Ever since Adam and Eve: The Evolution of Human Sexuality

Ever since Adam and Eve: The Evolution of Human Sexuality, by Malcolm Potts and Roger Short. Cambridge, UK; New York, NY; Melbourne, Australia: Cambridge University Press, 1999. 358 pp. $74.95 (hardback); $29.95 (paperback).

Interest in the evolution of human behavior has soared in the years since primatologists began bringing back detailed data on monkey and ape sociality and sexuality from the field nearly half a century ago. The developments in sociobiology and evolutionary psychology pushed curiosity about behavioral evolution further. Potts and Short's book attempts to integrate the picture of the adaptability of human sexuality from a broad range of topics and several major themes.

One major theme is the difference between male and female reproductive strategies. It shows up in their discussion of the asymmetrical investment of males and females; the polygynous human male, seeking numerous sexual partners, and the monogamous female, focusing on fewer, committed sexual relationships. It underlies their chapters on gender roles and love and marriage; emphasizing the variations on control and freedom of the sexes in societies as diverse as the San Bushmen, agricultural communities in India, and urban industrial in east and west. It has full force when they talk about changes in social group size, power between the sexes, and the effects of economic changes from gathering societies, through agricultural to industrial and postindustrial economies.

The first seven chapters deal with the physiology of reproduction (sex, bonding, birth, growth), focusing on the individual or pair and their relationships. The last six chapters take on broader issues of the reproducing couple in the larger society and the effects of civilization, power, politics, and disease. This book is replete with examples from many different cultures and has numerous sidebars with examples to support the text (though in some cases it is hard to see the relationship). It deals primarily with recent and living humans and leaves the evolution of human sexuality to an occasional mention rather than extended discussion.

The plates are elegant, almost worthy of a coffee-table volume.

Even with its impressive range of information about human reproduction, growth, sociality, and sexuality, the book suffers from a number of inaccuracies. In the areas of the authors' expertise they do well. When they stray beyond those limits the information is often wrong, misinterpreted, or incomplete. For the fossil human record, on page 84 they claim large canines for Australopithecus. Even the earliest have nothing like the large fighting canines of the chimpanzee or gorilla male. There is a disconcerting tendency to use European cultural practices as a norm for humans in general. On page 87, they note that "Sometime in the nineteenth century it became almost universal for the married couples to sleep in the same bed." Many humans in other parts of the world do so.

As another example: they say that most birds have to find their own food right after they hatch and that pigeons, who produce crop milk, are one of the few examples of birds providing nourishment for their young. While producing "milk" is rare in birds, in fact, many birds regurgitate food to feed their young and many others lead their young to feeding grounds. Further, on page 167 they note that humans lack instinctive bonding at birth, leading to the ability to adopt and share children. We have numerous cases in the wild of other primates adopting infants when the mother dies. Another problem in this statement is that it ignores the evidence of bonding between mother and infant at birth and contrasts with the authors' own discussion of bonding when they later discuss the effects of wet-nursing on the birth mother-child relationship. It also ignores the complexities of development and interaction involved in what used to be called instinct. Most humans are less free of their biology, and most animals are freer of theirs than we used to think.

A further example of using older concepts and a missed chance to discuss evolution shows up on page 115, where they mention a high proportion of abnormal sperm in human males. There are strong indications that many of the different forms of sperm have different functions. Some are for fertilization, others help those reach the egg and do their job.

The authors miss many chances to integrate evolution into the mainstream of the book. The occasional mention of other primates is not organized to show an evolutionary relationship, but more to set humanity apart from our relatives. They note that no ape males sleep in nests with females, while the human sexes recently began sleeping together. At least the shared nesting (even if separated by sex in them) abilities could have been used to show shared object manipulation. The discussion of bonobo sex beyond that necessary for reproduction when raising human sexual bonding as an issue did not stimulate a discussion of possible evolutionary implications. Most of the book is a compilation of variations on the human patterns of marriage, power, growth, development, and response to disease, useful in its own right, but not particularly helpful in understanding how we came to be what we are.