Temporal variation and interaction between nutritional and developmental instability in prehistoric Japanese populations.

We examined nutritional and developmental instability in prehistoric Japan, using data from 49 individuals across 13 archaeological sites. Hypoplasia incidence was used as a measure of nutritional stress, and fluctuating asymmetry (of upper facial breath, orbital breadth, and orbital height) as an indirect assessment of developmental instability. Abundant resources due to a stable climate during the Middle Jomon (5,000-3,000 BP) encouraged population growth, which led to regional cultural homogeneity and complexity. A population crash on Honshu in the Late/Final Jomon (roughly 4,000-2,000 BP) led to regionally divergent subsistence economies and settlement patterns. We find that the nutritional stress was consistent between periods, but developmental instability (DI) decreased in the Late/Final Jomon. While the DI values were not statistically significant, the higher values for Middle Jomon may result from sedentism, social stratification, and differential access to resources. On Hokkaido, Jomon culture persisted until the Okhotsk period (1,000-600 BP), marked by the arrival of immigrants from Sakhalin. Nutritional stress was consistent between Middle and Late/Final Jomon, but DI increased in the Late/Final. Nutritional and developmental instability decreased from Late/Final to Okhotsk, suggesting a positive immigrant effect. We expected to find an association between stress markers due to the synergistic relationship between nutrition and pathology. The data support this hypothesis, but only one finding was statistically significant. While high critical values from small sample sizes place limits on the significance of our results, we find that the impact of environmental and cultural change to prehistoric Japanese populations was minimal.