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

Abstract

The climate of the Great Plains during the middle Holocene varied considerably, but overall it was marked by a north–south gradient of increasingly warmer and drier conditions, with a reduction in effective moisture, surface water, and resource abundance, and an increase in resource patchiness, sediment weathering, erosion, and aeolian activity. Pronounced drought conditions were most evident on the Southern High Plains. Understanding the human responses to middle Holocene climates is complicated by a lack of archaeological data, which is partly a result of geomorphic processes that removed or deeply buried sites of this age, and by the varying adaptive responses of hunter-gatherers during this period. On the Southern High Plains, where drought was most severe, surface and groundwater sources dried and bison populations were diminished, prompting substantial adaptive changes, including local abandonment, well-digging to tap underground water, and a widening of the diet breadth to incorporate higher-cost, lower-return seed and plant resources. Sites of this age on the Central and Northern Plains also show a possible increase in diet breadth (with the incorporation of plant foods in the diet), and perhaps changes in settlement mobility (including possible shift into higher elevation areas, or mapping-on to extant rivers and springs). But linking those changes to middle Holocene drought is less straightforward.

Reconstruction of hydrological changes and response to effective moisture variations from North-Central USA lake sediments

“…Although available moisture decreases, and lake salinity increases, from east to west, there can be considerable variation in total salinity and major-ion water types that is not due to simple precipitation-evaporation gradients. The midHolocene was drier than today, although magnitude and duration of aridity varied considerably (Meltzer, 1999;Fritz et al 2000b).…”

Climate change, adaptive cycles, and the persistence of foraging economies during the late Pleistocene/Holocene transition in the Levant

“…This cultivation is certainly a possibility; however, we maintain that low-level cultivation would have been one of many options available to foragers and did not have a significant impact on foraging economies until well into the Holocene (9). The shift in resource emphasis during the YD was merely a common response used by hunter-gatherers worldwide when faced with climatic deterioration (6,10,11). We suggest that this argument is illustrated best through the heuristic use of an alternative model, the theory of adaptive change (TAC; also known as resilience theory).…”

Paleoclimate and Amerindians: Evidence from stable isotopes and atmospheric circulation

“…Consequently, large game animals and hunting parties pursuing them ventured infrequently onto the High Plains between 8,000 and 5,000 yr BP. After Ϸ5,000 yr BP, declining insolation, cooler summers, and warmer winters established conditions similar to the present (7), so that year-round use of the High Plains by both large game animals and hunter-gatherers increased (6).…”

“…Thus, mid-Holocene summers might have been wet as well as hot and, indeed, limited seasonal hunting and gathering apparently occurred on the open plains during the mid-Holocene (3,5). Nevertheless, the relative and absolute number of archaeological sites on the entire Great Plains decreased significantly between 8,000 and 5,000 yr BP (6).…”