Have you ever eaten earth or clay and enjoyed it? If so you are not alone. Q.E.D. talks to Joyce from Liverpool who daily licks the soil from potatoes, Joanna from Mississippi who sprinkles dirt from beside the road over ice-cream and Sherry from Ghana who sells a selection of edible clays in the market. Q.E.D. asks the experts about this puzzling habit, why is it that millions of people like eating earth?