Primatologist Jane Goodall, in her studies of the wild chimpanzees of Tanzania, found that chimpanzees demonstrate the abilities to use tools, convey abstract concepts, express a broad range of emotions, and make decisions based on reason—all characteristics that were previously thought to be uniquely human. If Goodall’s conclusions are accurate, the distinction between animals and humans is no longer easy to define. This notion that the differences between humans and chimpanzees are merely differences of degree has inspired a proposal to grant chimpanzees, gorillas, and orangutans the same legal rights as children and mentally retarded adults. The Great Ape Project, developed in 1993 by a group of anthropologists, ethicists, and scientists, aims to give apes the right to life, liberty, and freedom from torture—which means that they could no longer be used in medical experiments or kept in...