NEW YORK — NEW YORK With hindsight, we may find that the 2016 U.S. presidential race began last week, when Hillary Rodham Clinton made a politically electrifying point. “Why extremists always focus on women remains a mystery to me,” she said at the Women in the World conference in New York. “But they all seem to. It doesn’t matter what country they’re in or what religion they claim. They want to control women.”

At a time when birth control has re-emerged as a political issue in the United States, 94 years after the first legal ruling to permit it, Mrs. Clinton’s comments were an inspiring rallying cry for worried American women. But what about the mystery she identified? Why, as the secretary of state asserted, do extremists, from the Taliban to conservative Christians, want to control women?

An intriguing new study by two professors at the Rotman School of Management at the University of Toronto suggests a possible answer. (Disclosure: I am on the school’s dean’s advisory board.) Soo Min Toh and Geoffrey Leonardelli didn’t set out to discover why extremists want to control women. Their question was more familiar: Why aren’t there more female leaders?

Ms. Toh and Mr. Leonardelli argue that women are held back by “tight” cultures and can emerge more easily as leaders in “loose” cultures. “Tight” cultures are ones that have clear, rigid rules about how people should behave and impose tough sanctions on those who color outside the lines. Socially conformist, homogeneous societies like Japan, Malaysia, Norway and Pakistan are tight cultures.