Genetic engineering revives extinct dire wolf with 3 healthy pups after 13,000 years

A groundbreaking scientific achievement announced in early April has sent ripples through the worlds of biotechnology and environmental conservation. Colossal Biosciences, a U.S.-based startup, revealed the birth of three pups genetically engineered to resemble the dire wolf, a massive species extinct for about 13,000 years. Named Romulus, Remus, and Khaleesi, these animals are the result of years of research involving gene editing and cloning, using modern gray wolves as a foundation. Born in October 2024, the pups—two six-month-old males and a three-month-old female—represent a significant leap in de-extinction, the process of bringing back vanished species. They currently reside in a sprawling 2,000-acre ecological reserve in the northern United States, under meticulous care.

This project not only reignites discussions about the potential of genetic engineering but also sparks questions regarding its ecological and ethical implications. While the company hails the breakthrough as a historic milestone, independent scientists caution that these pups are not exact replicas of ancient dire wolves but rather modern hybrids with approximated traits. The technology, which involved editing 20 genes in gray wolf DNA, aimed to recreate features like larger size, thick light-colored fur, and powerful jaws that defined the prehistoric predator.

Valued at $10 billion, Colossal Biosciences has broader ambitions beyond the dire wolf. The company is also working to resurrect other extinct species, including the woolly mammoth, the dodo, and the thylacine, or Tasmanian tiger. Their goal extends past scientific innovation: they argue that reintroducing extinct animals could help restore damaged ecosystems and mitigate the effects of climate change.

How the dire wolf was brought back

Reviving the dire wolf required a collaborative effort from paleontologists, geneticists, and cloning experts. The journey began with analyzing well-preserved fossils, such as a 13,000-year-old tooth from Ohio and a 72,000-year-old skull from Idaho. These specimens yielded enough DNA to reconstruct the species’ genome, which was then compared to that of its closest living relative, the gray wolf. Despite sharing over 99% of their genetic material, researchers identified differences in approximately 80 genes, many tied to distinct physical traits.

Armed with this genetic blueprint, the team employed CRISPR, a precise gene-editing tool, to modify gray wolf cells. They altered 15 genes to introduce dire wolf traits, while adjusting five others with alternative mutations to avoid health issues like deafness or blindness, which can arise from certain genetic changes. The edited DNA was inserted into nucleus-free canine eggs, creating embryos implanted into large-breed female dogs serving as surrogates.

The process faced hurdles. Many embryos failed to develop, and one of the four pups born died ten days after birth due to an intestinal rupture, though autopsies ruled out any link to the genetic modifications. The surviving trio—Romulus, Remus, and Khaleesi—emerged in October 2024, stunning observers with their size: the six-month-old males already measure about 4 feet and weigh 80 pounds, with projections to reach up to 6 feet and 150 pounds as adults.

A milestone in de-extinction

Colossal Biosciences’ achievement is considered a game-changer in biotechnology. Beth Shapiro, the company’s chief scientific officer, described the pups as “functional copies” of a species that roamed the Earth millennia ago. Unlike traditional cloning, such as that of Dolly the sheep, this method didn’t directly use ancient DNA but rewrote modern wolf genes to mimic their extinct ancestor. This approach enabled the creation of animals that, while not identical to original dire wolves, exhibit key characteristics like enhanced size and dense, light fur.

Dire wolves, scientifically known as Aenocyon dirus, thrived across the Americas during the Pleistocene epoch, from 250,000 to 10,000 years ago. These formidable predators were about 25% larger than gray wolves, with jaws strong enough to crush the bones of prey like bison, wild horses, and possibly mammoths. Their extinction is linked to the disappearance of these large herbivores, a decline likely accelerated by human hunters during the Ice Age.

Details of the genetic process

The project’s success hinged on cutting-edge scientific techniques. Researchers started by isolating blood cells from gray wolves, which were cultured in a lab. Using CRISPR, they introduced specific dire wolf mutations into 15 genes controlling traits like size, muscle mass, and ear shape. For fur, they opted for variants found in modern canids to ensure the pups’ health. The modified nuclei were then transferred into empty canine eggs, producing embryos via nuclear transfer.

Gestation posed another challenge. Large-breed dogs were chosen as surrogates due to their compatibility with the engineered embryos. All litters were delivered via cesarean section, and the pups received round-the-clock monitoring in a protected reserve. Despite the loss of one pup, the three survivors display robust health, with veterinarians tracking their progress closely.

Traits of the new wolves

The pups stand out for their differences from typical gray wolves. Romulus and Remus, the six-month-old males, already boast reinforced bone structures and thick, light-colored coats reminiscent of fossil records. Khaleesi, the three-month-old female, follows suit, showing accelerated growth that hints at similar proportions in adulthood. Genetic analyses confirm the activation of long-dormant genes, bringing ancient traits back to life.

• Size: Ancient dire wolves could weigh up to 175 pounds, compared to the gray wolf’s average of 110 pounds.
• Fur: Their light, dense coats, likely an Ice Age adaptation, set them apart from darker gray wolves.
• Jaws: Edited genes suggest greater biting strength, suited for tackling large prey.
• Behavior: Though raised in captivity, the pups exhibit wild instincts, keeping their distance from handlers.

Why target the dire wolf

The choice of the dire wolf wasn’t random. In 2023, Colossal Biosciences shifted focus after struggles with mammoths and dodos, species more genetically distant from living relatives. Dire wolves, closely related to modern dogs and wolves, offered a practical starting point, leveraging decades of canine cloning research. This foundation reduced the risk of failure and sped up the timeline.

Beth Shapiro, who helped extract the first dire wolf DNA in 2021, saw the project as a testbed for scalable de-extinction. Abundant fossils from sites like La Brea Tar Pits in Los Angeles provided high-quality genetic material. The dire wolf’s cultural cachet—boosted by its role as the inspiration for the giant wolves of Game of Thrones—also made it an appealing candidate, amplifying public interest.

Potential conservation impacts

Beyond reviving extinct species, Colossal Biosciences views its technology as a lifeline for endangered animals. Take the red wolf, native to the U.S. and now confined to a tiny population in North Carolina. In 2022, hybrids of red wolves and coyotes were spotted in Texas and Louisiana, signaling genetic dilution. The company recently cloned four of these hybrids, which could bolster the wild population’s diversity and stave off extinction.

The technique might also aid other at-risk species, like the gray wolf, facing mounting threats. Last month, 60 environmental groups rallied against a U.S. bill that would strip gray wolves of endangered status, potentially increasing hunting pressure and shrinking their numbers. Genetic engineering could enhance these populations’ resilience, offering a new tool for conservationists.

Leia Tambem

Drones atingem 3 petroleiros no Mar Negro, ao largo da costa norte da Turquia, relata agência

Incêndio florestal perto de Varsóvia mobiliza 45 unidades de bombeiros e aeronaves especializadas contra chamas

Temu recebe multa de 200 milhões de euros da União Europeia por venda de brinquedos e carregadores inseguros

Insights from fossils

Reconstructing the dire wolf’s history unveiled fascinating evolutionary details. They belonged to a lineage including wolves, jackals, and African wild dogs, diverging about 4.5 million years ago. Around 2.6 million years ago, they interbred with ancestors of gray wolves and coyotes, explaining their genetic overlap. During the Pleistocene, they ruled vast swathes of southern Canada and the U.S., preying on large herbivores in a now-vanished ecosystem.

Paleontologist Julie Meachen from the University of Des Moines notes that dire wolves were apex predators, with teeth and jaws designed to take down bison and horses. Their demise coincided with the loss of these prey species, a collapse likely worsened by human arrivals in the Americas. Fossils from La Brea, where over 3,600 skeletons have been unearthed, highlight their past abundance.

SOUND ON. You’re hearing the first howl of a dire wolf in over 10,000 years. Meet Romulus and Remus—the world’s first de-extinct animals, born on October 1, 2024.

The dire wolf has been extinct for over 10,000 years. These two wolves were brought back from extinction using… pic.twitter.com/wY4rdOVFRH

— Colossal Biosciences® (@colossal) April 7, 2025

Ethical and ecological challenges

Not everyone cheers the dire wolf’s return. Bioethicists and ecologists warn of significant risks. Releasing an extinct species into modern ecosystems could trigger unforeseen imbalances, disrupting current predators and prey. Dire wolves, evolved for a world of giant herbivores, would need to hunt smaller game or compete with gray wolves, potentially destabilizing fragile populations.

The welfare of surrogate mothers is another concern. Gestation carries risks, including fatalities during birth, prompting critics to question whether the ends justify the means. Long-term health uncertainties for the pups, raised in a controlled setting far removed from their ancestral wild, also loom large.

A future with resurrected species

Colossal Biosciences isn’t alone in pursuing de-extinction. Projects like Revive & Restore have cloned the endangered black-footed ferret, while Chinese researchers birthed an Arctic wolf clone in 2022. In Australia, efforts to recreate the thylacine using living marsupials are underway. These initiatives signal a global push to harness biotechnology against biodiversity loss.

For now, the dire wolf pups will remain in captivity, though Colossal is engaging with indigenous groups like the MHA Nation in North Dakota about potential ecological reserves. Tribal leader Mark Fox sees the wolves as a reminder of stewardship duties, but acknowledges the challenges of rewilding them in a transformed world.

Dire wolf fun facts

The dire wolf transcends science with its cultural allure. Here are some highlights:

• Immortalized in Game of Thrones, it inspired the Stark family’s massive wolves.
• Featured in the 1970 Grateful Dead song “Dire Wolf” as a mythical figure.
• La Brea Tar Pits fossils include over 400 skulls, showcasing its former prevalence.
• Its scientific name, Aenocyon dirus, translates to “terrible wolf,” befitting its stature.

De-extinction timeline

The dire wolf revival fits into a broader chronology:

• 2009: Spanish scientists clone the extinct Pyrenean ibex, though the pup dies shortly after birth.
• 2020: Elizabeth Ann, a cloned black-footed ferret, is born in the U.S.
• 2021: Beth Shapiro’s team extracts dire wolf DNA from fossils for the first time.
• 2022: China clones an Arctic wolf, advancing conservation efforts.
• 2024: Romulus, Remus, and Khaleesi are born, solidifying Colossal’s project.

Life in captivity

The three pups currently inhabit a 2,000-acre reserve in northern U.S., its exact location undisclosed to shield them from prying eyes. Fenced and monitored continuously, the site provides a safe haven, though far from a wild existence. Fed a tailored diet, the wolves are under constant veterinary supervision, with every growth milestone documented.

Despite their captive upbringing, the pups display wild instincts, shying away from human contact. This hints that their edited genes retain ancient behavioral traits, even in an artificial setting. Beth Shapiro quips they live “like at a Ritz Carlton,” but admits their pampered existence reveals little about how they’d fare in nature.

Colossal’s next steps

The company has bold plans ahead. The woolly mammoth, its original target, is slated for revival by 2028 using Asian elephants as a genetic base. The dodo, gone for three centuries, and the thylacine, extinct since 1936, are also in the pipeline. Earlier this year, Colossal showcased mice with mammoth-like fur, a stepping stone for larger endeavors.

Beyond de-extinction, conservation remains a focus. Cloning red wolf hybrids aims to support endangered species, while partnerships with indigenous communities seek to blend science with tradition. CEO Ben Lamm argues the technology can undo human-inflicted harm, though he stresses each move requires careful consideration.