Dire wolves have been brought back from extinction. What does this mean?

Colossal Biosciences created the wolves using gene-editing technology.

By 

Matthews Martins 

on April 9, 2025

Dire wolves Romulus and Remus next to each other in the snow at five months old. Credit: Colossal Laboratories and Biosciences

The sci-fi fairytale of de-extinction may become a reality. Colossal Laboratories and Biosciences announced they have revived dire wolves from extinction, unveiling three canines it has genetically engineered to resemble the long-dead species.

On Tuesday, Colossal revealed that two genetically identical male "dire wolf" puppies named Romulus and Remus were born on Oct. 1 last year, with their sister Khaleesi following a few months later on Jan. 30. (Sansa or Arya may technically be more appropriate Game of Thrones-inspired names for a dire wolf, or even Lady or Nymeria, but you can't deny that "Khaleesi" is immediately recognizable.)

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"They're beautiful, they're cute, they're incredible," said Ben Lamm, co-founder and CEO of Colossal Biosciences told Mashable, sounding every bit the enthusiastic new dog parent. "We took a 13,000-year-old tooth and a 72,000-year-old skull, and made puppies."

Created from edited grey wolf genomes, Colossal states that these three canines are proof that a "standardized toolkit for de-extinction" is possible. 

How did Colossal create its dire wolves?

Colossal's dire wolf puppies Romulus and Remus at 15 days old. Credit: Colossal Laboratories and Biosciences

Directly using dire wolf cells to clone a new animal isn't currently possible, as such material simply doesn't exist. Instead, Colossal used ancient DNA and comparative genomics, following a methodology similar to the one in its woolly mouse project. Revealed in March, Colossal's woolly mice were created by editing the genome of normal mice to display physical traits similar to those found in woolly mammoths — most significantly their long, fluffy fur.

For its dire wolf project, Colossal began with the aforementioned 13,000-year-old tooth from Ohio and 72,000-year-old inner ear bone from Idaho. Sampling these specimens and building on previous findings, Colossal's team extracted and sequenced dire wolf DNA, assembled genomes, then compared the results to that of living canines. This enabled them to pinpoint where dire wolves' genomes differ from that of other species. In doing so, they discovered that grey wolves share 99.5 percent of their DNA with dire wolves, making them the extinct animal's closest living relative.

Using this information, Colossal then employed a gene-editing method called CRISPR to edit the grey wolf's genome to more closely resemble that of a dire wolf. To do this, they made 20 strategic edits across 14 genes, with 15 of the edits recreating extinct gene variants. The nuclei were then removed from the resultant cells and transferred into donor egg cells, creating embryos that Colossal transplanted into surrogates. Leave it to bake, and soon you have a dire wolf pup.

It wasn't a simple process though, and just as in human fertilisation treatments, not every embryo resulted in a pregnancy. Colossal made multiple attempts in an effort to increase the odds of success, completing eight embryo transfers, involving between 30 to 45 specimens each. 

"There were a couple of times where a pregnancy was established early on, but was resorbed, and in the end we ended up with these three animals that are healthy," Colossal's chief science officer Beth Shapiro told Mashable. 

Creating dire wolves from blood

A Colossal Laboratories and Biosciences' dire wolf at five months old. Credit: Colossal Laboratories and Biosciences

Colossal also announced that it had developed a new, less invasive cloning method to create its dire wolves, using cells never previously used in such procedures. Specifically, its scientists used endothelial progenitor cells (EPCs) gathered by drawing an animal's blood, as opposed to using other cells retrieved via a skin biopsy. 

EPCs aren't undifferentiated stem cells, but they haven't been entirely differentiated either, falling somewhere in between the two. Shapiro told Mashable that the cells Colossal's new blood draw method extracted were of a higher quality than other cells previously used in their research, being healthy and easily grown. 

"These progenitor cells will eventually become the cells that make up the lining of the blood vessels," said Shapiro. "Because they're not all the way down the path to having a very specific job as a cell, it's easier to reprogram them. And we've also found that it's easier to establish really healthy cell lines, so it's great for biobanking." (Biobanking is the collection and storage of biological samples for conservation or research purposes.)

Colossal also used the same method to clone four red wolves — one female and three males. A critically endangered species, it's estimated there are fewer than 20 red wolves currently in the wild. Shapiro said that though they only conducted two embryo transfers for the red wolves, both resulted in successful pregnancies.

"Normally when you're doing this, the reprogramming step is such that it takes many more tries than that to have a successful pregnancy from a cloned cell," said Shapiro. "So we're pretty confident that this is a really great technology that can be used for cloning animals in the future."

"We're pretty excited because we think that de-extinction and species preservation goes hand in hand," said Lamm.

What makes a wolf a dire wolf?

Two-month-old dire wolf Khaleesi stretching open her mouth. Credit: Colossal Laboratories and Biosciences

Whether or not Colossal's dire wolves are "real" dire wolves depends on how strictly one defines the species. Technically, Colossal doesn't have any viable material straight from a dire wolf to work with. The company didn't find this an insurmountable obstacle though, working with a grey wolf genome base as an acceptable substitute instead.

"We focus on what genes kind of drive — like, what makes a dire wolf a dire wolf, and then how do we engineer them into the grey wolf," said Lamm "Because they are 99.5 percent the same genetically."

Colossal discovered during its DNA sequencing that dire wolves would have had thick white coats. They were also around 25 percent larger than grey wolves, with wider heads and stronger jaws. Accordingly, Colossal's wolves have a distinctly more muscular build than the leaner grey wolf. They're also already over 80lbs (36kg) at six months old, which is a comparable weight to a fully grown grey wolf. As such, Lamm expects that the dire wolves may end up weighing around 140lbs (64kg) once they reach adulthood.

"When we talk about de-extinction, we're talking about bringing back the core features, the core traits that resemble — that are — the species that used to be alive," explained Shapiro. "There are many different ways that people can consider what a species is. But we're talking about this functional trait. So we're bringing back these functional [traits]. 

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"We know that dire wolves were larger, more muscular, that they had this particularly interesting coat, thick coat. And so when we target the DNA that we're going to edit… those 20 edits brought back these dire wolf phenotypes, and the animals that are born are our dire wolves."

This isn't Jurassic Park

A Colossal Laboratories and Biosciences' dire wolf. Credit: Colossal Laboratories and Biosciences

Unsurprisingly, Colossal's de-extinction efforts have repeatedly drawn comparisons with the sci-fi film Jurassic Park. This association is only likely to continue now that their first de-extinction project has made a larger, stronger version of a charismatic carnivore. However, Lamm notes that there are important differences between Jurassic Park and Colossal's work, and that its real scientists have very different goals from the movie's fictional ones. 

"The three reasons why we built the dire wolves in the first place was: One, we were working with some Indigenous tribes here in the United States that actually asked us to bring back the dire wolves," said Lamm. "They said it was akin to the Great Wolf in their culture, they said it has ancestral knowledge and it's spiritually important to them. So I don't think they did that in Jurassic Park."

Specifically, Lamm noted that the Mandan, Hidatsa, and Arikara Nation (MHA Nation) was Colossal's biggest partner on its dire wolf project. They also partnered with the Nez Perce Tribe, the Karankawa Tribe of Texas, INDIGENOUS LED, and the Wind River Tribal Buffalo Initiative.

"Number two, we were working on building technologies for conservation of wolves, and to specifically save the red wolves from the brink of extinction that it's on," Lamm continued, referring back to Colossal's cloning of the endangered species. "Unless there was a subplot I missed in Jurassic Park, I don't think that they were focused on the conservation aspects. 

"And then the third thing is… we do want to inspire the next generation, get kids excited about the science and whatnot," said Lamm. "Maybe Jurassic Park tried to do that in their 'theme parks.' But it's definitely a very different set of goals."

What happens to Colossal's dire wolves now?

Colossal's dire wolves won't simply be released into the wild to repopulate. They're currently being kept on an enclosed, protected preserve measuring over 2,000 acres, with potential plans to eventually move them to a larger such space on Indigenous land. The company further noted that the preserve is certified by the American Humane Society, and registered with the United States Department of Agriculture.

The wolves also have a 10-person team looking after them, and are constantly monitored with cameras and drones like a dire wolf Truman Show. This team manages factors down to the wolves' social dynamics and moves them through feeding cycles.

"They have 24-hour veterinary care," said Shapiro. "These animals can't get a splinter without us knowing about it. So they're not exactly living like wild wolves. They're living the luxury style of life for wild wolves."

One of Colossal's dire wolf pups being handfed with a bottle at 15 days old. Credit: Colossal Laboratories and Biosciences

They're also being hand-raised by humans. While Romulus, Remus, and Khalissi were initially cared for by their surrogate mothers, Colossal eventually separated them due to concern the dog parents weren't up to the task of caring for their large dire wolf pups.

"The mother was getting a little overzealous, she was like over-cleaning them, moving them away," said Lamm.

There were also issues with the surrogate mothers disturbing the puppies' sleep by continually waking them to feed, as well as concerns regarding the amount of nutrition the mothers' milk could realistically provide.

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"[The dire wolf puppies] were larger than a standard grey wolf, and we wanted to make sure that they were getting enough food," said Shapiro. "The surrogates were large hound domestic dogs, so… they might not have produced as much nutrition as a large wolf would have needed. So we were just being overly careful [by separating them]." 

A three-month-old dire wolf holding a stick in the snow. Credit: Colossal Laboratories and Biosciences

There is the issue of how the dire wolves will learn to be dire wolves, considering that there aren't any animals of the same species to teach them how. The wolves' human parents can't very well pass on skills such as how to take down a deer. However, Shapiro told Mashable that the dire wolves are already displaying innate behaviour similar to that seen in wild wolves or those raised in captive or semi-captive environments.

"A lot of what we see is behavior that we predicted to see in these wolves," said Shapiro. "That's another thing that's really great about this group as our first de-extinction project, because we can watch these animals sort of interact with their habitat and see how they learn from each other, what they pick up from each other and from other animals with which they interact in their habitat, and we will gradually make their experience in life more and more similar to the wild. 

"But mostly what we're focused on right now is making sure that they're healthy. We want to make sure that they are growing the way they should grow. We want to keep tabs on this because we really want to understand the impact of the edits that we made on their growth patterns and their physiology and their behavior."

This includes the dire wolves' social dynamics. Though Khaleesi is currently being kept separate from her brothers, Shapiro told Mashable that she's getting old enough to be introduced to them soon.

A dire wolf puppy at one month old. Credit: Colossal Laboratories and Biosciences

Colossal is also being cautious to avoid unintended dire wolf puppies. Having the dire wolves reproduce au naturel would no doubt be exciting in theory, and the company is indeed planning on creating three to five more of them to build the pack dynamics it wants. However, any such additions must be carefully planned and monitored.

As such, in addition to tracking the animals' reproductive cycles and keeping them strategically separated, Colossal has also administered wolf birth control in the form of subdermal hormonal contraception.

"We really need to manage the population, study them, decide what the long term plan is with rewilding, [and] on what size area," said Lamm. "Potentially on Indigenous land, on MHA Nation, for example. And then we'll go from there."

A three-month-old dire wolf in the snow. Credit: Colossal Laboratories and Biosciences

In the meantime, Romulus, Remus, and Khalissi are apparently living relatively pampered lives by wolf standards. Lamm told Mashable that the wolves initially ate colostrum and milk, first from their mothers and then synthetic versions. Now they're eating a combination of horse, bison, and elk meat, as well as some dry food. Colossal is also planning to introduce carcasses soon to enable the dire wolves to figure out socialisation and behavior surrounding mealtimes.

While the dire wolves haven't hunted for themselves yet, Lamm stated that their future diet would likely be a combination of hunted and supplied meals. Though technically, all of the meals would be supplied.

"It's not like we're going to let them out to compete with grey wolves," said Shapiro. "They're on a protected reserve, so if they are introduced to hunting it will have to be because we've put animals or the trainers or the handlers have put animals there."

"They're starting to exhibit hunting-like behaviors," said Lamm. "So they're starting to act more and more wolf-like by the minute."

Though it may be beneficial for the dire wolves to learn to hunt from a development perspective, they're unlikely to ever genuinely need the skill, living out their days under researchers' watchful care. Colossal doesn't have a definitive idea of its dire wolves' life expectancies, however Lamm noted that regular wolves can live for 10 to 15 years. 

It's a fair estimate. Even so, exactly how long genetically engineered dire wolves live is something we'll only find out through lengthy observation. These are the first ones, after all.

Topics  Animals