In a remarkable—if likely controversial—feat, scientists announced today that they have created the first successful human-animal hybrids. The project proves that human cells can be 21 into a non-human organism, survive, and even grow inside a host animal, in this case, pigs. This biomedical advance has long been a dream for scientists hoping to address a critical 22 of donor organs. Every ten minutes, a person is 23 the national waiting list for organ transplants. And every day, 22 people on that list die without the organ they need. What if, 24 relying on a generous donor, you could grow a custom organ inside an animal instead? That's now one step 25 reality, an international team of researchers led by the Salk Institute reports in the journal Cell. The team created what's known scientifically as a chimera: an organism that contains cells from two different species.