Doctors put a pig's heart into a man for the first time. The man is 57. He was very ill. The pig's heart was the only way he could stay alive. He is now doing well. He said: "It was either die or do this transplant. I want to live." Scientists changed the pig's genes so its heart would work in a human.

The transplant took seven hours. There could be more transplants like this in the future. It could mean more organs are available. The man's doctor said animal organs give people an important choice in the future. The man hopes he will live longer. He said: "I look forward to getting out of bed after I recover."