By sequencing 523 ancient humans, we show that the primary source of ancestry in modern South Asians is a prehistoric genetic gradient between people related to early hunter-gatherers of Iran and Southeast Asia. After the Indus Valley Civilization’s decline, its people mixed with individuals in the southeast to form one of the two main ancestral populations of South Asia, whose direct descendants live in southern India. Simultaneously, they mixed with descendants of Steppe pastoralists who, starting around 4000 years ago, spread via Central Asia to form the other main ancestral population. The Steppe ancestry in South Asia has the same profile as that in Bronze Age Eastern Europe, tracking a movement of people that affected both regions and that likely spread the distinctive features shared between Indo-Iranian and Balto-Slavic languages.

The genetic formation of Central and South Asian populations has been unclear because of an absence of ancient DNA. To address this gap, we generated genome-wide data from 362 ancient individuals, including the first from eastern Iran, Turan (Uzbekistan, Turkmenistan, and Tajikistan), Bronze Age Kazakhstan, and South Asia. Our data reveal a complex set of genetic sources that ultimately combined to form the ancestry of South Asians today. We document a southward spread of genetic ancestry from the Eurasian Steppe, correlating with the archaeologically known expansion of pastoralist sites from the Steppe to Turan in the Middle Bronze Age (2300-1500 BCE). These Steppe communities mixed genetically with peoples of the Bactria Margiana Archaeological Complex (BMAC) whom they encountered in Turan (primarily descendants of earlier agriculturalists of Iran), but there is no evidence that the main BMAC population contributed genetically to later South Asians. Instead, Steppe communities integrated farther south throughout the 2nd millennium BCE, and we show that they mixed with a more southern population that we document at multiple sites as outlier individuals exhibiting a distinctive mixture of ancestry related to Iranian agriculturalists and South Asian hunter-gathers. We call this group Indus Periphery because they were found at sites in cultural contact with the Indus Valley Civilization (IVC) and along its northern fringe, and also because they were genetically similar to post-IVC groups in the Swat Valley of Pakistan. By co-analyzing ancient DNA and genomic data from diverse present-day South Asians, we show that Indus Periphery-related people are the single most important source of ancestry in South Asia—consistent with the idea that the Indus Periphery individuals are providing us with the first direct look at the ancestry of peoples of the IVC—and we develop a model for the formation of present-day South Asians in terms of the temporally and geographically proximate sources of Indus Periphery-related, Steppe, and local South Asian hunter-gatherer-related ancestry. Our results show how ancestry from the Steppe genetically linked Europe and South Asia in the Bronze Age, and identifies the populations that almost certainly were responsible for spreading Indo-European languages across much of Eurasia.One Sentence SummaryGenome wide ancient DNA from 357 individuals from Central and South Asia sheds new light on the spread of Indo-European languages and parallels between the genetic history of two sub-continents, Europe and South Asia.

This paper explores the contribution of plant food to the diet of societies in Kazakhstan that are often assumed to be pastoralist. Carbon and nitrogen stable isotope analysis, together with radiocarbon dating, was carried out on human and animal bones from 24 Chalcolithic, Bronze Age, Early Iron Age, Hunic and Turkic sites across Kazakhstan. We use these data to examine dietary differences across time and space within and between populations. Our results show that at the Bronze Age sites of mountainous southern Kazakhstan people consumed C4 plants, likely domesticated millets (Panicum miliaceum or Setaria italica) and probably cultivated C3 plants (wheat or barley). By directly dating individuals with high δ 13 C values we were able to find the earliest evidence of the consumption of large quantities of millet in Central Asia to date. By contrast, there is little input of C4 plants to diets of individuals dating to the Bronze Age from northern Kazakhstan. Stable isotope data from later periods all across the region has shown that from the Early Iron Age and continuing through to the Turkic period, C4 plants were a major component of the human food web. The wide variety of stable isotope results, both within and between contemporary sites, indicates a diversity of foodways, rather than a uniform focus on pastoralism.

No abstract