The scientists grew hair in their laboratory in Clichy, Paris and found that hair shape depends on the hair bulb, or follicle. People with curly hair have a hook-shaped bulb, and those with straight locks have straight ones, according to their findings."A curly follicle makes curly hair," said Bruno Bernard, head of hair biology at L'Oreal. "This is a breakthrough. It is now possible to use biological methods to make curly hair straight and vice versa." The team has yet to find the "master switch" that controls follicle shape, but said it wass possible to think about how to change hair styles with hormones or drugs. The discovery may also turn gray hair back to its original color.