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In 1991, after a high-speed chase, four Los Angeles police officers pulled Rodney King, a black man, out of his car, and beat him. In what seems strikingly familiar in 2016, an amateur videographer captured the scene. The next year, in 1992, a mostly white jury acquitted the officers, setting off riots that left over 50 people dead. In response to the attack, an independent commission reviewed the LAPD. In their report, the commission found that one type of officer was much less predisposed to force: No female cops were among the 120 police with the most use-of-force reports.

Males are the more belligerent sex in virtually all mammalian species that biologists have studied …

Female cops accounted for just 3.4 percent of officers involved in the “83 most serious lawsuits” against the LAPD from 1986 to 1990. While the stats suggested that female cops aren’t reluctant to use force, the commission reasoned, they’re not nearly as likely to use excessive force. “With some exceptions, female officers interviewed believed they were more communicative, more skillful at de-escalating potentially violent situations and less confrontational,” the report reads. “A suspect’s defiance and disrespect of an officer often gives rise to use of force by an officer. Many officers, both male and female, believe female officers are less personally challenged by defiant suspects and feel less need to deal with defiance with immediate force or confrontational language.” After the killings of Alton Sterling and Philando Castile, the murder of five Dallas police officers last week, and the 586 people killed by cops in the U.S. in 2016 thus far, much of the cultural conversation has been around the role of race, and racial bias, in the conducting of police work. But, as Danielle Paquette argues at the Washington Post, another factor of identity that needs to be evaluated is gender. Not only is it a matter of having a gender-homogeneous field in the form of policing, but social science finds that men and women relate to force very differently. It may be in our very biology.

Policing remains one of the most male-dominated professions in America: in the 1970s, about 97 percent of American cops were men, and in 2013, that had fallen only to 88 percent, meaning that the police force is even more gender imbalanced than the active-duty military, which was 84.9 percent male as of 2014. And while there are way more men than there are women policing American streets, the gender disparity for police use of force is even greater. Paquette reports that of the 54 officers that have been charged with killing someone with a gun while they were on duty, just two have been female. A 2002 report on gender and use of force from the National Center for Women and Policing found that male cops are way more expensive to employ than their female peers because of force, finding that male cops are two to three times more likely to have citizens name them in excessive force complaints than female cops, that male cops cost taxpayers between 2.5 and 5.5 times more than the average female officer in the payouts of excessive-force liability lawsuits, and that a male cop is 8.5 times more likely to have allegations of excessive force sustained against him than a policewoman would.

The gender disparity in the police force, argues Feminist Majority executive director Katherine Spillar, comes from the way policing is marketed. Would-be cops are recruited with promises of car chases and helicopter rescues, which fit traditional masculine values, while most of police work is nonviolent beat-walking and working with communities, with appeal to traditionally feminine values. Additionally, testing still has a physical strength component, while it should focus more on the ability to de-escalate potentially violent situations, which appears to be the direction of progress in policing. But there’s something even more basic at work here as well: Research on how elite companies like law firms and consultancies hire has found that if there isn’t a rigorous, standardized protocol for evaluating potential candidates, hiring managers just use themselves as the proxy of worthiness for a position, so people end up hiring people who are just like them, and thereby organizations replicate themselves.

Which makes the gender differences in predispositions to aggression and violence goddamn frightening. Back in the 1970s, psychologists were concluding that there weren’t many differences in psychology traits between men and women, except for aggression. A 2004 meta-analysis on sex differences in aggression found that men are more aggressive than women at every age, particularly so in their 20s, and this held in every country the analysis looked at, from the U.S. to the U.K. to Canada to Spain to New Zealand to Japan to Finland to Australia to the Netherlands. Indeed, as psychologists Hal Arkowitz and Scott O. Lilienfeld reported in Scientific American in 2010, men are more likely to be “aggressive in their mental lives,” fantasizing about revenge and homicide and dreaming more frequently of violent acts. A 2007 study of babies found that at 17 months, 5 percent of baby boys will bite you, kick you, or do other physically aggressive acts, compared with 1 percent of girls. And those differences hold at 29 months, which makes you think that the male disposition to violence is not wholly a matter of socialization to traditional gender roles, or, more bluntly, acculturation to toxic masculinity. Even more astounding, there’s evidence that humans aren’t the only one with gender disparities in aggression: “Males are the more belligerent sex in virtually all mammalian species that biologists have studied,” write Arkowitz and Lilienfeld. “Even the one marked exception to this trend — the spotted (“laughing”) hyena — may prove the rule. The female hyena, which is more physically aggressive than her male counterpart, has higher testosterone levels than the male does.”

So there’s a pretty clear logic to reducing excessive force in American policing. If de-escalation is the way of the future — as it’s been shown to be in Las Vegas, Dallas, and New York — then it makes lots of sense to have the humans doing the police work be more biologically and culturally disposed to peace. They’re called women.