A head transplant is a surgical operation involving the replacement of one organism’s head with another’s. The first successful head transplant took place in the 1970s, when the head of a monkey was transplanted onto another’s body. The animal retained most of its senses but was paralyzed below the attachment site. Though still hypothetical for humans, proponents believe the procedure can help people facing widespread organ failure. What has prevented human head transplants from taking place? Discuss