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

Abstract

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. 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). 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. 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.