Dire wolves and woolly mammoths: Why scientists are worried about de-extinction

BBC News

25-04-2025

The creation of three "dire wolf" pups has raised hopes that it may be possible to resurrect extinct animals. But some scientists have grave concerns.
When news broke that Colossal Biosciences, a Dallas-based biotechnology company, had resurrected three extinct dire wolves, the internet reacted with awe. It is a species that last roamed the earth some 13,000 years ago, but has found recent fame thanks to Game of Thrones, which features fictional dire wolves.
The story was stoked further when a photograph of Game of Thrones author George R R Martin holding one of the adorable white pups was released. "I have to say the rebirth of the direwolf has stirred me as no scientific news has since Neil Armstrong [walked] on the moon," Martin wrote on his blog.
Martin, who is an investor in Colossal, added that more extinct species were on the way, including the woolly mammoth, Tasmanian tiger and dodo.
Colossal – which is currently valued at $10bn (£7.6bn) and is backed by high-profile donors such as Chris Hemsworth, Paris Hilton and the CIA – boldly states on its website that it's "going to fix" the problem of extinction.
According to Matt James, the company's chief animal officer, the aim is not to create a Jurassic Park-like zoo full of extinct animals, but to reintroduce lost species back into the habitats they once occupied. Once those animals are settled in, Colossal expects them to exert positive change on their habitats. "We're trying to focus on species that can have cascading effects on an ecosystem to improve stability, lift biodiversity and maybe even help with climate change buffering," James tells the BBC.
De-extinction has been talked about for decades. But Colossal's three dire wolves – which are actually grey wolves that possess 20 edited genes that are meant to give them dire wolf-like features – represent the most serious effort to date to make that lofty vision a reality.
In the wake of the dire wolf announcement, however, many scientists have criticised Colossal's approach. They see efforts to bring back long-extinct species as costly wastes of resources and a distraction from the significant work that's needed to save still-living species.
The BBC spoke with several experts in fields ranging from conservation biology to paleontology about efforts to resurrect species from extinction and whether they are likely to achieve the goals that Colossal hopes.
Chief among the concerns raised was that claiming it is possible to bring back extinct species may actually lead to more existing species being lost. It could give politicians and industries the idea that damage to the environment can be fixed by resurrecting species.
Such a message could be particularly damaging at a time when the US is withdrawing from international agreements on climate change and revoking measures intended protect the environment and wildlife, says David Shiffman, a marine conservation biologist and independent consultant based in Washington, DC.
"It's beyond irresponsible for these people [Colossal] to be claiming some sort of conservation victory in this environment," he says.
This worry was quickly reinforced when Doug Burgum, the US Secretary of the Interior – who the Colossal team met with in advance of their dire wolf announcement – praised the company's work on X as a new "bedrock for modern species conservation". Burgum also criticised the ineffectiveness of the "endangered species list" – presumably a reference to the Red List of Threatened Species, drawn up by the International Union of Conservation (IUCN) or the list of threatened & endangered species maintained by branches of the US Government – thanks to what he characterised as a focus on regulation. "Since the dawn of our nation, it has been innovation – not regulation – that has spawned American greatness," he wrote.
Super-cool science
Biodiversity is under a seemingly endless onslaught of threats, virtually all of which are imposed by humans. The leading reasons, according to the IUCN, are habitat destruction, invasive species, overexploitation from fishing and hunting, illegal wildlife trade, pollution and climate change.
Colossal claims that its de-extinction work will directly benefit conservation. But the company needs to tie its work to "ameliorating, alleviating or reversing something that's on that list" of threats to biodiversity, says Kent Redford, former director of the Wildlife Conservation Society who now works as an independent conservation consultant in Portland, Maine.
While Colossal's de-extinction work is "super-cool science," he continues, he does not see it alleviating any of the threats highlighted by the IUCN.
Colossal sees things otherwise. The company states on its website that woolly mammoths reintroduced to the Arctic, for example, will increase those habitats' resilience to climate change through their foraging behavior, which they say will help to keep carbon locked in permafrost in the ground. By scraping away snow, the company says, mammoths will expose the soil below to cold air, causing it to stay frozen.
However, Nitin Sekar, a conservation scientist with the Asian elephant specialist group at the IUCN, says he has struggled to find evidence in the scientific literature to support this claim. One study comparing carbon storage in the Arctic tundra to taiga forest found the soil in areas covered in trees could store nearly twice as much carbon overall. Only slightly more was found in the permafrost of the tundra than in the taiga. Nor could he find anything else about how mammoths might have affected carbon in general.
Some research on existing species of arctic herbivores suggests that they can reduce permafrost thawing. One scoping study by researchers at the University of Oxford does point to the role mammoths had on the climate during the Pleistocene and suggests bison and horses could replicate some of that role. But those species need to be maintained at high densities – where they are fenced, fed and managed by humans – to have any protective effect. The Arctic ecosystem is also different today than it was in the Pleistocene, so it is also hard to say whether mammoth hybrids would have that same effect on today's landscape as species like caribou and reindeer.
There could be other ways that mammoths affect carbon levels. As temperatures increase, the act of trampling and scraping away snow could actually accelerate permafrost melting by exposing it to the Sun – an effect that some research suggests is already happening in wet lowlands in the Arctic.
"Overall, with the data we have now, it's just impossible to know how mammoths affected their environment millennia ago, or how the mammoth-elephant hybrids will behave in our warmer future," Sekar says. "It seems like a strange thing to gamble on in the face of an existential crisis, given the alternatives."
James calls for more research to resolve these questions and show "direct links and causation in a way that can help to bring the rest of the scientific community along on this journey".
Dire wolves and woolly mammoths were driven extinct by the complex forces of a changing planet, not just by human activities. For species that humans are responsible for annihilating, though, simply bringing them back does not help to address the threats that pushed them to extinction in the first place, says Corinne Kendall, programme director for Southern Africa at the Peregrine Fund, a non-profit organisation that aims to conserve birds of prey around the world.
Modern conservationists recognise this and are increasingly focused on landscape-level solutions rather than saving a particular favourite species, Kendall adds.
"That's what's missing in the way Colossal is approaching this," she says. "If you only address the genetics and technology side of things, it's interesting from a scientific discovery standpoint, but you're creating the trees without the forest."
Julie Meachen, a vertebrate paleontologist and morphologist at Des Moines University in Iowa, believes, however, that the genetic techniques Colossal used to create its dire wolves are applicable to conservation. The company is also exploring ways to help still-living species such as the northern white rhino, elephants and endangered pigeons, she points out. "These techniques could be applied to any species suffering from genetic diversity loss and to combat inbreeding or genetic bottlenecks in low population sizes," she says.
"I think the conservation work that Colossal is doing is far more important than the de-extinction work, but this conservation work does not get the same press coverage as the flashy de-extinction part," she adds. "That is unfortunate."
James at Colossal agrees that de-extinction technologies are just "one piece of a very complex puzzle" that must also include things like habitat protection. But he says that attention-grabbing headlines about extinct species being brought back to life can act like "a giant ship" pulling "all these other projects in its wake".
Nature and nurture
It is also important to be clear about what Colossal is actually able to achieve. It is unlikely to ever be possible to truly resurrect long-gone species like dire wolves or woolly mammoths, say scientists not involved with the company. Tissue samples from animals that have been extinct for tens of thousands of years lack the intact cells needed for traditional cloning techniques, says Jacquelyn Gill, a paleoecologist at the University of Maine. "What Colossal is engaging in is genetic modification of modern species to give them physical characteristics to make them look like extinct species."
This in itself is a significant technical achievement, argues Colossal and its supporters.
In the case of the dire wolves, the three puppies it managed to breed are in reality "genetically modified grey wolves", say researchers. Essentially the genome of modern wolves was edited to replicate small segments of ancient DNA obtained from the fossilised remains of dire wolves. They are, the company admits, grey wolves with dire wolf characteristics.
But scientists have even questioned some of those characteristics.It's unlikely, for example, that dire wolves would have been white, but Colossal chose to make its animals white "because of popular conceptions from Game of Thrones", Gill says. "This was an aesthetic choice, not a biological or scientific one."
Even if Colossal did bring back animals that very closely resembled Ice Age species, they still would not be the same as the bona fide ones that lived thousands of years ago because the Pleistocene ecosystem they inhabited no longer exists, Meachen says. "A dire wolf or any other species is not only its genes, but also its environment and all the other species living there."
Colossal says it has no plans of releasing dire wolves into the wild. But it does aspire to eventually repopulate parts of the Arctic with woolly mammoths. This would require engineering a lot of baby mammoth proxies, which the company plans to do by using Asian or African elephants as surrogates.
In the West especially, though, some people are starting to question the ethics of whether elephants – extremely intelligent, social and sentient beings – should be kept in captivity at all, much less be experimented on, Sekar says. Asian elephants in modern zoo facilities also frequently suffer from infertility and lose their calves to stillbirths and infanticides twice as often as elephants in semi-wild conditions, he says, while mothers deeply mourn dead calves. "Are we really ok putting elephants through that so we can have these visually entertaining animals that aren't even real mammoths?" asks Sekar.
James says that Colossal will have many quality control steps to ensure things go well for the elephants, and that the company will also be working with leading animal welfare experts to "avoid potential welfare pitfalls ahead".
Lack of returns
Colossal has not disclosed how much it invested in the dire wolf programme – but it's likely in the many millions of dollars. While costs of new technologies do eventually go down with scale, even if de-extinction does get cheaper, it will still be orders of magnitude more affordable and effective to stop species from going extinct in the first place, Shiffman says. Moreover, if the original drivers of extinction are not addressed, then de-extinct species could quickly become re-extinct, he warns.
While Redford acknowledges that money is not fungible, if Colossal's primary goal really is conservation, then he says he has a hard time viewing its work on de-extinction as being "the right investment to make".
For every extinct species that Colossal is bringing back, however, James says the company is also investing in a surviving endangered species. Work is being done to introduce greater genetic diversity to populations of endangered red wolves in the US, for example, and to engineer elephants to be resistant to herpes virus.
But while red wolves do have some issues with genetic diversity, their biggest threats are road collisions and human persecution, Kendall says. Without addressing "how the animal is going to survive on the ground", the genetic component becomes "kind of irrelevant".
Herpes also only kills a fraction of the number of wild Asian elephants each year compared to those killed by humans, says Sekar, who is planning to publish data from the Indian government about causes of elephant deaths. Around eight wild elephants die per year of herpes compared to around 100 killed in some way by humans, he says.
Colossal could leverage its synthetic biology expertise in ways that are clear wins for the planet, experts say. Crops that are engineered to more efficiently take up nitrogen, for example, could be a huge boon for reducing the steep climate costs of nitrogen fertiliser and lessening the major dead zones that its runoffs cause in water bodies. Finding ways to engineer high quality animal proteins for human consumption could, likewise, be a game-changer for alleviating the many environmental and animal welfare concerns that plague the livestock industry, the experts say.
"Colossal clearly has very talented biologists on their team," Sekar says. "If they were to turn their attention to addressing problems like that, they could really be the heroes of conservation."
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