Researchers have created part-human-part-pig embryos in what other scientists are calling an "exciting" step toward proving the viability of human-animal chimeras, the BBC reports. The researchers injected human stem cells into pig embryos, then implanted those embryos into adult pigs. After a month or so, the developing pig was part human, and the stem cells were turning into the makings of a heart, liver, and neurons, according to the Washington Post. Researchers published their findings Thursday in Cell. Still, the embryos were less than 0.001% human. And Seeker reports the host pigs were "euthanized and incinerated" after four weeks to prevent the accidental creation of super-smart pigs or something equally horrifying.
The goal of the research is to eventually be able to grow human organs inside "large host animals." Approximately 22 people in the US die every day while waiting for an organ transplant. Researchers say this new process could allow organs to be grown on demand, ending organ shortages. But they warn that's far in the future. In the meantime, it could be used to research diseases and test drugs in animals. But there are still moral questions surrounding the creation of animal-human chimeras, with some scientists expressing concern about making animals with human brains or reproductive organs. (A "human chimera" resulted in a dad learning that his unborn twin "fathered" his son.)