Tarim Basin mummies genomic study genetics

The surprising origins of the Tarim Basin mummies

The surprising origins of the Tarim Basin mummies

Genomic study of the Tarim Basin mummies in western China reveals an indigenous Bronze Age population that was genetically isolated but culturally cosmopolitan

In a new study, an international team of researchers has determined the genetic origins of Asia’s most enigmatic mummies - the Tarim Basin mummies in western China. Once thought to be Indo-European speaking migrants from the West, the Bronze Age Tarim Basin mummies are revealed to be a local indigenous population with deep Asian roots and taste for far-flung cuisine.

Tarim Basin mummies genomic study genetics
Aerial view of the Xiaohe cemetery. Credits: Wenying Li, Xinjiang Institute of Cultural Relics and Archaeology

As part of the Silk Road and located at the geographical intersection of Eastern and Western cultures, the Xinjiang Uyghur Autonomous Region has long served as a major crossroads for trans-Eurasian exchanges of people, cultures, agriculture, and languages. Since the late 1990s, the discovery of hundreds of naturally mummified human remains dating to circa 2,000 BCE to 200 CE in the region’s Tarim Basin has attracted international attention due to their so-called ‘Western’ physical appearance, their felted and woven woolen clothing, and their agropastoral economy that included cattle, sheep and goat, wheat, barley, millet, and even kefir cheese. Buried in boat coffins in an otherwise barren desert, the Tarim Basin mummies have long puzzled scientists and inspired numerous theories as to their enigmatic origins.

Excavation of burial M75 at the Xiaohe cemetery. Credits: Wenying Li, Xinjiang Institute of Cultural Relics and Archaeology

The Tarim Basin mummies’ cattle-focused economy and unusual physical appearance had led some scholars to speculate that they were the descendants of migrating Yamnaya herders, a highly mobile Bronze Age society from the steppes of the Black Sea region of southern Russia. Others have placed their origins among the Central Asian desert oasis cultures of the Bactria-Margiana Archaeological Complex (BMAC), a group with strong genetic ties to early farmers on the Iranian Plateau.

To better understand the origin of the Tarim Basin mummies’ founding population, who first settled the region at sites such as Xiaohe and Gumugou circa 2,000 BCE, a team of international researchers from Jilin University, the Institute of Vertebrate Paleontology and Paleoanthropology, the Max Planck Institute for Evolutionary Anthropology, Seoul National University of Korea, and Harvard University generated and analyzed genome-wide data from thirteen of the earliest known Tarim Basin mummies, dating to circa 2,100 to 1,700 BCE, together with five individuals dating to circa 3,000 to 2,800 BCE in the neighboring Dzungarian Basin. This is the first genomic-scale study of prehistoric populations in the Xinjiang Uyghur Autonomous Region, and it includes the earliest yet discovered human remains from the region.

The Tarim Basin mummies were not newcomers to the region

Typical Xiaohe boat coffin with oar. The coffin is covered with a cattle hide. Credits: Wenying Li, Xinjiang Institute of Cultural Relics and Archaeology

To their great surprise, the researchers found that the Tarim Basin mummies were not newcomers to the region at all, but rather appear to be direct descendants of a once widespread Pleistocene population that had largely disappeared by the end of the last Ice Age. This population, known as the Ancient North Eurasians (ANE), survives only fractionally in the genomes of present-day populations, with Indigenous populations in Siberia and the Americas having the highest known proportions, at about 40 percent. In contrast to populations today, the Tarim Basin mummies show no evidence of admixture with any other Holocene groups, forming instead a previously unknown genetic isolate that likely underwent an extreme and prolonged genetic bottleneck prior to settling the Tarim Basin.

“Archaeogeneticists have long searched for Holocene ANE populations in order to better understand the genetic history of Inner Eurasia. We have found one in the most unexpected place,” says Choongwon Jeong, a senior author of the study and a professor of Biological Sciences at Seoul National University.

In contrast to the Tarim Basin, the earliest inhabitants of the neighboring Dzungarian Basin descended not only from local populations but also from Western steppe herders, namely the Afanasievo, a pastoralist group with strong genetic links to the Early Bronze Age Yamanya. The genetic characterization of the Early Bronze Age Dzungarians also helped to clarify the ancestry of other pastoralist groups known as the Chemurchek, who later spread northwards to the Altai mountains and into Mongolia. Chemurchek groups appear to be the descendants of Early Bronze Age Dzungarians and Central Asian groups the from Inner Asian Mountain Corridor (IAMC), who derive their ancestry from both local populations and BMAC agropastoralists.

“These findings add to our understanding of the eastward dispersal of Yamnaya ancestry and the scenarios under which admixture occurred when they first met the populations of Inner Asia,” says Chao Ning, co-lead author the study and a professor of School of Archaeology and Museology at Peking University.

The Tarim Basin groups were genetically but not culturally isolated

Tarim Basin mummies genomic study genetics
A naturally mummified woman from burial M11 of the Xiaohe cemetery. Credits: Wenying Li, Xinjiang Institute of Cultural Relics and Archaeology

These findings of extensive genetic mixing all around the Tarim Basin throughout the Bronze Age make it all the more remarkable that the Tarim Basin mummies exhibited no evidence of genetic admixture at all. Nevertheless, while the Tarim Basin groups were genetically isolated, they were not culturally isolated. Proteomic analysis of their dental calculus confirmed that cattle, sheep, and goat dairying was already practiced by the founding population, and that they were well aware of the different cultures, cuisines, and technologies all around them.

“Despite being genetically isolated, the Bronze Age peoples of the Tarim Basin were remarkably culturally cosmopolitan – they built their cuisine around wheat and dairy from the West Asia, millet from East Asia, and medicinal plants like Ephedra from Central Asia,” says Christina Warinner, a senior author of the study, a professor of Anthropology at Harvard University, and a research group leader at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

“Reconstructing the origins of the Tarim Basin mummies has had a transformative effect on our understanding of the region, and we will continue the study of ancient human genomes in other eras to gain a deeper understanding of the human migration history in the Eurasian steppes,” adds Yinquiu Cui, a senior author of the study and professor in the School of Life Sciences at Jilin University.

Tarim Basin mummies genomic study genetics
A profile view of the burial M13 from the Xiaohe cemetery. Credits: Wenying Li, Xinjiang Institute of Cultural Relics and Archaeology

References:

The genomic origins of the Bronze Age Tarim Basin mummies, Nature, DOI: 10.1038/s41586-021-04052-7

 

Press release from the Max Planck Institute for Evolutionary Anthropology.


5,000-year-old milk proteins point to the importance of dairying in eastern Eurasia

5,000-year-old milk proteins point to the importance of dairying in eastern Eurasia

Recent findings push back estimates of dairying in the eastern Steppe by more than 1,700 years, pointing to migration as a potential means of introduction

 

Today dairy foods sustain and support millions around the world, including in Mongolia, where dairy foods make up to 50% of calories consumed during the summer. Although dairy-based pastoralism has been an essential part of life and culture in the eastern Eurasian Steppe for millennia, the eastward spread of dairying from its origin in southwest Asia and the development of these practices is little understood. The current study, led by Shevan Wilkin and Jessica Hendy of the Max Planck Institute for the Science of Human History, presents the earliest evidence for dairy consumption in East Asia, circa 3000 BCE, and offers insights into the arrival and evolution of dairy pastoralism in prehistoric Mongolia.

dairying Eurasia
These are horses on the steppe. Credits: Björn Reichhardt

Earliest dairy consumption & a possible path of entry

The highly mobile nature of pastoralist societies and the severe winds of the Eastern Steppe make detecting occupied sites with direct evidence into the lives and culture of ancient Mongolians exceedingly rare. Instead, the researchers looked for clues in ritual human burial mounds, often marked by stone monuments and occasionally featuring satellite animal graves.

In collaboration with the National University of Mongolia, researchers analyzed dental calculus from individuals ranging from the Early Bronze Age to the Mongol Period. Three-quarters of all individuals contained evidence that they had consumed dairy foods, which demonstrates the widespread importance of this food source in both prehistoric and historic Mongolia. The study's results include the earliest direct evidence for dairy consumption in East Asia, identified in an individual from the Afanasievo site of Shatar Chuluu, which dates to roughly 3000 BCE. Previous DNA analysis on this individual revealed non-local genetic markers consistent with Western Steppe Herder populations, presenting Early Bronze Age Afanasievo migrations westward via the Russian Altai as a viable candidate for the introduction of dairy and domestic livestock into eastern Eurasia.

Multiple different animal species were used for their milk

dairying Eurasia
These are sheep and goat herds in Mongolia. Credits: Björn Reichhardt

By sequencing the milk proteins extracted from the dental calculus, the scientists were able to determine which animal species were being used for dairy production, and thereby help to trace the progression of domestication, dairying, and pastoralism in the region. "Modern Mongolians use cow, sheep, goat, yak, camel, horse and reindeer for milk today, yet when each of these species were first utilized for dairy in Mongolia remains unclear," says Shevan Wilkin, lead author of the study. "What is clear is that the crucial renewable calories and hydration made available through the incorporation of dairying would have become essential across the arid and agriculturally challenging ancient Eastern Steppe."

The earliest individuals to show evidence of dairy consumption lived around 5000 years ago and consumed milk from ruminant species, such as cattle, sheep, and goats. A few thousand years later, at Bronze Age sites dated to after 1200 BCE, the researchers find the first evidence of horse milk consumption, occurring at the same time as early evidence for horse bridling and riding, as well as the use of horses at ritual burial sites. In addition, the study shows that during the Mongol Empire circa 1200-1400 CE, people also consumed the milk of camels. "We are excited that through the analysis of proteins we are able to see the consumption of multiple different animal species, even sometimes in the same individual. This gives us a whole new insight into ancient dairying practices" says Jessica Hendy, senior author of the study.

Millenia after the first evidence of horse milk consumption, horses remain vital to the daily lives of many in modern Mongolia, where mounted pastoralists rely on them to manage large herds of livestock, transport people and supplies, and provide a primary source of meat and milk. "Our findings suggest that the incorporation of horses into dairy pastoralism in Eastern Eurasia was closely linked to a broader economic transformation in the use of horses for riding, movement, and diet," says William Taylor of the University of Colorado-Boulder, one of the study's coauthors.

Although the earliest individual sampled in this study showed evidence of dairy consumption, the researchers hope future studies will examine individuals from previous time periods. "In order to form a clearer picture of the origins of dairying in this region, we need to understand the impact of western steppe herder migrations and confirm whether dairying was occurring in Mongolia prior to their arrival," Shevan Wilkin concludes.

dairying Eurasia
This is a horse burial at Morin Mort, Mongolia. Credits: William Taylor

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Publication information:

Title: Dairy pastoralism sustained Eastern Eurasian steppe populations for 5000 years

Authors: Shevan Wilkin, Alicia Ventresca Miller, William T.T. Taylor, Bryan K. Miller, Richard W. Hagan, Madeleine Bleasdale, Ashley Scott, Sumiya Gankhuyg, Abigail Ramsoe, S. Uliziibayar, Christian Trachsel, Paolo Nanni, Jonas Grossmann, Ludovic Orlando, Mark Horton, Philipp W. Stockhammer, Erdene Myagmar, Nicole Boivin, Christina Warinner, Jessica Hendy

Publication: Nature Ecology & Evolution

DOI: 10.1038/s41559-020-1120-y

 

Press release from the Max Planck Institute for the Science of Human History / DE