The Troubled Ethics of Animal Cloning

Why scientists are manufacturing monkeys and hybrid embryos

Brandy L Schillace
5 min readMay 3, 2021


Photo: Andre Mouton/Unsplash

On September 12th of 2020, scientists from US-based Revive and Restore cloned a Przewalski colt, last of the true wild horses, from 40-year-old DNA. Just this past February, scientists cloned a North American black footed ferret at a breeding facility in Fort Collins, Colorado.

In both cases, low population numbers led to a lack of genetic diversity — often an evolutionary death knell, leaving a species vulnerable to disease. Wildlife cloning has been hailed as a conservation success, but some of the strangest features of cloning often get left out of the story.

For one thing, the DNA donors were both dead. The colt had been born of DNA acquired and frozen 40 years earlier, and “Willa” the recently deceased ferret had her DNA sent to a “frozen zoo,” where over 1000 species and subspecies await possible rebirth in a cloning future.

Want to read this story later? Save it in Journal.

The frozen repository resides at San Diego Zoo Global, but there’s no denying that cloning is big business. Viagen, a Texas company that performed the nuts and bolts of colt cloning, charged $50,000 for the embryo (and will also clone your cat or dog, if you can raise the $35,000 in capital).

These methods could, conservationists suggest, stop the clock on extinction using these procedures. But that isn’t the end of cell cloning’s potential, and while we might not be in danger of creating a real life Jurassic Park, risks — and troubled ethics — remain.

So, how do we make a clone in the first place? Most of us have met at least one set of twins in our lifetime; they represent the most natural and common type of “clone,” the splitting of an embryo in-utero. But clones may also be created via somatic cell nuclear transfer (SCNT). It begins with a somatic cell, which may be from anywhere in the body except the egg or sperm (skin cells are often used).

DNA lives inside the nucleus of that cell, and special techniques are used to remove it without damage — and then insert the harvested nucleus into a hollow egg. A little shock and cells start to divide, ultimately becoming a blastocyst (early embryo); put that inside a host animal’s womb and you get the colt, or ferret, or the now-famous Dolly the Sheep. The animal, at its birth, is a cloned copy of the tissue donor. But, say scientists at work in China, it doesn’t have to be. Somewhere in the process, the genetic code could be altered. The clone, that is, may be tinkered with.

On November 27, 2017, Dr Mu-ming Poo, director of the Chinese Academy of Sciences’ Institute of Neuroscience, announced the birth of Zhong Zhong and Hua Hua, cloned macaque monkeys. Scientists intend a progressive cloned-monkey breeding program, but this time it isn’t about the preservation of species. Rather, it is to create an editable line of lab-grown research animals.

In this possible future, one group of monkey clones would remain as the control, and the other would be altered genetically to develop, for instance, a neurodegenerative disease. The point, they explain, will be to explore the nature of such diseases, or even to study the effect of drugs on the brain, using completely identical animals, without the variation that individual creatures always introduce to an experiment.

Zhong Zhong and Hua Hua are, so far, scampering about in good health, so the question is not about whether Dr. Mu-Ming Poo’s goal of creating scores of lab-cloned monkeys is possible — but whether it’s a good and reasonable idea.

Most people have been very welcoming of the conservationist aim to encourage genetic diversity in endangered species. Zoos have been doing this is less technological ways for decades, shuttling potential animal mates across the country (or even across the world) to try and preserve a species. Do the ethics of such preservation cover the creation of animals cloned with the intent to edit their genes and introduce mutations?

The argument for such practices hinges on the potential gains in human health that might result, but the very possibility of editing embyros has been fraught long before now. A heated debate about the use of CRISPR (to edit genes) has some claiming it will eradicate disease, while others fear it revives the horrors of eugenics… And that’s before the announcement of the monkey-human hybrid embryo that hit the news in April 2021.

Sometimes called “chimera,” hybrid embryos generally refer to genetic mixtures of human and animal DNA. In a 20-day experiment, researchers injected 25 human stem cells into monkey embryos. The point? To see if monkeys could ever grow organs for human transplant (the same has been attempted with pigs). Most of the embryos perished during the experiment, and those that lived only retained 4–7% of the human DNA, hardly Island of Dr. Moreau. The team (of US and Chinese scientists) remain hopeful, however, that the human-monkey hybrids may yet yield results.

Given the extraordinary numbers on waiting lists for organ transplant, it’s understandable why the experiments have their enthusiasts. But some in the scientific community question the need for such experiments, particularly on primates, as our closest evolutionary kin. After all, when does a monkey-human hybrid cease to be a monkey and begin to be a human?

The animal clone will always raise the specter of the human clone. Even Dr. Mu-ming Poo admits its possibility; what can be done with monkeys may be done with human beings. The dilemma it raises can’t be solved simply — it perhaps can’t be resolved at all. Meanwhile, the technology has changed. It’s easier. It’s less expensive. And it’s happening right now across the world.

Viagen continues to quietly clone animals at its Texas facility — and the frozen zoo continues to collect its ark of tissue samples for the future of species survival. We are left, then, with a mostly unanswered question: where are the limits of science, and who decides? Because in our rapidly changing technological age, we often arrive at the “can” well ahead of the “should.”

📝 Save this story in Journal.



Brandy L Schillace

(skil-AH-chay) Author in #history, #science, & #medicine. Bylines: SciAm, Globe&Mail, WIRED, WSJ. EIC Medical Humanities. Host of Peculiar Book Club. she/her