Individuals are genetically programmed to work together and cooperate with those who most resemble themselves

A tendency for similar individuals to cooperate selectively with one another, even if they are not close relatives, can evolve spontaneously in organisms. This may help to explain why cooperation is so widespread in nature. Similarity discrimination evolves quickly and powerfully in many types of social encounters. It evolves spontaneously in populations of organisms who are merely programmed to behave either cooperatively or selfishly, initially at random, and can recognize others who are genetically similar to themselves.