Kin Selection

Kin selection theory is a formulation of natural selection theory that is particularly suitable for understanding cases of reproductive self-sacrifice. For example, sterile workers in insect societies help the queen to reproduce by rearing her offspring. This phenomenon can be favored by natural selection when the workers are genetically related to the queen and thereby help her to transmit genes identical to theirs in the queen. The origin of this idea can be traced back to anecdotal comments by Haldane and Fisher, and even to the Origin of Species, but a systematic development of the idea began with Hamilton’s development of the concept of inclusive fitness. Natural selection by way of effects on genetic relatives has been named kin selection, and can thus occur whenever relatives preferentially interact together, in family-structured or spatially structured populations. The concepts of kin selection theory now provide powerful methods for analyzing models of evolution of social behaviors, including not only reproductive self-sacrifice in social insects but also the occurrence of conflicts within such societies, and more broadly any ecological interaction that includes cooperative or competitive interactions between individuals. The theory has contributed substantially to the development of ideas in diverse fields beyond behavioral ecology, including parasitology, and to the study of epigenetic processes in developmental biology.