My favorite books for understanding the biological basis of social life

The author seeks to use evolutionary principles to explain why human violence within societies is uncommon whereas violence between societies, expressed mainly as war, is very common. Chimpanzees are a violent species in which both types of violence are extremely common. Males compete for dominance in violent ways and males frequently direct their violence toward females. But with respect to within-society violence humans have “domesticated” themselves, mostly by, over hundreds of thousands of years, killing the most violent and dangerous males. With respect to between-society violence, however, humans remain chimp-like. Chimps are notorious for intercommunity raiding and killing, and the anthropological and archaeological evidence shows that humans are equally notorious. Humans have therefore evolved to be both nice and nasty—and therein lies the paradox expressed in the book’s subtitle.

This husband-wife team uses Darwinian natural selectionist thinking to account for the most important features of homicide throughout the world. A basic principle of Darwinian theory is known as kin selection, which means that people favor kin over nonkin and close kin over distant kin. In this regard, the authors show, for example, that people are much more likely to kill unrelated acquaintances and strangers than genetic kin, and that child homicide is perpetrated much more often by stepparents than by natural parents. The authors also show that there is a huge sex difference in rates of killing. Throughout the world the vast majority of killing is done by men. This is because men are competing with other men for the status and resources needed to secure mates for reproduction.

In this exceptionally well-written and engaging book, the author, an evolutionary anthropologist and feminist, shows that women need to mother but that successful mothering is highly contingent on context. Mothers are primed to bond with their infants, but this process can be short-circuited when the conditions for successfully rearing an infant are poor. Infanticide is a common practice throughout the world but is most likely to occur when there is a lack of sufficient resources, when the infant is defective, when a mother lacks social support, or when there are doubts about paternity.

The author challenges the prevailing orthodoxy that the differences between men and women, and their respective roles in the work world, are the result of differential socialization. His view is that there are important biological differences between the sexes that lead them to choose different kinds of work. Women, for example, prefer jobs that involve working with people whereas men prefer working with things. Women also frequently choose part-time work because this allows them to spend more time with their children. Men are more likely than women to compete for high-status jobs because they are naturally more competitive than women. Male-female differences have been shaped over hundreds of thousands of years by evolution.

This is a classic work taking a Darwinian perspective on human sexual behavior. A central theme is that there are sharp differences between male and female sexuality. Male sexuality is more urgent and less discriminating than female sexuality. Males also have a stronger desire than females for sexual variety. This is because males can promote their reproductive success by mating with many females, whereas sexual variety provides no real reproductive advantage for females. Males are in competition with other males for access to mates, especially mates of high reproductive value. The author takes up the question of whether the female orgasm is an adaptation or a by-product of the male organism, concluding that it is a by-product.