Teeth defects and stress in prehistoric Japan. Linear enamel hypoplasia (LEH) defects are pits or grooves on the tooth surface that are typically caused by malnutrition, chronic infection, stress, and trauma. A study of LEH defects in prehistoric Japanese cultures was published in the American Journal of Physical Anthropology

(May 2010). Three groups of Japanese people were studied:

Yayoi farmers (early agriculturists), eastern Jomon foragers (broad-based economy), and western Jomon foragers (wet rice economy). LEH defect prevalence was determined from skulls of individuals obtained from each of the three cultures. Of the 182 Yayoi farmers in the study, 63.1% had at least one LEH defect; of the 164 Eastern Jomon foragers, 48.2% had at least one LEH defect; and, of the 122 Western Jomon foragers, 64.8%

had at least one LEH defect. Two theories were tested.

Theory 1 states that foragers with a broad-based economy will have a lower LEH defect prevalence than early agriculturists. Theory 2 states that foragers with a wet rice economy will not differ in LEH defect prevalence from early agriculturists. Use the results to test both theories, each at a = .01.