Bone collagen hydrogen isotopes as tracers of local palaeoclimate: The Aurignacian from Isturitz cave (France) as a case study

Hydrogen stable isotopes ({delta}2H) preserved in bone collagen have been proposed as a promising proxy for palaeoclimatic reconstruction, though empirical applications remain limited. To evaluate the reliability and scope of this approach, we performed a multiisotopic analysis ({delta}13C, {delta}15N, {delta}34S, and {delta}2H) 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 {delta}2H depletion over [~]3000-year interval, consistent with predicted increasing aridity. We also identified species-specific {delta}2H differences, underscoring the need for taxonomic resolution in future applications and in 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. Overall, our findings support the potential of bone collagen {delta}2H as a sensitive indicator of past hydrological conditions and a complementary tool for reconstructing both climatic trends and humanenvironment dynamics.