Comparing the Use of Magnetic Beads with Ultrafiltration for Ancient Dental Calculus Proteomics.

Over the past two decades, proteomic analysis has greatly developed in application to the field of biomolecular archaeology, coinciding with advancements in LC-MS/MS instrumentation sensitivity and improvements in sample preparation methods. Recently, human dental calculus has received much attention for its well-preserved proteomes locked in mineralized dental plaque which stores information on human diets and the oral microbiome otherwise invisible to other biomolecular approaches. Maximizing proteome recovery in ancient dental calculus, available only in minute quantities and irreplaceable after destructive analysis, is of paramount importance. Here, we compare the more traditional ultrafiltration-based and acetone precipitation approaches with the newer paramagnetic bead approach in order to test the influence of demineralization acid on recovered proteome complexity obtained from specimens as well as the sequence coverages matched for significant proteins. We found that a protocol utilizing EDTA combined with paramagnetic beads increased proteome complexity, in some cases doubling the number of unique peptides and number of proteins matched, compared to protocols involving the use of HCl and either acetone precipitation or ultrafiltration. Although the increase in the number of proteins was almost exclusively of bacterial origin, a development that has implications for the study of diseases within these ancient populations, an increase in the peptide number for the dairy proteins ß-lactoglobulin and casein was also observed reflecting an increase in sequence coverage for these dietary proteins of interest. We also consider structural explanations for the discrepancies observed between these two key dietary proteins preserved in archaeological dental calculus.

Inheritance and inequality among nomads of South Siberia.

At the headwaters of the Yenisei River in Tuva and northern Mongolia, nomadic pastoralists move between camps in a seasonal rotation that facilitates their animals' access to high-quality grasses and shelter. The use and informal ownership of these camps depending on season helps illustrate evolutionary and ecological principles underlying variation in property relations. Given relatively stable patterns of precipitation and returns to capital improvement, families generally benefit from reusing the same camps year after year. We show that locations with higher economic defensibility and capital investment-winter camps and camps located in mountain/river valleys-are claimed and inherited more frequently than summer camps and camps located in open steppe. Camps are inherited patrilineally and matrilineally at a ratio of 2 : 1. Despite its practical importance, camp inheritance is not associated with livestock wealth today, which is better predicted by education and wealth outside the pastoral economy. The relationship between the livestock wealth of parents and their adult children is significantly positive, but relatively low compared to other pastoralists. The degree of inequality in livestock wealth, however, is very close to that of other pastoralists. This is understandable considering the durability and defensibility of animal wealth and economies of scale common across pastoralists. This article is part of the theme issue 'Evolutionary ecology of inequality'.

Central Mongolian lake sediments reveal new insights on climate change and equestrian empires in the Eastern Steppes.

The repeated expansion of East Asian steppe cultures was a key driver of Eurasian history, forging new social, economic, and biological links across the continent. Climate has been suggested as important driver of these poorly understood cultural expansions, but paleoclimate records from the Mongolian Plateau often suffer from poor age control or ambiguous proxy interpretation. Here, we use a combination of geochemical analyses and comprehensive radiocarbon dating to establish the first robust and detailed record of paleohydrological conditions for Lake Telmen, Mongolia, covering the past ~ 4000 years. Our record shows that humid conditions coincided with solar minima, and hydrological modeling confirms the high sensitivity of the lake to paleoclimate changes. Careful comparisons with archaeological and historical records suggest that in the vast semi-arid grasslands of eastern Eurasia, solar minima led to reduced temperatures, less evaporation, and high biomass production, expanding the power base for pastoral economies and horse cavalry. Our findings suggest a crucial link between temperature dynamics in the Eastern Steppe and key social developments, such as the emergence of pastoral empires, and fuel concerns that global warming enhances water scarcity in the semi-arid regions of interior Eurasia.