| Description |
Unraveling answers related to movement and diet choice at the individual or population level has been critical to understanding the life history and ecology of different organisms. Researchers have used stable isotope ratio analyses to understand events in an individual's life without needing to constantly follow or track them. In particular, keratin tissues (hair, fingernails, feathers) have served as tape recorders of isotope information that reflects the environment that the individual was living in at the time the tissue was formed, therefore making it useful for diet and travel history reconstruction. Recently, nutrition and forensic science disciplines have applied stable isotope ratio analyses to examine human diet, nutrition, and travel history reconstruction studies. These studies have primarily used human scalp hair, which has limitations. Specifically, scalp hair is not present among all individuals and hair strands do not continuously grow throughout life. Fingernail tissues represent an alternative keratin tissue that has been under represented in these disciplines. They are ubiquitous among all individuals and continuously grow throughout life. The specific goals of this study was to examine the use of stable isotope ratio measurements using fingernail keratin to assess two aims: (1) to examine individual diets and changes in diets over time and (2) to assess their utility for region of origin and travel history reconstruction in resident and nonresident populations. These aims have been examined and tested in four chapters of this dissertation, with a focus on two research iv studies (high school and a resident and nonresident population studies) conducted in Salt Lake City, UT. Results of the study revealed that fingernail keratin tissues are useful to reconstruct diet and travel history among individuals. Fingernail isotope ratios of adolescents uncovered socioeconomic patterns and highlighted the importance of school lunch programs on adolescent diets. Fingernail isotope ratios also displayed patterns that were consistent with reported travel history and when compared to prediction models for isotope turnover performed well. This work has highlighted the use of stable isotope ratio biomarkers in fingernail tissues to reconstruct diet and travel histories that may have direct applications to nutrition and forensic science studies. |
