Stable carbon and nitrogen isotope analysis of archaeological human hair: Reconstructing diet and health of ancient individuals

•Human scalp hair is an ideal bioresource in stable isotope analyses.•A 0.5-cm-long segment of a single hair fibre can reconstruct a palaeodiet.•Bulk and compound-specific approaches address different archaeological questions.•More research is needed in the field of hair keratin amino acid isotope analysis.•The potential of keratin δ13C values in physio-pathological studies is unexplored.