Chinese-US researchers implanted human stem cells inside a monkey embryo

The resulting hybrid was able to grow and develop for up to 20 days in a lab

This discovery could create non-human but human-like embryos for research

The team say they could test chemicals and processes you can't test on humans

Other scientists say this raises serious ethical questions over 'what a human is' 

Ethical questions have been raised over the moral status of a new 'monkey-human' hybrid created as an embryo by scientists in the US and China. 

Experts from the Salk Institute injected human stem cells into primate embryos, creating a new hybrid that continued to grow for up to 20 days. 

The team say their work has the potential to provide insights into developmental biology and evolution, as well as aid research efforts into cancer treatments.