Comment by mothballed

Sure but you can advance your genes even more by taking a woman for yourself. And if there are already enough other males to ensure the survival of the females and children then it might be worth some of the males going to war to get some females.

At some point the marginal utility of warring is better for both the individual and the group than the marginal utility of yet another non-reproducing male hanging around "helping" out their kin while eating the resources.