The global scholarship leaves no doubt: Women in political office make it a priority to advance rights, equality and opportunity for women and girls, in a way and to a degree that men in power overwhelmingly do not.

A large body of research has been devoted to answering a fundamental question: Do women substantively represent women more effectively than men do? In hundreds of studies examining large data sets of roll call votes, bill sponsorship, laws enacted and other measures the answer is clear. "Across time, office, and political parties," political scientist Beth Reingold writes in a comprehensive review, "women, more often than men, take the lead on women's issues, no matter how such issues are defined."

Such findings don't mean that all female officeholders seek to advance women's rights, or that women govern only from the standpoint of gender. But the research does speak strongly to the fact that women and men in power have different priorities.

And then there's the danger that if women aren't at the table, they might be on the menu. In late 2009, the all-male Senate Democratic leadership team met privately to decide what would be included in the final Affordable Care Act. They eliminated a women's healthcare amendment that had passed overwhelmingly in committee, and that included coverage for such things as contraceptives and mammograms. The amendment's sponsor, Sen. Barbara A. Mikulski (D-Md.), had to demand its reinstatement just as the caucus was about to vote on the final bill.