D. T. Max in the Times Magazine:
The quagga was a horselike animal native to southern Africa that went extinct in 1883. Its head, neck and shoulders and sometimes the forward part of its flank were covered with stripes; the back part of its torso, its rump and legs were unstriped. An old joke among the Dutch, the first Europeans to settle in South Africa, was that the quagga was a zebra that had forgotten its pajama pants. Rau's goal, which he has been working toward for three decades, is to breed the quagga back into existence. His approach is to take zebras that look more quaggalike than the norm and mate them with one another, generation after generation, progressively erasing the stripes from the back part of their bodies.