It gets worse. In a study of several hundred people, Jennifer Berdahl of the University of British Columbia found that women who “deviated from traditional gender roles—by occupying a ‘man’s’ job or having a ‘masculine’ personality” were disproportionately targeted for sexual harassment.

But sexual harassment isn’t more likely only when women violate traditional gender roles. It’s also more likely when men consider those roles sacrosanct. In another study, Italian researchers arranged for male students to collaborate online with a fictitious man and one of two fictitious women. One of the women said she wanted to become a bank manager “even though it takes so much time away from family” and that she had joined “a union that defends women’s rights.” The second woman said she wanted to be a teacher, which she considered “the ideal job for a woman because it allows you to have sufficient time for family and children.” Having told the subjects that they were participating in a test of visual memory, the researchers gave them an assortment of images to exchange, some of which were pornographic. In each group, the fictitious male interlocutor proceeded to send pornographic images to the fictitous female; the researchers studied which of the male students would do the same, and to which of the women. They reported that the feminist interlocutor received the most pornography, and that male students who endorsed traditional gender roles were most likely to send it.

Other studies have reached similar conclusions. Two analyses of American murder statistics, for instance, suggest that in cities in the South, where men tend to hold traditional attitudes about gender, greater economic equality between men and women correlates with higher rates of male-on-female murder. The same correlation was not found in areas with less traditional attitudes.

Why is this relevant to Hillary Clinton? It’s relevant because the Americans who dislike her most are those who most fear emasculation. According to the Public Religion Research Institute, Americans who “completely agree” that society is becoming “too soft and feminine” were more than four times as likely to have a “very unfavorable” view of Clinton as those who “completely disagree.” And the presidential-primary candidate whose supporters were most likely to believe that America is becoming feminized—more likely by double digits than supporters of Ted Cruz—was Donald Trump.

The gender backlash against Clinton’s candidacy may not defeat her. But neither is it likely to subside if she wins. Jennifer Lawless, the director of the Women & Politics Institute at American University, suggested to me that Clinton has generally grown more popular when she stops seeking an office and begins occupying it. This accords with the research showing public hostility toward overt displays of female ambition. On the other hand, the pollster Anna Greenberg notes that Clinton has generally been most popular when conforming to traditional gender roles (working on women’s issues as first lady, sticking by her husband during the Monica Lewinsky scandal, loyally serving Barack Obama as secretary of state) and least popular when violating them (heading the health-care task force, serving in the Senate, running for president). Being the first female president, needless to say, violates traditional gender roles.

Edmon de Haro

Another troubling omen comes from Australia and Brazil, where, in recent years, pioneering female leaders have suffered a brutal backlash. To be sure, some women leaders—Margaret Thatcher, Angela Merkel, Indira Gandhi—have thrived despite sexist opposition. Still, research suggests that women leaders are less likely than their male counterparts to be accepted as legitimate, a problem that plagued both Australian Prime Minister Julia Gillard, who was ousted in 2013 after only three years, and Brazilian President Dilma Rousseff, who was impeached earlier this year for corruption even though her male predecessors and some of her key male tormentors had likely done worse.