In a private Senators Only room in the Capitol in March 2012, Sen. Barbara Mikulski (D-Md.) (center), is toasted by fellow female senators Lisa Murkowski (I-Alaska) (left) and Kay Bailey Hutchison (R-Tex.) for her record years of service in Congress. (Melina Mara/The Washington Post)

My colleague over at The Fix, Philip Bump, dug into this question:

What if the composition of Congress reflected the gender composition of the United States?

The (surprising) answer? Nothing. The results of Congressional action are determined almost entirely by party identification, not by gender.

This conclusion is based on examining roll call votes and simulating the impact of a Congress that was 80 percent female instead of 80 percent male.

It confirms the political science research on gender and roll call voting. Although male and female members of the House once voted in at least somewhat different ways, this was no longer true as of the mid-2000s.

In the Senate, there were some more durable differences, mainly because female Republicans were more liberal than male Republicans. But that may no longer be true, with the addition of conservative female Republicans like Joni Ernst and Deb Fischer (you can see their voting patterns captured here).

But “congressional action” involves a lot more than roll call voting. And here’s where larger differences between male and female legislators emerge — differences that could affect Congress as a whole if the representation of women were increased.

For one, women are more likely than men to advocate for issues often associated with women’s interests — child care, women’s health, abortion, pay equity and the like. There are many studies, but see Michele Swers’s two books to start with. This shows up, for example, in in floor speeches and legislative debates, where women are more likely to discuss issues in terms of women’s interests. (Women are also more likely than men to give floor speeches, period.)

Via e-mail, Swers noted some of the recent examples — such as how Democratic Sens. Kirsten Gillibrand (N.Y.) and Claire McCaskill (Mo.) have focused on sexual harassment in the military (albeit with differing points of view), or how Sen. Barbara Mikulski (D-Md.) pushed the Lily Ledbetter Fair Pay Act.

Other research suggests that women may be more effective legislators than men. Craig Volden, Alan Wiseman and Dana Wittmer find that, within the minority party, women are able to get their sponsored bills further through the legislative process.  Sarah Anzia and Christopher Berry have shown that women sponsor and co-sponsor more bills than men do, and deliver about 9 percent more funding to their districts.

Now at least some of these findings, as Kathryn Pearson and Logan Dancey note, may arise because women must function in a predominantly male institution. Were women to dominate Congress, it’s possible that women (and men) would behave differently.

At the same time, Tali Mendelberg, Chris Karpowitz and Nicholas Goedert show that as women become more numerous in a decision-making body, they are more likely to articulate the distinctive concerns of women. Moreover, men do likewise. These results are based on experiments, not on actual deliberations in Congress. But they suggest that female legislators may have intrinsic goals and interests that they would work even harder to advance — maybe even joined by male legislators — were women’s representation increased.

There’s little doubt that a lopsidedly female Congress would still be pretty partisan.  But it would likely be different in many other respects.