Why Are Men So Violent?

It will not have gone unnoticed that men are more violent than women. Men perpetrate about 90 percent of the world's homicides and start all of the wars. But why?

A recent article in a prominent science journal contends that evolution has shaped men to be warriors. More specifically, the authors claim that men are biologically programmed to form coalitions that aggress against neighbors, and they do so in order to get women, either through force or by procuring resources that would make them more desirable. The male warrior hypothesis is alluring because it makes sense of male violence, but it is based on a dubious interpretation of the science. In my new book, I point out that such evolutionary explanations of behavior are often worse than competing historical explanations. The same is true in this case. There are simpler historical explanations of male violence, and understanding these is important for coping with the problem.

A historical explanation of male violence does not eschew biological factors, but it minimizes them and assumes that men and women are psychologically similar. Consider the biological fact that men have more upper-body strength than women, and assume that both men and women want to obtain as many desirable resources as they can. In hunter-gatherer societies, this strength differential doesn't allow men to fully dominate women, because they depend on the food that women gather. But things change with the advent of intensive agriculture and herding. Strength gives men an advantage over women once heavy ploughs and large animals become central aspects of food production. With this, men become the sole providers, and women start to depend on men economically. The economic dependency allows men to mistreat women, to philander, and to take over labor markets and political institutions. Once men have absolute power, they are reluctant to give it up. It took two world wars and a post-industrial economy for women to obtain basic opportunities and rights.

This historical story can help to explain why men are more violent than women. The men who hold power will fight to keep it, and men who find themselves without economic resources feel entitled to acquire things by force if they see no other way. With these assumptions, we can dispense with the male warrior hypothesis, which is advanced by Melissa McDonald, Carlos Navarrete, and Mark Van Vugt in the latest issue of Philosophical Transactions of the Royal Society. These three psychologists imply that male violence is natural and inevitable, but all the evidence they offer can be explained by the simpler assumption that farming technologies allowed men to co-opt power over the course of human history.

• The authors claim that men are more xenophobic than women, because they are wired to wage war. But this is also predicated on the historical account, because men control governments and handle foreign relations. It follows, too, that men start all wars.
• The authors contend that, compared to women, men prefer social dominance hierarchies, which testifies to their innately competitive nature. But this is easily explained on the social story: in male dominant societies, men gain from dominance hierarchies, and women lose.
• The authors note that men are more prone to cooperate when under threat than otherwise, which may suggest an instinct to form armies. But a simpler explanation is that, having obtained power, men are reluctant to cooperate except under pressure.
• The authors cite a disturbing study in which men endorse war after being primed with a picture of an attractive woman, which suggests that male violence has a sexual motive. But the link between sex and violence may derive from the fact that sex is often coercive in male dominant societies.
• The authors link the male warrior hypothesis to racism: white men, they say, show greater fear responses to pictures of black men, than do white women. But this is difficult to explain on any evolutionary hypothesis, since there would have been little ethnic diversity in our ancestral past. Racism is more readily linked to the social history of slavery, an industry run by men.
• The authors also remark that women become more racist at times of peak fertility, suggesting fear of impregnation by foreign invaders. A different explanation is that menstrual peaks also bring out strong emotions, which lets latent racism come to the fore.

The male warrior hypothesis makes many predictions that don't pan out. There is no evidence that men prefer foreign women—the Western ideal is Barbie—and women often like effeminate men: David Bowie would not be sexier with an enormous beard. On the male warrior hypothesis, women should fear foreigners as much as men do, because foreign men are hardwired to attack them, but women are actually more sympathetic to foreigners. This may stem from their firsthand knowledge of discrimination. Women are also more cooperative than men, which makes little sense if men are innate coalition builders.

There are dubious presuppositions as well. The warrior hypothesis assumes there was constant warfare in our evolutionary past, but some anthropologists argue that ancestral populations were too sparse for frequent contact. It also presupposes that warfare increases male fertility, when it may actually reduce fertility for all. Fertility is probably maximized when men are non-violent and share in childcare, but in many societies men beat their wives, neglect their children, and practice sex-selective infanticide against girls. The authors perpetuate the myth that evolution prefers men to be polygamous and females to be monogamous, but we see every variation in other species. In chimpanzees, both sexes seek multiple partners.

Social history explains such facts by proposing that men have taken power by their greater strength, leading to violent competition and the abuse of women. This approach correctly predicts cross-cultural variation in gender differences. As women gain economic power, they cease being treated as male property, age differences between romantic partners shrink, and violence against women diminishes. On the flipside, women who gain power, like Margaret Thatcher and Condoleezza Rice, are often hawkish, suggesting that power, not gender, determines belligerence. Women in the judiciary dole out harsher penalties than men. And woman are committing more acts of domestic violence than previously recorded.

To reduce male violence, it is not sufficient to reform men, as the defenders of the male warrior hypothesis recommend. Nor will it suffice to empower women. This will reduce domestic violence, but not war, because women can be as aggressive as men. Warfare did not decline precipitously with women's suffrage, and during recent conflicts with Russia, 43 percent of Chechen suicide bombers have been women. Crucially, we must reduce the incentives for violence. In a recent book, Steven Pinker documents a radical reduction in violence with the rise of democracy and global trade, a comforting confirmation that social factors matter (for two reviews see here and here). I think Pinker's optimism may be overstated: global trade has done less to remedy the poverty that devastates lives of people outside the economic partnerships between wealthy nations; healthy trading relationships can lead one nation to overlook the human rights abuses in another; and there have also been dozens of attempts at genocide since the Second World War. In fact, Pinker too eagerly accepts the myth of the ignoble savage: the idea that humans are violent by nature. But his book does contain a crucial insight. He shows that patterns of violence can be dramatically altered by historical forces. Attitudes towards slavery, torture, and honor killing change over time, and this should make us realize that the biological contributions to violence may be greatly outweighed by the sociological.

Violence is a complex problem, which no simple biological approach can diagnose or remedy. Factors such as political instability, population density, and income inequality are associated with massive differences in violence across cultures, and these differences are observed while gender ratios remain constant. Of course, men still hold most of the power in the world, and it is no surprise, then, that they perpetrate most of the violence. But that too is a historical fact, not a biological given. If we focus on biology instead of economic and historical variables, we will miss out on opportunities for progress.