• breastfeeding and weaning;
  • foragers;
  • subadults;
  • demography;
  • Central Asia


Analysis of stable nitrogen and carbon isotopes (δ15N and δ13C) from subadults and adults allows for assessment of age-related dietary changes, including breastfeeding and weaning, and adoption of an adult diet. In one of the first studies of hunter-fisher-gatherer subadults from Eurasia, three Neolithic (8,800-5,200 calBP) mortuary sites from southwestern Siberia are analyzed to evaluate hypothesized differences in weaning age between Early versus Late Neolithic groups. An intra-individual sampling methodology is used to compare bone formed at different ages. Collagen samples (n = 143) from three different growth areas of long bones—the proximal metaphysis, diaphysis, and distal metaphysis—were obtained from 49 subadults aged birth to 10 years. In infants (birth to 3 years, n = 23) contrasting the δ15N values of the metaphysis, which contains newer bone, to the δ15N values of the diaphysis, which contains older bone, permits a more precise determination of breastfeeding-weaning status. In Early and Late Neolithic groups breast milk was the major protein source until the age of 2–3 years. However, there are differences in the age of weaning completion and duration: Early Neolithic groups weaned their infants at a later age and over a shorter amount of time. Differences may have affected infant morbidity and mortality, and female fecundity and inter-birth intervals. Stable isotope values in older subadults (4–10 years, n = 26) do not differ from adults suggesting the absence of age-based food allocation. Am J Phys Anthropol, 2011. © 2011 Wiley-Liss, Inc.