Human Chimera Research's Huge (and Thorny) Potential

It is striking just how little we know about human development, especially given we are now decades into the modern era of biology. How is it possible that we understand exquisitely well how worms, fruit flies, and rodents develop, but our own species' development remains a black box? Paul Knoepfler (@pknoepfler) is a stem cell biologist at UC Davis and writes about science at The Niche. His most recent book is GMO Sapiens: The Life-Changing Science of Designer Babies. One big reason is that for a long time, the politics of doing science on human embryos and fetuses have been radioactive.