 Arguments for the claim that only psychological mechanisms should be considered to be adaptations rest on the idea that behavior is really only ever a manifestation of the underlying psychology. Behavior is not an adaptation so much as it is the effect of an adaptation. Cosmides and Tooby (1987) also argue that the really interesting evolutionary generalizations emerge at the level of psychology, not behavior. Again, however, this argument depends on understanding “behavior” as “overt behavior”, individual chunks of physical activity that are not necessarily reproduced over time and which do not occur in evolutionary social science generalizations, verses understanding “behavior” as “complex behavioral strategies”, which do seem potentially transmissible (via the psychological mechanisms that support them). It is also notable that such strategies are the subject of a significant evolutionary literature—such as evolutionary game theory, on which Cosmides and Tooby themselves depend: the argument for expecting their famous “Cheater Detection” module (Cosmides, 1989; Cosmides and Tooby, 1992) is derived from Axelrod and Hamilton (1981) and Trivers’ (1971) work showing that TIT FOR TAT, which requires its players to be able to detect cheaters on reciprocally altruistic interactions, is an evolutionary stable  strategy[9].