Dairying enabled Early Bronze Age Yamnaya steppe expansions.

During the Early Bronze Age, populations of the western Eurasian steppe expanded across an immense area of northern Eurasia. Combined archaeological and genetic evidence supports widespread Early Bronze Age population movements out of the Pontic-Caspian steppe that resulted in gene flow across vast distances, linking populations of Yamnaya pastoralists in Scandinavia with pastoral populations (known as the Afanasievo) far to the east in the Altai Mountains1,2 and Mongolia3. Although some models hold that this expansion was the outcome of a newly mobile pastoral economy characterized by horse traction, bulk wagon transport4-6 and regular dietary dependence on meat and milk5, hard evidence for these economic features has not been found. Here we draw on proteomic analysis of dental calculus from individuals from the western Eurasian steppe to demonstrate a major transition in dairying at the start of the Bronze Age. The rapid onset of ubiquitous dairying at a point in time when steppe populations are known to have begun dispersing offers critical insight into a key catalyst of steppe mobility. The identification of horse milk proteins also indicates horse domestication by the Early Bronze Age, which provides support for its role in steppe dispersals. Our results point to a potential epicentre for horse domestication in the Pontic-Caspian steppe by the third millennium BC, and offer strong support for the notion that the novel exploitation of secondary animal products was a key driver of the expansions of Eurasian steppe pastoralists by the Early Bronze Age.

Life in the fast lane: Settled pastoralism in the Central Eurasian Steppe during the Middle Bronze Age.

OBJECTIVES: We tested the hypothesis that the purported unstable climate in the South Urals region during the Middle Bronze Age (MBA) resulted in health instability and social stress as evidenced by skeletal response. METHODS: The skeletal sample (n = 99) derived from Kamennyi Ambar 5 (KA-5), a MBA kurgan cemetery (2040-1730 cal. BCE, 2 sigma) associated with the Sintashta culture. Skeletal stress indicators assessed included cribra orbitalia, porotic hyperostosis, dental enamel hypoplasia, and tibia periosteal new bone growth. Dental disease (caries, abscess, calculus, and periodontitis) and trauma were scored. Results were compared to regional data from the nearby Samara Valley, spanning the Early to Late Bronze Age (EBA, LBA). RESULTS: Lesions were minimal for the KA-5 and MBA-LBA groups except for periodontitis and dental calculus. No unambiguous weapon injuries or injuries associated with violence were observed for the KA-5 group; few injuries occurred at other sites. Subadults (<18 years) formed the majority of each sample. At KA-5, subadults accounted for 75% of the sample with 10% (n = 10) estimated to be 14-18 years of age. CONCLUSIONS: 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.

Weaning practices among pastoralists: New evidence of infant feeding patterns from Bronze Age Eurasia.

OBJECTIVES: This paper investigates infant feeding practices through stable carbon (δ13 C) and nitrogen (δ15 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 (15+ 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 δ13 C and δ15 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.

Cauldrons of Bronze Age nomads reveals 2700 year old yak milk and the deep antiquity of food preparation techniques.

Cauldrons, vessels that are simultaneously common and enigmatic, offer insights into past cultural and social traditions. While assumed to possess a special function, what these cauldrons contained is still largely mysterious. These vessels, such as those made from bronze or copper alloys, function as reservoirs for ancient organics through the antibacterial qualities provided by the metal surfaces. Here we show, through protein analysis, that cauldrons from the Final Bronze Age (ca. 2700 BP) were primarily used to collect blood from ruminants, primarily caprines, likely for the production of sausages in a manner similar to contemporary practices in Mongolia's rural countryside. Our findings present a different function from the recent findings of cooked meat in copper-alloy vessels from the northern Caucasus 2000 years earlier, exposing the diversity in food preparation techniques. Our secondary findings of bovine milk within the cauldron, including peptides specific to Bos mutus, pushes back their regional domestication into the Bronze Age.

Genetic population structure of the Xiongnu Empire at imperial and local scales.

The Xiongnu established the first nomadic imperial power, controlling the Eastern Eurasian steppe from ca. 200 BCE to 100 CE. Recent archaeogenetic studies identified extreme levels of genetic diversity across the empire, corroborating historical records of the Xiongnu Empire being multiethnic. However, it has remained unknown how this diversity was structured at the local community level or by sociopolitical status. To address this, we investigated aristocratic and local elite cemeteries at the western frontier of the empire. Analyzing genome-wide data from 18 individuals, we show that genetic diversity within these communities was comparable to the empire as a whole, and that high diversity was also observed within extended families. Genetic heterogeneity was highest among the lowest-status individuals, implying diverse origins, while higher-status individuals harbored less genetic diversity, suggesting that elite status and power was concentrated within specific subsets of the broader Xiongnu population.

Curated cauldrons: Preserved proteins from early copper-alloy vessels illuminate feasting practices in the Caucasian steppe.

Large metal and metal-alloy cauldrons first appear on the far western steppe and Caucasus region during the Maykop period (3700-2900 BCE); however, the types of foods or beverages cooked in and served from these vessels have remained mysterious. Here, we present proteomic analysis of nine residues from copper-alloy cauldrons from Maykop burial contexts where we identify muscle, blood, and milk proteins specific to domesticated, and possibly wild, ruminants. This study clearly demonstrates that the earliest, large-volume feasting vessels contained both primary and secondary animal products, likely prepared in the form of a stew.

Permafrost preservation reveals proteomic evidence for yak milk consumption in the 13th century.

Domesticated yaks endure as iconic symbols of high-altitude frozen landscapes, where herding communities depend on their high-fat milk, transport, dung, and natural fibers. While there is established proteomic evidence for ancient consumption of ruminant and horse milk in the mountains and steppes of northern Eurasia, yak dairy products have yet to be detected. Yak domestication and the species' dispersal from Tibet into the mountainous zones to the north are also poorly resolved due to a paucity of zooarchaeological data. To examine the potential of paleoproteomics to shed light on domesticated yak in Mongolia, we analyzed human dental calculus from Mongol era elite individuals recovered from permafrost burials in Khovsgol province, where people continue to herd yak to this day. We report the first evidence for yak dairy consumption, linked to local resource control. In addition, we confirm a large diversity of recovered whey, curd, tissue, and blood proteins, likely reflecting the excellent preservation conditions found at permafrost sites.

The spread of herds and horses into the Altai: How livestock and dairying drove social complexity in Mongolia.

The initial movement of herders and livestock into the eastern steppe is of great interest, as this region has long been home to pastoralist groups. Due to a paucity of faunal remains, however, it has been difficult to discern the timing of the adoption of domesticated ruminants and horses into the region, though recent research on ancient dairying has started to shed new light on this history. Here we present proteomic evidence for shifts in dairy consumption in the Altai Mountains, drawing on evidence from sites dating from the Early Bronze to the Late Iron Age. We compare these finds with evidence for the rise of social complexity in western Mongolia, as reflected in material remains signaling population growth, the establishment of structured cemeteries, and the erection of large monuments. Our results suggest that the subsistence basis for the development of complex societies began at the dawn of the Bronze Age, with the adoption of ruminant livestock. Investments in pastoralism intensified over time, enabling a food production system that sustained growing populations. While pronounced social changes and monumental constructions occurred in tandem with the first evidence for horse dairying, ~1350 cal BCE, these shifts were fueled by a long-term economic dependence on ruminant livestock. Therefore, the spread into the Mongolian Altai of herds, and then horses, resulted in immediate dietary changes, with subsequent social and demographic transformations occurring later.

Re-evaluating Scythian lifeways: Isotopic analysis of diet and mobility in Iron Age Ukraine.

The Scythians are frequently presented, in popular and academic thought alike, as highly mobile warrior nomads who posed a great economic risk to growing Mediterranean empires from the Iron Age into the Classical period. Archaeological studies provide evidence of first millennium BCE urbanism in the steppe while historical texts reference steppe agriculture, challenging traditional characterizations of Scythians as nomads. However, there have been few direct studies of the diet and mobility of populations living in the Pontic steppe and forest-steppe during the Scythian era. Here, we analyse strontium, oxygen, and carbon isotope data from human tooth enamel samples, as well as nitrogen and carbon isotope data of bone collagen, at several Iron Age sites across Ukraine commonly associated with 'Scythian' era communities. Our multi-isotopic approach demonstrates generally low levels of human mobility in the vicinity of urban locales, where populations engaged in agro-pastoralism focused primarily on millet agriculture. Some individuals show evidence for long-distance mobility, likely associated with significant inter-regional connections. We argue that this pattern supports economic diversity of urban locales and complex trading networks, rather than a homogeneous nomadic population.

Economic Diversification Supported the Growth of Mongolia's Nomadic Empires.

Populations in Mongolia from the late second millennium B.C.E. through the Mongol Empire are traditionally assumed, by archaeologists and historians, to have maintained a highly specialized horse-facilitated form of mobile pastoralism. Until recently, a dearth of direct evidence for prehistoric human diet and subsistence economies in Mongolia has rendered systematic testing of this view impossible. Here, we present stable carbon and nitrogen isotope measurements of human bone collagen, and stable carbon isotope analysis of human enamel bioapatite, from 137 well-dated ancient Mongolian individuals spanning the period c. 4400 B.C.E. to 1300 C.E. Our results demonstrate an increase in consumption of C4 plants beginning at c. 800 B.C.E., almost certainly indicative of millet consumption, an interpretation supported by archaeological evidence. The escalating scale of millet consumption on the eastern Eurasian steppe over time, and an expansion of isotopic niche widths, indicate that historic Mongolian empires were supported by a diversification of economic strategies rather than uniform, specialized pastoralism.

Dairy pastoralism sustained eastern Eurasian steppe populations for 5,000 years.

Dairy pastoralism is integral to contemporary and past lifeways on the eastern Eurasian steppe, facilitating survival in agriculturally challenging environments. While previous research has indicated that ruminant dairy pastoralism was practiced in the region by circa 1300 BC, the origin, extent and diversity of this custom remain poorly understood. Here, we analyse ancient proteins from human dental calculus recovered from geographically diverse locations across Mongolia and spanning 5,000 years. We present the earliest evidence for dairy consumption on the eastern Eurasian steppe by circa 3000 BC and the later emergence of horse milking at circa 1200 BC, concurrent with the first evidence for horse riding. We argue that ruminant dairying contributed to the demographic success of Bronze Age Mongolian populations and that the origins of traditional horse dairy products in eastern Eurasia are closely tied to the regional emergence of mounted herding societies during the late second millennium BC.

Intensification in pastoralist cereal use coincides with the expansion of trans-regional networks in the Eurasian Steppe.

The pace of transmission of domesticated cereals, including millet from China as well as wheat and barley from southwest Asia, throughout the vast pastoralist landscapes of the Eurasian Steppe (ES) is unclear. The rich monumental record of the ES preserves abundant human remains that provide a temporally deep and spatially broad record of pastoralist dietary intake. Calibration of human δ13C and δ15N values against isotope ratios derived from co-occurring livestock distinguish pastoralist consumption of millet from the products of livestock and, in some regions, identify a considerable reliance by pastoralists on C3 crops. We suggest that the adoption of millet was initially sporadic and consumed at low intensities during the Bronze Age, with the low-level consumption of millet possibly taking place in the Minusinsk Basin perhaps as early as the late third millennium cal BC. Starting in the mid-second millennium cal BC, millet consumption intensified dramatically throughout the ES with the exception of both the Mongolian steppe where millet uptake was strongly delayed until the end of first millennium cal BC and the Trans-Urals where instead barley or wheat gained dietary prominence. The emergence of complex, trans-regional political networks likely facilitated the rapid transfer of cultivars across the steppe during the transition to the Iron Age.

Sampling and Pretreatment of Tooth Enamel Carbonate for Stable Carbon and Oxygen Isotope Analysis.

Stable carbon and oxygen isotope analysis of human and animal tooth enamel carbonate has been applied in paleodietary, paleoecological, and paleoenvironmental research from recent historical periods back to over 10 million years ago. Bulk approaches provide a representative sample for the period of enamel mineralization, while sequential samples within a tooth can track dietary and environmental changes during this period. While these methodologies have been widely applied and described in archaeology, ecology, and paleontology, there have been no explicit guidelines to aid in the selection of necessary lab equipment and to thoroughly describe detailed laboratory sampling and protocols. In this article, we document textually and visually, the entire process from sampling through pretreatment and diagenetic screening to make the methodology more widely available to researchers considering its application in a variety of laboratory settings.