Seasonality and season of birth of modern and late Neolithic sheep from south-eastern France using tooth enamel δ18O analysis

Stable oxygen isotopic analysis of tooth enamel was used to investigate seasonality and season of birth in sheep. Analyses were performed on the teeth of eight modern sheep bred at the Carmejane farm in south-eastern France and born in different periods of the year. This reference data set confirms that oxygen isotopic records in the second and third molars can be used to differentiate between sheep born in late winter and those born in early autumn. The results show that inter-individual variability in the timing of tooth formation is low for the second lower molar and more pronounced for the third lower molar in this population. The duration of the process of enamel mineralization has been estimated at approximately six months. The teeth of four sheep and two goats from the late Neolithic site of Collet-Redon in south-eastern France were analyzed using the same methodology. At this site, lambing occurred between the late winter and early spring. A slight difference appears in the seasonal sequence recorded in sheep and goat, although it cannot be determined, whether this is due to different timing of tooth development, or an actual shift in the birth period. From the distribution of slaughter ages and birth period, it is suggested that domestic caprines were killed throughout the year and that Collet-Redon was probably a permanent settlement.

► Sequential analysis of enamel δ18O were performed on modern sheep 2nd and 3rd molars.
► This protocol allowed differentiating late winter and autumn births.
► Some variability appears in the timing growth of the modern sheep third molar.
► The completion of enamel mineralization may have required approximately six months.
► In the late Neolithic, at Collet-Redon, births occured in late winter to early spring.