Scientists resurrect the extinct dire wolf

Texas-based Colossal Biosciences said it has de-extincted dire wolves by producing three genetically engineered wolf cubs using ancient DNA.

The cubs—two males named Romulus and Remus, and a female named Khaleesi—were born between last October and this January.

The trio are being currently raised at an undisclosed 2,000-acre site monitored by drones and security personnel.

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

A top predator during its days, the dire wolf roamed North America until its extinction around 12,500 years ago. The animal was known for its size, strength, and powerful jaws.

Scientists at Colossal used DNA extracted from fossils that are estimated to be between 11,500 and 72,000 years old and reconstructed segments of the extinct species’ genome.

They then introduced these genetic sequences into the blood cells of a modern gray wolf, with modifications made at 20 specific genomic sites.

Meet Romulus, when he was a four week old puppy. The world’s first dire wolf in 12,500 years. @colossal bringing magic to life. pic.twitter.com/aXIg7ErEBW

— Ben Lamm (@BenLamm) April 7, 2025

Colossal’s team, led by chief scientist Beth Shapiro, moved the edited genetic material into egg cells from domestic dogs, and were then implanted into surrogate dog mothers. The pups were born 62 days later.

Ben Lamm, Colossal’s co-founder and chief executive officer (CEO), described the outcome as a landmark moment.

“This massive milestone is the first of many coming examples demonstrating that our end-to-end de-extinction technology stack works,” he said in a statement. “Our team took DNA from a 13,000-year-old tooth and a 72,000-year-old skull and made healthy dire wolf puppies.”

We’re Colossal Biosciences, the de-extinction company responsible for bringing back the first animals from extinction. Our dire wolf pups, Romulus and Remus, were born on October 1, 2024. Watch these pups grow up on our YouTube channel. Link in bio.

These two wolves were… pic.twitter.com/hbk1wFQ3lf

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

The dire wolf cubs are now aged between three and six months old, and measure nearly four feet in length and weigh over 36 kilograms.

The bioscience company said it expects them to grow to 1.8 meters and weigh up to 68 kilograms once full grow adulthood, effectively crossing the size of typical gray wolves. The dire wolf cubs are being fed a mixture of beef, horse, and deer meat, along with offal and puppy chow.

While the company has attracted attention for the so-called revival of dire wolves, the scientific community has expressed apprehension over the claims. Some researchers argue that the animals cannot be classified as true dire wolves.

Jacquelyn Gill, a paleoecologist at the University of Maine, expressed strong disapproval.

“Colossal Bioscience[s] did not revive dire wolves. … To see this work being done with such a casual disregard not only for the truth but for life itself is genuinely abhorrent to me,” she wrote on Bluesky social media platform, according to Science.

Independent experts also pointed to the limitations of genetic reconstruction.

“All you can do now is make something look superficially like something else,” Vincent Lynch, a biologist at the University at Buffalo told the Associated Press (AP). He also said that this did not equate to reviving extinct species.

Behavioral observations of the dire wolf cubs showed further differences from modern wolves.

According to Time, Romulus and Remus show little interest in human interaction, even with their primary handler.

They are wary and keep their distance, behavior that Colossal suggests might reflect traits of the original dire wolf, known for its solitary nature.

Colossal’s chief animal care expert Matt James said that the cubs would likely not develop hunting skills similar to wild predators. “They had no parents to teach them,” he said.

George Church, Colossal’s co-founder and a genetics professor at Harvard and the Massachusetts Institute of Technology (MIT), told Time that the ability to clone from easily cultured blood cells could be transformative.

“The idea that we could just take a vial of blood, isolate EPCs, culture them, and clone from them, and they have a pretty high cloning efficiency, we think it’s a game changer,” Church told the magazine.

Amid the scientific debate, the company plans to use this method to bring back other extinct species, including the woolly mammoth, dodo, and Tasmanian tiger.

It argues that its genetic technologies may also help conserve endangered species.