Difference in linear enamel hypoplasia frequency between the 16th- to 19th-century agrarian populations of the Korean Joseon dynasty and Siberian Russia

We studied linear enamel hypoplasia (LEH) in cranial series representative of Eurasian farmers with divergent lifestyles and natural environments: Siberian Russian settlers and Joseon dynasty people. The teeth of Siberian settlers and Joseon people of the 16(th)-19(th) centuries were ex- amined in this study. We inspected specimens to detect signs of LEH, and the intergroup prevalence was statistically compared. The proportions of LEH were compared by age and sex across each group. Statistical analysis was performed with R software. Russian settlers' LEH incidence per individual was 4.1% (3/73), whereas that of the Joseon people was 61.5% (56/91). In the case of LEH per tooth, Russian settlers and Joseon Koreans exhibited rates of 1.9% (24/1297) and 16.8% (336/2001), respectively. The statistical difference in the incidence of LEH between the two groups was highly significant (per individual: P = 9.188 x 10(-14); per tooth: P < 2.2 x 10(-16)). The prevalence of LEH was observed to be much higher in the Joseon population than in the West Siberian settlers. In conclusion, we hypothesize that East Asian people's physiological stress in childhood was far higher than that of Russian settlers. Historical LEH frequency on the Eurasian continent was truly diverse, possibly due to divergent stress conditions affecting different groups of people.