At the San Diego Zoo, in Southern California, little Kurt looks and acts like any other baby horse. He likes to play, pushes against anything that gets in his way, and runs to his mother for milk when he is hungry. But the 2-month-old differs from every other baby horse in the world in a major way. Kurt is a clone. He was created in a laboratory. Scientists used cells taken from a male Przewalski’s horse in 1980. The cells had been frozen for the last forty years. The scientists also took an egg from a female horse of a different breed. Then, they removed the egg’s nucleus and replaced it with the cells from the Przewalski’s horse. The resulting embryo was placed in the womb of another female horse for development. She gave birth to Kurt on August 6. Scientists have cloned more than twenty other kinds of animals, including dogs, cats, pigs, cows, and mice.