I would be interested to hear your views on the current conditions of captive gracile chimpanzees across the US, as well as the world, and would be interested to learn how the benefits of such research might out-weigh the costs to the imprisoned individuals.

The orangutan evidence does not presuppose that there are no uniquely shared features between humans and bonobos, or humans and chimpanzees, or with both. But at present the reality seems to be that humans share far more features uniquely in common with orangutans (at least 30 well documented features) than chimps or bonobos (perhaps 2-3 such features). Even in face to face mating that was highlight for bonobos has a more common occurence between males and females in humans and orangutans than bonobos.

Semendferi’s work is important and I hope in future she will be able to corroborate or falsify apparent similarities between the human and orangutan brain with respect to asymmetry and the sylvian sulcus.

John Grehan

In reply to Jim Moore – the relatively smaller area 13 apepars to represent a potential synapomorphy for humans and bonobs, i.e. that bonobos are most closely realted to humans in this feature, followed by the gibbon being more closely related to humans and bonobos than the other great apes. Given that gibbons are not seen to have this close relationship the proportional similarity of area 13 in humans and bonobos would have to be seen as having an origin independant of the evolutionary sequence.

The Semendeferi et al paper includes quite a variety of measurements that may or may not be phylogenetically significant (they not the need for more sampling). Humans and orangutans have the lowest neuronal density, but whether that difference is significnat compared with the bonobo with the next lowest is anyone’s guess.

John Grehan

Your religious emailer has a problem – it’s one that has troubled all honest Christians: If people decided to sin after living in a perfect world, then where did the decision come from? If everything was created by God, then God created the aspect of humankind that led to the decision! And if the decision emanated from elsewhere, then from whom? And how?

This is a perfectly valid question, surely, and one that Christians have to explain rather than skate over. In my view, it would have been impossible for an omniscient being not to know that his creation was going to go severely off-track.

As a devout agnostic, I don’t think there is a problem in explaining our imperfect behavior; I believe that there are factors (like shortages of resources) which encourage us to pursue interests that lead us into conflict with others. This doesn’t mean that we should stand by and do nothing, but rather that we should understand and use this understanding to create a less conflict-ridden society. This isn’t something that Christianity can do since it simply labels our negative behavior as innate – we supposedly are born in sin.

Anyway, Vanessa, great article, I can understand ponderfool’s concern that things can be oversimplified, but we do need to get a message out that will keep these amazing creatures alive and may help us too. Thank you for doing that.

I have to note, they use *only* brains of individuals who have died from causes unrelated to research (it’s tricky saying “natural causes” for captives, but that’s the essence).

I think the data support chimpanzees as being the better model for human evolution, but that does NOT mean bonobos are irrelevant OR that we can’t learn important lessons about mechanisms underlying the expression of violence of various sorts in all the apes (including ourselves). Whether understanding will help us to be less violent as a species … one can only hope.

In sexual and reproductive behavior humans are not only more like orangutans, but some fetures are uniquely shared within the large bodied hominoids(e.g. lack of genital swelling during the menstrural cycle, prolonged average intromission, similar female and male genital structure). If people don’t want to talk about bonobos because of the sex this is perhaps not much different to scientists and science media not wanting to talk about the orangutan similarities to humans and the implications for their having a unique common ancestor.

Homosexuality is present in orangutans and other primates so the bonobo is not the only example. The pervasive use of sex as a means of social mediation in bonobos does would seem to show how much they are not like humans in this respect.

John Grehan

As a primatologist, I was wondering whether what we call “sex” in bonobos should truly be considered so. What I am suggesting, therefore, is that across all species (including humans), sex is used for procreation and that, I guess, is sex. Humans definitely use the sexual act for pleasure and let’s then continue to call this sex. If, however, bonobos do use the same act for seeking help or releasing tension or peacemaking, then perhaps (and we can definitely define it as such) this is not “sex”. It is a bodily act that serves a specific function, just as shaking hands could be considered a sign of an affiliative action in some socities but could be considered a taboo, “sexual” interaction in another society. If this can be accepted thus, many of us would perhaps heave a sigh of relief and the bonobos could finally get out of their “over-sexed” label. I am with my friend, Gottfried, in this! As for orgasm, I am not sure whether they always reach orgasm during these interactions. If they do, it could be considered a byproduct of this bodily interaction, and if they don’t, q.e.d!

In fact, I had the same reaction when a series of studies were published several years ago reporting homosexual activity in female Japanese macaques. Although some of these could perhaps have been genuinely homosexual acts, mounting of a female by another was often used to establish social dominance – an extremely common phenomenon amongst male macaques, virtually across all species. Yet, we never call them homosexual!

Just a thought – but thank you once again, Vanessa, for what promises, no doubt, to be a fascinating account of a fascinating species. Whether there is something to be learnt from them is another issue, but we certainly do need to know them before they disappear in the twilight of our times.

Seems to me like the bonobos cooperative social systems are based upon more than sex. I mean, people have a LOT of sex, of all varieties. It’s not as all-pervasive as in bonobo interactions, but human sexual activity goes far beyond reproductive necessity, and far beyond that of most other species I know of.

The squeamishness concerning bonobo sexual practices goes beyond the gay issue too. Last I heard, bonobos also routinely engage in activities we would term as incest, child abuse, sexual compulsion, and so on. Bonobos are difficult to watch unless you can completely abandon anthropomorphic thinking.