The National Institutes of Health, a U.S. federal agency and a major research center, is studying the implications of human cell growth in non-human non-primate embryos. The clarification may sound like bureaucratic jargon. It is not. It captures the essence of the agency’s ethical review. The conditions it has set—transfers of human cells into the non-primate embryos for no longer than 14 days, and other restrictions—are aimed at preventing the development of human traits in the animals. In other words, the agency does not want the new beings to become chimeras, those mythological creatures made up of parts of different animals. Yet the aim of this experiment is not playing God. It seeks to develop organs—such as livers and hearts—to help save human lives. It begs the question: is human life worth more than any animal’s? And should our salvation, physical if nothing else, rely on the suffering of other lives?