The unusual social structure and behavioural repertoire of bonobos make them especially interesting. Alhough bonobos are philopatric (males stay in their birth group and females move at adolescence), it is the females who are dominant and it is bonding between them, and between mothers and sons, which holds groups together. Bonobo sexuality is also notable. "Sex occurs in virtually all partner combinations and in a unique variety of positions" and among other behaviours bonobos regularly engage in homosexual sex, face-to-face mating, and masturbation. Sex has many uses other than reproduction: for pleasure, for resolving tensions over food, and as an alternative to confrontation. (De Waal theorises that the origins of these traits lie in the importance of avoiding infanticide: while infanticide is a common cause of death for chimpanzee infants, it seems to be non-existent in bonobos.)
Most of the material in Bonobo is anecdotal, consisting of informal descriptions of bonobo behaviour. But de Waal does address issues of observational methodology (there are differences between the two main study sites in Zaire and, of course, with captive populations) and as a balance to his own interpretations includes interviews with other primatologists who have studied bonobos. References and a bibliography are also provided. But what leaps out from the book are the scores of pages of Lanting's full-page colour photographs, which bring bonobos before the reader with stunning immediacy.
De Waal warns against idealising bonobos; he is also cautious about drawing inferences about H sapiens from them. Others have not always been so careful, however, and one thing this book will do is to counter some of the wilder ideas about our own species based on extrapolation from gorillas and chimpanzees or on speculative guesswork (such as "killer ape" theories or claims for the uniqueness of female orgasm). Certainly it should help to put the final nails in the coffin of claims that various human sexual behaviours are "unnatural".
Sex does sell, so Bonobo: The Forgotten Ape is likely to have wide appeal. My fear is that the price that goes with the large format and the colour photographs will prevent it reaching as large an audience as books like The Naked Ape. On the other hand, it's a great conversation-starter to leave lying around the coffee table — if you aren't worried about upsetting the prudish!