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From herds to empire: Biomolecular and zooarchaeological investigations of mobile pastoralism in the ancient Eurasian steppe

Periodic Reporting for period 1 - ASIAPAST (From herds to empire: Biomolecular and zooarchaeological investigations of mobile pastoralism in the ancient Eurasian steppe)

Reporting period: 2018-04-01 to 2019-09-30

The emergence of mobile pastoralism in the Eurasian steppe five thousand years ago marked a unique moment in human history, when for the first time, people relied almost exclusively on herd animals of sheep, goat, cattle, and horses for their daily food. Eventually, these mundane animals came to serve as dynamic symbols of community, negotiation, and power that helped give rise to nomadic states and empires that transformed Asia and Europe alike. ASIAPAST focuses on identifying the transmission pathways via which livestock moved into the steppe, understand how the scale of human social worlds changed with animal herding, and investigate the ways in which entirely new food sources provided by livestock, in particular dairy, shifted the seasonality and predictability of human diets. ASIAPAST articulates these developments with shifts in the ritual use of animals associated with charismatic stone monuments that epitomize ancient steppe dwellers. In particular, ASIAPAST explores when and where livestock became more than a food source but a vital means to political expression, and looks to understand how ritual treatment of animals brought together widely dispersed mobile pastoralists and facilitated socio-political negotiations. ASIAPAST recovers these dietary, mobility, and ritual histories of pastoralists and their herd animal, recorded in bones, teeth, and pottery, and unlocks that information using ancient genomics, proteomics and isotopic analyses.
Key results have been achieved so far in WP1, WP2, WP3, and W4. WP 1 results include a wholly new information on ancient husbandry practices and population turnover in both the Eurasian Steppe belt and the Mongolian steppe. Zooarchaeological analyses indicate horses were of primary importance at some Eneolithic settlements in Altai with a minor contribution from cattle, while sheep were the primary focus of animal production throughout the Eurasian steppe belt during the mid-second millennium cal BC. Demographic analyses of sheep and goat remains indicate intensive wool production in densely inhabited settlements sites in northern Kazakhstan where metals were forged, suggesting animals fibers were an important form of wealth generation that supported nascent political structures. Biometrical analyses have revealed a marked turnover in steppe cattle populations across both regions which coincides with the establishment of trans-regional exchange networks during the Iron Age. In Mongolia, zooarchaeological results demonstrate a shift in the symbolic role of animals in mortuary arenas, with horses increasingly replaced by sheep, goats, and cattle, suggesting livestock, rather than horses, became a means to broadcast prestige.
WP2 results included compound specific stable isotopic data measured from ancient human remains from Mongolia indicating Bronze Age herders consumed diets consisting primarily of terrestrial animal proteins. Bulk carbon isotope analyses of human remains also indicate that millet came into use extraordinarily late in Mongolia, coinciding with the rise of the Xiongnu empire. Strontium and oxygen isotopes analyses of ancient human teeth from Mongolia demonstrate regional circulation of Xiongnu intermediary elites that served to consolidate the power of the first ‘state on horseback’. Zooarchaeological analyses have revealed a shift in the importance of animals in mortuary monuments in Mongolia from the Bronze Age to the Iron Age, reflecting a shift in role of animals as a means of political negotiation. Stable isotope analyses of animal remains from Mongolia demonstrate a sharp increase in stocking rates during the Iron Age indicating the intentional generation of animal wealth was a key to the rise of the Xiongnu Empire.

Main results from WP3 from organic residue analyses of pottery suggest that animal meats and fats had an outsized importance in the northern Kazakh steppe ca 2000 – 1200 BC, with little or no contribution from dairy, but dairy was an important food in the drier southern Kazakh steppe at ca 1400-1000BC. Proteomics analyses of dental calculus from Bronze and Iron Age human remains from Mongolia identify only uneven consumption of dairy across the Mongolian steppe despite previous work, based on a small sample size, asserting that dairy consumption was a key part of Bronze Age diets there. Initial proteomic analyses for dairy proteins (beta lactoglobulin) hint at marked temporal shifts in dairy consumption in the Russian Altai, with early Bronze Age herders associated with the Afanasievo consuming dairy but a possible decrease or cessation of dairy in later periods.

For WP4, ancient DNA analyses work on goats indicate that goats spread along two transmission pathways into the Eurasian steppe, the first along a northern route along the open steppe belt (northern Kazakhstan) and the second along the Inner Asian Mountain Corridor via the Tian Shian mountain range. WP4 results also include genetic evidence for the earliest domesticated sheep and cattle in the Altai at ca 3000 BC associated with the Afanasievo culture.
Progress beyond the state of the art was achieved isotope analysis with protocol development for compound specific-analyses of amino-acids in an effort to increase throughput for project. Development of a two-point normalisation method for GC-C-IRMS determination of amino acid δ15N values was attempted using three sets of mixed amino acid standards of known isotopic composition, in order to improve accuracy of determined isotopic values and decrease instrument downtime.

Additional protocol development in proteomic analyses for the identification of beta lactoglobulin pushed the approach beyond the current state of the art. There is no standardized technique for sample preparation in terms of buffers or the techniques implemented for isolation of potential proteins from dental calculus. ASIAPAST systematically tested several separate methods (Filter Aided Sample Preparation, Gel Aided Sample Preparation, and Single Pot Sold Phase Enhanced Sample Preparation) for the isolation of protein biomolecules and microfossils. The resulting modifications of protocols appears to enhance milk protein recovery.

Expected results until the end of the project include isolating establishing where and when hunter-gatherer and pastoralist mobility patterns changed and under what conditions, determine if there were regional distinctions in the demographic composition of livestock herds and the husbandry strategies used to manage them, document whether shifts in the intensity of processing of ruminant fat, milk fat, and fish oil correspond with changes in pastoralist dietary intake, and establish when and where the distinction between livestock as a primarily subsistence resource and livestock means to ideological and political expression emerged.