Effect of diet, physiology and climate on carbon and nitrogen stable isotopes of collagen in a late pleistocene anthropic palaeoecosystem: Marillac, Charente, France

Abstract

In fossil mammal bones and teeth from Marillac (40,000–45,000 years Br), collagen has been found to be preserved. This collagen presents a similar amino acid composition to modern collagen. An isotopic difference between collagen of herbivorous and carnivorous species is clearly documented in this paper and it is shown that the decrease of the amount of collagen in bones and teeth through diagenesis has not altered the original isotopic signal. It has been possible to demonstrate the carnivorous diet of Neanderthals. In addition, more subtle isotopicdifferences have been documented between the different species within each trophic group consumed. These differences can be linked to physiology, or to particular kinds of food of each animal species. Another isotopic signal due to nursing effects has also been observed. A young mammal suckling its mother's milk is one trophic level higher than an adult of the same species. Consequently, the collagen of deciduous teeth records an isotopic signal from the food consumed before weaning. Also, in species where most of the tooth growth occurs before weaning time, the collagen of permanent teeth records, in part, information about the milk diet. Thus the 15N composition of such teeth is different from the isotopic composition of bones in the same individual. The variation of the 15N composition of bone collagen along the stratigraphical sequence of the site shows that this isotopic signal may also be used for the palaeoclimatic reconstruction; for example, evidence of an arid period is seen in the layer #7 in Marillac.