On the Universality of Human Nature and the Uniqueness of the Individual: The Role of Genetics and Adaptation


  • We gratefully acknowledge David Buss for his detailed comments and many patient and helpful discussions of the issues addressed in this article Dan Weinberger for his assistance as our local “personologist” in residence, Don Brown, W D Hamilton, Don Symons, and two anonymous reviewers for their extensive and detailed comments on earlier versions of this article, Jerry Barkow, Martin Daly, Roger Shepard, and Margo Wilson for assorted ideas, feedback, and inspiration, and Roger Shepard (and NSF Grant BNS 85–11685 to Roger Shepard) and Irven DeVore for their ongoing support of our efforts We would also like to thank Kathleen Much for her help with the manuscript, and the Gordon P Getty Trust and the Harry Frank Guggenheim Foundation for their financial support Correspondence should be addressed to John Tooby or Leda Cosmides, Center for Advanced Study in the Behavioral Sciences, 202 Jumpero Serra Boulevard, Stanford, CA 94305


ABSTRACT The concept of a universal human nature, based on a species-typical collection of complex psychological adaptations, is defended as valid, despite the existence of substantial genetic variation that makes each human genetically and biochemically unique These apparently contradictory facts can be reconciled by considering that (a) complex adaptations necessarily require many genes to regulate their development, and (b) sexual recombination makes it improbable that all the necessary genes for a complex adaptation would be together at once in the same individual, if genes coding for complex adaptations varied substantially between individuals Selection, interacting with sexual recombination, tends to impose relative uniformity at the functional level in complex adaptive designs, suggesting that most heritable psychological differences are not themselves likely to be complex psychological adaptations Instead, they are mostly evolutionary by-products, such as concomitants of parasite-driven selection for biochemical individuality An evolutionary approach to psychological variation reconceptualizes traits as either the out-put of species-typical, adaptively designed developmental and psychological mechanisms, or as the result of genetic noise creating perturbations in these mechanisms