Imaging-assisted time-resolved dentine sampling to track weaning histories

© 2018 John Wiley & Sons, Ltd. 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.