Illuminating high elevation seasonal occupational duration using diversity in lithic raw materials and tool types in the greater Yellowstone Ecosystem, USA

Abstract

This paper offers a method for estimating relative occupational duration at high elevations using lithic tool and raw material diversity. Presuming high elevation occupations are seasonal, we adapt methods traditionally used to estimate occupational duration for individual sites to the scale of landscapes, using data from the Beartooth and Absaroka Mountains of the Greater Yellowstone Ecosystem. Essentially, we work to understand how much of foragers’ seasonal rounds they were spending at high elevations. Averaged over the Holocene, the Beartooths appear to experience longer high elevation occupational duration than the Absarokas. In addition, Beartooths occupational durations are longest during the Early Archaic, likely related to the Early Holocene Warming. In the Absarokas, meanwhile, occupational durations are longest during the cooler, wetter Middle Archaic. Indeed, seasonal occupational durations consistently differ between the two ranges, suggesting diversity in mountain adaptations despite their similarities in resources and climate. Finally, the evidence suggests a gradual mid-to-late Holocene migration of Shoshonean peoples from the south and west rather than a sudden, unidirectional Numic Expansion.