Abstract | Behavioral ecologists combine evolutionary models of mechanism andecological models of circumstance to analyze the origins and forms ofintragroup exchange among social foragers, a category that includes primates,hominids, and recent and modem hunter-gatherers. Evolutionary mechanismsencompass individual, sexual, reciprocal, kin, group, and cultural selection;models of circumstance include tolerated theft, scrounging, marginal value,trade, show-offs, and risk reduction. After a critical review, I develop a partialsynthesis of these models. The results show that exchange behaviors havemulticausal origins and they likely will be diverse due to differing combinationsof mechanism and circumstance. They also help explain seemingly uniquefeatures of foraging economies, including constrained production and routinedemand sharing. |