Our purpose was not to accurately estimate the real diets of YNP black bears. SIRs have been measured in a variety of human sample types, including hair , , , , fingernails 18, 95, urine and feces 76, and blood fractions including whole blood 33, RBC 97, , clot 74, plasma , and serum 42, 74, , Breast milk production draws upon the body water of the mother, which has higher levels of 18 O due to the preferential loss of 16 O through sweat, urine, and expired water vapour. Concentrations for Quercus spp. Biomed Mass Spectrom. We believe this expeditious process will result in the abandonment of many models currently used to estimate the diets of animals and the creation of many new models e. We assumed hairs collected during spring and early summer months were grown the previous year, whereas hairs collected in the fall were grown the current year . Abstract Diet is a leading modifiable risk factor for chronic disease, but it remains difficult to measure accurately due to the error and bias inherent in self-reported methods of diet assessment.
Isotopic evidence for early maize cultivation in New York State. The predicted discrimination factor for each natural food source was the difference between the isotope value of the food source and the predicted isotope value for the tissue; the latter calculated from entering the food isotope value into the regression model. Hoefs J. This article needs additional citations for verification. Stable isotope deltas: tiny, yet robust signatures in nature. B Gas chromatography — Combustion — isotope ratio mass spectrometry GC-C-IRMS, in which samples are injected into a gas chromatograph for separation prior to combustion and introduction into the isotope ratio mass spectrometer. Semmens et al. International Journal of Osteoarchaeology. We removed each feature from the model independently and compared inference to results from the full IsotopeR model Fig.
Prehistoric Human Bone pp Cite as. The use of stable carbon isotopes for diet reconstruction is predicated on the assumption that you are what you eat. In other words, the carbon isotopic composition of animal tissues is assumed to be a direct and constant function of the diet. Is this assumption valid? Precise dietary reconstruction requires as accurate knowledge of the isotopic composition of locally available dietary resources, as well as an adequate understanding of the effects of nutrition, environment, and physiology on the diet-tissue function van der Merwe , ; Chisholm ; Norr ; Matson and Chisholm ; Tieszen ; Ambrose The dietary proportions of isotopically distinct food resources e. Unable to display preview. Download preview PDF. Advertisement Hide.