species is the extent t0 which behavior is acquired by teaching and imitation. The rapid radiation of the human species into a large variety of ecological niches over a wide geographical range during the last 100,000 years suggests that this mode of adaptation may be quite effective. Until recently, however, few evolutionary biologists have attempted to identify the properties of cultural transmission that make it an effective way of acquiring behavior. Very different answers to this question have been suggested by Charles Lumsden and E. O. Wilson in...