Cork—the spongy, lightweight material of bulletin boards and linoleum—has been exploited by people for at least 4000 years.  In the ancient world, it was used for fishing floats and sandal soles, as plugs for jugs and barrels, and as insulation for soldiers’ helmets and beehives. Swimmers used it to keep themselves above water: in Virgil’s Aeneid, the infant princess Camilla is saved from capture when her father stuffs her into a “case” of cork and flings her into a river. Dioscorides—first-century Roman physician and author of a five-volume medical encyclopedia—recommended cork for baldness, stating hopefully that “charred cork rubbed on bald patches with laurel sap makes the hair grow again, thicker and darker than before.” Amphorae, still stoppered with cork,