Could we ever clone Neanderthals?
Popular Science...
Almost a decade ago, I finished my doctoral degree in archaeology with a thesis that investigated the hunting and gathering behavior of early Homo sapiens and our extinct relatives, the Neanderthals.
To my non-archaeologist family members and friends, I was the Stone Age Expert, to whom all questions about anything Paleolithic should be directed. I developed some strong opinions about the viral “ancestral” or “Paleo” diet. I did my part to contribute to the rebranding of the Neanderthals’ image as a type of human and not a bunch of backwards, hairy brutes. To this day, my mom still emails me a link to any news article she finds on Neanderthals, Denisovans (another Paleolithic relative), or other ancient humans.
When I explain my research interests to new acquaintances, I’m often asked questions like “what would you do if you met a Neanderthal?” or “do you think we’ll ever find a perfectly preserved frozen Neanderthal?” And, inevitably, “Could we clone a Neanderthal?”
On the surface, that last question seems exciting. Considered more deeply, though, would we really want to bring back a species of human that hasn’t existed on Earth for tens of thousands of years? What gives us the right to decide? Would it be ethical to do so?
What even is “de-extinction?”
In recent years, the idea of “de-extinction,” the re-engineering or cloning of extinct species, has gained a lot of media buzz.
Colossal Biosciences, a biotechnology and genetic engineering firm, made headlines in 2024 claiming they had achieved the first de-extinction of the dire wolf. These are large, extinct canines (scientific name Aenocyon dirus) related to modern gray wolves (Canis lupus).
Tens of thousands of years ago, dire wolves roamed grassland habitats in what is today North and South America. Visit the La Brea Tar Pits in Los Angeles and you can see an entire exhibit wall lined with dire wolf skulls excavated from their sticky graves, their bones stained a glossy walnut from the tar.
Dire wolves have been extinct for around 10,000 years, dying out around the same time as the mastodons, giant sloths, and other megafauna that once lived in the Americas. Colossal’s initial “de-extinction” claims received a lot of backlash from the scientific community.
A project summary on the company website reads: “[Colossal Biosciences] produced three living dire wolves: Romulus and Remus, born October 1, 2024, and Khaleesi, born January 30, 2025, marking the first successful de-extinction of a large apex predator in scientific history.” A few lines further down the page, though, the summary states:
“Colossal Biosciences brought back the dire wolves by making 20 targeted edits across 14 genes in the common gray wolf genome.”
The gray wolf genome contains around 19,000 genes. Colossal Biosciences edited 14 of those genes, a minuscule 0.073 percent change in the whole package of wolf DNA. Compared to a standard gray wolf, Colossal’s experimental pups are a bit larger, and their coats are white instead of patterned gray. However, dire wolves are still a totally different species and genus from gray wolves.
In other words, these groups last shared a common ancestor about 5.7 million years ago—far more distant than the relationship between wolves and dogs. Put another way, wolves and dire wolves are no more closely related than wolves and African jackals, or bison and gazelles.
The two species are so genetically different from one another that they wouldn’t likely be able to have offspring together. Despite their bold claims, Colossal hasn’t done much more than to make a gray wolf dressed in a dire wolf overcoat.
How does cloning work?
In 1996, a team of scientists at the University of Edinburgh took DNA from the nucleus of a cell from a sheep’s udder and implanted it in a different sheep’s egg cell.
Normally, an egg or sperm cell contains only half of an animal’s chromosomes, i.e. half of their total genetic code. When the sperm fertilizes the egg, the two sets of half-chromosomes merge, creating a new, unique combination. A cell from any other part of the animal’s body, called a somatic cell, contains the full chromosomal complement.
By swapping a somatic cell’s nucleus into an egg cell, the research team created an embryo that would develop exactly as a fertilized egg normally would but without any genetic contribution from a male parent. The resulting lamb, named Dolly, was an exact genetic copy of the sheep that the original udder-cell nucleus came from.
After Dolly’s birth, cloning became a hugely exciting field of study, and it wasn’t long before people were asking questions like “if we can clone an existing animal, can we clone an extinct species?”
Unfortunately, the answer is no, even with the leaps and bounds that genetic engineering has taken over the past decades. The issue is that to clone an extinct species requires a complete, intact DNA sample from that species, and that is something we don’t yet have.
What would we actually need to create a true clone of a Neanderthal?
The Human Genome Project, an international effort to map out the individual genes on all 23 pairs of human chromosomes, formally kicked off in 1990. The project officially ended in 2003, but the final complete map of the human genome wasn’t finished until in 2022, with the Y chromosome completed in 2023.
DNA fragments from Neanderthal remains have also been pieced together and stitched into a genome map over the past couple of decades. DNA is a surprisingly stable, robust molecule for something that looks so thin and fragile, but DNA that sits in the ground for tens of thousands of years is still susceptible to damage from its environment.
Barring any miraculous Encino Man-style discoveries of frozen Neanderthal remains, a complete genome would have to be engineered in a lab, not extracted from bone.
Puzzling out the Neanderthal genome is a huge accomplishment, but knowing the locations of all of the genes is only part of the picture. It’s still not completely clear how many of those genes work with one another, and how environmental factors might affect them.
To clone a Neanderthal by engineering the genome on a molecular level, scientists would need to recreate all the same kinds of complex relationships that allow our genes to tell every cell in our body what to do.
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There are big ethical concerns
We Homo sapiens have been the only species of human on Earth for tens of thousands of years, and as a population, we’re quite used to the idea. But go back 60,000 years or so, and there were multiple members of the genus Homo living in different parts of the world.
Neanderthals were one type of human. We know this because remnants of Neanderthal DNA still exist in our genome, meaning that our respective populations crossed paths and mingled gene pools in the past. Thus, the idea of cloning a Neanderthal raises the same kinds of ethical concerns that come along with the prospect of cloning humans today.
Currently, the mortality rate for experimentally cloned animals is exceptionally high. Even when a cloned animal is born successfully, severe health problems often emerge. Would we allow a human infant to undergo these stresses for the sake of scientific curiosity?
Human cloning also raises the issue of what happens when we challenge individuality. Would a cloned human always see themselves as a shadow of their cell donor? We can’t know for sure. This is why, whenever anyone asks me if I think we could clone a Neanderthal, I say no. For the time being, Paleolithic archaeologists will continue to ask and answer questions about the past by investigating the myriad materials that our early human relatives left behind.
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