Genetics: Unexpected origins of the Bronze Age Tarim mummies revealed

Naturally preserved, Bronze Age mummies discovered in the Tarim Basin of Xinjiang, China, belonged to a genetically isolated, local population, according to genome-wide analysis of their DNA. These findings, published in Nature, contradict previous hypotheses that these mummies descended from populations that migrated from what is now southern Siberia, northern Afghanistan or the Central Asian mountains.

The origins of the Tarim mummies and the Xiaohe culture to which they belonged have been debated since their discovery in the early 20th century, notably because of the distinct appearance of the mummies, as well as the associated clothing and farming practices. Three major hypotheses remain disputed; namely, that these people descended from migrating steppe herders from what is now southern Siberia or farmers from mountain Central Asia or desert oases in northern Afghanistan.

Choongwon Jeong and colleagues analysed genomic DNA of 13 mummies dating to around 2100–1700 BC from the Tarim Basin in South Xinjiang, as well as 5 mummies dating to around 3000–2800 BC from the northern Dzungarian Basin. These mummies are believed to represent the earliest human remains to have been discovered in Xinjiang to date. The authors found that the Dzungarian mummies had largely Afanasievo ancestry (steppe herders from the Altai–Sayan mountains in what is now southern Siberia) with some local genetic influences, whereas the Tarim mummies only had local ancestry. Milk proteins discovered within deposits on the teeth of seven Tarim mummies indicated that this population probably relied on dairy farming. Taken together, these findings contradict previous hypotheses of migration, and instead imply that, although the genetic lineages of local Dzungarian populations and Afanasievo migrants may have mixed, Tarim Basin cultures probably arose from a genetically isolated, local population. However, they suggest that this population was culturally cosmopolitan and maintained close ties with its herder and farmer neighbours.

In an associated News & Views, Paula Dupuy delves further into the key findings of the paper and their implications for our knowledge of Inner Asian prehistory. In her conclusion, she remarks that the authors ‘have answered the question of the genetic origins of the Xiaohe culture. Now it is up to the collaborative input of scholars to further explain the dynamic and varied patterns of cultural exchange that define the Bronze Age of Inner Asia.’