in 1984, a california surgeon named leonard bailey whose hobby was transplanting organs from one species into another transplanted a baboon's heart into a human baby girl ('baby fae') who was born with a heart defect. baby fae died soon after the operation; her immune system rejected the non-human heart. as it turned out, dr. bailey was aware that baby fae would die; none of the 160 animals that he had done transplants on had lived more than 6 months.

when reporters asked why he chose an animal so evolutionarily distant from human beings to be the donor, rather than a human heart, dr. bailey said that he did not believe in evolution. he continues to practice surgery, and was never charged with any crime.