Reports on research related to the theory that the nervous systems, and hence the behavior, of animals may be permanently modified during initial periods of early life in response to environmental stimuli. (GS)

Presents models that ascribe social behavior, such as altruism and parental sacrifices for the young, to a kind of genetic imperative wherein individuals maximize their genetic contribution to the next generation. (GS)

Presents the idea that social systems evolve to increase the genetic fitness of individuals in specific environments. Cites examples of animal behavior and environmental influences that may indicate why different social systems have evolved. (GS)