Bi-variate scatter plot of the δ13C and δ15N values of animal and human bone collagen from Xipo.
The predictive ranges for C3, mixed and C4 dietary groups are determined by the mean values of C3 plants [19, 21] and C4 millets [67, 68], plus 13C enrichment of 5 ‰ between diet protein and collagen [69, 70]. Human isotopic data are from the Institute of Archaeology CASS and Henan Provincial Institute of Cultural Heritage and Archaeology . 95% prediction confidence ellipses are drawn for Sus, Bos, Cervus and humans; other species have too few data points. ‘PIG-1’ and ‘PIG-2’ were recovered from the bottom of the moat. ‘Kiln-1’ was recovered associated with the ceramic kiln. The modelled values for different consumer groups are symbolised by open diamonds and calculated as follows. The pure ‘millet consumer’ is based on published millet mean δ13C values + a stepwise diet-consumer collagen shift of +5 ‰, and mean δ15N value with an estimated trophic step of + 4 ‰. For ‘pig consumer’ we used the Xipo pig mean δ13C + 1 ‰ as the trophic step for δ13C, and mean δ15N + 4 ‰ as the trophic shift. For ‘natural C3 feeder’, we used the mean δ13C and δ15N for wild herbivores and for any wild animal consumers we used the latter + 1 ‰ and + 4 ‰ for δ13C and δ15N respectively.