Kimberly Kjaisa Foecke

KIMBERLY FOECKE, then a graduate student at George Washington U., Washington, DC, was awarded funding in October 2019 to aid research on “Deconstructing the _15N Paleodietary Proxy: Putrefaction, Processing Effects, Proteomics, and Implications for Hominin Diets,” supervised by Dr. Alison Brooks. Dietary strategies are often key drivers of biological evolution. Understanding past diet is critical to understanding environment, behavior, and ecological relationships of both hominins and modern humans. Chemistry is useful to examine microscopic dietary traces inside organisms to reconstruct their origins. This project focused on isotopic mass effects in processes involving nitrogen, an element commonly used in paleodietary reconstruction. The ratio of nitrogen isotopes in organisms (_15N) is reflective of trophic position, but nitrogen isotope fractionation is complex and subject to many sources of variation. This dissertation explored how human behavior might influence this variation. The project investigated the impact of food-related behaviors on the _15N dietary proxy, and is broken down into four chapters. An experimental approach to assessing the impact of food processing and prey selection found small effects. A growth assessment of plant foods examined the impact of physiology and nitrogen partitioning, which produced much larger effects. The COVID-19 pandemic necessitated a pivot to a data mining approach to this question using the modern food science literature, where impacts of processing on compound specific isotope analyses were seen. Finally, a case study related to Neanderthal diet utilized a mixing model to calculate potential dietary impacts of processing.