Fig. 2
Density plots of the 76 human 87Sr/86Sr isotope values across the chronological phases considered in this study. The grey dashed line indicates the density distribution of all human 87Sr/86Sr values. The individuals dating to the second half of the 5th millennium BCE (red curve) and to the early 2nd –early 1st millennium BCE (orange curve) exhibit broad, low distributions spanning a wide range of values, reflecting high isotopic variability. Conversely, the green and blue curves correspond to the individuals dating between the late 4th millennium BCE (graveyard UA53) and the early 2nd millennium BCE (graveyard K1 XII-XIII) and display narrower distributions. Within these, isotope values for individuals from graveyard UA53 follow a bimodal distribution, whereas those for individuals from graveyard K1 XII-XIII are multimodally distributed, indicating internal heterogeneity in both samples.
