Infant and childhood diet at the passage tomb of Alto de la Huesera (north-central Iberia) from bone collagen and sequential dentine isotope composition

During the Late Neolithic (ca. 3500-2900 cal BC), the Rioja Alavesa region of north-central Spain witnessed great demographic pressure and social unrest, manifested as widespread violent conflict. Drawing upon the ethnographic literature, it is possible that this situation impacted upon child-rearing practices, both through food shortages and differential parental investment, favouring male infants. Here, carbon (C-13) and nitrogen (N-15) stable isotope measurements from bone collagen of 17 juveniles and from 163 serial microsamples of dentine from first and second molars of seven adults from the site of Alto de la Huesera are used to examine breastfeeding, weaning, and childhood diets. Bone and dentine collagen C-13 and N-15 isotope values both decrease from infancy to early childhood and increase slightly towards adolescence, but dentine provides a more time-sensitive means of monitoring dietary changes. High C-13 and N-15 values compatible with exclusive breastfeeding are detected up to ca. 1year, with a significantly shorter duration among males, suggesting differential sex-related parental strategies from infancy. This is tentative given the small number of individuals being compared, but does suggest that further work would be worthwhile. A gradual decline in both C-13 and N-15, compatible with the weaning process, is then observed up to ca. 4years in both sexes. This delayed cessation of nursing is interpreted as a possible response to food shortage. With regard to postweaning patterns, shifts to lower C-13 and N-15 values in females at around age 9-11, and a general progressive increase in both isotope values from childhood to adolescence, are detected. These could be linked either with differential protein intake due to social age-related nutritional practices or to physiological demand. The comparison between bone and dentine values shows differences between survivors and nonsurvivors in both isotopes, so that assessments based on deceased children may be biased by their potentially compromised health status.