The past few weeks, both on this website and on the RELEVANT podcast, we’ve been talking a lot about 3-D printers, which are devices that can print, well, just about anything. Scientists are looking to use them to print an actual moon base, and not a few people think they could completely replace retail shops in the very, very near future. But all of that pales in comparison to the accomplishments of a group of scientists in Ireland and the U.K., who’ve managed to just straight up print human stem cells. They use something called “bio-ink” to create cells that can actually morph into any type of cell in the human body. The immediate uses—being able to print new cells to replace old ones—are obvious. The possible future ramifications are slightly more ominous …