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, 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?

Toh and 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.

Tight cultures, Toh and Leonardelli believe, hold women back because "cultural tightness provokes a resistance to changing the traditional and widespread view that leadership is masculine."

Loose cultures, by contrast, do not have clear norms and are more tolerant of deviation from the rules. Heterogeneous societies and countries in the midst of social and political transition, like Australia, Israel, the Netherlands and Ukraine are loose cultures.

These are cultures in which "societal members tend to be more open to change, and this openness may become manifest in changing expectations and attitudes about the masculinity of leadership."

Here is where Clinton's mystery comes in. Tight cultures are not necessary sexist ones - witness the inclusion of Norway in the list. But extremist subcultures are certainly tight cultures, and they are built on historical assumptions of male dominance. The perspective of Toh and Leonardelli helps to explain why these rigid ideologies are so fixated on keeping women down.

But what about the places like Norway: tight cultures where women do extremely well? Toh's and Leonardelli's answer to that apparent paradox is that, where there has been a top-down decision to support female leaders, tight cultures are very good at executing that directive. That is because these societies are effective at acting on the collective will. If the decision is made to elevate women, tight societies will implement it.

"Although a culturally tight country, Norway ranks high in terms of gender egalitarianism," the study's authors point out. In Norway, egalitarianism is not a rebellion against prevailing cultural norms. It is, instead, what Norway's new top-down consensus requires: "Norway has among the most ambitious equal opportunity legislation in the world that legally requires firms to reach a 40 percent women board representation by 2017."

The study's framework also helps to explain one peculiarity of women in the workplace. Tight societies that choose egalitarianism, like Norway, have been good at pushing women into the corporate establishment. Loose societies that are open to change have been good at empowering women more broadly, encouraging them to join the workforce and to start their own small businesses.

But the one thing women around the world have failed to do is create paradigm-shifting companies. None of the great technology start-ups - for example, Google, Apple and Facebook - were founded by a woman. Nor were any of the leading hedge funds, the innovators in the world of money, established by a woman. Women are not just underrepresented in this space of transformative entrepreneurs - they are entirely absent.

At first blush, this gap seems to contradict the analysis by Toh and Leonardelli. After all, start-ups embody a profoundly loose culture. It does not matter whether you are a misfit or an ultraconformist, so long as you have a brilliant idea and are able to implement it.

But the authors point out that leadership is not just about how others view you, it is also about how you view yourself.

Centuries of sexism, they argue, mean that "even when possessing and demonstrating leadership behavior that is superior to others in the group, women leaders may sometimes prefer to cede the formal leadership role to men in the group because they, too, believe that being male or masculine is more leaderlike."

Loose cultures can counteract those self-imposed stereotypes to some degree. But the final frontier for women, even in societies that allow them to lead established institutions, is to be ruthless and to take big risks, essential qualities in world-changing entrepreneurs. Instead, as the authors found of female entrepreneurs in Malaysia, women often have to "lead as if they were mothers or teachers."

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