Fibular diaphyseal curvature of the Jomon population

This study investigated differences in the fibular diaphyseal curvature between prehistoric Jomon hunter–gatherers and modern Japanese people. A total of 115 skeletal remains of 40 individuals from the Late/Final Jomon period (approximately 4300–2500 years BP) and 75 modern Japanese individuals were included in the analysis. The degree of anteroposterior and mediolateral diaphyseal curvature was measured based on digital photographs taken from the frontal and sagittal planes at every 5% diaphyseal region between the range of 20–80% of the fibular length. Fibular diaphyseal curvature was compared between both populations and sexes, and the correlation between fibular diaphyseal curvature with diaphyseal cross-sectional morphology and body size variables were confirmed. The results showed significant differences in the anteroposterior diaphyseal curvature between the Jomon and modern Japanese populations, and a significantly curved anterior direction was noted for Jomon males and females, compared with modern Japanese males and females. On the contrary, little populational difference was noted in terms of mediolateral diaphyseal curvature. The curvature of the fibular diaphysis showed less correlation with body size variables. Moreover, anteroposterior diaphyseal curvatures were correlated with diaphyseal robustness and had low correlation with diaphyseal shape. A relationship between anteroposterior curvature and diaphyseal cross-sectional morphology, an indicator of habitual activity, was confirmed. This suggests that the fibular curvature is possibly influenced by mechanical loading from daily activities as well.