NEW STATISTICAL APPROACHES TO INTRA-INDIVIDUAL ISOTOPIC ANALYSIS AND MODELLING OF BIRTH SEASONALITY IN STUDIES OF HERD ANIMALS

摘要

This paper introduces improved methods for statistically assessing birth seasonality and intra-annual variation in δ~(18)O from faunal tooth enamel. The first method estimates input parameters for use with a previously developed parametric approach by C. Tornero et al. The second method uses a non-parametric clustering procedure to group individuals with similar time-series data and estimate birth seasonality. This method was successful in analysing data from a modern sample with known season of birth, as well as two heterogeneous archaeological data sets. Modelling indicates that the non-parametric approach estimates birth seasonality more successfully than the parametric method when less of the tooth row is preserved. The new approach offers a high level of statistical rigour and flexibility in dealing with the time-series data produced through intra-individual sampling in isotopic analysis.