Evolution of Altruism

Dawkins and Darwin both state that altruism evolves if there are not a lot of "cheaters" in the groups within a species and not.  Altruism can evolve through genes passed on by parents who are cooperativ, altrusitc, and "helpers", especially in meerkats.  Helpers that are in the meerkat social-group put off giving birth to most offspring while caring for its kin by the dominant Alpha female because they are safer from predation, may get more food supplies, and indirectly pass on their genes to their brother and sisters, half-sibs, and even cousins.  In other species that are not related but live in the same ecological niche, may give reciprocal altruism if they know the other species will pay back in return.  Another example, is the Vambire bats that will use reciprocal altruism by feeding a non-kin member if they have extra blood to give without to much cost to themselves; and the benifactor should return the favor the next time he or she feeds.