What is the nature of “I want …”?

It seems to me that the original attitude for an evolving mammal would have been: I want that thing for me.

Or maybe, in a social group: I want that thing for me, despite what you want.

Intergroup competition might have changed that to: I know that you want it, but I want it too, for myself, not because I know that you want it.

More intergroup selection pressure might bring the individual to: I will abstain from taking the things that another has and will defend my things from anyone else trying to take them.

These modifications reduced intragroup conflict. They did not advance intragroup solidarity in the face of intergroup competition.

What would advance intragroup solidarity in the face of intergroup competition?

How about this: I want what you want, because I know what you want, and because I know that, what you want, is what I want.

This would increase intragroup solidarity.