Introduction

1The dietary information recorded by the skeleton during an individual’s life is prone to diagenetic modification during burial. In some situtations however, taphonomic conditions protect skeletal tissues from alteration. This is the case for the Dogon and Tellem bones buried for a few centuries (11^th-18^th) in sepulchral caves of the Bandiagara Cliff in Mali.

2The cultural habits of the modern Dogon have been extensively studied by ethnologists because of the richness and complexity of their societies. This offers the potential to test the quality of the dietary information recorded by the skeletons. However, little is known about the Tellem who were occupying the Bandiagara Cliff before the arrival of the Dogon. Their provenance, as well as their way of life are yet to be solved.

Preservation of the tellem and dogon bones

3The preservation of the studied material is investigated using crystallinity analysis (XRD), thin sections, organic matter content (OM, loss on ignition) and elemental composition (ICP-AES, ICP-MS, colorimetry and specific electrods) carried out on bone samples taken from the midshaft femurs of Tellem (24 individuals, XI-XVI^th century) and Dogon (10 individuals, XVIII-XX^th century). The data are compared with that of Neolithic bones from the Mauritanian Dhar and the Daounas (Mali).

4The crystallinity (CI) of the Dogon and Tellem bones is similar to that of a fresh bone (CI=0), and therefore is very low compared to bones from the Mauritanian Dhar (South-Eastern Mauritania) and the Daounas (N.-W. Mali).

5The histological thin sections of the skeletons from the Mauritanian Dhar and the Daounas show numerous cracks and signs of bacterial attack from which the Dogon and Tellem bones are protected.

6The Dogon and Tellem bones show a clear contrast with saharo-sahelian Neolithic human bones in terms of crystallinity, histology and geochemical composition. This demonstrates that the taphonomic conditions in the burial caves of the Bandiagara Escarpment lead to the same exceptional preservation of features in both the Dogon and Tellem bones.

Preservation of the dietary information

Discussion and conclusion

7This geochemical, mineralogical and histological study of the femurs of Dogon and Tellem skeletons shows that the cool and stable temperature of the burial caves and additionally the stable humidity levels have protected the human bones for the past thousand years. The mineralogical and structural characteristics of the bones (crystallinity, Ca/P) together with the histological features, and the trace elemental content (Mg, Na, F, Fe, Mn, Y, La, Ce and U) match those of fresh bones.

8We used a linear mixing model in order to estimate bone apatite δ13C as a function of varying amount of C4 in the diet, and applied enrichment values (ε) between bone apatite and whole diet ranging from 9 to 13‰ as commonly applied in past dietary reconstructions. δ¹³C values measured in the archaeological Dogon bones are in agreement with bone δ¹³C values expected for modern rural populations in Mali regarding ethnological surveys and considering ε around 9-10‰. However, subtle dietary changes seem to have occurred between the Tellem and the Dogon phases, according to slightly lower δ¹³C values yielded by the Tellem bones. In addition, δ¹⁸O of the Tellem bones suggest that these population settled onto the Plateau as opposed to the Dogon, who probably occupied the Cliff. Moreover, the geochemical composition of faunal remains (Bos) argues for a non-local origin of the cattle, most likely eating wild grasses growing on a Ba-enriched soil substrate.