People feel like they need to be surrounded by or close to other people because we are what evolutionary biologists call "eusocial." Eusociality is the tendency for an organism to organize cooperatively, with overlapping adult generations and a division of labour by reproductive and non-reproductive groups. This theory of eusociality was first pioneered by E.O. Wilson. It has since been discovered that the only other organisms that have evolved "true eusociality" are ants, bees, termites, and wasps. Examples of this social organization in mammals is currently controversial. However, it is clear we are eusocial, and as a result, it may be best to think of us as a super-organism (which is how we imagine the eusocial insects). If we really are a super-organism, this would explain why we have a need to be surrounded by others. In a sense, a lone human isn't a human. That is not to say that if you go off into the woods by yourself and never talk to anyone again you would cease to be human. But, consider for a moment what you would be like if you were born in isolation and grew up never knowing another human. Many animals could do this and they would not be that much different as an adult than they would have been in more social circumstances. Some animals do this naturally. They are born and then just live by themselves for most of their lives. But a human would be a shell. You really wouldn't possess any of the behaviours that we would think of as uniquely human. EDIT: Also, I've been thinking about consciousness a lot lately. b_b and I will be doing a podcast on consciousness soon. And I have started to develop the belief that if a human grew up in complete isolation, they would be less conscious than a human that grew up around other humans. So much of my consciousness, and my ability to reflect on consciousness, is intrinsically linked to my connection with other people and the ideas I have shared with other people. Anyway, it's a thought.