The Primitive Streak

the-primitive-streakIn 2016 two research groups announced a breakthrough: they each grew human embryos, in the lab, longer than ever before. In doing so, they witnessed a period of human development no one had ever seen. But in the process, they crashed up against something called the ’14-day rule,’ a guideline set over 30 years ago that dictates what we do, and possibly how we feel, about human embryos in the lab.

Radiolab