Social foraging and the behavioral ecology of intragroup resource transfers

Two chimpanzees stalk, isolate, and kill a red colobus monkey. An attendant primatologist notes that parts of the prey are relinquished selectively to onlooking scroungers (Fig. 1). A human forager returns to camp mid-afternoon with a freshly killed, medium-sized ungulate. Later in the day, an ethnographer observes that shared portions of the animal have found their way into the cooking pots of most or all of those in the small band. Examining a prehistoric scatter of food residues, an ethnoarcheologist wonders when early hominids began to scrounge or share food, and with what consequences for our evolution. All of these settings represent one problem: the analysis of intragroup resource transfers among social foragers. New studies in the behavioral ecology of transfers show them to be more commonplace in nature, more complicated and variable, and more subject to comparative analysis than has been appreciated.