On Wednesday, Jan. 24, researchers in China reported that they have successfully cloned two Long-tailed Macaques. According to The New York Times, these monkeys, named Zhong Zhong and Hua Hua are exact copies of each other and were born at the Chinese Academy of Sciences in Shanghai.

Zhong Zhong and Hua Hua were created using a method called Somatic Cell Nuclear Transfer, or SCNT. According to CNN, SCNT was the process used to create Dolly the sheep (the first cloned mammal) back in 1996, as well as 20 other different animals, including mice, frogs, and even cows. While these monkeys are the first primates to be copied using SCNT, they aren’t necessarily the first primate ever cloned overall. According to Science Alert, in 1999, a Rhesus monkey named Tetra was cloned using a simpler procedure called the embryo-splitting method. This is essentially what happens when identical twins are growing.

Although embryo-splitting is an easier technique, SCNT is more advanced and does not have as many limitations. One advantage is that it can create many more identical animals, whereas, according to Science Alert, the maximum amount of animal replicas embryo-splitting can create is four. So, how does SCNT work? To put it simply, according to Science Alert, scientists take the nucleus of a somatic cell (a body cell) from another creature and change that out with the original nucleus. Unfortunately, even with this approach, the monkeys didn’t survive for a long amount of time. So, researchers had to tweak the procedure specifically for primates. In fact, according to CNN, it took these scientists three years to correct the technique.

The creation of Zhong Zhong and Hua Hua also brings up many questions like the following: since humans are primates, could they technically be cloned, too? According to CNN, it is theoretically possible, but unlikely to happen any time soon, because researchers believe that it will raise unnecessary questions about laws involving human cloning. Additionally, the monkey look-alikes were created in the hope that they could help scientists to better understand diseases, including autism and Parkinson’s, so there is no reason to create human clones.

Scientists will continue to work on improving and testing out the SCNT technique. They will also keep tabs on Zhong Zhong and Hua Hua to make sure that they are developing normally and stay healthy.