Those are very, very logically distinct, species and tribe, I mean. You can conceivably have people doing things for the good of the tribe because in a natural environment they're probably related to the other members of the tribe so if the behaviour helps teh sponsoring gene spread, on average it will propagate. "It's good for the species" is never a good explanation for anything, ever. The other members of of a species (of one's own sex) are the competition, the ones you want to fail in comparision to you. Group selection works fine if there's a guiding intelligence behind it, but there are no examples in nature, ttbomk.