Human ancestors first set foot on the interior of the Qinghai-Tibetan Plateau around 30,000-40,000 years ago, according to new research by scientists from the Chinese Academy of Sciences(CAS). This new finding moves back the earliest data of habitation in the interior by 20,000 years or more.

The research team was led by Dr. ZHANG Xiaoling and Prof. GAO Xing from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of CAS. Their study, published in Science, was based on investigations of Nwya Devu, the oldest evidence of peopling in Tibet and the highest early Stone Age (Paleolithic) archaeological site known anywhere in the world.

This archaeological achievement is a major breakthrough in our understanding of the human occupation and evolution of the Qinghai-Tibetan Plateau as well as larger-scale prehistoric human migration and exchanges. It caps 60 years of effort trying to find evidence of the earliest human habitation on the plateau.

The high altitude, atmospheric hypoxia, cold yearround temperatures and low rainfall of the plateau creates an extremely challenging environment for human habitation. Archaeological evidence indicates it was one of the last terrestrial habitats colonized by Homo sapiens. Today, the Qinghai-Tibetan Plateau is the third least-populous spot on the planet.

常规成形工艺为钛锭先镦粗，保证镦粗后截面尺寸≥φ1450mm后再进行平砧间拔长展宽。锻造过程由于TA2的材料特性，容易造成镦粗过程中表面折叠缺陷，为防止折叠过深，需分多道次进行镦粗，出现折叠现象后立即进行轻滚圆拔长后再进行镦粗，严重影响锻造效率及锻造质量。采取直接拔长的方式进行展宽，在试验前通过有限元数值模拟分析软件对试制方案进行分析，最终通过实际生产验证工艺方案的可行性。

Location of the Dwya Devu site and the excavation unit in central Tibet, China (Image by courtesy of ZHANG and GAO's team)

Stone artifacts unearthed from the Nwya Devu site. (Image by courtesy of ZHANG and GAO's team)

每当季风季节到来时，金枪鱼就会迁徙到大陆架来产卵。在东太平洋地区，洪水带来的漂流木上通常都有许多刚刚破卵而出的黄鳍金枪鱼，研究人员认为漂流木上的栖息环境对于这些幼小的金枪鱼是否能够成长到繁殖年龄是十分重要的。在西太平洋和热带太平洋地区，金枪鱼渔业在10年内从极小的规模发展到世界顶级规模，是因为人们发现金枪鱼鱼群出现的规律，它们通常都喜欢聚集在浮木周围，20世纪90年代末，大西洋东部的西班牙渔民甚至在海上人工设置浮木来吸引更多的金枪鱼。

The Nwya Devu Paleolithic site discovered by this team confirms that human ancestors set foot on the Qinghai-Tibet Plateau at elevations approaching 5,000 meters above sea level around 30,000-40,000 years ago.It is the first Paleolithic archaeological site discovered in Tibet that preserves intact stratigraphy allowing agedating of the site's antiquity. Nwya Devu is located in the Changthang region of northern Tibet, about 300 km northwest of Lhasa, the capital of Tibet Autonomous Region, at about 4,600 meters above sea level.

首先，在机械设备购置之前，需要做好相关的调查工作，按照地质勘察施工的实际情况以及工程项目的整体内容做好核算，保证选择的设备型号能够符合工程实际。

Before now, no concrete evidence existed of people inhabiting the interior of the Plateau before the Holocene geological epoch (4,200-11,700 years ago). In addition, only a few reliably dated Pleistocene(11,700-2.58 million years ago) archaeological sites had been discovered around the Plateau's margins.

The site comprises an extensive, dense surface distribution of stone artifacts and a buried continuous record of human occupation. It is the earliest Paleolithic site known on the Qinghai-Tibetan Plateau and the highest yet discovered anywhere in the world. Before this discovery, the earliest archaeological record of highaltitude human activity was from the Andean Altiplano,at about 4,480 meters above sea level, showing human habitation about 12,000 years ago.

This discovery deepens considerably the history of human occupation of the Qinghai-Tibetan Plateau and the antiquity of human high-altitude (＞4,000 masl)adaptations.

The Late Pleistocene (about 12,000-125,000 years ago) was a crucial period for human evolution. During that time, the behavior and cognitive ability of ancient humans developed rapidly and the ability to adapt to a broader range of environments similarly increased. The prehistoric cultural artifacts from Nwya Devu provide important archaeological evidence of the survival strategies of early anatomically and behaviorally modern people to what is arguably the most rigorous terrestrial environment on earth. It also allows analysis of Paleolithic exchange and interactions between East and West suggesting possible migration routes.

The paper was vetted by three reviewers during the evaluation process, with one concluding it as “… quite original and very exciting, and will be of utmost interest to the readers of Science and researchers studying the origin and dispersal of modern humans and high-altitude colonization. The results have profound implications for the understanding of the timing and dynamics of human settlement of the Tibetan Plateau.”