Why are you interested in differences between the sexes?
I had a more classical, modern, liberal view of sex differences when I was very young. I thought there were no important contributions of biology to the differences in male and female psychology and behaviour. I thought all of the differences were due to cultural influences of upbringing and media and so on. But after doing research on child development in Botswana among the Bushmen, and comparing them with preschool children in London, I saw the sex difference in physical aggression – hitting, kicking, wrestling and so on – was there in both places. Then I started to rethink the question and learned a lot more about the genetic and hormonal differences between males and females. I came to the conclusion that there are a limited number of areas of behaviour where biology can help to explain the differences.
What are the examples of this?
Testosterone levels are far higher in men than women after puberty. But it turns out they are also higher in male foetuses. A number of lines of experiment have converged to convince me and other people, though not everyone, that testosterone operating on the male brain before birth makes it somewhat different to the female brain. Modern imaging studies show that the part of the brain that generates violent impulses, the amygdala, is larger in men than in women. It’s also dotted with receptors for testosterone. Plus, the part of the brain that inhibits those violent tendencies, the frontal lobes, is more active in women than men. For me, that adds up to the conclusion that men are more predisposed towards aggression and it’s got a biological explanation.
In the book you say that male domination is an anomaly, and that for most of history women have played a more prominent role…
The Bushmen in Botswana did exemplify a male predominance in physical aggression. But it also showed me that in a very small face-to-face society, the decision-making processes inevitably includes women. Men might tell you that they’re superior to women in some way or another – you will hear that from men in most cultures – but in a culture like this they can’t exclude women from participation. It would be really stupid to do so because you need all the intelligence and good ideas you can get to survive in such a challenging environment. That’s the way our ancestors lived for scores of thousands, or even hundreds of thousands of years.
So what happened?
At the beginning of the period we call the ‘rise of civilisation’ – after the invention of agriculture – people settled down in large, dense populations. You didn’t have a face-to-face society anymore. You started to have specialised roles: you had a priesthood, a military, a merchant class. These became male-dominated because there was a critical mass of men that could get together and exclude women. Another way to think of it is that in the previous period with the small face-to-face culture, there was no real separation between private space and public space. In the more dense populations, when you had a real separation, men began to exclude women from public space and just relegated them to the home and the children. That prevailed for thousands of years until a century and a half or maybe two centuries ago, when women started to make inroads into various areas of public life.
You use a lot of colourful examples from the animal kingdom. What can animals tell us about humans?
It tells us that there is a lot of variety out there. You don’t see males dominating everywhere. There are species in which the females are larger and more dangerous than the males. I love the example of the praying mantis. There they are in mid-copulation and she bites his head off! He keeps right on going. She gets the sperm donation and eats the rest of him. He’s making a sacrifice for the nourishment of his offspring. So it’s not universal in nature for males to predominate. You also get snails shooting darts carrying sperm at each other. These are species where each individual is both male and female. But there is still a battle of the sexes – even without sexes. Each individual in the mating act is trying to get an advantage over the other one. What that tells us is that conflict is inherent in nature; we can’t expect to eliminate it in sex. But we might be able to change the arrangements so that the conflict is less damaging and maybe less frequent.
Are there any examples of this in the animal kingdom?
We have two very close relatives among the apes: the chimpanzee and the bonobo. They have different levels of violence and different patterns of sex. Chimpanzees are very violent: males kill other males, they are violent towards females and there is coercive sex. In bonobos there is conflict but it doesn’t reach anything like the same level. People call them the ‘make love, not war’ species. Females keep males in line by having coalitions among themselves. But it looks like a great society for males too. They get plenty of sex and they don’t have to fight for it like the chimps do. I think of bonobos as a kind of model for our future as females get more influential.
Could we ever go beyond this and have a human race without men?
Technically, yes. Some people think because I talk about this I’m in favour of it. I’m not. But scientists have reverse engineered skin cells to make eggs and sperm. This raises the possibility that a gay or lesbian couple will be able to have biological children in the not too distant future. Two men could have their genes joined and two women could. But there’s a difference: the men would have to borrow a womb from a woman, but the women wouldn’t need to because they will have two of them. I have it on pretty good authority that most women don’t want to see the end of men but it is a technical possibility.
You can read more in Melvin Konner’s book Women After All: Sex, Evolution And The End Of Male Supremacy (£16.99, WW Norton & Co)
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