Does the aim justify the suffering? Chinese scientists have made a breakthrough by recreating a rhesus monkey. But animal rights campaigners say their work is deeply immoral.
Fury over monkey cloned for medical research
Same fame: Zhong Zhong, a long-tailed macaque, has lived in a laboratory for six years. Glossary
Cloning - Creating an exact copy.
Physiology - The study of how the human body works.
Advocates - Someone who publicly supports or recommends a particular policy. The word originates from the Latin vocare, meaning to call.
Vaccine - A biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, but in its weakest form.
Polio - An infectious disease that affected children all over the world. It left victims paralysed or unable to move their muscles.
DNA - Deoxyribonucleic acid is the material in an organism that carries genetic information.
Nucleus - Where the DNA of a cell is stored.
Embryo - A fertilised egg that is developing into a foetus.
Miscarriages - When a pregnancy is suddenly lost during the first 20 weeks (for humans). It is estimated that 10 to 20% of pregnancy end in miscarriage.
RSPCA - The Royal Society for the Prevention of Cruelty to Animals.
Primates - The order of mammals that includes humans, alongside apes like chimpanzees and gorillas.
Sentient - Able to perceive or feel things.
Louis Pasteur - A 19th Century French chemist known for his discoveries on vaccination and pasteurisation.