More than 120,000 Americans are currently on waiting lists for lifesaving organ transplants. Every day some 22 of them die before they can receive a transplant. Wouldn't it be great if organs precisely matched to their recipients could be grown inside domesticated animals, such as pigs or sheep? Scientists are trying to achieve just this goal, but some bioethicists are opposed to the research. They worry that growing human organs might make the animals too human and perhaps it violates "something sacrosanct." Nonsense.