How did educational practices in southern Portugal develop over the course of 1500 years? An international study has uncovered this. It offers an unprecedented insight into breastfeeding and weaning practices in Roman, Muslim and Christian societies. The work uses advanced Bayesian statistical modeling and stable isotope analysis to reconstruct infant and child feeding patterns from ancient skeletal remains.
Led by Jun-Prof. Dr. Alice Toso from the Bonn Centre for Archaeosciences, the international team analyzed carbon and nitrogen isotopes from the bones of 143 adolescents and 46 adults from sites across Portugal and compared them with published data from other parts of the Iberian Peninsula. The results show prolonged weaning periods well beyond the age of two, different breastfeeding strategies in different religious communities and evidence of a high-protein weaning diet that included seafood and possibly meat.
“By combining bulk bone and incremental dentin isotope data with Bayesian modeling, we were able to illustrate how dietary habits changed from infancy to adolescence,” said Jun. Prof. Dr. Toso. “We found that even within the same city - Lisbon - breastfeeding duration and weaning foods varied over time, reflecting shifts in social roles, maternal autonomy and religious norms.”
Among the key findings: Prolonged breastfeeding (up to three years or longer) was common in most time periods, but Muslim populations breastfed the longest in all locations. Roman women in Lisbon breastfed the shortest - a practice that may be related to increased female fertility and population growth. Muslim child-rearing practices were often in line with religious texts that prescribe two full years of breastfeeding. Individual life histories reconstructed from dental dentines revealed different feeding patterns, including shifts during childhood growth spurts.
“This is the most comprehensive isotopic study of childhood nutrition in the Iberian Peninsula to date,” says Alice Toso, who is a member of the Transdisciplinary Research Areas ‘Life & Health’ and ‘Present Pasts’. The study not only enriches our understanding of historical childcare and nutrition. It also shows how children's health and survival were closely intertwined with broader cultural and economic changes.
The team hopes that the study will inspire further isotope studies of historical populations, particularly historically marginalized populations such as women and children. This should include the use of methods that take into account individual differences and at the same time reveal community-wide strategies for feeding the next generation.