Human Responses to Middle Holocene (Altithermal) Climates on the North American Great Plains

H w p The climate of the Great Plains during the middle Holocene aried considerably, but overall it was marked by a north–south radient of increasingly warmer and drier conditions, with a reuction in effective moisture, surface water, and resource abunance, and an increase in resource patchiness, sediment weatherng, erosion, and aeolian activity. Pronounced drought conditions ere most evident on the Southern High Plains. Understanding he human responses to middle Holocene climates is complicated y a lack of archaeological data, which is partly a result of eomorphic processes that removed or deeply buried sites of this ge, and by the varying adaptive responses of hunter-gatherers uring this period. On the Southern High Plains, where drought as most severe, surface and groundwater sources dried and bison opulations were diminished, prompting substantial adaptive hanges, including local abandonment, well-digging to tap underround water, and a widening of the diet breadth to incorporate igher-cost, lower-return seed and plant resources. Sites of this age n the Central and Northern Plains also show a possible increase n diet breadth (with the incorporation of plant foods in the diet), nd perhaps changes in settlement mobility (including possible hift into higher elevation areas, or mapping-on to extant rivers nd springs). But linking those changes to middle Holocene rought is less straightforward. © 1999 University of Washington.