On Monday, biotech company Colossal announced what it views as its first successful de-extinction: the dire wolf. These large predators were lost during the Late Pleistocene extinctions that eliminated many large land mammals from the Americas near the end of the most recent glaciation. Now, in a coordinated PR blitz, the company is claiming that clones of gray wolves with lightly edited genomes have essentially brought the dire wolf back. (Both Time and The New Yorker were given exclusive access to the animals ahead of the announcement.)
The dire wolf is a relative of the now-common gray wolf, with clear differences apparent between the two species' skeletons. Based on the sequence of two new dire wolf genomes, the researchers at Colossal conclude that dire wolves formed a distinct branch within the canids over 2.5 million years ago. For context, that's over twice as long as brown and polar bears are estimated to have been distinct species. Dire wolves are also large, typically the size of the largest gray wolf populations. Comparisons between the new genomes and those of other canids show that the dire wolf also had a light-colored coat.
That large of an evolutionary separation means there are likely a lot of genetic differences between the gray and dire wolves. Colossal's internal and unpublished analysis suggested that key differences could be made by editing 14 different areas of the genome, with 20 total edits required. The new animals are reported to have had 15 variants engineered in. It's unclear what accounts for the difference, and a Colossal spokesperson told Ars: "We are not revealing all of the edits that we made at this point."
Nevertheless, the information that the company has released indicates that it was focused on recapitulating the appearance of a dire wolf, with an emphasis on large size and a white coat. For example, the researchers edited in a gene variant that's found in gray wolf populations that are physically large, rather than the variant found in the dire wolf genome. A similar thing was done to achieve the light coat color. This is a cautious approach, as these changes are already known to be compatible with the rest of the gray wolf's genome.
There were some cases where the variants found in the dire wolf were edited in. Without the full catalog of edits, it's impossible to tell how many of the 15 changes were dire wolf-specific. But it's clear that a significant amount of the new "dire wolf's" appearance is the product of using gene editing to achieve what might otherwise take years of selective breeding of existing gray wolf populations. Colossal's Ben Lamm told Ars that imaging of the animal's skeletal morphology to determine which species it resembles will occur during the pups' first annual exam.
Currently, the three animals are being kept at an undisclosed site with a veterinary facility and lots of access to the outdoors.
While this is being portrayed as the return of the dire wolf, these animals are primarily a variant of gray wolves, as many of the genetic changes that create their large size and pale coat already exist in some gray wolf populations. They carry only a few changes that are specific to dire wolves. (This is very much like what the company announced with woolly mice.)
And, more significantly, they're likely to be instinctually like a gray wolf, and so would play the same role in present-day ecosystems. In fact, it has been hypothesized that the dire wolf went extinct during the late Pleistocene extinctions because it specialized in hunting large prey that also went extinct. So, it's unclear whether, even if we could bring the dire wolf back, there'd be anything for it to do.