What is our toolbox of analytical chemistry for exploring ancient hominin diets in the absence of organic preservation?

This short review aims at drawing up an inventory of the existing chemical techniques that can help reconstruct past hominin diets in the absence of organic preservations (such as collagen). Preservation issues necessitate the preferential use of dental enamel over bones for bioapatite trace and minor element analyses. The trace element ratios in dental enamel-as opposed to bones-can distinguish browser, grazer and marine diets, but their use as a trophic level indicator is irrelevant. So far, carbon isotopes have been the most fruitful tracer to reconstruct Lower Paleolithic hominin diets and ecology. The application of new isotope systems opens up very promising perspectives for the characterization of Pleistocene hominin diets as they generally reveal trophic level information. The combination of these promising tracers with carbon isotopes in dental enamel could therefore provide similar information to the isotopes (C and N) usually analyzed in collagen, which brought useful insights into the diets of Late Neandertals and Upper Paleolithic modern humans. However, before investigating nontraditional isotope ratios in precious hominin samples, more work is needed to test their response to various dietary types and environments as well as their resistance to diagenesis.