So eventually we became relatively hairless.
Primitive tribal societies often run around mostly or completely nude, but, as we became more armoured and found ourselves carrying around a powder keg of repressed sexuality, the wearing of clothes became a priority for us. They made us feel less personally vulnerable, but also they covered up the flesh of others which was a potential stimulus for our anarchic erotic feelings. If you are hungry, and you are on a diet, it is easier if all that yummy food is covered up. It helps you maintain your discipline.
Now we can see the significance of our myth about Adam and Eve in the Garden of Eden. They were naked and lived an idyllic existence. Then a predator (a snake in the story) inspired them to seek knowledge of good and evil (in this case the destructive behaviour of predators, which seemed evil to them in their idyllic state), and, as a result, they developed a sense of shame about their nudity. And they were expelled from the Garden, which is what ultimately happened to us. We became alienated from the natural world and condemned to a life in the wilderness of our own neurosis.
Over time we would develop cities which were external expressions of our own armoured state in which we would shelter from the natural world of which we no longer felt a part. This had the advantage of allowing us to work together in larger networks on the problem of understanding the world and ourselves. On the downside it allowed forms of social alienation such as loneliness, crime and homelessness to flourish. The invention of the internet makes urban living no longer necessary for networking, but we have too large a population for most of us to live any other way. Psychologically this isn’t a problem as the emotionally healthy individual can thrive in a somewhat artificial environment. The only problem is reorganising our lives in such a way that our cities are ecologically sustainable.