National Academy of Sciences
Source: Fecal carbon and nitrogen isotopic analysis as an indicator of diet in Kanyawara chimpanzees, Kibale National Park, Uganda – Phillips – 2016 – American Journal of Physical Anthropology – Wiley Online Library
The major components of human diet both past and present may be estimated by measuring the carbon and nitrogen isotope ratios (δ 13 C and δ 15 N) of the collagenous proteins in bone and tooth dentine. However, the results from these two tissues differ substantially: bone collagen records a multi-year average whilst primary dentine records and retains time-bound isotope ratios deriving from the period of tooth development. Recent studies harnessing a sub-annual temporal sampling resolution have shed new light on the individual dietary histories of our ancestors by identifying unexpected radical short-term dietary changes, the duration of breastfeeding and migration where dietary change occurs, and by raising questions regarding factors other than diet that may impact on δ 13 C and δ 15 N values. Here we show that the dentine δ 13 C and δ 15 N profiles of workhouse inmates dating from the Great Irish Famine of the 19th century not only record the expected dietary change from C 3 potatoes to C 4 maize, but when used together they also document prolonged nutritional and other physiological stress resulting from insufficient sustenance. In the adults, the influence of the maize-based diet is seen in the δ 13 C difference between dentine (formed in childhood) and rib (representing an average from the last few years of life). The demonstrated effects of stress on the δ 13 C and δ 15 N values will have an impact on the interpretations of diet in past populations even in slow-turnover tissues such as compact bone. This technique also has applicability in the investigation of modern children subject to nutritional distress where hair and nails are unavailable or do not record an adequate period of time.