animals. The Indians (of India) dealt with the same situation by creating religions that favored vegetarianism (Jainism, maybe Buddhism) or allowed meat only to the Brahmin caste (Hinduism). The sisterhood social structure of some insects (ants and bees) is due to the ability to reproduce by haplodiploidy, the ability to determine the sex of offspring males coming from unfertilized eggs, females from fertilized eggs. Among humans, females are more commonly conceived during times of stress, because females are more durable. Female humans tend to mate with someone of equal or higher social rank. Some social behaviors are hypertrophies of earlier adaptations, meaning that they are exaggerated forms of them. Most altruism has been limited in scope, favoring one's own relations or group.  Religions tend to unite people together, helping to create and maintain a group identity. So, people have evolved to have some tendency toward religion. Gay animals are common, and gays may have evolved to limit destructive competition among members of the same gene pool, because there is more survival advantage for the genes in gay uncles taking care of nieces and nephews than there is in brothers killing brothers for the same woman.