a bonobo humanity?

Something I encountered in S J Gould’s book Life’s Grandeur, added to other little encounters in my readings and researchings, has caused a few concerns. In trying to promote bonoboism, of a kind, the last thing I’d want to do is limit humanity’s intellectual pursuits, curiosity, adaptability and general gung-ho cleverness. As if I had the power haha. So whenever I read or hear something that might suggest that bonobos aren’t as smart as chimps I get worried. 

Anyway, my reading, as usual, took me on some internet journeys, in one of which I found that the average chimp brain volume is 398 cc while that of bonobos is 348 cc. Remember of course that bonobos used to be known as pygmy chimps, and the average difference in overall size between the two species pretty well corresponds to the difference in brain size, and, as smart corvids and other birds remind us, size isn’t always an indicator of such things. 

But there are other worries. I’ve gotten the impression that chimps are very much tool-users, bonobos perhaps not so much. But now, on consulting the literature more closely, I’m finding that maybe this isn’t so, and so I’m losing the point of this post. But of course there are differences, behaviourally, and so cognitively, between the two species, which would be worth exploring, for our future’s sake. 

A scientific article, linked below, going back to 2010, and not fully available to amateurs like me, has this to say in its abstract:

Our observations illustrate that tool use in bonobos can be highly complex and no different from what has been described for chimpanzees. The only major difference in the chimpanzee and bonobo data was that bonobos of all age–sex classes used tools in a play context, a possible manifestation of their neotenous nature. We also found that female bonobos displayed a larger range of tool use behaviours than males, a pattern previously described for chimpanzees but not for other great apes. Our results are consistent with the hypothesis that the female-biased tool use evolved prior to the split between bonobos and chimpanzees.

As to their ‘neotenous’ (i.e. eternally childlike) nature, I’m wondering. Are they really any more childlike than chimps? Apparently, that’s the consensus. A more recent piece in Current Biology by Isabel Behncke, ‘Play in the Peter Pan ape’ (Peter Pan being the boy who never grows up) looks into this issue of bonobo neoteny, and play, noting that there’s a ‘small cluster of species in which adult play occurs, such as elephants, primates, social carnivores, cetaceans, parrots and corvids’. These are all highly social species, with otherwise little in the way of evolutionary connection. They do have other connections, though, apart form sociality – longevity, and neural complexity. 

Behncke, in studying bonobos in the wild, argues that bonobos are more neotenous and playful than chimps, and one of her reasons for this corresponds with my own thoughts, happily. They live in a relatively abundant calorific habitat, and ‘play is energetically expensive and dwindles in conditions of resource scarcity’. Hence all those videos featuring pets at play. Hence, also, our own playful nature – sport, art, music, salons and pub chit-chat. Even our scientific explorations can be considered a form of play, at a stretch. 

And then there’s sex, that Big Issue that humans beat themselves up about. Bonobo play is less solitary than that of chimps, and more sexual. I also would note that the development of tool use, which has, as mentioned, been more associated with females than males, in both bonobos and chimps, is surely associated with play. But much play between bonobos is genital-based. ‘Chasing’, especially around a solitary object such as a tree, and genital-grabbing is common, which of course can be potentially painful, but according to Behncke virtually never results in serious injury. This often happens between members of different troupes, and Behncke points out here a vital difference between the two tightly related primates. Chimps exhibit hostility between troupes, with ‘wars’ sometimes ending in wipeouts, as Jane Goodall and others have reported. Of the often fatal injuries sustained, mutilated genitals are high on the list. 

So, about the sex. But first, it should be noted that communal or paired play is often about trust. The ‘hanging’ game, for example, is often played between an adult and a juvenile bonobo, in which the adult lets the child dangle from her arm, from a more or less high tree branch. Like bungee jumping, without the elasticity, but with much of the thrill. Also, play (and sex) occurs with a multitude of partners, with attendant advantages:

Play-partner diversity is important when thinking about adaptability: playing 100 times with the same individual requires less variation and adjustment of behaviour than playing 10 times with 10 different individuals. Playing with individuals of different sizes, personalities and sex requires learning about contextual-dependent behaviour: with whom and when a bite is appropriate, a chase over a push, a gentle tickle rather than a stomping slap, and so on.

References

https://www.sciencedirect.com/science/article/abs/pii/S000334721000343X#:~:text=Chimpanzees%2C%20Pan%20troglodytes%2C%20are%20the,been%20described%20as%20particularly%20poor.

Click to access S0960-9822(14)01481-X.pdf