Systemic Stress in Hunter-gatherers From the Central Pampas Dunefields (Argentina). Evaluating Linear Enamel Hypoplasia During the Holocene

Abstract This article aims to evaluate whether the socio-environmental changes observed in the Central Pampas Dunefields (Argentina) throughout the Holocene (ca. 11.700-350 cal yr BP) caused episodes of systemic stress in hunter-gatherer populations. Linear enamel hypoplasia was analyzed macroscopically with a 40X magnifying glass and oblique light in 337 teeth from 26 adult individuals recovered from 11 archaeological sites. Data were analyzed following three levels of observation: individual, tooth, and number of dental enamel lines. 42.3% of the individuals analyzed presented linear enamel hypoplasia. The lines affected males and females similarly. A higher frequency was observed in the Late Holocene (ca. 4200-350 cal yr. BP) about earlier periods. The age of growth-disruption events occurred between 2 and 6.05 years, and stress events are observed at earlier ages in the Late Holocene than in the Middle Holocene. The causes could be related to metabolic stress associated with weaning, variations in the availability of natural resources over time, development of infectious and parasitic diseases during changes in social organization strategies in the Late Holocene, and gastrointestinal diseases by water intake in poor conditions. Comparison at the level of the Pampas region indicates moderate to high values of linear enamel hypoplasia, suggesting the exposure of hunter-gatherer groups to recurrent episodes of stress during the early stages of postnatal life.