Abstract

Hydrogen stable isotopes (δ2H) preserved in bone collagen have been proposed as a promising proxy for palaeoclimatic reconstruction, though empirical applications remain limited. We performed multi-isotopic analyses to evaluate the reliability and scope of this approach, integrating novel δ2H data with recently published δ13C, δ15N and δ34S, on 50 herbivore bone samples collected from three archaeostratigraphic layers spanning the Aurignacian sequence of Isturitz Cave (France). This archaeological, well-preserved, dated and studied site provides a robust framework for testing isotopic proxies across temporal and taxonomic gradients. Our results reveal a progressive δ2H decline over ∼3000-year interval, broadly consistent with regional paleoenvironmental records indicating cooling and a shift towards drier conditions, but in contrast with previously proposed local climate changes. We also identified species-specific δ2H differences, underscoring the need for taxonomic resolution in future applications and general palaeoclimatic interpretations. While these samples reflect faunal remains accumulated through human activity—introducing potential ecological and sampling biases—they nonetheless provide valuable records of past local conditions at the time humans inhabited the site. Overall, our findings support the potential of bone collagen δ2H as a sensitive indicator of past hydrological conditions and a complementary tool for reconstructing both climatic trends and human-environment dynamics.