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)

This study discusses the behavior of the females of the parasitic wasp Nasonia vitripennis, which adjust the sex ratio of their broods according to whether or not they are the first or second wasp to parasitize a host. The results provide a quantitative test of sex ratio theory. (Author/SA)