An investigation of enamel hypoplasia and weaning through histomorphological analysis and Bayesian isotope mixing models

Abstract

Enamel hypoplasia (EH) is a developmental defect, frequently used in bioarchaeological research to assess the nutrition and health in infants and children. Anthropological studies suggest that EH relates to disease and malnutrition especially during weaning, a hypothesis that up to now has not been examined empirically in ancient populations.

In the present study, we reconstructed the weaning process of 66 individuals from ancient Thessaloniki (4th c. BC-16th c. AD), a metropole in southeastern Europe, to explore the effect of breast milk consumption and infant diet on the development of EH. For this, we estimated the duration of weaning using stable isotope analysis on dentinal collagen of permanent first molars and breast milk proportions using Bayesian modeling. In parallel, we determined the exact formation age and duration of EH defects on the canines or the incisors of the same individuals using histomorphological analysis.

The combined results of our analyses show that individuals consuming less than 50% of breast milk during weaning, developed multiple EH defects (between 2.0-5.0 years), mostly formed close to the age of weaning or later. Our results are consistent with similar studies and provide new insights into the living conditions of children in pre-industrial and pre-vaccination contexts.