Survival Environments And Adaptation Strategies Of Prehistoric Humans In The Yellow River Basin Of The Qinghai-Tibetan Plateau

The Qinghai-Tibetan Plateau（QTP）responds sensitively to climate change and,with its cold and hypoxic conditions,strong ultraviolet radiation,and relatively scarce food resources,it is an ideal location for studying past human-environment interactions.Understanding of the evolution,regulation,and mechanisms of ancient human adaptation to the extreme environment of the QTP provides an essential reference for addressing the current and future challenges posed by global climate change and extreme weather events.The upper Yellow River Basin drains an area of the QTP that is transitional between the western Loess Plateau and the eastern QTP and is characterized by relatively gentle topography.The basin is an important location for the interaction of different archaeological cultures.In recent decades,there have been advances in understanding of prehistoric human-environment interactions in the QTP and Yellow River Basin,providing important baseline evidence for studies of regional integration and comparisons of different cultures.However,due to the constraints of the natural environment and limited archaeological finds,the spatial and temporal distribution,behavioral pattern,and environmental context of prehistoric hunter-gatherer populations in the region and their connection with Neolithic culture is still poorly understood.This study reconstructs early-mid Holocene human subsistence patterns,regional environmental conditions,and human-environment interrelationships in the upper Yellow River Basin based on collection and analysis of archaeological,chronological,and environmental samples from representative low and high altitude sites in the Yellow River Basin on the QTP.The low altitude site is at Shalongka in the Huanghuang Valley（evidence from ethe official archaeological excavation）and the high altitude site is in the Yellow River source area at E’ling Lake（evidence from field survey）.Chronological and environmental samples were collected from a420-cm thick archaeological section at Shalongka site and a 210-cm thick natural section at E’ling Lake sites.At Shalongka,the established chronological framework of human occupation was enhanced using accelerator mass spectrometry ¹⁴C dating of 9charcoal samples and optically stimulated luminescence（OSL）dating of 3 Yangshao culture Miaodigou type pottery sherds.For the E’ling Lake section,the Bacon model was used to establish the age-depth framework based on OSL dating of 7 sediment samples.The environmental history of the E’ling Lake area was reconstructed from analysis of grain size,color index,and magnetic susceptibility of 313 sediment samples,and pollen,fungal spore,and charcoal of 98 samples.The particle size end-model analysis method（EMMA）and other methods were used to further interrogate the results.The main findings of the study are as follows.（1）The Shalongka site is stacked with Mesolithic,Yangshao,and Qijia cultural layers,with prehistoric human activities dating to 8.5–7.3 cal ka BP（subdivided into early and late stages at 8.5–8.2 cal ka BP and 8.0–7.3 cal ka BP,respecively）,and5.9–5.1 ka.The Shalongka site was clearly influenced by the local fluvial depositional environment,with prehistoric human occupation coinciding with intervals of greater water energy,i.e.,in the Mesolithic,Yangshao,and Qijia culture periods.Pollen analysis for T1406E section shows that arboreal pollen mainly comprises Pinus,accompanied by a few Picea and Cupressaceae,while non-tree pollen mainly comprises Artemisia,Chenopodiaceae,Cyperaceae,Poaceae,and Asteraceae.Further analysis shows that the Mesolithic,Yangshao,and Qijia culture periods were characterized by forest-steppe,forest-steppe with relatively reduced tree cover,and sparse forest-shrub-steppe dominated vegetation,respectively.（2）People occupying the Shalongka site evolved from highly mobile in the early Mesolithic to seasonal settlement in the late Mesolithic,with the industrial landscape focused on microblade technology production.In the Neolithic Yangshao culture period,pottery and cooking pits began to appear,and early agriculture and a more settled lifestyle emerged;these settlements represent the earliest villages on the QTP,but people were still engaged in highly mobile hunting and gathering activities.The Qijia culture period was characterized by a cold and dry climate and people continued to live a mainly settlement-based lifestyle,but used resources in a more diverse way.Cold-tolerant wheat crops appeared for the first time,presumably to reduce the risk of failure brought by environmental changes.（3）A total of 112 stone artifacts were collected from the E’ling Lake sites,including 2 microblade core blanks,1 core,4 microblade cores,5 blades,39microblades,27 flakes,14 tools,3 chunks,and 17 fragments,showing a combination of"cores+microblade+flake+tools+chunk+fragment".The identification of lithics at the high-altitude E’ling Lake extends the known range of prehistoric hunter-gatherer activity on the QTP.Techno-typological analysis indicates the area was important for selection of raw materials and production of stone artifacts,and it is likely that ancient humans were engaged in hunting and food processing and other consumption activities.（4）Four stages of Holocene environmental development can be identified in the E’ling Lake area:（i）10.3 to 5.9 ka BP,alpine meadow or meadowized grassland,with low aeolian activity and a wetter and warmer climate;（ii）5.9 to 3.6 ka BP,increasing alpine meadow vegetation;（iii）3.6 to 2.0 ka BP,expansion of alpine grassland/alpine desert,with increased aeolian activity and a colder and drier climate;（iv）After 2.0 ka BP,alpine meadow vegetation,with a colder and drier climate.Based on the technical typology evidence of stone artifacts,pollen-based vegetation reconstruction,and peak charcoal concentration,it is likely hunter-gatherer people occupied the E’ling Lake area around 7.2 ka BP when environmental conditions were relatively warm and humid.（5）There is no evidence of prehistoric hunter-gatherer activity in the Yellow River Basin of the QTP prior to about 15.0 ka BP.The first evidence of human activity in the upper Yellow River Basin dates to around 8.5 ka BP and occurs at different elevation gradients in basin,suggesting it was an important channel for prehistoric human dispersal and exchange at this time.Human occupation intensified in the Neolithic and thereafter.The influence of the climatic environment on human activities is discernable since the Mesolithic;the spatial differentiation and intensification of human survival strategies and the introduction of technology a concrete manifestation of the constraints imposed by the climatic environment.