In biology an altruistic act increases the reproductive fitness of a member of the same species (a conspecific) while reducing the reproductive fitness of the one committing the act. Reproductive fitness refers to the differential ability of an organism to influence gene frequencies in future generations. Altruism is distinguished from mutualistic behavior, which increases the reproductive fitness of others as well as the actor. Altruism also is distinguished from selfishness, which benefits the actor and either does not benefit or harms others’ reproductive fitness.
Encyclopedia of Genocide and Crimes Against Humanity
Field, Alexander J. 2004. “Altruism,” in Encyclopedia of Genocide and Crimes Against Humanity, New York: Macmillan.