Boys and girls don't pair off at birth and scurry off to a dank cave together. Humans have always been social animals. We live in cooperative groups. Our bodies sort us out into groups of males or females. We interact socially as members of one group or the other. These groups aren't arbitrary or cultural- they're basic and biological. Males have to negotiate male and female groups as males. Males aren't simply reacting to female groups as males. We react to other males, as males. Who we are has a lot to do with how we see ourselves in relationship to other males, as members of the male group.