Diachronic patterns of dental hypoplasias and vault porosities during the predynastic in the Naqada region, Upper Egypt.

The diachronic pattern of the frequencies of linear enamel hypoplasias and porotic hyperostosis was studied in temporally separated samples of adult predynastic Egyptian remains from the Naqada region, Upper Egypt. The samples covered a period of increasing population density and social complexity as well as decreasing Nile flooding in Egypt. First and second molars were evaluated for hypoplasias in material from the Naqada I, II, and III periods; sample sizes were 13, 30, and 25, respectively, for the first molar, and 11, 28, and 24 for the second molar. Cranial vaults were examined for porotic hyperostosis using several approaches; sample sizes were 26, 66, and 51 for Naqada I, II and III, respectively. Linear regression showed a decreasing trend for several variables: for the individual frequency of first molar hypoplasias (rho = 0.025), the vault porosity score, which indicates the severity of the lesions (rho < 0.001), and the extent score, which indicates the number of superior vault bones having porosities (rho < 0.001). Logistic regression showed a temporal decline in the percentage of crania per sample having any vault porosities and only higher grade lesions (rho < 0.012 and rho < 0.003, respectively). Lesions of the second molar showed no directional trend. The results contrast with the common observation that these skeletal markers usually increase in contexts of increasing population density and social complexity.