title: Dietary and physiological controls on the hydrogen and oxygen isotope ratios of hair from mid-20th century indigenous populations.
abstract: 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 delta(2)H and delta(18)O 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 (2)H-enriched water and (2)H-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 delta(2)H and delta(18)O 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.
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, UT 84112, USA. gabe@purdue.edu
authors.forename: Gabriel J
authors.initials: GJ
authors.lastname: Bowen
authors.forename: James R
authors.initials: JR
authors.lastname: Ehleringer
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Chesson
authors.forename: Alexandra H
authors.initials: AH
authors.lastname: Thompson
authors.forename: David W
authors.initials: DW
authors.lastname: Podlesak
authors.forename: Thure E
authors.initials: TE
authors.lastname: Cerling
mesh_terms: D003903:Deuterium / Q000032:analysis*; D004032:Diet; D004777:Environment; D005006:Ethnicity; D006197:Hair / Q000737:chemistry*; D006801:Humans; D013058:Mass Spectrometry; D008956:Models, Chemical; D010103:Oxygen Isotopes / Q000032:analysis*; D012044:Regression Analysis; D014481:United States
chemical_list: D010103:Oxygen Isotopes; D003903:Deuterium