As a newborn you might not have a sense of difference from the outside world. Everything is part of you. You may not have known the difference between you and your mother. Only after few months that distinction starts to appear. That is the first sense of being a separate person from others. You and mother. Then the list increases. You try seeing connection between people of same gender. If you have noticed some children go and call someone else as father just because he is a male. The realization that they are outsider and separate from your parents appear only later. That is when you start seeing children cry when they see strangers, have separation anxiety.

We survive as a collective. Most of the behaviors revolve around being part of the collective. To be accepted means to survive. In prehistoric time this was crucial to survival. Let us see why. Food is a collective resource so is protection. Being isolated means not able to receive food and protection. Considering the hunt and gather nature of how food was allocated it meant you may either have to macho up go hunt and try not being killed in order to eat. This macho way is not possible for everyone because hunting used to be a group activity not solitary. Now when a predator comes it is a collective effort to ward it off. You are not part of the group then you may have to face the predator alone. Well if you are confident you may but you have to consider if it is worth it.