Do you ever wonder about why humans like to divide themselves into exclusive, insulated and increasingly smaller groups?

Especially in regards to sociopoliticial issues, though not only there. It happens in pretty much everything. The natural response of a large group forming often seems to be to break away into increasingly niche groups over time, even if the end result sabotages or contradicts their initial goal. Often paired with an outright refusal to reach out and band together to solve the problem that is faced. Do you think it's some kind of evolutionary psychological response to reduce overpopulation maybe? Like to break up tribal groups in primitive man.

And for the record I do get it, that people like having an exclusive group to belong to and call their own and that it simplifies worldview to just basically shut off outside input. It's comforting in a strange and perverse way.

I for some reason doubt this will get much if any in the way of serious responses, but whatever. Mostly just elucidating thought.