Over many decades, now, a popular idea across the humanities and social sciences has been that of patriarchy. Etymologically the word means the rule of the fathers – or at least the elder males (father-like). It has taken on, though, a more general reference to the idea of men ruling over women. If one looks historically and geographically there’s a good case to be made that women have not been well represented in or by the public practices of politics and law within human institutions. This legacy is pointed to as revealing the oppression of women by men. This general dynamic has been so pervasive – though certainly degrees have varied in different times and places – that regarding it as coincidental seems farfetched; a structural process seems to be at work.

The only force in the known world that provides functional and enduring structure among biological entities is evolution. So, it seems worth examining patriarchy’s evolutionary plausibility. In broad strokes, there are two avenues for such male dominance over women: psychological and physical. Obviously patriarchy could be a product of the two combined, but that would require both to be plausible prospects. Consequently, I’ll treat each separately.

So, is it plausible that men have exercised psychological dominance over women? Intelligence would seem to be valuable in such a case and it is true that the smartest people in the world are, have long been, men. Those who claim that the fact men have been responsible for most of the world’s great intellectual achievements is a by-product of patriarchy veer toward a tautology: if historical, intellectual achievements by men are only a product of patriarchy, then how is it that men have apparently been so smart as to be able to oppress women everywhere, through the many thousands of years of history? Or, maybe intelligence isn’t the key factor. Upon slightly closer examination, it turns out that, though the most intelligent humans are men, it is equally true that so are the least intelligent ones. It is not a coincidence that the prisons, poor houses and insane asylums have been filled vastly disproportionately through history with men.

As psychologists put it, men have a wider normal curve than do women. If you overlay the male bell curve on intelligence, distributed over population, over the female one, you find that males stretch further off at both ends, while women are clustered much closer together around the mean. There’s good evolutionary reasons for this, which will be touched upon below. The upshot though is that if you take the average intelligence for all men and all women, it is in fact about the same. So, while perhaps one can’t entirely rule out the prospect of men out-thinking women into patriarchy, as we look closer at the data, it seems less likely than at first blush. It would be interesting to see the results of computer simulations on this: would men have the advantage because they had the smartest members or would women because they had more, smarter members above a certain threshold? It’s not clear there’s an advantage for men on this front.

Maybe though men’s psychological advantage wasn’t intellectual; is it plausible they managed patriarchy through social norms and emotional manipulation? Here, a much stronger case can be made, not for male advantage, but disadvantage. The research has long shown that on the key skills for managing such dynamics – theory of mind (discerning the mental state of others), language aptitude and social relationship negotiation – women are significantly more skilled on average than are men. Again, there seems to be good evolutionary reasons for this. Among the hunter-gatherer societies, which is the closest evidence we have for the lifestyles of our distance ancestors, a sexual division of labor had women deeply immersed in village life on a daily basis, while men were often away for days or longer on more socially isolating hunts. Under those conditions, selective evolutionary pressures favored our female ancestors who were most adept at navigating social relations. This likely explains why today it’s so common for women to lament men’s lack of emotional intelligence and their resistance to relational dialogue. Women clearly have the upper hand in this domain of human experience, so it seems an implausible explanation for patriarchy – at least understood as oppression of women by men.

What then might we say about the prospect of males enforcing patriarchy physically? As with intelligence, again, at first blush, this appears a credible avenue. Certainly, on average, men are physically stronger than women. And this advantage is especially expressed in the upper body strength which is so valuable for physically overpowering an opponent. Further, the evidence is that men are prone to employing this strength – and the psychological advantages, by the way, it has been shown to provide – in threatening and violent acts. (See my discussion of this phenomenon, with Aaron Sell.) Though, if we’re defining patriarchy literally, such violence is highly concentrated in younger men. Also, the overwhelming majority of victims of male violence are not women, but other men: also overwhelmingly younger men. Still, this does not rule out the possibility that women have been intimidated into submission by the prospect of male violence. Indeed, some who promote the explanatory value of patriarchy argue precisely this.

To avoid slipping into logical fallacies, though – like cherry picking evidence and confusing correlation with causation – an evolutionarily informed examination of the issue at hand requires a fuller examination of the evidence. Men may have the physical strength to suppress women out of the social institutions that provide legal and political privileges, but is that the best explanation in light of the evolutionary evidence? Answering this hinges on answering a couple other questions: is male superior strength an evolutionary product of their relation to women? And, is male dominance in social institutions a product of their physical strength?

The comparative study of our closer evolutionary relatives, other mammals and in particular other primates, reveals that the evolution of male strength is not selected for dominance over females. On the contrary, it is selected for dominance over other males, because females prefer to mate with dominant males. The degree of relevant dimorphism (greater male than female strength) is a function of how many females are likely to mate with the male that successfully suppresses the mating aspirations of other males. This doesn’t mean male strength is never used against females, but it is the exception and certainly not the primary selective pressure. The evolution of superior male strength then is not about suppression of females, but suppression of other males, in response to female mating preferences.

If female chimpanzees or humans preferred to mate with submissive or physically weaker males, there’d be no fitness advantage to being stronger than the other males and thus no (what evolutionary biologists call) arms races for greater male strength, leading to the currently noted dimorphism. So greater male strength is not a product of suppressing females, but of female mating preferences. Given this primatological and hunter-gatherer evidence, it starts to seem farfetched speculating that male dominance of social institutions is the evolutionary product of men’s physical suppression of women. This now is a claim not well supported by the evolutionary evidence. A greater challenge still to such a claim though arises from consistently following of the evolutionary evidence. For, the evolutionary effects of female sexual preferences have not been limited to the dyadic mating couple, but manifested in the forming of humanity’s social institutions. A more evolutionarily consistent explanation for male predominance within human public institutions requires a brief digression through the evolution of parental investment differences.

Males and females invest in the creation of their offspring, but almost never do they invest equally. Since they both benefit equally from the successful production of offspring, the one that invests the most is effectively working for the lower investing sex. This “working for them,” by the complementary sex, allows the lower investing sex to redirect its energies in other directions: like finding more mates who’ll also do the greater share of work on their common offspring. Additionally, the greater investment of the one sex actually reduces the number of its potential offspring. The sex that is prepared to work for the other sex, and share its more limited reproductive potential, is then a valuable and scarce resource for that other sex. The lower investors compete for the higher investors; the higher investors, so as to not waste their own limited resources, tend to be much more choosey about for whom they’ll do that extra work.

Across the animal world, the greater investing sex is almost always the female. This is not universal. There are as many as 50 species, mostly birds, in which it is the male who invests more. And, unsurprisingly, the effects of parent investment differences skew the other way in those species. For the majority, including humans, though, females already are investing more even before conception: their bodies produce much more nutritionally rich gametes. This creates a cascading effect in which right from the start females have a greater interest in seeing through to fruition a fertile zygote. Only unique and rare ecological conditions are likely to see males engage in greater post-conception parental investment. Female gametes take much longer to produce and are much rarer. Human females only produce usually a little less than 300 ova in a lifetime. Males have millions of sperm available throughout their reproductive phase of life, which is considerably longer than a females’. Women therefore invest in the gestation and nurturing periods necessary for a sustainable offspring, stretching their time-investment out for years and involving high nutritional demands. The only investment essential for a male is a few moments to ejaculate and whatever length of time and resource investment to persuade her to mate with him. This may not turn out to be the best investment choice of a human male, but that’s a separate concern, which is influenced by ecological factors. The key point is that the reproductive economy of humans created an evolutionary dynamic in which males had to appeal to the preferences of females.

The prior two paragraphs illustrate why women’s mating preferences have had such powerful impacts upon men’s evolution. One of the consequences of these evolutionary pressures has been the emergence of the social practices cited as evidence of patriarchy. This is because among the key mating preferences of women, across cultures and through history, has been attraction to male dominance (particularly, over other males), high social prestige and control over resources. Dominance, prestige and resources are competitive goods, only known to be possessed if they’re shown to be possessed. Given these female preferences, fitness enhancement impels males to display their relatively greater possession of these goods, compared to other males. Thus, even before our ancestors had social institutions, whatever might have been thought of as public space was going to be primarily occupied by males.

This might be thought of as the lek walk of humans. In many other species, in the public place of their mating grounds, males strut about displaying to the observing females their traits. Lekking is practiced widely among birds, as well as other species, including some mammals. Those with the traits preferred by the females win the reproductive lottery. As our ancestors formed more social bonds with common living spaces, along with our growing brains, village life became a kind of lekking: males occupied this embryotic public space as the lesser investing sex always does the lek walk. Human females had little incentive to occupy that space, while doing so was highly fitness enhancing for human males. Then, as social complexity rose, as group defense and social coordination practices gradually congealed into institutions, it was males who already occupied the nascent public space. It remained males who had the most fitness to gain by distinguishing themselves, whether as hunters, warriors, shamans or chieftains. Little has changed in our evolutionary dispositions since.

Clearly, the technological explosion of the last 10,000 years – through agriculture, industry and cybernetics – has changed many of our social dynamics and practices. Whether this is evolutionarily sustainable is an empirical question that natural selection will decide for us. If it proves to be, perhaps female mating preferences will change. In the meanwhile, though, women continue to prefer male traits that require social display. (NB: other high female mating preferences, like wit and intelligence, are also traits that need to be publicly performed to attract female attention.)

The conclusion then seems to be that if by patriarchy one means the suppression of women, the facts of superior male upper body strength, increased propensity for violence and prospect for greater intelligence certainly provides credible grounds for such a perspective. And there has been plenty enough institutional coercion of women in history. If by patriarchy, though, one is referring to the fact that males have, until very recently, almost entirely monopolized social institutions, this is less a result of male suppression or oppression of women than as a by-product of women’s mating choices. Likewise, of course, the extent to which males have used control over public life and social institutions to suppress or coerce women, it has been female mating preferences that endowed males with both the physical strength and the psychological preference for dominating public space.

Moralizing and finger pointing, of course, misses the point about evolutionary processes. They exist, always, only, because in the distant past they provided the best functional architecture available to optimize the movement of genes into future generations. The above observations, though, should not be read as describing the limits of possibility for women living today; the evolutionary future is not etched in stone. As humans transform their ecology with technology new evolutionary possibilities may emerge. And the scientist’s description of “what is” is never a prescription of what “should be.” Still, those who decry the current state of the world as patriarchy, if interested in a sincere exploration of the nature and history of human society, would profit from deeper evolutionary understanding of the contemporary world’s biological origins. Patriarchy, if it exists, is as much as product of women as it is of men.