Inclusive Fitness

From the SL4 Lexicon:

Inclusive Fitness:

A term used in Evolutionary Psychology to explain kin selection, or the tendency of organisms to behave altruistically towards those they share genetic material with. Siblings share 50% of new genetic material with one another. First cousins share 12.5% of new genetic material with one another. Parents share 50% of new genetic material with their children. Organisms may sacrifice themselves for kin if enough is at stake. Altruism beyond the family probably evolved by bootstrapping itself from kin altruism. Instead of simply saying "an organism is behaving in the interests of its own fitness", modern evolutionary psychologists say "an organism is behaving in the interests of Inclusive Fitness", which carries the connotation of kin altruism.