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 (δ13C) and nitrogen (δ15N) 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 δ13C and δ15N 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 δ13C and δ15N values compatible with exclusive breastfeeding are detected up to ca. 1 year, 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 δ13C and δ15N, compatible with the weaning process, is then observed up to ca. 4 years 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 δ13C and δ15N 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.

The coexistence of cultural identities and their interaction is a fundamental topic of social sciences that is not easily addressed in prehistory. Differences in mortuary treatment can help approach this issue. Here, we present a multi-isotope study to track both diet and mobility through the life histories of 32 broadly coeval Late Neolithic individuals interred in caves and in megalithic graves of a restricted region of northern Iberia. The results show significant differences in infant- and child-rearing practices, in subsistence strategies, and in landscape use between burial locations. From this, we posit that the presence of communities with distinct lifestyles and cultural backgrounds is a primary reason for Late Neolithic variability in burial location in Western Europe and provides evidence of an early “them and us” scenario. We argue that this differentiation could have played a role in the building of lasting structures of socioeconomic inequality and, occasionally, violent conflict.

Tooth dentine serial sampling followed by isotope analyses allows detection of shifts in an individual's diet during the periods of tooth formation, providing information on breastfeeding, weaning, and childhood nutrition. Current sampling methods, however, do not fully capture the potential resolution of dentine increments because of the difficulties caused by the conical growth pattern, and changes in growth rate during tooth development resulting in uncertain timing. Here, we present an imaging‐assisted microsampling approach that takes the biological growth pattern of dentine into account in an effort to improve temporal resolution. We used high‐resolution light microscopy images of first molar longitudinal thin sections to generate an accurate optical reference of growth pattern and formulated a new scheme to assign collected microsamples to age. This allowed us to track dietary changes over more precisely confined and shorter time periods, providing greater detail and resolution for the breastfeeding and weaning process. We applied our method to track early life dietary history in four individuals from a small cemetery in Alsace, France, dated to the early 5th century AD (the Late Antique/Migration period). Even within this short timescale, 13C/12C and 15N/14N ratio sequences suggest variability in diets and weaning periods, and hint at early maternal mobility.