Why are bonobos female dominant? Culture or genetics?
I was going to entitle this post ‘How did bonobos become female dominant?’, but that assumes that they weren’t always so. To assume makes an ass out of u and me, and I don’t care about u, but I have my pride. And speaking of pride, lions live in those groups (of up to forty, but usually much smaller) and malely dominate, even though the women bring home most of the bacon, chevaline (well, zebra), venison, rattus and the occasional long pork, if they’re lucky.
The point is, we wouldn’t consider this a product of leonine (okay, lion) culture. It’s just what lions – male and female – are genetically programmed to do, just as marmosets, magpies (Australian) and macaroni penguins are programmed to be monogamous (more or less). But considering that separating genetic and cultural evolution in humans is a tricky business, the same would surely go for our closest living relatives. We’re generally convinced that the male dominance in most human history is cultural. I’ve often read the claim that the transition to an agricultural lifestyle in many parts of the world from about 11,000 years ago resulted in a more patriarchal society, with the concept of property, including women, becoming essential to power and dominance. This seems plausible enough, though I would assume that the first claims to property relied primarily on brute strength. Male muscularity is different from that of females, and, more importantly, they’re not hampered by pregnancies and child-rearing. And whereas hunter-gatherers (and it now seems the distinction between these lifestyles is by no means cut and dried) tend to migrate along with food resources, some concept of land ownership, based on kinship over time, clearly developed with an agricultural lifestyle. Again, such a fixed lifestyle would have essentially created the notion of ‘domesticity’, which became associated with the female world. And it seems also have encouraged a degree of polygyny as a sign of male social status. And as we left all this behind, in the WEIRD world so fulsomely described in Joseph Henrich’s book, we’re starting to leave patriarchy behind, though way too slowly for my liking.
So, let’s get back to bonobos. I was struck by an observation I read a while ago in some otherwise forgotten piece on bonobos. Female bonobos are smaller than male bonobos to much the same degree as in chimps and humans, but slightly less so. Considering that the split between bonobos and chimps occurred only between one and two million years ago (and I’d love that margin of error to be narrowed somehow), any reduction in this sexual dimorphism seems significant – and surely genetic. But then genes are modified by environment, and by the behaviour that environment encourages or necessitates. Here’s what I found on a Q&A forum called Worldbuilding:
Bonobos have less dimorphism because they all feed close together and females can almost always protect each other. Male A tries to monopolize female A and gets driven off by female B, C, and D.
Hmmm. There’s something in this, but not quite enough. Why wouldn’t the males bond together to monopolise a particular female? In non-euphemistic human terms this is called pack rape, and it does seem to be confined to humans, though coercive sex, on an individual level, is quite common in other species, and for obvious anatomical reasons it’s always the male who coerces.
This leads to the reasonable conclusion, it seems to me, that for females to have control in the sexual arena – at least in the mammalian world – requires co-operation. And that requires bonding, arguably over and above the bonding associated with ‘girl power’ in WEIRD humans. So here’s how the Max Planck Society explains it:
To clarify why same-sex sexual behavior is so important specifically for female bonobos, we collected behavioral and hormonal data for over a year from all adult members of a habituated bonobo community at the long-term LuiKotale field site in the Democratic Republic of Congo. In addition to our focus on sexual interactions, we identified preferred partners for other social activities such as giving support in conflicts. We also collected urine to measure the hormone oxytocin, which is released in the body in other species after friendly social interactions, including sex, and helps to promote cooperation.
We found that in competitive situations, females preferred to have sex with other females rather than with males. After sex, females often remained closer to each other than did mixed sex pairs, and females had measurable increases in urinary oxytocin following sex with females, but not following sex with males. Among same-sex and opposite-sex pairs, individuals who had more sex also supported each other more often in conflicts, but the majority of these coalitions were formed among females. “It may be that a greater motivation for cooperation among females, mediated physiologically by oxytocin, is the key to understanding how females attain high dominance ranks in bonobo society,” explained co-lead author Martin Surbeck, a researcher at the Max Planck Institute for Evolutionary Anthropology and Harvard University.
Now, I know I’ve written about the peptide hormone oxytocin before, somewhere, and suffice to say its role in behaviour and its relation to the general endocrine and neurotransmission systems are extremely complex. Having said that, there will doubtless be strong similarities for its role in humans and in bonobos. And, reflecting on the above quote, what came first, the oxytocin release, or the bonding? Should we encourage more oxytocin doses, or more female-female sex? Doing both sounds like a fine idea.
To tell the truth, I find the willingness to see bonobos as any kind of female model somewhat lacking. They’re ‘jokingly’ referred to as the scandalous primate, and their revolutionary nature is underplayed. Yet their relatively comfortable, largely frugivorous lifestyle in the southern Congo region, where their only real threat is humanity, reflects in miniature the comforts of the WEIRD world, with its hazards of overspending at the supermarket, lazing too long at the beach, or pokies, cocktail bars and ‘Lust-Skin Lounges’ for the true thrill-seekers.
Of course, we got to our ascendant position today through the explorations, calculations and inventions produced by our brains, and the super-brains of our cities, corporations and universities. What can we learn from a bunch of gangly, hairy mutual masturbators dangling about in the Congolese rainforest? Well, we brains and super-brains can still learn a bit more about sharing and caring – as any study of our own history can tell us – and we can certainly learn to stop being so dumb and fucked-up about sexuality, gender and power. Learning lessons from bonobos doesn’t mean getting hairier and improving our brachiation skills, but, well, eating less meat would be a start, given what we know about the environmental damage our current diet is causing. And that’s just one of many lessons we can learn. For me, of course, the most important lesson is the role played by females. How ridiculously long did it take for us – I mean we male humans who have been in control of almost all human societies since those societies came into being – to recognise and admit that females are our equal in every intellectual sphere? This is still unacknowledged in some parts. And although we call this the WEIRD world, the Industrial part of that acronym has lost its machismo essence, a loss Susan Faludi has sensitively analysed in her book Stiffed: the betrayal of the modern man – though I think ‘betrayal’ is the wrong word. After all, men were never promised or guaranteed to be breadwinners and heads of households, they took or were given the role through social evolution, and it’s being taken from them, gradually, through the same process.
Finally, getting back to the question in the title, the answer, for Pan paniscus as surely as for Homo sapiens, is culture, which can affect gene expression (epigenetics), which can ultimately affect genetics. I suspect that the slight diminution in the sexual dimorphism between male and female bonobos, over a relatively short period of time, evolutionarily speaking, might, if they’re left to their own devices (which is unlikely, frankly), lead to a size reversal and a world of male sexual servitude. Vive les bonobos, I’d like to be one, for the next few million years!
References
Joseph Henrich, The WEIRDest people in the world, 2021
Susan Faludi, Stiffed, 1999
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