I am interested in the origin and significance of functional variation in epithelial proteins - molecules located at the barrier between the 'inside' and the 'outside' of the body - in particular mucins (MUCs) and digestive enzymes such as lactase. We study inter-individual variation at the DNA level as well as looking at the RNA and protein products of these genes and asking questions about gene/environment interactions. For example, together with others in the Research Department of Genetics, Evolution and Environment, we are pursuing the molecular basis and evolutionary significance of the lactase persistence polymorphism.