What can variation in stature reveal about environmental differences between prehistoric Jomon foragers? Understanding the impact of systemic stress on developmental stability

Abstract

This study reconstructs patterns of stress and phenotypic variation in prehistoric Japan. Greater evidence for stress is indicated by elevated enamel hypoplasia frequency among Jomon foragers from western compared to eastern Japan. Geographic variation in stress between Jomon people is related to plant-based diets and resource scarcity in western Japan. The hypothesis that Jomon people from western Japan had shorter stature than those from the east is, therefore, tested. Relationships between individual stature, geographic location, and enamel hypoplasia presence/absence are also explored. In addition, increased population density and reliance on plant foods are observed during the Late/Final Jomon period in western Japan. A second hypothesis proposing shorter stature for Late/Final Jomon people compared to those from the Middle Jomon period is tested. Statistically significant differences in stature between males and females from eastern and western Japan were not observed. Individual relationships between enamel hypoplasia and stature were rejected. Stature decreased significantly over time in western Japan. It is possible that stature between the eastern and western Jomon did not differ because the western Jomon experienced catch up growth after childhood stress episodes. It is also likely that variation in stress between the two groups was not severe enough to warrant stature reduction. Decreases in stature through time in western Japan are related to increased exposure to chronic infection and dietary stress. Overall, these results indicate that enamel hypoplasia frequencies provide an adequate index of general stress but may fail to predict the impact of stress on the human phenotype.