Figure 4.

(a) Principal component analysis (PC1 and PC2, accounting for 80% of the variance) based on stable isotope values for archaeological walrus rostra and control samples. The variables included are δ¹³C, δ¹⁵N, non-exchangeable δ²H and δ³⁴S. The 95% CI for all specimens of the western genetic clade is shaded in grey. (b–d) Stable isotope values for archaeological walrus rostra and control samples: (b) δ¹³C and δ¹⁵N, (c) δ¹³C and δ³⁴S and (d) δ¹⁵N and non-exchangeable δ²H. Symbols indicate sex and genetic clade where known. For all plots, the Kyiv specimens are circled, and labels indicate the origin of control samples (B is the Barents Sea region, G is Greenland and I is Iceland).