Research to try and find ways to create human organs in animals for harvesting iin organ transplants has included injecting human stem cells into macaque monkey embryos.
Three out of more than 100 remained viable for 19 days. The scientists were able to study how the human cells communicated with the animal cells.
But this research poses huge ethical questions both in terms of animal rights and ethics surrounding human behaviour.
Where does it lead to? Do we want human embryos inside monkeys? Will it lead to hybrid animals, half human half monkey? The ethical issues need to be ironed out before the research progresses.
Please click on the link above the image to read more about this if you want to.