The great apes -- gorillas, chimpanzees, bonobos, and orangutans -- are known to be our closest living relatives. Chimpanzees in particular share 98 percent of our DNA, and scientists widely agree that they exhibit intellectual abilities long thought to be unique to humans, such as self-awareness and the ability to interpret the moods and identify the needs of others. The close relation of apes to humans raises important ethical questions. Are they better protected in the wild or in zoos? Should they be used in biomedical research? Should they be afforded the same legal protections as humans?...