Intra‐tooth isotopic analysis (δ¹³C and δ¹⁵N) of dentine collagen in high‐crowned teeth: A new experimental study with modern sheep specimens

Abstract

Hypsodont teeth molars develop in a short lapse of time. Both dentine and enamel dental tissues do not regenerate once formed. This fact allows the reconstruction of isotopic sequences covering short moments of the individual's life span, a useful approach in current zooarchaeological and paleontological studies. Sampling design usually follows a serial or sequential extraction of dental bands perpendicular to the tooth growth axis, from the apex to the root. However, dentine develops following a secretion of layers oblique to the tooth vertical axis, and this pattern makes hard to isolate isotopic signals. A new experimental study with modern sheep breeds was conducted, covering a whole year and where carbon and nitrogen isotopic signatures of consumed plants were known. Three diet periods with different isotopic compositions were alternated during sheep's life. In this contribution, we test the resolution of a dentine sampling procedure to obtain intra-tooth isotopic variability of δ 13 C collagen and δ 15 N collagen values tied to diet shifts in sheep. Dentine was sequentially sampled in previously demineralized second and third mandibular molars.Samples were treated with standard protocols of collagen purification and then subjected to stable carbon and nitrogen isotope analysis. In M2 and M3 isotopic sequences obtained, diet shifts are recorded along two progressive trends of increasing-decreasing values, but some affections of the sampling procedure are also present. We conclude that the dentine sequential sampling here implemented allows for obtaining reliable intra-tooth isotopic data tied to dietary conditions in highcrowned teeth, although dentine growth patterns should be considered in detail in final interpretations. The integration of this high-resolution analysis in archaeological studies offers a new scope of possibilities for studying dietary patterns, seasonal dietary changes, and animal husbandry practices in past populations.

Extending our understanding of past animal diet using stable isotope analysis

“…Díez‐Canseco et al (2022) provide an important methodological contribution for extending the potential of intratooth carbon and nitrogen isotopic analysis of dentine collagen in high‐crowned animal teeth. In the study of archaeological animal diets, sequential stable isotope analyses on dentine have been underutilized to date, especially when compared with the more numerous studies on sequentially sampled tooth enamel.…”