Middle Holocene climate change and human population dispersal in western North America

Abstract

Available climate records in western North America (7000-3800 cal yr BP) indicate a severe dry interval between 6300 and 4800 cal yr BP embedded within a generally warm and dry Middle Holocene. Dry conditions in western North America between 6300 and 4800 cal yr BP correlate with cold to moderate sea-surface temperatures (SST) and relatively high-marine productivity along the Southern California Coast evident in Ocean Drilling Program (ODP) Core 893A/B (Santa Barbara Basin). Based on archeological, linguistic, and genetic data, we argue for a movement of Uto-Aztecan people from western desert environments to the Southern California Coast, including the southern Channel Islands, and into portions of the Central Valley by at least 5500-4500 cal yr BP. We hypothesize that population dispersal from the desert interior was primarily in response to severe and prolonged drought and that people moved selectively to coastal and aquatic habitats because of the ameliorated effects of drought and their overall productivity.

Quantified intermediate water oxygenation history of the NE Pacific: A new benthic foraminiferal record from Santa Barbara basin

“…Late Holocene oxygenation at sill depth probably resulted from increased ventilation by NPIW related to regional cooling in the northern Pacific during the middle to late Holocene [ Mix et al ., ]. Based upon these records and others, the early Holocene, marked by relatively high sea surface temperatures in SBB, was much more poorly oxygenated than the cooler late Holocene [ Kennett et al ., , ; Kennett and Kennett , ].…”

10,000 years of human predation and size changes in the owl limpet (Lottia gigantea) on San Miguel Island, California

“…We then compare the results to paleoecological records of sea surface temperature (SST) and marine productivity from varved sediments of the Santa Barbara Basin (Kennett and Kennett, 2000;Kennett, 2005;Kennett et al, 2007) to determine if changes in Lottia populations are primarily the result of human predation or environmental change.…”

“…There have also been long-term changes in sea surface temperatures (SSTs), upwelling, marine productivity, and kelp forest cover (Kennett, 2005;Kinlan et al, 2005), all potential sources of natural variation in molluscan growth rates. Fortunately, studies of a long sequence of varved sediments in the Santa Barbara Basin provide a relatively welldefined, high-resolution record of environmental change in the area over the last 15,000 years (e.g., Kennett and Ingram, 1995;Kennett and Kennett, 2000;Kennett et al, 2007).…”

“…Trans-Holocene changes in mean Lottia gigantea length measurements for 19 San Miguel Island archaeological components shown relative to a summary of broadscale Holocene SST changes from Santa Barbara Basin cores shown at bottom; W¼Warm, C¼Cool, N¼Neutral; (seeKennett et al, 2007 for a higher resolution record).…”

Extreme cultural persistence in eastern-central Brazil: the case of Lagoa Santa Paleaeoindians

“…We can advance some possibilities related to the geographic position of the northern portion of the continent and its possible cultural links to both Asia (Goebel et al 2008, Goebel 2013 and Europe (Bradley e Stanford 2004, Stanford e Bradley, 2012, and higher population numbers in North America when compared to South America, resulting in more innovation rates per se. If this demographic difference is coupled with higher climatic variability in parts of North America during the Holocene (e.g., Anderson et al 2007, Kennett et al 2007), the outcome would be a lack of territorial pliability, which would prevent some human groups from adopting the strategy of moving into a new area while maintaining their cultural standards.…”