“Colossal Biosciences has successfully de-extincted the dire wolf.”

The recent announcement of a genetically engineered organism resembling the extinct dire wolf (Aenocyon dirus) has reignited a media and academic debate over the ecological, ethical, and philosophical implications of de‐extinction. Although the revival was later clarified to be a modified grey wolf with a small fraction of the dire wolf DNA, the case illustrates how close biotechnology is to achieving a true de‐extinction.

Now, the dire wolf is back, brought bounding into the 21st century by Colossal Biosciences, a Dallas-based biotech company. On April 8, Colossal announced it had used both cloning and gene-editing based on two ancient samples of dire wolf DNA to birth three pups, the six-month-old males Romulus and Remus and the two-month-old female Khaleesi.

In a new interview, Colossal's chief science officer Beth Shapiro has confirmed that the 'dire wolves' are indeed just gray wolves with 20 modified genes. However, she also argued that the company never tried to hide the wolves' identity. ... 'It's not possible to bring something back that is identical to a species that used to be alive. Our animals are grey wolves with 20 edits that are cloned,' Shapiro told New Scientist. 'And we've said that from the very beginning. Colloquially, they're calling them dire wolves and that makes people angry.'

The animatronic creature is technically a dire wolf, a recently revived/re-engineered version of a species that died out several thousand years ago, though it became a cultural meme after taking a prominent place in George R.R. Martin's Game of Thrones novels and subsequent HBO series. Such revivals have stirred controversy among some conservationists and biologists, especially in persnickety corners of taxonomic species definition, but also have drawn the interest of investors.

Colossal has now announced what it describes as the first successful example of animal de-extinction. In exciting news for Game of Thrones fans, the animal is the dire wolf – a canine that was native to the Americas until its extinction roughly ~12,500 years ago. This “version” is not a clone – it does not possess the exact same genetic material as the extinct organism. Rather, it is a genetic hybrid.

Texas biotech startup Colossal Biosciences claims to have “de-extincted” ancient dire wolves, producing three pups named Romulus, Remus and Khaleesi, who carry genetically modified genomes. “The only way to 'de-extinct' something would be to transfer a fully intact cell nucleus, such as one that has been frozen, into an egg that's had its nucleus removed,” Brian Davis, Ph. D. and A&M professor of biomedical genetics, said. Professor of rice genomics and genetics Michael Thomson, Ph. D, said CRISPR Cas-9 modifies native genes, or genes that are already in a species.

Shortly after the dire wolf announcement, and to much less fanfare, a group of the world's leading experts on canids concluded that the company had not really resurrected the species. Rather, they had made 20 edits to the DNA of grey wolves, and the resulting animals did not substantially differ from those that now roamed North America.

While investors have flocked to Colossal's mission and ambitious goals, the company also has gotten heat from scientists over the ethics of tinkering with lost species and whether its modified animals can even be considered “de-extinct.” But Colossal is charging ahead with promises to replicate its dire wolf success with dodo birds and the woolly mammoth, among others.

Michael Le Page at New Scientist published a more recent interview with Beth Shapiro, Colossal's chief scientist, who appeared to concede to critics' points that the company had not actually de-extincted a dire wolf. 'It’s not possible to bring something back that is identical to a species that used to be alive. Our animals are grey wolves with 20 edits that are cloned,' Shapiro told New Scientist.

So what Colossal Biosciences have produced is a gray wolf with dire wolf-like characteristics – this is not a de-extincted dire wolf, rather it's a “hybrid”. And importantly, it's what they think are the important dire wolf-like characteristics. Dire wolves diverged from gray wolves anywhere between 2.5 to 6 million years ago. It's in a completely different genus to gray wolves.

In scientific literature, true de-extinction requires cloning from intact ancient DNA or close genetic reconstruction to produce genetically identical individuals to the extinct species; gene-editing modern relatives to express select traits is considered proxy or functional revival, not full de-extinction (e.g., as discussed in Nature Reviews Genetics and IUCN guidelines on extinct species proxies).

Colossal introduced 20 targeted genetic edits into gray wolf DNA to recreate key traits associated with dire wolves, primarily size and coat characteristics. “We were targeting specifically size and the hair phenotype for dire wolf, and that's it,” Shapiro explains. ... Romulus, Remus, and Khaleesi now eat together, play together, and attempt hunts together.

Colossal Biosciences' project to revive the once-extinct dire wolf... team named Khesi. Each wolf is on track to grow to as large as 6 feet long and 150 lb... Colossal has used techniques learned from the direwolf project to clone four red wolves.

We're Colossal Biosciences, the de-extinction company responsible for bringing back the first animals from extinction. Our dire wolf pups...