Nature 437, 33-34 (1 September 2005)
We are closely related to other apes, but how similar are we really?
BOOK REVIEWED - Our Inner Ape by Frans de Waal, Riverhead: 2005. 288 pp. $25.95.
To be published in November by Granta, London.
cientists often become agitated when confronted with someone who does not believe in evolution - especially when, as in the United States, such people try to dictate what facts our schoolchildren are taught. Only slightly less distressing is meeting someone who enthusiastically embraces evolution but with enough misconceptions to make Darwin turn in his grave. In this excellent book for the public, Frans de Waal tackles some exasperating misconceptions about the evolution of the social behaviour of apes, particularly humans.
The misconceptions rest on two things: Jane Goodall and the number 98. Goodall has long astonished the world with her discoveries about the behaviour of wild chimpanzees. And it was she who reported the profoundly disturbing fact that chimpanzee social life can include murder, cannibalism and organized inter-group violence, findings widely disseminated by the National Geographic. And 98 is approximately the unnervingly high percentage of DNA that humans share with chimps. Combine those two and our fate appears sealed: our closest relative, with whom we are nearly genetically identical, is a murderous thug. There you have it, our human-as-killer-ape destiny.
The antidote to all this is the bonobo. Once known as the pygmy chimp, the bonobo is now recognized to be a separate species, and from taxonomic and genetic standpoints, we are as closely related to it as to the chimpanzee. And the bonobo is very different. Males are not particularly aggressive, and lack the massive musculature typical of species (such as chimps) in which a male's ability to pass on copies of his genes depends heavily on his ability to pummel other males. Moreover, the bonobo social system is female dominated, food is often shared, and there are well developed means for reconciling social tensions.
And then there is sex. Bonobo sex is the prurient highlight of primatology conferences and it makes parents shield children's eyes when watching nature films. Bonobos have sex in every conceivable (and inconceivable) position, in pairs or otherwise, within gender, between gender, to greet someone, to solve social conflicts, to work off steam after being scared by a predator, to celebrate finding food, to cajole the sharing of it... or just because. As has become the sound bite to contrast the two species, chimps are from Mars and bonobos are from Venus.
De Waal is uniquely qualified to be our guide to the different social worlds of these two relatives, as an immensely accomplished primatologist and an expert on both species. For example, his book Chimpanzee Politics (Jonathan Cape, 1982) is a classic analysis of chimp machinations over power, and Bonobo (University of California Press, 1997) is one of the few monographs on the species.
Our Inner Ape is organized into chapters analysing the two species' use of power, their sexual and aggressive behaviours, and their capacity for kindness. What's more, the writing is clear and witty.
So, one asks breathlessly, is de Waal's line that we humans are like chimps or bonobos? A lesser scientist with one ideological bent would say this isn't a perfect world and surrender to our unfortunate chimpness. And an ideologue of a different stripe would debunk the idea of our chimpish nature and search for our inner bonobo. But de Waal raises deeper points.
First, neither chimps nor bonobos are what humans were like in our ancestral past. While we've been busy evolving in the 5 million or so years since the last ancestor we shared with these species, chimps and bonobos have not been frozen museum displays: they are our contemporaneous cousins, not our ancestors.
Second, in every realm of our behaviour and biology, we humans bear some striking similarities, and differences, to each of the species. Studying another species in order to gain an understanding of our own is as much about the differences as the similarities, observing the unique solutions that each species has come up with to solve its own evolutionary, ecological and social challenges.
Finally, the dramatic dichotomy between those fun 'party animal' bonobos and those mean old chimps is somewhat exaggerated. Bonobos still have hierarchies and conflict (why else have reconciliation?); their peaceful kingdom is not built on inherent egalitarianism, but on necessary tolerance, and bonobos have most plausibly developed that frothy sexuality as a means of avoiding infanticide. Meanwhile, chimps too are capable of affiliation and altruism; their violence and competition are embedded in an array of social checks and balances, and they even display something resembling empathy.
De Waal covers this with great wisdom and subtlety. I have problems with his views in only one domain. In considering that even bonobos are hierarchical, de Waal suggests that hierarchies are inevitable for social species - "we simply could not live without them" - for a number of reasons. First, if we lacked easy ways to discern rank, "no one would be able to tell who is who". A response to this is that when rank and merit dissociate, a lack of easy symbols for the former makes it easier to recognize and value the latter. Second, de Waal sees rank as allowing for grander human accomplishments. "This is why the most cooperative human enterprises, such as large corporations and the military, have the best-defined hierarchies." But this assumes that corporations or armies are truly cooperative enterprises, as opposed to subordinating systems that benefit profiteers (such as shareholders, or leaders who control armies). Finally, de Waal sees an ironic and paradoxical benefit to hierarchy, as it can take an abusive hierarchy to provide the impetus for cooperation from below to overthrow it and establish something fairer. Naturally, one hopes instead for hunter-gatherers writ large, where justice emerges naturally from bottom-up local interactions, rather than "democracy as born from violence", to use de Waal's phrase. But, as John Lennon put it, you may say I'm a dreamer, which is quite possible.
That difference of opinion aside, this is a rarity, a superb scientist producing an excellent book for non-specialists. This should be required reading for the opinionated cousins (or better yet, world leaders) whose ancient encounters with Robert Ardrey or Konrad Lorenz have led them to believe that they understand what kind of ape we are.
(Robert Sapolsky is in the Department of Biological Sciences, Stanford University, Stanford, California 94035, USA)