bonobos, chimps, humans, testosterone and the future, again…
What kind of societies did our primate ancestors live in? Could they have been more egalitarian than the ones we have now?
Angela Saini
hormones follow social evolution?
So I wrote a piece a few months ago on this topic, and my most recent piece starts to revisit the issue. Human males, at least in the WEIRD world, are experiencing reduced testosterone levels, which in terms of general health, is apparently a bad thing. Females on the other hand, already have testosterone levels at between a tenth and a twentieth those of males. What does this mean, for their health, and their behaviour? And what about testosterone levels of male and female bonobos and chimps, our equally closest living relatives, whose behaviour is so strikingly different from each other, and from us? To paraphrase Sabine Hossenfelder, ‘that’s what I’m going to write about today’. Or maybe not!
First caveat – it’s far from being all about testosterone, as regards behaviour or physicality. And I’m interested in changes to behaviour, re humans, rather than changes to testosterone. So I’m looking for clues in bonobos for promoting more of the changes I already see occurring in male human behaviour, partly due to the increasing empowerment of women. It’s likely that testosterone levels, and endocrine changes generally, will follow changes in social behaviour, rather than vice versa. But I’m certainly no expert.
I mentioned in one of my previous pieces that bonobo sexual dimorphism is equal to that of chimps, and of humans. However, I’ve since read that the sexual dimorphism is a wee bit less in bonobos than in chimps and humans (and given that the split between bonobos and chimps is quite recent, in evolutionary terms, that difference might continue to diminish, and even reverse, if both species manage to survive…). Every little bit helps in the power struggle, though it’s likely that female bonding is the real key to bonobos’ female dominance. A key to our human future?
Having said that, let’s still consider testosterone, and its reduction, and what it means for men in the future. Carole Hooven says this in Testosterone:
The consensus of experts is that testosterone’s main job is to support the anatomy, physiology and behaviour that increases a male’s reproductive output – at least in nonhuman animals. And men are no exception – T helps them reproduce, and directs energy to be used in ways that support competition for mates.
So it’s probably true to say that the reduction in T among males, in ‘developed’ nations, over such a short period in evolutionary terms, is more disturbing than exciting. However, male aggression and violence has long been a problem, to say the least. Hooven again:
Men are much more likely than women to be sexually attracted to women, and they are far more physically aggressive than women in every pocket of the earth, at every age. For example, they are responsible for around 70 percent of all traffic fatalities and 98 percent of mass shootings in the United States, and worldwide commit over 95 percent of homicides and the overwhelming majority of violent acts of every kind, including sexual assault.
All of which is hardly new news (though I’ve encountered disbelieving males), and in most mammalian species males are the more aggressive sex, but there are exceptions. Hooven cites the naked mole rat, the meerkat and the spotted hyena as examples of high levels of female aggression, but the role of hormones in these animals’ behaviour is complex and not fully understood. In bonobos, female dominance isn’t achieved in anything like the way male dominance is achieved in chimps. They do it though female solidarity, most often achieved through ‘sexual closeness’, to speak euphemistically.
Surprisingly, while there’s a massive difference between male and female human testosterone levels, this is not the case for bonobos or chimps. Male chimps ‘have on average 397 ng/dl testosterone, which is below the human male average’,
On this basis,I’d like to do everything I can to support female-female bonding. One inspiring story I first heard about years ago is a coalition of Palestinian and Israeli women trying to find a way around the impasse that exists within Israeli-Palestinian lands, where both groups have an in-group approach to the cultural history of the region they share.
These women — both independently and part of nonprofits and organizations — are working to bridge the gap, break down the walls — both literally and metaphorically — and build a world where Israelis and Palestinians aren’t enemies but neighbors and friends.
I suspect that the walls they’re trying to break down are those of macho insistence on the rightness of their ‘ownership’ of the land they inhabit. This insistence, and resultant violence, has resulted in trauma on both sides. Considering this trauma (naturally felt more on the militarily weaker side than the other), and the fact that both sides in the conflict are dominated by belligerent males, women are often reluctant to speak out about the situation, particularly on the Palestinian side. Take this example, from an article linked below:
We struggled to find a Palestinian woman in Gaza to openly speak in fear of retribution from Hamas, the “Palestinian resistance group,” or fundamentalist, militant, and nationalist organization that controls the region.
The same article features Jewish women, brought to Israel as children from persecution in Middle Eastern or African countries, expressing mixed feelings of gratitude and shock on being exposed to apartheid-style conditions in their adopted country, and Palestinian Arab women, dedicated to education and a historical understanding of the complexities of belonging and loss experienced by both sides of the conflict in the region.
All of this has taken me far from what I earlier promised to talk about – the more speculative question of our ancestry. Were those ancestors less or more violent than we are now? Or – was the CHLCA (the last chimp-human common ancestor) more like chimps (and humans) or bonobos?
One of the features most notable in ape and monkey societies – and also in humans – is hierarchy. We don’t notice it so much in our vastly populous society, in which we might be born to ‘unskilled’ labourers, teachers, small business owners, billionaire entrepreneurs or royalty – the gradations are so numerous that it may take us quite a while to know where in the hierarchy we belong, if we ever do – and whether we’re failing or improving in terms of the rung on the ladder we started out on. And there’s no doubt that failure or success can be measured in a much greater variety of ways than ever before, by ourselves or by anyone who chooses to measure us. In any case, the fact that there are people we ‘look up to’ – artists, scientists, parents, activists, monarchs, whatever – is an indication that we strive to better ourselves in an essentially non-egalitarian cultural environment.
But there have been notable changes in that environment in the last 100 years or so – not only with respect to female empowerment, but major transformations due to science and technology, in transport, communications, medicine and industry. We’re living longer, educating ourselves more, and working less hard, in a physical sense. We’re having fewer children, and a greater diversity of sexual relations. Though there are still many who ‘fall through the gaps’, we’ve developed human welfare systems to reduce dire poverty and to enable the intellectually and physically disabled to experience better lives than was previously afforded them. We’ve become generally more sensitive to the web of life from which our species has emerged, and what we owe to it and to the planet whose environment has enabled all living things to survive and more or less thrive. Some of these developments have long roots, but most of their fruits have been recent, though of course far from universal in human societies and nations. Democracies and open societies have proved to be the most healthful and beneficial for their people, and the general tendency has been to grow those societal types, through migration or activism against repressive regimes.
We live in a world of growing prosperity, often compromised by the belligerence and repression of the odd authoritarian national leader. It might seem a mite ridiculous to compare this massive and complex human population with the tiny bonobo world in a small corner of a sadly benighted African country, but I see some utility in the comparison, precisely because I see signs that our best societies are heading in the bonobo direction. Not that we’re getting hairier or more arboreal, but that we’re gradually becoming more caring and socially responsible, less violent and more sexually tolerant and diverse. The circle has expanded, the better angels of our nature are managing to prevail, and like David Deutsch, though perhaps for slightly different reasons, I feel little cause to despair of the human species.
References
Carole Hooven, Testosterone, 2022
Click to access Surbeck_et_al_2012a.pdf
https://qz.com/1033621/scientists-assumed-that-patriarchy-was-only-natural-bonobos-proved-them-wrong
https://www.sciencedaily.com/releases/2008/07/080715204745.htm
https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2010.1572
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