Genetic continuity of Indo-Iranian speakers since the Iron Age in southern Central Asia

Perle Guarino-Vignon,Julio Bendezu-Sarmiento,Nina Marchi,Evelyne Heyer,Céline Bon

doi:10.1038/s41598-021-04144-4

Abstract

Since prehistoric times, southern Central Asia has been at the crossroads of the movement of people, culture, and goods. Today, the Central Asian populations are divided into two cultural and linguistic groups: the Indo-Iranian and the Turko-Mongolian groups. Previous genetic studies unveiled that migrations from East Asia contributed to the spread of Turko-Mongolian populations in Central Asia and the partial replacement of the Indo-Iranian populations. However, little is known about the origin of the latters. To shed light on this, we compare the genetic data on two current-day Indo-Iranian populations — Yaghnobis and Tajiks — with genome-wide data from published ancient individuals. The present Indo-Iranian populations from Central Asia display a strong genetic continuity with Iron Age samples from Turkmenistan and Tajikistan. We model Yaghnobis as a mixture of 93% Iron Age individual from Turkmenistan and 7% from Baikal. For the Tajiks, we observe a higher Baikal ancestry and an additional admixture event with a South Asian population. Our results, therefore, suggest that in addition to a complex history, Central Asia shows a remarkable genetic continuity since the Iron Age, with only limited gene flow.

Highlights

IntroductionSouthern Central Asia has been at the crossroads of the movement of people, culture, and goods
Since prehistoric times, southern Central Asia has been at the crossroads of the movement of people, culture, and goods
At the end of the Bronze Age, from about 1800 BCE, the Oxus civilization underwent during its final phase important transformations: while remaining in the same tradition, the material culture was impoverished with some ceramic forms and artifacts disappearing; some habitat sites were abandoned, monumental architecture disappeared, the level of technological development seemed to decrease[5]; international trade, which had been flourishing during the previous peak phase, slowed down considerably, or even came to a halt, except for contacts with the steppes of northern Central A sia[6]; funerary practices changed with the appearance of new modes of burial, before the total disappearance of burials during the Early Iron Age, that can be linked to an ideological evolution[7]

Summary

Introduction

Southern Central Asia has been at the crossroads of the movement of people, culture, and goods. Central Asia is a large region stretching from the Caspian Sea in the west to Lake Baikal in the east, encompassing Tajikistan, Kazakhstan, Turkmenistan, Uzbekistan, Kyrgyzstan and north Afghanistan This region has found itself at the crossroads of migration routes since modern humans left A frica[1,2], leading to a long-term presence of humans, a rich history, and a high cultural diversity. Modern DNA studies suggested that the Indo-Iranian group was present in Central Asia before the Turko-Mongol g roup[11], maybe as early as Neolithic times; the Turko-Mongol group emerged later from the admixture between a group related to local Indo-Iranian and a South-Siberian or Mongolian group[11,13,14] with a high East-Asian ancestry (around 60%). In southern Central Asia where most of the ancient genomes date back to the late Neolithic and the Bronze Age, it was shown that populations from the BMAC were strongly related to southern Iranian ancient populations with some individuals displaying additional steppe-ancestry[18]

Methods

Results

Discussion

Conclusion