Bone Mineralisation Disorders in Bronze and Iron Age Skeletal Assemblages from Mongolia

Maria Kathryn Purnell1,2*, Kimberly Plomp3, Erdene Myagmar4, Hallie Buckley5, and Melandri Vlok6

High latitudes and seasonal variation in ultraviolet radiation increase the risk of vitamin D deficiency; this study assesses whether skeletal assemblages from prehistoric Mongolia, a region of high altitude and strong seasonality, exhibit bone mineralisation disorders and whether frequencies changed diachronically between the Bronze Age (ca. 2500–300 BC) and the Iron Age/Xiongnu period (ca. 300 BC–200 AD). Ninety‑two Bronze Age and 69 Iron Age individuals, representing adults and non‑adults, were examined macroscopically for lesions and radiographed where lesions had high diagnostic potential; the Brickley and Ives (2010) criteria for differential diagnosis of rickets and osteomalacia were applied. Overall, 4.3% of Bronze Age and 16.2% of Xiongnu individuals presented with skeletal changes consistent with probable rickets or residual rickets, and 6.2% of Bronze Age and 21.7% of Xiongnu individuals presented with changes consistent with probable osteomalacia. Mineralisation disorders affected individuals across age groups in both periods, but sex‑specific frequencies shifted: females showed higher frequencies in the Bronze Age, whereas the converse occurred in the Xiongnu, a change that is statistically significant for probable osteomalacia (). Given a pastoral diet rich in meat and dairy, calcium and phosphorus deficiency are unlikely primary causes; seasonal vitamin D deficiency is proposed as the most plausible explanation. These results highlight the influence of environment, subsistence and social factors on skeletal health and demonstrate how bioarchaeological evidence can illuminate past patterns of physiological stress and adaptation in prehistoric Mongolia.