Health and sexual dimorphism at Ban Non Wat: The effects of the intensification of agriculture in prehistoric Southeast Asia

Abstract

The intensification of agriculture is regarded as a major transition in human prehistory that affected key aspects of the physical and cultural environments over time. One of the ways to measure human adaptation to this transition is through sexual dimorphism in body size. Previous bioarchaeological studies have shown that when the difference in body size between males and females decreases over time, general population health also declines. Using a biocultural approach, this PhD research project examines health and sexual dimorphism in body size during the intensification of rice agriculture at the prehistoric site of Ban Non Wat, Northeast Thailand (1750-420 b.c.).Based on a broad context of bioarchaeological research, three hypotheses were developed and tested using a sample of adults (n=190). Sexual dimorphism was quantified using bone lengths and breadths, and health was analysed using two indicators of non-specific systemic stress (linear enamel hypoplasia and subperiosteal new bone formation).Contrary to expectations, the results indicated that when sexual dimorphism decreased over time, health improved. Temporal changes in sexual dimorphism were attributed to greater variation in female body size, whereas male body size remained stable. No sex-specific differences were found in either indicator of non-specific systemic stress. This research suggests that sexual dimorphism in body size is a complex, but useful, measure of human biocultural adaptation, but not necessarily of general population health.