It’s now been over two decades since scientists in Scotland successfully cloned a sheep and named the newborn Dolly. In the years since, the technology that powers cloning has advanced slowly but steadily, and while many scientists fear the inevitability that one day a human clone will be created, others are pushing the field into new areas. The latest example of cloning’s ceaseless march forward is the birth of Hua Hua and Zhong Zhong, a pair of baby monkeys that are the byproduct of the first successful somatic cell nuclear transfer performed with primates.

The newborn monkeys, who are currently just shy of two months old, were created by scientists at the Chinese Academy of Sciences. Early indications are that the little fellas are doing quite well and appear perfectly healthy, but many questions about their long-term health have yet to be answered. The research was published in the journal Cell.

The monkeys were cloned using a technique that swaps out the nucleus of an egg cell for the nucleus of a cell from the animal that scientists wish to clone. That new cell then grows and multiplies to the point where it can be implanted into a female of the species where, if all goes well, it eventually forms a viable fetus.

It might sound fairly straightforward, but the work itself is incredibly difficult and success is hard to come by. Out of the 79 clone cell packages placed in 21 surrogate females, only six pregnancies resulted, and of those six only Zhong Zhong and Hua Hua actually made it to birth.

It’s a truly remarkable achievement, but the reason behind the monkey cloning program might not sit well with many in the scientific community. According to the researchers, the ultimate goal is to clone monkeys on a large scale for use as test subjects thanks to their similarities to humans. The idea being that if scientists can give the monkeys specific diseases before they’re born, like Parkinson’s, they can be used to test various treatments.

Is intentionally breeding primate clones with disease-causing mutations for the sake of testing sketchy? I’ll let you be the judge. That said, such a thing would be a hard sell in the United States and much of Europe, but Chinese regulations are notoriously lax when it comes to scientific endeavors, and there’s little doubt that the country will push ahead with the program.