Dire wolves reborn? Scientists spark debate with gene-edited wolves ‘resembling’ extinct ancestors

A United States-based biotechnology company has claimed it has “brought back” the extinct dire wolf — the imposing Ice Age predator popularised by noted television series Game of Thrones — through genetic engineering techniques that have resulted in the birth of three modified wolf pups.

Colossal Biosciences, a Dallas-based startup known for its high-profile experiments on the woolly mammoth and the dodo, announced that it had genetically engineered three grey wolf pups, two male and one female, to carry key traits of the dire wolf, a species that went extinct over 10,000 years ago, according to fossil records and genetic analysis stated by the company.

The pups — named Romulus, Remus and Khaleesi — were born in late 2024 through cloning and gene-editing techniques, according to Colossal’s social media announcements.

Their deoxyribonucleic acid or DNA was edited to include 20 genes identified from ancient dire wolf remains, including fossils retrieved from Ohio and Idaho that were between 11,500 and 72,000 years old, Beth Shapiro, the company’s chief scientific officer, told newspaper The New York Times (NYT).

These edited genes influence physical characteristics such as body size, coat colour and density — traits associated with dire wolves, which were roughly 25 per cent larger than their modern grey wolf cousins and had powerful jaws suited to hunting megafauna like bison and horses, Julie Meachen of Des Moines University told NYT.

Colossal has called the birth of these pups the “world’s first successful de-extinction,” describing the project as a “transformational moment in human history,” according to its website and YouTube announcements.

However, many scientists argue that the company’s claims overstate the scientific reality of what has been achieved and that the animals are not dire wolves in any biological sense, according to conservation geneticist Emily Roycroft of Monash University. “This is a grey wolf with an edited genome, not a dire wolf,” Roycroft said in an interview with Australian public news service ABC News.

She added that editing a handful of genes could not replicate millions of years of evolution, a view echoed by professor Nic Rawlence of the Otago Palaeogenetics Laboratory, who described the pups as “hybrids” with some dire wolf-like traits, but not true representatives of the extinct species.

“What Colossal has produced is a grey wolf with dire wolf-like characteristics,” Rawlence told ABC News. “This is not a de-extincted dire wolf.”

Colossal has responded to criticism by introducing the term “functional de-extinction,” which it defines as “the creation of organisms that resemble and are genetically similar to extinct species, with engineered traits to help them thrive in the modern world,” according to a post on the company’s X (formerly Twitter) account.

“We refer to these animals as dire wolves because they embody the key morphological traits, behavioural characteristics and ecological functions that defined the species,” the company stated in another X post.

Still, scientists have pointed out that behavioural traits, epigenetic changes and microbiome composition — all shaped by evolutionary and environmental context — cannot be re-engineered through selective gene editing alone.

“There are many other factors that make dire wolves unique, including an entire suite of genetic, epigenetic and behavioural differences that we don't currently understand,” Roycroft was quoted as saying by ABC News.

One key criticism of the project is the absence of a peer-reviewed scientific paper describing the methodology and results of the gene editing, which makes it difficult for other scientists to independently verify the claims, an X user and palaeontology volunteer Taylor McCoy of the Carnegie Museum of Natural History stated in a post.

Colossal has said that a paper is forthcoming and will be submitted to bioRxiv before undergoing peer review, according to a statement in response to McCoy on X.

The company’s messaging has also leaned heavily into pop culture, with Game of Thrones creator George RR Martin — an investor and “cultural advisor” to Colossal — lending his brand and symbolism to the project. According to ABC News, the press packet for the dire wolf project includes a 53-page document referencing the species’ cultural legacy, including mentions of Teen Wolf, Metallica and Bon Iver, according to Colossal’s website.

Despite this, the company insists its work serves serious scientific and ecological goals. It has pledged to make its de-extinction tools freely available to conservationists and has partnered with Native American communities such as the MHA Nation in North Dakota, according to statements from the company and tribal chairman Mark Fox, stated the NYT report.  “Its presence would remind us of our responsibility as stewards of the Earth,” Fox stated.

The pups are currently being raised in a secure 8-square-kilometre preserve at an undisclosed location in the northern US, which is monitored in partnership with the American Humane Society, according to Colossal’s YouTube channel and website. “They’re essentially living the Ritz Carlton lifestyle of a wolf,” said Shapiro told NYT.

This, she admitted, limits scientists’ ability to study authentic behaviour that would have been seen in wild dire wolves, since the pups are being raised in an artificial environment without access to ancestral prey or social structures. “I would love to know the natural behaviour of a dire wolf,” she was further quoted as saying by NYT, “but these animals are not living in the Pleistocene.”

While the gene-edited wolves cannot be released into the wild, Colossal argued that its technological breakthroughs could help endangered species like the red wolf by increasing genetic diversity through cloning and gene analysis, according to Alta Charo, a bioethicist associated with the company, speaking on its official YouTube channel.

The red wolf, native to the southeastern US, has been reduced to small populations in North Carolina and hybridisation with coyotes poses an ongoing threat to its survival, according to conservation biologists cited in the NYT article. However, in 2022, red wolf–coyote hybrids were discovered in Texas and Louisiana, according to researchers studying canid populations.

Acccording to Colossal, it has successfully produced four clones from these hybrids, stating that, hypothetically, introducing them into North Carolina could bolster the genetic diversity of the population and enhance its chances of survival.

Last month, more than 60 environmental groups protested proposed legislation in the US Congress that would delist grey wolves from the Endangered Species Act, warning that it would “sign death warrants for thousands of wolves across the country,” according to an open letter released by the coalition.

Despite the scientific scepticism, Colossal’s achievement remains technically impressive. The company used multiplex gene editing to introduce dire wolf variants into cultured grey wolf cells, which were then used to produce embryos via somatic cell nuclear transfer — a process similar to that used to clone Dolly the sheep, according to Colossal’s research team in a video titled The Making of the Colossal Dire Wolves.

The embryos were implanted into large domestic dogs, who served as surrogates. Out of several dozen attempts, four pups were born — one of which died due to a ruptured intestine unrelated to genetic issues, Colossal’s chief animal officer Matt James told NYT.

The remaining pups were found to be about 20 per cent larger than grey wolves of the same age and exhibited white, dense fur, bushy tails and mane-like necks — visual traits matching fossil-based reconstructions of dire wolves, according to Colossal’s veterinary team. 

Colossal insists that the project’s significance lies not only in the creation of these pups, but in what the technology could mean for endangered species, habitat restoration and ecosystem repair.

“Extinction is a colossal problem,” said Alta Charo in a company video. “But if we can learn to edit traits that help animals adapt to climate stress and shrinking habitats, we can prevent extinction before it happens.”