Why do men and women behave differently from one another in group settings?

Or do they? It’s possible my sample is biased, but I have noticed this sort of thing happening consistently.

I was at a journal club meeting today that consisted of 7 women and 8 men. The entire 90-minute discussion was executed by the men in the room. Every one of them participated, and about six of them dominated the discussion. One woman contributed one comment, and I asked a few questions.

Why is this? Do you think it’s as simple as women having softer voices, leading the men to not hear them and talk over them? (This happened at least once today.) Are women too insecure to speak up? Are the men just cleverer and more full of insightful things to say? Are women less likely to consider their contributions meaningful? What’s going on here?