Comparing apples and oranges: Why infant bone collagen may not reflect dietary intake in the same way as dentine collagen.

δ13 C profiles for both dentine and bone are similar and more robust than δ15 N for estimating the age at which weaning foods are introduced. Our results suggest δ15 N values from dentine can be used to evaluate the maternal/in utero diet and physiology during pregnancy, and that infant dentine profiles may reflect diet PLUS an element of physiological stress. In particular, bone collagen fails to record the same range of δ15 N as co-forming dentine, especially where growth is stunted, suggesting that infant bone collagen is unreliable for weaning studies.