Chinese researchers recently announced the successful cloning of macaque monkeys. We look at the impact and potential consequences of such a significant development.

On 20 January 2018 scientists from the Chinese Academy of Sciences in Shanghai announced that they had successfully cloned a monkey. Using the same cloning technique that produced Dolly the Sheep in 1996, Zhong Zhong and Hua Hua, female crab-eating macaques, were born two weeks apart.

Using somatic cell nuclear transfer ("SCNT") (by which a viable embryo is created from a body cell and an egg cell), the scientists inserted nuclei from an aborted foetal monkey into egg cells. 21 eggs were then implanted into surrogate mother monkeys, resulting in 6 pregnancies; 2 of which produced Zhong Zhong and Hua Hua.

Since Dolly's dramatic entrance onto the world stage, SCNT has been used to create about 20 different animals, including frogs, mice, rabbits, pigs, cows and even dogs (an Afghan Hound named Snuppy). However, this is the first time the technique has successfully been used to produce primates. Zhong Zhong and Hua Hua are not the first primate clones however; Tetra, a rhesus monkey born in 1999 as a result of embryo splitting (a process similar to the natural development of twins) bears that title. Embryo splitting is considered a less beneficial technique, however, as it can generate no more than four offspring at a time; with SCNT the possibilities are (theoretically) endless.

The scientists' announcement has created widespread publicity, and divided reactions – whereas some see it as a positive advancement of science, others fiercely condemn the cloning of monkeys and question where this will lead us.

The advantage of cloning primates lies in the opportunity it presents for animal testing-based research. Non-human primates have long been considered valuable for research purposes, because of their high degree of genetic, anatomical and physiological similarities to humans. Macaques in particular are used extensively in animal testing (79% of all non-human primate testing in the UK uses macaques).

Using cloned macaques in testing, i.e. genetically identical test subjects, makes it easier to pinpoint the cause of different test results. Various treatments can be tested on the macaques without the need to consider any other factors (if the monkeys are genetically identical then different outcomes can only result from the treatment method). The scientists have also highlighted that SCNT can produce macaques with 'the same genetic background except the gene manipulated'. Research can therefore assist in studying diseases with a genetic basis (the team have specifically indicated the potential research opportunities into Alzheimer's and Parkinson's).

Inevitably, many question the morality of using animals in this way, and query their welfare during the testing process. Previous attempts, with similar processes, have led to macaques dying from impaired body development and respiratory failure, and criticisms have been compounded by questions over the efficiency of this process (79 embryos were implanted into 21 surrogate mothers with 6 resulting pregnancies, only 2 of which survived). Furthermore, censure of animal testing is often heightened when the animal in question is a primate, in which many of us recognise human features.

The potential impact for humans of Zhong Zhong and Hua Hua's cloning has also led to fierce public debate. Whilst the scientists involved stressed that 'there's no intention for us to apply this method to humans', many commentators drew a link between the two. Work on human reproductive cloning is already banned in many countries (including the UK) and so it is unlikely that we will see developments in this area any time soon. However, the successful cloning of macaques does mean that such a process is feasible (if not necessarily desirable). Is it just a matter of time?