An intriguing article on the National Geographic website about a study of human bones suggests that ancient Nubians benefited from antibiotic properties in the clays from which beer storage jars were made. "The brew was made from grain contaminated with the bacteria streptomycedes, which produces tetracycline. The ancient Nubians . . . stored their grain in mud bins. A soil bacteria, streptomycedes is ubiquitous in arid climates like Sudan's". Although there are no medical books from Nubia, there are from neighbouring Egypt, and the uses of beer for medicinal purposes are well documented. See the article for a description of the beer and the theories regarding the antibiotic properties.