We present a high-quality genome sequence of a ~45,000-year-old modern human male from Siberia. This individual derives from a population that lived prior to – or simultaneously with – the separation of the populations in western and eastern Eurasia and carries a similar amount of Neandertal ancestry as present-day Eurasians. However, the genomic segments of Neandertal ancestry are substantially longer than those observed in present-day individuals, indicating that Neandertal gene flow into the ancestors of this individual occurred 7,000–13,000 years before he lived. We estimate an autosomal mutation rate of 0.4–0.6×10−9/site/year and a Y chromosomal mutation rate of 0.7–0.9×10−9/site/year based on the additional substitutions that have occurred in present-day non-Africans compared to this genome, and a mitochondrial mutation rate of 1.8–3.2 × 10−8/site/year based on the age of the bone.
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.
Objectives: This paper investigates infant feeding practices through stable carbon (d 13 C) and nitrogen (d 15 N) isotopic analyses of human bone collagen from Kamennyi Ambar 5, a Middle Bronze Age cemetery located in central Eurasia. The results presented are unique for the time period and region, as few cemeteries have been excavated to reveal a demographic cross-section of the population. Studies of weaning among pastoral societies are infrequent and this research adds to our knowledge of the timing, potential supplementary foods, and cessation of breastfeeding practices.Materials and methods: Samples were collected from 41 subadults (<15 years) and 27 adults (151 years). Isotopic reference sets from adult humans as well as faunal remains were utilized as these form the primary and complementary foods fed to infants.Results: Slight shifts in d 13 C and d 15 N values revealed that weaning was a multi-stage process (breastfeeding, weaning, and complete cessation of nursing) that began at 6 months of age, occurred over several years of early childhood, and was completed by 4 years of age. Discussion:Our results indicate that weaning was a multi-stage process that was unique among late prehistoric pastoralist groups in Eurasia that were dependent on milk products as a supplementary food. Our discussion centers on supporting this hypothesis with modern information on central and east Eurasian herding societies including the age at which complementary foods are introduced, the types of complementary foods, and the timing of the cessation of breastfeeding.Integral to this work is the nature of pastoral economies and their dependence on animal products, the impact of complementary foods on nutrition and health, and how milk processing may have affected nutrition content and digestibility of foods. This research on Eurasian pastoralists provides insights into the complexities of weaning among prehistoric pastoral societies as well as the potential for different complementary foods to be incorporated into infant diets in the past. K E Y W O R D S dairy products, life histories, paleodiet, Sintashta, stable isotope analysis 1 | I N T R O D U C T I O N Research on ancient weaning has often focused on agricultural societies with access to domesticated grains, rather than pastoral groups that often lacked cultivars. Our study investigates weaning practices among pastoralists in the Eurasian steppe to determine if unique patterns of weaning are evident when complementary foods focus on ani-mal products rather than domesticated grains. Recent stable isotopic and paleobotanical studies indicate that the pastoral societies under study had a diet based primarily on livestock complemented by wild plants and fauna, but lacking cultivars (Hanks et al., forthcoming; R€ uhl, Herbig, & Stobbe, 2015;Ventresca Miller et al., 2014). We hypothesize that pastoral societies using animal products as the primary complementary food in weaning, rather than domesticated grains, may be Am. J. Phys. Anthropol. 2017; 162: 409-422 wileyonlinelibrary...
Skeletal stress markers and injuries were uncommon among the KA-5 and regional groups, but a MBA-LBA high subadult mortality indicates elevated frailty levels and inability to survive acute illnesses. Following an optimal weaning program, subadults were at risk for physiological insult and many succumbed. Only a small number of individuals attained biological maturity during the MBA, suggesting that a fast life history was an adaptive regional response to a less hospitable and perhaps unstable environment.
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