Diet reconstruction through stable isotope analysis of ancient mummified soft tissues from Kulubnarti (Sudanese Nubia)

Abstract

Carbon and nitrogen stable isotope values were measured in tissues of Nubian mummies from two Christian cemeteries (AD 550–800) located on the island of Kulubnarti about 130km south of Wadi Halfa in Sudanese Nubia. Protein suitable for isotopic analysis for dietary reconstruction was extracted from soft tissue samples of 90 naturally mummified individuals (47 adults, 42 immatures and one of unknown age at death). The isotopic data indicated that the diet of these Nubian populations included a mix of C3 and C4 plants (predominantly C3) in addition to a relatively small contribution of animal protein from terrestrial sources and no aquatic protein sources. A significant difference was found regarding the δ13C values between the two cemeteries which may indicate a diet enriched in 13C (more C4 plants) in the individuals buried in the Kulubnarti R cemetery. No significant difference in the δ15N values was found between the two cemeteries indicating nearly the same proportion of animal protein in the diets of the two population samples. Significant differences were found between different soft tissues in the nitrogen isotopic signatures with meninges and periosteum being the most 15N-enriched tissues, followed by skin, while cartilage was the least 15N-enriched tissue. No significant differences were found in the δ13C values between different tissues. Although the δ13C and δ15N values from bone collagen of the same material showed significant differences between age groups, the soft tissue samples did not show any significant isotopic differences between age and sex categories. Moreover, comparing soft tissue with bone collagen results showed 15N-enrichment in the soft tissues, most probably as a result of physiological and fractionation differences between the collagen of the soft tissues and bone collagen.