Are zebras black with white stripes?

Are any people particularly susceptible to alopecia-linked hair loss? Also, what causes eczema and why does it keep recurring, why are the progeny of different species infertile, why does hair go grey but not always symmetrically, and Is asthma a risk factor for bronchitis? Plus, are zebras actually black with white stripes, or white with black stripes?! Join Dr Chris Smith and Clarence Ford to Ask the Naked Scientist... Like this podcast? Please help us by supporting the Naked Scientists (thenakedscientists.com/donate)