W. D. Hamilton's theory of kin selection, published in 1964, reshaped how biologists think of animal behavior. His theory caused biologists to see that familial relationships are a critical element of animal behavior. This, in turn, led to the application of molecular technology in animal behavior studies. Kinship is a key element of most contemporary field studies of social behavior in animals.

Kin selection

An animal has two ways of gaining fitness. The first, and obvious, is to reproduce. The second is less obvious; an animal can gain fitness by aiding close relatives. This is kin selection. Close relatives share genes (have genes that are identical by descent). In fact, if a relative's reproduction is increased enough, it may even benefit an animal to behave in ways that reduce its own reproduction. In the extreme case of the eusocial insects (termites, ants, bees, wasps, and a few other types of insect) workers give up their reproduction to assist their mother in raising her offspring.

Hamilton, W. D. (1964a,b). The genetical evolution of social behaviour. I, II. J. theor. Biol. 7:1-52

Kin recognition

For kin selection animals usually need to be able to discriminate kin from non-kin. Kin recognition can create "structured demes" in which kin are positively associated by helping dynamics and negatively associated by mating dynamics. If a deme is structured, then there are effects on a variety of population processes at the genetic and behavioral levels.

Recognition works on several levels: Species recognition, sexual recognition, social group recognition, individual recognition, or kin recognition. Kin recognition has the special property of being generalizable to previously unmet individuals; an animal that is unfamiliar can still be discriminated as kin or non-kin. This may be particularly important in social sytems of animals with discrete litters; non littermate siblings can only avoid mating if there is a generalizable mechanism for discriminating kin.

Social group or individual recognition, however, can function as kin recognition systems if family members that are collectively (group recognition) or individually recognized.

Greenberg L. 1979. Genetic component of bee odor In kin recognition. Science 206:1095-1097

Waldman, B. 1987. Mechanisms of kin recognition. J. Theor. Biol. 128:159-185.

Lacy R.C., Sherman P.W. 1983. Kin recognition by phenotype matching. Am. Nat. 121:489-512

Assessing the importance of kinship in behavior

Kin recognition is known in a wide range of animals.

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copyright ©2001 Michael D. Breed, all rights reserved