Hunter-gatherer adaptations to long-term fluctuations in regional resource structure require mechanisms to cope with periodic subsistence stresses. Among documented groups, a common response to such stress is temporary movement into adjacent occupied areas-moving in with "relatives" when things go wrong. However, in the case of early (ca. 12,000-10,000 B.P.) Paleoindian groups in the Americas, the availability of neighboring groups with a detailed knowledge of local resource geography could not be relied upon. Post-Pleistocene environmental changes and the low initial population of the New World are important factors conditioning a lifeway characterized by a dependence on hunting (though not exclusively of megafauna), and by high residential, logistical, and range (territorial) mobility. Early Paleoindian groups had to adopt a subsistence technology that could be employed regardless of the specific resource microstructure. In some regards, Paleoindians seem to have behaved like tropical foragers while in others like arctic collectors. Use of high quality lithic raw materials from large quarry sources, reliance on a bifacial technology, limited use of caves and rockshelters, and a low level of processing of food products for storage all may be indicative of such a subsistence technology, which would have been unlike that of any modern hunter-gatherers.
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