Akademisk avhandling för avläggande av filosofie doktorsexamen i laborativ arkeologi vid Stockholms universitet som offentligen kommer att försvaras fredagen den 19 april 2013 klockan 10.00 i Nordenskiöldsalen, Geovetenskapenshus, Svante Arrhenius
väg 12, 114 18 Stockholm.

Abstract
This thesis is concerned with how prehistoric infants were fed in different physical and cultural environments, and in particular what impact the economic, social, and epidemiological changes associated with the development of agriculture had on infant feeding practices. In order to examine these effects, stable isotope ratio analysis has been used to assess the duration of breastfeeding and weaning in a variety of prehistoric contexts. The first study is of Pitted Ware Culture hunter-gatherers at the site of Ajvide on Gotland, Sweden. Breastfeeding usually continued for at least two years, but there was some variation in supplementary foods, which is attributed to seasonal variations in resource availability. The second study analysed a number of Neolithic and early Bronze Age sites from south-east Poland. Breastfeeding duration varied both within and between sites and ranged from six months to five years. The third study found that the infant feeding practices of two Iron Age populations on Öland, Sweden, were very varied, and infants may have been fed differently depending on their social status. The fourth study is of the childhood diet in the Únětice Culture of south-west Poland. Individual diets changed little during the lifetime, suggesting that eventual adult identity was determined early in life. A small number of infants in the study were found to have breastfed for differing lengths of time. The final paper considers the health consequences of introducing animal milks into the infant diet in a prehistoric context, and finds that their availability is unlikely to have made it possible to safely wean infants earlier.

Comparison of the results from the four stable isotope studies to those of other published studies reveals that the modal age at the end of weaning was slightly lower in agricultural communities than hunter-gatherer communities, but the range of ages was similar. Weaning prior to the age of eighteen months was rare before the post-medieval period. It is argued that the gradual reduction in breastfeeding duration since the Neolithic, and the replacement of breastmilk with animal milk products, means that on the whole the development of agriculture probably served to increase infant morbidity and mortality.