Like kinship selection? It's a concept somewhat contradictory to darwins survival of the fittest in which the ability of an individual to survive and produce numerous offspring defines his fitness.
It's essentially the existence of traits within a species that can actually lower an individual fitness but enhance the population's fitness. An example I remembered from one of my professors... is lets say a certain member of a Deer population runs out into the middle of the highway, if it gets hit by a car the rest of the group knows not to cross, if no cars are there, then the rest of the group knows to pass. I don't know if that example is real or just hypothetical but its the one I always remember
