Texas-based biotech startup Colossal Biosciences has announced the creation of three gene-edited animals that it claims are the world’s first “de-extinct” creatures. The announcement, made in April and reported by Nature, has split the scientific community and sparked heated controversy over what it means to bring a species back from extinction.
Working in secrecy for months, researchers at Colossal cultivated grey-wolf blood cells and edited their DNA to include genetic traits believed to be from the long-extinct dire wolf (Aenocyon dirus). The team then transferred the nuclei of these edited cells into dog egg cells and implanted the embryos into surrogate dogs. The result: three pups — Romulus, Remus, and Khaleesi — that Colossal says carry 15 genetic sequences found in dire wolf DNA, including traits that affect body size and coat color.
Romulus and Remus were born in October 2024, followed by Khaleesi in January 2025. “The first de-extinct animals are here,” declared Colossal in April — but not everyone agrees.
Scientific Skepticism and Public Confusion
Many scientists have challenged Colossal’s claims, arguing that the animals are not true dire wolves, but genetically modified dogs with a handful of ancient traits. “I don’t think they de-extincted anything,” said Jeanne Loring, a stem-cell biologist at the Scripps Research Institute, in Nature’s detailed report.
Critics argue that calling the animals “de-extinct” misleads the public and inflates the capabilities of current technologies like CRISPR–Cas9, the genome editing tool that enabled the genetic tweaks. Others point out that the pups lack the full genome, behavior, and ecological role of actual dire wolves — which went extinct around 11,500 years ago.
Tom Gilbert, an evolutionary geneticist at the University of Copenhagen and a Colossal adviser, was blunt: “It’s a dog with 20 edits.”
Colossal, valued at nearly $10 billion and backed by celebrity investors including Paris Hilton and director Peter Jackson, has defended its work fiercely. Co-founder Ben Lamm insisted the company welcomes criticism, even while pushing back against detractors. “We have had this attitude of running towards critics, not away,” he said.
A Familiar Science-Fiction Dream
The field of de-extinction—once the realm of science fiction popularized by Jurassic Park—has gained new momentum thanks to advances in genome editing and cloning. Projects aiming to resurrect the woolly mammoth, passenger pigeon, and thylacine are in various stages of progress. But defining what counts as a “de-extinct” animal remains contentious.
“Do we need an exact genetic replica? Or just an animal that behaves like the extinct species?” asked Beth Shapiro, Colossal’s chief scientific officer and a noted evolutionary geneticist. Shapiro, who once questioned the very premise of de-extinction in her book How to Clone a Mammoth, joined Colossal in 2024 to help steer the company’s expanding portfolio of projects — including efforts to revive the dodo and Tasmanian tiger.
According to Nature, Colossal says that of the 20 genome edits made to the new animals, 15 were sourced from two ancient dire-wolf genomes dating back 13,000 and 72,000 years. The firm claims these edits affect key traits such as size and coat color, and says Romulus and Remus are already 20% heavier than typical grey wolves of the same age.
Still, many scientists argue that Colossal’s announcement prioritizes spectacle over science.
“This fits the Jurassic Park model beautifully,” said Ben Novak of Revive & Restore, a non-profit focused on conservation through biotech. “But it is clearly for spectacle.”
Mounting Controversy and Allegations
The backlash has gone beyond academic debate. Several scientists have accused Colossal of retaliating against critics. Evolutionary geneticist Vincent Lynch of the University at Buffalo, one of Colossal’s more outspoken skeptics, says he was targeted by anonymous online attacks following his criticisms of the company’s claims. He later received a defamation threat from Colossal’s lawyers.
Colossal denies any involvement in these attacks, with a spokesperson saying the company was unaware of the posts until Lynch raised the issue. Still, Nature identified similar posts targeting other Colossal critics, including scientists in the UK, New Zealand, and Hawaii.
Despite the tension, Colossal maintains that its work is legitimate and groundbreaking. The animals, which are being raised in an 800-hectare preserve surrounded by high walls, will not be released into the wild. The company says it plans to produce more and study their development — with the goal of refining conservation technologies that could be applied to endangered species.
What’s Next?
The company is charging ahead. In July, Colossal unveiled plans to “de-extinct” moas, the giant flightless birds that vanished from New Zealand centuries ago. It remains committed to developing mammoth-like elephants by 2028.
But as Colossal moves forward, some in the scientific community remain wary.
“We have a company that is only listening to people who agree with them,” said biologist Victoria Herridge, who previously declined an invitation to advise Colossal. “This is not really where we want to be with a technology that has the potential to change the way our world will look.”
Lamm disagrees, saying Colossal is guided by data and open to evolving its approach. “As scientists, we will absolutely consider new data presented and adapt our hypotheses and conclusions.”
Whether the creatures born in Dallas are truly “dire wolves” or simply highly edited dogs may remain a matter of definition — and debate. But as Nature’s in-depth reporting shows, Colossal’s bold experiment has already left an indelible mark on the frontier of biotech and the future of conservation.
