In 2021, under the cover of Covid, scientists from China, Spain, and America created embryos that shared human and macaque monkey DNA. They were kept alive in the lab for 20 days before being terminated. By this stage, the embryos had progressed to the point of forming ‘cavities and layers’ but the bulk had already started dying off.

Still, it was a proof of concept that caused a flurry of panic regarding the ethics of genetic experimentation.