Two major criticisms of human sociobiology are: (1) Biological determinism, the view that behavior is determined by genes, is wrong when applied to humans; and (2) Culture makes man unique in the animal world, so one cannot extrapolate from the sociobiology of non-cultured animals to man. I argue that the two criticisms are related in that a range of the conditions that favor increased phenotypic plasticity (and so a decreased degree of genetic determinism) also favor culture. That is, I argue that cultural transmission is not universally favored by natural selection; but the ecological conditions that do favor culture also favor phenotypic plasticity. Homo sapiens clearly is a cultural species and the evolutionary dynamics of a cultural species differ in important respects from that of a non-cultural species. In particular, the central tenet of sociobiology — that the behaviors that evolve are those that maximize inclusive fitness — does not hold true of a cultural species. In effect, this paper offers an evolutionary argument against the general utility of human sociobiology.