Dietary and physiological controls on the hydrogen and oxygen isotope ratios of hair from mid-20th century indigenous populations

• Published in: American journal of physical anthropology 2009-08, Vol.139 (4), p.494-504
• Main Authors: Bowen, Gabriel J., Ehleringer, James R., Chesson, Lesley A., Thompson, Alexandra H., Podlesak, David W., Cerling, Thure E.
• Format: Article
• Language: English
• Subjects: 20th century; Anthropological analysis; Anthropology. Demography; Anthropometry; Biological and medical sciences; Biological anthropology; Correlation; Deuterium - analysis; Diet; Environment; Ethnic Groups; Hair - chemistry; Human physiology applied to population studies and life conditions. Human ecophysiology; Humans; Indigenous populations; keratin; Mass Spectrometry; Medical sciences; Models, Chemical; North Amerindians; Oxygen Isotopes - analysis; Physical anthropology; Regression Analysis; stable isotopes; U.S.A; United States
• ISSN: 0002-9483; 1096-8644
• DOI: 10.1002/ajpa.21008

A semimechanistic model has recently been proposed to explain observed correlations between the H and O isotopic composition of hair from modern residents of the USA and the isotopic composition of drinking water, but the applicability of this model to hair from non‐USA and preglobalization populations is unknown. Here we test the model against data from hair samples collected during the 1930s–1950s from populations of five continents. Although C and N isotopes confirm that the samples represent a much larger range of dietary “space” than the modern USA residents, the model is able to reproduce the observed δ2H and δ18O values given reasonable adjustments to 2 model parameters: the fraction of dietary intake derived from locally produced foods and the fraction of keratin H fixed during the in vivo synthesis of amino acids. The model is most sensitive to the local dietary intake, which appears to constitute between 60% and 80% of diet among the groups sampled. The isotopic data are consistent with a trophic‐level effect on protein H isotopes, which we suggest primarily reflects mixing of 2H‐enriched water and 2H‐depleted food H in the body rather than fractionation during biosynthesis. Samples from Inuit groups suggest that humans with marine‐dominated diets can be identified on the basis of coupled δ2H and δ18O values of hair. These results indicate a dual role for H and O isotopic measurements of keratin, including both biological (diet, physiology) and environmental (geographic movement, paleoclimate) reconstruction. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.