Biomolecular Evidence of Early Human Occupation of a High-Altitude Site in Western Central Asia During the Holocene

Abstract

Reconstructions of early human occupation of high-altitude sites in Central Asia and possible migration routes during the Holocene are limited due to restricted archeological sample material. Consequently, there is a growing interest in alternative approaches to investigate past anthropogenic activity in this area. In this study, fecal biomarkers preserved in lake sediments from Lake Chatyr Kol (Tian Shan, Kyrgyzstan) were analyzed to reconstruct the local presence of humans and pastoral animals in this lowhuman-impact area in the past. Spanning the last ∼11,700 years, this high-altitude site (∼3,500 m above sea level) provides a continuous record of human occupancy in Western Central Asia. An early increase of human presence in the area during the mid-Holocene is marked by a sharp peak of the human fecal sterol coprostanol and its epimer epicoprostanol in the sediments. An associated increase in 5β-stigmastanol, a fecal biomarker deriving from herbivores indicates a human occupancy that most probably largely depended upon livestock. However, sterol profiles show that grazing animals had already occupied the catchment area of Lake Chatyr Kol before and also after a significant presence of humans. The biomarker evidence in this study demonstrates an early presence of humans in a high-altitude site in Central Asia at ∼5,900-4,000 a BP. Dry environmental conditions during this period likely made high altitude regions more accessible. Moreover, our results help to understand human migration in Western Central Asia during the early and mid-Holocene as part of a prehistoric Silk Road territory.

Lake Sedimentary DNA Research on Past Terrestrial and Aquatic Biodiversity: Overview and Recommendations

“…While currently no mammalian DNA and faecal DNA datasets have been compared, this is, nevertheless, a promising complementary approach. Indeed, ratios between different stanols and bile acids can be used to distinguish between omnivore and ruminant species and between humans and pigs [131,[133][134][135]. Though limited, evidence from archaeological sites suggests that shotgun metagenomic reads assigned to a range of different animal taxa, mirror their respective biomass estimated using classical analyses of bone remains [136].…”

Seasonal deposition processes and chronology of a varved Holocene lake sediment record from Chatyr Kol lake (Kyrgyz Republic)

“…This is partly due to the large contrasts of landscapes (high mountains, deep basins, large water bodies, and deserts), the low spatial and temporal coverage of high-resolution palaeoclimate archives, and the partly problematic dating of these archives in this area. Information about Holocene climate variability in CA derives from several types of archives, including tree rings (Esper et al, 2003), speleothems (Fohlmeister et al, 2017;Wolff et al, 2017), ice cores (Aizen, 2004), aeolian deposits (Huayu et al, 2010), and lakes (Heinecke et al, 2017;Lauterbach et al, 2014;Mathis et al, 2014;Rasmussen et al, 2000;Ricketts et al, 2001;Schwarz et al, 2017). However, none of these lake records have reported annually laminated sediments.…”

Southwest Asian cereal crops facilitated high-elevation agriculture in the central Tien Shan during the mid-third millennium BCE

“…The presence of domesticated sheep and goats dated to~2700 cal BCE were identified by mitochondrial DNA at Dali located in the Dzhungar Mountains of southeastern Kazakhstan [15]. It is possible that pastoralist subsistence spread northward through the Tien Shan mountains along the Inner Asian Mountain Corridor earlier than the occupation of Chap II [64,65], although additional excavation of a wider area of Chap II will aid in the recovery of additional faunal specimens. Judging from the rest of the wild plant and weed taxa, it is difficult to be certain whether the recovered crops from Chap II were sown in the autumn or spring, or precisely reflect that the landscape was used for crop cultivation, as not all plants were identified to species.…”