QuoteI have been discussing the topic with a friend of mine and we agreed on the wolf-pack theory.

It goes as follows: men are far less individual as they like to see themselves. From an evolutionary point of view we could define them as the protectors of the tribe, the horde or family. Normally we protect 'our own' from everything that is different. This comprises any kind of xenophobia and general distrust against 'outsiders'. We are all tribal animals at heart and the lines of our tribe can be defined by almost anything: the color of our skin, religion, income divide, gender, lobby or culture. Men, on top of being tribal, enjoy high levels of testosterone: the stronger the testosterone-driven aggression, the healthier the leader of the pack appears to all others. Self-definition as the 'leader of a wolf-pack' and the use of aggression are mutually interdependent in this alpha-male scenario. The reason why aggression against transgender people is so explicit can be explained easily:{more in article}