An isotopic investigation on diet and inequality: the human remains from Gannì (Sardinia, 3rd millennium BC)

•Significant δ15N difference between different tombs points to notable intra-site dietary differences between groups.•Status difference may have been marked by better access to some kinds of plant foods.•FTIR data are used to explore reliability of isotopic values and variation in taphonomic environments.•Stature higher than average may support a non-local ancestry.•Tomb features, grave goods, isotopic values and dental health do not show direct and simple associations. The Mediterranean Copper Age has been recognized as a time of profound changes related to metal circulation, better maritime connections and intensified mobility, and in many areas economic intensification, to some degree dependent on the concept of Secondary Products Revolution. This paper presents data on osteology and stable isotopes of N, C and O from collagen and bioapatite of human remains from a small cemetery in Sardinia, Italy, dating to the 3rd mill. BC and composed of three tombs and 10 individuals; to date, this is the second assemblage of skeletal remains from the chalcolithic Monte Claro culture to have been studied according to modern standards. While the absence of faunal or vegetal baseline values prevents a quantitative assessment of the proportion of different foods in the diet, a remarkably large intra-group variation in δ15N as quantifiable by the standard deviation (= 1.4‰) was recorded. Considering this is one among the greatest recorded standard deviations in δ15N in the Western Mediterranean, while using caution due to limited sample size, it is compatible with a sharp differential access to resources, especially to animal protein, and such dietary inequality can be interpreted as a sign of status distinction between two groups buried in different tombs. These results are discussed in their complex, problematic relationship to the patterns of material culture.