In the recent US elections, we kept hearing of the Lilly Ledbetter law, and if we go beyond that nicely alliterative name, it was really about this: in the US, a man and a woman are doing the same job, with the same qualifications, and the man is paid more because he is a man. So in a literal way, men rule the world. This made sense--a thousand years ago. Because human beings lived then in a world in which physical strength was the most important attribute for survival; the physically stronger person was more likely to lead. And men in general are physically stronger. (There are of course many exceptions.) Today, we live in a vastly different world. The person more qualified to lead is not the physically stronger person. It is the more intelligent, the more knowledgeable, the more creative, more innovative. And there are no hormones for those attributes. A man is as likely as a woman to be intelligent, innovative, creative. We have evolved. But our ideas of gender have not evolved very much.