Last July, I wrote a piece here at Forbes about how the underrepresentation of women in corporate boards is a big problem, a clear indication of both how women are systematically excluded from leadership positions and the end result of that process. The shutting-out of women from leadership is a problem built into the system; men are simply more likely to promote men. Which means that, all things being equal, a predominantly male leadership regime will tend to remain so. Even companies with a self-conscious commitment to gender equality still repeat the same old patterns. Inertia, simply put, is hard to overcome without a push from a stronger force. That’s basic physics.