Alyawara plant use and optimal foraging theory

Various authors have remarked on the importance of seeds in the pre-European diet of central Australian Aborigines. The Alyawara, an Arandic-speaking group, were typical in this respect. They collected edible seeds from nearly half the eighty-five plant species in their traditional subsistence inventory. In the past thirty years, Alyawara subsistence practices have changed dramatically because of the availability of European foods. Nevertheless, native foods continue to play a small but important role in the economies of some communities. Curiously, seeds are now seldom taken by the modern Alyawara, although they are often very abundant and readily accessible. We argue here that this phenomenon is best accounted for by models drawn from the theory of optimal foraging, which seeks to explain subsistance patterns in terms of the costs and benefits of exploiting various resources. Specifically, we maintain that since seeds are expensive to take relative to their nutritional value, they should be used only when the returns from other resources are very low, regardless of their own absolute abundance. This explanation appears to account for the modem Alyawara situation. It also contradicts the commonly accepted notion that hunter-gatherers take plant and animal foods in direct proportion to their abundance or nutritional value, except where considerations of palatability, or "cultural" preference or prohibition, intervene.