a bonobo humanity?

Jacinta: Okay Canto, I rather hesitate to open up this subject, because I can’t see an end to it, but I want you to repeat here something you’ve said to me before about women and power, which goes to differences between men and women, an area subject to endless debate and contestation.

Canto: Ah well, I was considering how political power, in the world, is largely in the hands of men, and what the world would be like if the situation was reversed. It’s my humble opinion that the world would be less violent, more collaborative, and a lot more fun.

Jacinta: Well as a woman I’m obviously pleased to hear you say that, but we do try to look at evidence rather than personal opinion here, so what in the way of evidence leads you to this conclusion?

Canto: Well… where do we begin? Simone de Beauvoir famously wrote that women are made and not born, a highly contestable truism as it seems that women are actually wired differently from men, having less neurons but more connections between neurons, in toto and on average, so the very question of what it means to be a woman, or a man is one we’re unlikely to get to the bottom of, but I’d like to start with bonobos, always a favourite topic of mine. They appear to have diverged from chimpanzees only between a million and two million years ago, and they look very similar to chimps, which is likely why they weren’t identified as a separate species until the 1930s, and the differences seem to be far more social than anatomical. I mean, they share the same sexual dimorphism as chimps, and humans, and yet they’re essentially matriarchal, due it seems to social arrangements rather than individual size and strength. That gives me great hope for humans, especially now that physical size and strength are less relevant than ever as leadership qualities.

Jacinta: Ah, well now I get the fun part – you think a human matriarchal society will turn out to be a gigantic mutual wankfest. But what about civilisation? What about science and technology? Considering that women, regardless of culture or nationality, are more into astrology, fortune-telling, spiritualism, religion, naturopathy, and virtually every other pseudo-science and primitivism you care to mention, than men are.

Canto: Well, you’re talking about statistical differences, but you well know that there are many fine female astrophysicists, neurosurgeons, geneticists, experimental psychologists, whatever. You’re hardly the only female skeptic, even if they’re in a minority. And who knows what would happen if females were in a majority, with a history of being in a majority, with respect to leadership and power? Maybe you’d find then that it was men who were more into pseudo-science, statistically speaking.

Jacinta: True, and that brings me to a study analysed on the Skeptics’ Guide to the Universe recently. I had read, like you, that women, overall, had more white matter (the myelinated connections between neurons) than men – by a large factor, and that men had more grey matter, though this was concentrated around particular areas such as the amygdalae and the hypothalamus. However, in the study referred to, the researchers wanted to find if there were any categorical differences between male and female brains. They looked at 4 data sets of MRI and fMRI scans, checking out anatomical and connectional or networking differences, to make comparisons. According to SGU’s Steven Novella (a practising neurologist), the media over-simplified the findings as saying there were no differences, but in fact it was more interesting than that. Novella found this study to be essentially an exercise in examining how we categorise things (how do we define and categorise a disease, for example, or a planet, or a species). How we do so depends on a range of factors, and increasing knowledge, and better technology, helps us to develop parameters for categorising…

Canto: Though this also raises more problems… the more we know or learn, the more problematic our previous categories tend to become…

Jacinta: Anyway, in the case of female and male brains, the researchers distinguished between categorical differences and statistical differences. They used genitalia as a categorical difference. As Novella explains it, with genitalia we have a bimodal system, with male and female equipment…

Canto: I prefer to call it tackle…

Jacinta: And nothing really between. The vast majority of people, as subjects, can be placed in one category or another. Of course there are exceptions, but they are, always arguably, statistically insignificant. So, using this as a yardstick, the researchers wanted to know if there are categorical differences between male and female brains in the same way that there are categorical differences between male and female genitalia. One way to distinguish between categorical and statistical differences is whether, once you know which category an individual belongs to, that provides certainty about their particular traits. If it does, you have a categorical difference. So the researchers looked at about 40 different anatomical and functional aspects of the brain. They found that, generally speaking, there are statistical differences between males and females, in the size of various regions, the richness of the networks in various regions, but with a lot of overlap between the sexes; so it was statistical but not categorical. And the study didn’t look at causes of these differences, whether biological or social (we know that brains can be wired up through social conditioning to some degree). But they also did studies of individuals over the range of the 40 anatomical and functional features to determine how many were ‘typically’ male or female, or somewhere in between. One way to capture this was to ask – what percentage of people had 100% of their brain regions (those 40 features analysed) that were ‘typical’ of their sex? Among the 4 data sets, that percentage was 0 to 8%. So, very few men have ‘all-male’ brain regions, in terms of size and connections. Some 28% to 58% had a mixture of both.

Canto: So let me get this clear, the essential finding, according to Novella, was that though there were statistical differences in specific brain areas – and these are the differences described in ‘Do men and women have different brains?’ in How Stuff Works, from which the new ussr’s earlier post was largely derived – there is a lot of individual variation, which muddies the water rather a lot.

Jacinta: Yes, and I would say hopelessly, at least for those who want to think in stereotypes. As Novella puts it, people are mosaics of male and female traits. Another way of thinking about this, again put succinctly by Novella, is that we can’t assume that because a person is male – or female – we know what that person’s brain regions will be like. Statistical differences can’t automatically tell us about the brain region of any individual. There is no typically male or female brain in the way that there are typically male or female genitalia. And that is really interesting, and it might even mean that it’s illegitimate to say, ‘oh she’s female but she thinks like a man’, or ‘but she has a male brain’. There’s no male brain, or female brain, there are individual brains that are a product of all the influences, genetic, epigenetic, environmental, social, hormonal, psychological, whatever you can think of that influences brain activity and wiring.

Canto: And yet, and yet. Statistical differences do count for something don’t they? We still have the statistics showing that women are more into astrology and naturopathy than men…

Jacinta: Yes but what this study shows is that you can’t base this on some essentialist argument about female brains, and isn’t that a good thing?

Canto: Well, definitely, but then it works the other way. My argument that if women ruled we’d be so much better off can’t be based on anything essentialist either! Maybe being in power would turn their brains into something  like the statistically typical male brain. My hopes are turning to dust…

Jacinto: No, no, don’t despair Canto. Consider the bonobos of the jungle…