Familiar Neighbors but Not Relatives Enhance Fitness in a Territorial Mammal

Hamilton’s rule attempts to link costs, c, benefits, b, and genetic relatedness, r. Hamilton’s rule does not apply to spouses, because r is 0. Everyday life tells us that costly benefits are more likely to be given because of expediency, or because of mutuality, than because of consanguinity. A necessary condition for mutuality is that…