First human-monkey chimera raises concern among scientists

Researchers reprogrammed human cells before injecting them in the monkey embryo

Efforts to create human-animal chimeras have rebooted an ethical debate after reports emerged that scientists have produced monkey embryos containing human cells.

A chimera is an organism whose cells come from two or more "individuals", with recent work looking at combinations from different species. The word comes from a beast from Greek mythology which was said to be part lion, part goat and part snake.