The subsistence strategies of hunters and gatherers have been largely studied by anthropologists throughout the twentieth century. In the past few decades, researchers have increasingly turned to evolutionary theory, mainly behavioral ecology and optimal foraging, to explain observed patterning in hunter-gatherer food-getting behaviors. Evolutionary geared studies of hunters and gatherers have been successful and are useful in explaining behavioral patterning and generating new hypotheses. However, recent analyses suggest that evolutionary models of foraging behavior might not provide the best predictions of hunter-gatherer foraging. Here we develop a spatially explicit Central Place Foraging model to generate expectations of hunter-gatherer foraging behavior under variable constraints. Variable distances, number of carriers, prey encounter rates, and social foraging factors are specified over time and over a virtual landscape. We test our expectations with foraging return data from the Hadza, an African hunter-gatherer population from Tanzania. The Hadza data include return rates for prey of variable body size, and is seemingly constrained by distance and by the number of carriers delivering the optimal load to the central place.
Results/Conclusions
Results indicate that Hadza foragers follow predictions of the central place foraging model by maximizing the rate of net energy returned over time spent foraging. Composition of the optimal loads delivered show markedly different patterns of covariation between distance, number of carriers, and prey size. For example, while the number of carriers explains a great deal of the variation in optimal loads obtained from smaller prey, it does not seem to influence the optimal loads of larger game. We conclude that when analyzed within an optimization context, hunter-gatherers such as the Hadza of Tanzania clearly follow foraging predictions generated by evolutionary theory.
