Is it ensure, insure, or assure?
The scientific study of the biological basis of the social behavior of animals, based on the theory that such behavior is often genetically determined and that the genes governing this behavior are subject to the usual mechanisms of evolution. Sociobiology posits that an animal will normally behave in ways that will increase the survival of its genes in the gene pool, either by increasing its own reproductive success or the reproductive success of an individual or group that is closely related and thus shares some of the organism's genes. Sociobiologists seek to find explanations for animal behaviors such as aggression and altruism in relation to the survival of the animal's genes.
An area of inquiry in biology, still somewhat controversial but gaining wider acceptance. Its central tenet is that many human behavioral and social traits are genetically inherited and are thus determined by genetic makeup and not culture.
Note: Sociobiology is on the “nature” side in the nature-nurture controversy.