The evidence of violence against women is clear. So what does it mean for world peace? Consider the effects of sex-selective abortion and polygyny: Both help create an underclass of young adult men with no stake in society because they will never become heads of households, the marker for manhood in their cultures. It’s unsurprising that we see a rise in violent crime, theft, and smuggling, whereby these young men seek to become contenders in the marriage market. But the prevalence of these volatile young males may also contribute to greater success in terrorist recruiting, or even state interest in wars of attrition that will attenuate the ranks of these men. For instance, the sole surviving terrorist from the 2008 Mumbai attacks testified that he was persuaded by his own father to participate in order to raise money for the dower that he and his siblings needed in order to marry.

We also know through experimental studies that post-conflict agreements that are negotiated without women break down faster than those that do include women, and that all-male groups take riskier, more aggressive, and less empathetic decisions than mixed groups — two phenomena that may lead to higher levels of interstate conflict.

On an even deeper level, the template for living with other human beings who are different from us is forged within every society by the character of male-female relations. In countries where males rule the home through violence, male-dominant hierarchies rule the state through violence. This was most poignantly expressed by male Iranian dissidents who, during the ill-fated 2009 Green Revolution, explained their decision to wear headscarves as a sign of protest against the regime — and an act of solidarity with the women long oppressed by it. As one supporter of the protests explained it, “We Iranian men are late doing this.… If we did this when rusari[the headscarf] was forced on those among our sisters who did not wish to wear it 30 years ago, we would have perhaps not been here today.” This is a profound statement: Men who see women as beings to be subjugated will themselves continue to be subjugated. Men who see women as equal and valued partners are the only men who have a true chance to win their freedom and enjoy peace.