Reddit reviews Primeval Kinship: How Pair-Bonding Gave Birth to Human Society

Grooming is not altruism. It's a way for an individual to be favored by another one.

For the example of birds, it's really what I think I tried (at least, hehe) to explain: individuals will help kins because it is believed that sharing a common genotype is enough to ensure the cooperation. The survival of the genes will "talk": behaviors that favor the survival will be the ones passed down to other generations.

I'm not saying humans are any better, I say humans have more complex societies that go a lot more beyong the genetic factor: religions, laws, philosophy, per examples of cultural factors, enforce particular behaviors that are not, in essence, adaptative. Now, that's also why amongst humans war exists, for one thing, while, for what we know, only chimps have shown a similar (but very bowdlerized) behavior. I'm not specist at all and the more you learn about primates, the more you come to really be fascinated by the way they structure their societies.

If this is of your interest, Primeval kinship is a really good book on the subject, and it's quite the sum (for what I know) of the new ideas on this physical anthropology subject.