Abstract
Archeologically attested human occupation on the Tibetan Plateau (TP) can be traced back to 160 thousand years ago (kya) via the archaic Xiahe people and 30∼40 kya via the Nwya Devu anatomically modern human. However, the history of the Tibetan populations and their migration inferred from the ancient and modern DNA remains unclear. Here, we performed the first ancient and modern genomic meta-analysis among 3,017 Paleolithic to present-day Eastern Eurasian genomes (2,444 modern individuals from 183 populations and 573 ancient individuals). We identified a close genetic connection between the ancient-modern highland Tibetans and lowland island/coastal Neolithic Northern East Asians (NEA). This observed genetic affinity reflected the primary ancestry of high-altitude Tibeto-Burman speakers originated from the Neolithic farming populations in the Yellow River Basin. The identified pattern was consistent with the proposed common north-China origin hypothesis of the Sino-Tibetan languages and dispersal patterns of the northern millet farmers. We also observed the genetic differentiation between the highlanders and lowland NEAs. The former harbored more deeply diverged Hoabinhian/Onge-related ancestry and the latter possessed more Neolithic southern East Asian (SEA) or Siberian-related ancestry. Our reconstructed qpAdm and qpGraph models suggested the co-existence of Paleolithic and Neolithic ancestries in the Neolithic to modern East Asian highlanders. Additionally, we found that Tibetans from Ü-Tsang/Ando/Kham regions showed a strong population stratification consistent with their cultural background and geographic terrain. Ü-Tsang Tibetans possessed a stronger Chokhopani-affinity, Ando Tibetans had more Western Eurasian related ancestry and Kham Tibetans harbored greater Neolithic southern EA ancestry. Generally, ancient and modern genomes documented multiple waves of human migrations in the TP’s past. The first layer of local hunter-gatherers mixed with incoming millet farmers and arose the Chokhopani-associated Proto-Tibetan-Burman highlanders, which further respectively mixed with additional genetic contributors from the western Eurasian Steppe, Yellow River and Yangtze River and finally gave rise to the modern Ando, Ü-Tsang and Kham Tibetans.
Highlights
The Tibetan Plateau (TP), widely known as the third pole of the world, forms the high-altitude core region of Asia with an average elevation more than 4,000 meters above sea level
All modern Tibetans and Neolithic-to-historic East Asians were grouped in the East-Asian genetic cline along with the second component in the Eurasian-principal component analysis (PCA)
To focus on the genetic variations of East Asians, we constructed East-AsianPCA among 106 modern populations (Figure 1B) and found that modern East Asians grouped into four genetic clines or clusters: Mongolic/Tungusic genetic cline consisting of populations from northeast Asia; south-China/Southeast-Asian genetic cluster comprising of Austronesian, Austroasiatic, TaiKadai, and Hmong-Mien speakers; Sinitic-related north-to-south genetic cline, and Tibeto-Burman cluster, which were consistent with the linguistic/geographical divisions
Summary
The Tibetan Plateau (TP), widely known as the third pole of the world, forms the high-altitude core region of Asia with an average elevation more than 4,000 meters above sea level (masl). Archeological and genetic studies have demonstrated that archaic hominins who occupied the TP had well adapted to the high-altitude hypoxic environment long before the arrival of modern Homo sapiens. The present-day Tibetans are suggested to have uniquely adapted to the extreme high-altitude conditions since the initial colonization of the TP (Qi et al, 2013; Jeong et al, 2016; GnecchiRuscone et al, 2018; Chen F. et al, 2019). Over seven million indigenous Tibetans (2016 census) are living in the TP and have successfully adapted to the high-altitude hypoxic environment. The positively selected haplotypes of HIF-1α prolyl hydroxylase (EGLN1) and Endothelial PAS domain protein 1 (EPAS1) were introduced into modern Tibetans and surrounding highlanders via the Denisovan introgression, which further promoted Tibetan’s high-altitude hypoxia adaptation (Huerta-Sánchez et al, 2014). There are a limited amount of zooarchaeological and archaeobotanical data for reconstructing the subsistence strategy and ancient DNA (aDNA) data for dissecting the genomic correlation between ancient individuals and modern Tibetan-like highlanders
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