Economists take tastes as given. However, tastes must be derived from biological models of evolutionary survival; we exhibit those tastes which served to make our ancestors survive. In particular, economists have no theory which explains observed behavior towards risk; rather, we take behavior as a datum. In this paper we present a model which explains risk seeking by adolescents and risk aversion by mature males as the result of an evolutionary mechanism.While textbooks indicate that changes in tastes are a potential source of changes in demand, empirical and theoretical work ignores tastes. As a research methodology, this strategy has been extremely productivefor example, the work of Becker and his followers on areas of behavior as diverse as crime and marriage has given fruitful results without considering tastes at all (see Stigler and Becker (1977)). The presumption has been that tastes are constant (over space and time) and that therefore changes in behavior can be explained in terms of changes in relative prices. The other justification for ignoring changes in tastes is that we have no theory as to when and how tastes change, and thus it is impossible to make falsifiable statements on such changes.There exists, however, another body of literature which may have implications about tastes. This is the literature of "Sociobiology" (Wilson (1975))the emerging discipline dealing with biological determinants of social behavior. (See also Becker (1976) , Hirshleifer( 1977), Rubin, et. al. (1979), Tullock (1977), and Fredlund (1976) for contributions by economists to this literature, and Ghiselin (1974), for a contribution by a biologist using economic arguments.) Viewing human behavior in terms of evolution indicates that tastes may be the result of selection pressurethat is, the drives and goals of humans may have been selected for, in the sense that our ancestors who had such drives and desires in fact survived to become our ancestors, while their relatives with less fit (in the biological sense) goals did not survive or reproduce. (Coase (1 978) argues that sociobiology should enable us to determine the elements and form of the utility function.) In this sense, it is useful to view natural selection as maximizing, in an "as if" sense, for this methodology, if used correctly, would give valid predictions.In using biological arguments, it is important to specify the level of which selection operatesthat is, does selection operate at the level of 'The University of Georgia. The authors would like to thank two anonymous referees for helpful comments.
585Economic Inquiry Vol. XVII, Oct. I979
