Taste perception is controlled by taste receptor proteins, which respond to foods in the mouth by triggering sensation. Mutations in genes encoding these proteins cause variation in taste sensitivity. Research in our lab investigates patterns of mutation in bitter taste receptors, their evolutionary origins, and the ways they affect perception. The major emphasis in this work is on understanding the origins of genetic variability in bitter taste receptors (TAS2Rs) within and between species. We are particularly interested in the role of natural selection in shaping these patterns, which we investigate by analyzing patterns of genetic diversity in humans and primates. A second focus in our taste research is on the relationship between taste receptor mutations and
perception of specific bitter substances found in foods. We have found correlations between mutations in bitter taste receptors and perception of substances common in daily diets, including compounds found in table vegetables and artificial sweeteners, which likely affect dietary preferences and health.
Plant domestication was a pivotal event in human civilization. By providing abundant, readily available sources of nutrition, it fostered a shift from ancient hunter-gatherer lifestyles to permanent settlement. However, the cultural and biological processes underlying the domestication process itself remain murky. We are using genetic techniques to investigate the domestication of cassava (Manihot esculenta esculenta). Cassava, which is currently the seventh largest source of carbohydrate nutrition in
worldwide populations, was first domesticated in the Amazon Basin of South America and diversified via selective breeding by native peoples. However, the patterns of breeding used to accomplish diversification, such as which traits were favored and which cassava varieties were crossed to change them, are unknown. We are investigating these patterns on the upper Amazon river in Perú. In field expeditions to the region we have found more than 50 cassava subtypes varying greatly in appearance and nutritional characteristics. We are obtaining genotypic data from the samples, which will allow us to identify changes in traits over time indicative of human influence. The portrait of cassava domestication emerging from our work is shedding new light on the origins of this key crop, as well as on domestication more broadly.