Evolutionary theoretical models have predicted that extrinsic, but not intrinsic, personal mortality risk should alter the payoff from investment in health protection behaviors. One model also predicted that socioeconomic disparities in health behavior could be caused by differential exposure to extrinsic mortality risk driving reduced investment in health. We present observational and experimental tests of these predictions. Initially, we surveyed North American adults for reported investment in health, perceived personal extrinsic and intrinsic mortality risks, and measures of socioeconomic status. Reported health effort was robustly associated with perceived extrinsic mortality risk. Furthermore, the association between socioeconomic status and health effort was entirely mediated by perceived extrinsic mortality risk. In subsequent online and field experiments, we demonstrated that intrinsic mortality and longevity primes can be used to shift preferences from an unhealthy food reward towards a healthier alternative. Prior investigations have focused primarily on the effect of mortality risk on reproductive scheduling. We emphasize that mortality risk should influence a larger range of behaviors that involve current versus future trade-offs, including health behaviors.
"Extrinsic mortality risk and socioeconomic differences in health"
Gillian Pepper
Centre for Behaviour and Evolution
Newcastle University
