Dire wolves or not, these pups could help counter extinction

Romulus, Remus and Khaleesi are the first dire wolves to walk the Earth in more than 10,000 years. Or so claims one biotech company and a host of recent headlines.

On April 7, Colossal Biosciences announced it had achieved the “world’s first de-extinction” — an ice-age species brought back from the dead. It was referring to those three pups, all born in the last year.

With snowy-white coats and muscular bodies, these pups were instant icons. They looked like they could have walked straight out of the fantasy TV series Game of Thrones.

News reports called their birth “scientifically seismic” and said “the dire wolf is back.” Many biologists, however, aren’t buying it. “That is no more a dire wolf than I am Wonder Woman,” says Jacquelyn Gill. She’s a paleoecologist at the University of Maine in Orono. She’s an expert on ice-age species.

The issue largely comes down to genetics. Colossal didn’t create those pups from a dire wolf’s genome — an instruction book carrying all of that animal’s genes. Instead, the company worked with the genetic instruction book of a gray wolf. Then it tweaked some gray wolf genes based on ancient DNA recovered from two dire-wolf specimens.

“We’ve brought these extinct genes back to life in a living animal. … I’m happy to call that a dire wolf.”

Beth Shapiro, Colossal Biosciences chief science officer

“For something to be a dire wolf, it should have the full genetic blueprint of a dire wolf,” Gill argues.

That thinking “kind of misses the point,” counters Beth Shapiro. She’s chief science officer at Colossal Biosciences in Dallas, Texas. Her company’s goal wasn’t to create a true clone of a dire wolf, she says. Instead, it wanted to bring back some of the animal’s core traits. Like its size, body type and face shape.

With a handful of tweaks, “we’ve brought these extinct genes back to life in a living animal,” Shapiro says. In the end, she says, “I’m happy to call that a dire wolf.”

“At the moment, I think they’re creating interesting zoo-like novelties,” says Paul Wilson. A wildlife geneticist, he works at Trent University. It’s in Peterborough, Ontario, Canada. Even so, he finds the company’s technology impressive.

One reason: It goes beyond crafting a dire wolf, he says. Some of Colossal’s other research — on a living species, the red wolf — shows the same new tools could potentially aid species at risk of soon going extinct.

An artist’s illustration shows big, tawny dire wolves defending their prey — a downed bison — from their smaller gray wolf cousins.MAURICIO ANTON/Science Source

From ‘woolly mice’ to fluffy pups

Last month, Colossal Biosciences announced its creation of “woolly mice.” Those rodents bore genetic tweaks inspired by woolly mammoths.

Now Colossal claims to have done something similar for dire wolves (Aenocyon dirus). These predators roamed the Americas during the Pleistocene Epoch. It stretched from roughly 2.5 million years ago to about 12,000 years ago.

Colossal scientists extracted DNA from two of these animals. One source was a tooth from a 13,000-year-old specimen. The other was a 72,000-year-old fossil of an inner-ear bone.

It’s tough to read an animal’s full genome from ancient DNA. As soon as an animal dies, its DNA “starts to get chopped up into really tiny pieces,” Shapiro explains.

In the live animal, there would have been hundreds of millions of DNA letters arranged like long paper streamers. “Ancient DNA is more like confetti,” she says. Most of the snippets retrieved from dire wolves were only about 35 letters long.

Shapiro’s group lined up billions of these snippets on a computer. They compared them to the genome of a gray wolf (Canis lupus). This showed some of the ways DNA in the two species differed. They also showed that two-thirds of the dire wolf’s genes come from a sister lineage to that which evolved into the gray wolf, coyote and dhole.

Researchers used a cloning technique to create their white pups. They first removed nuclei from the egg cells of dogs. Then they inserted new nuclei with edited DNA into those eggs. These would later be implanted into dogs who would serve as the pups’ “moms.”Colossal Biosciences

The team used those data to see what tweaks might make the gray wolf more dire wolf–like. For instance, altering CORIN, a gene for coat color, gave the new pups light fur. Other gene tweaks sculpted their body size and the shape of their ears and skull.

In all, the team made 20 edits to gray-wolf DNA. Then, the researchers implanted embryos with this tweaked DNA into female dogs. These moms gave birth to two male pups — Romulus and Remus. Four months later a female, Khaleesi, was born.

To Heather Jay Huson, this dire-wolf work is a “gee whiz” project. “It’s sensational,” argues this animal geneticist at Cornell University in Ithaca, N.Y.

Still, that doesn’t mean this new work isn’t important science, she adds. Her reasoning: The tech Colossal used might one day make some endangered animals better able to withstand a world that’s changing all around them.

Red wolves, an endangered species, may one day benefit from Colossal’s technology. The company could boost the population’s genetic diversity, potentially making them more adaptable to climate change and other challenges.Colossal Biosciences

Colossal’s work with living wolves

In fact, the company behind the new dire-wolf pups is already working to save red wolves.

In the 1970s, the U.S. Fish and Wildlife Service concluded these animals were on the brink of extinction. It began catching wild ones for a captive-breeding program.

Born last October, these pups — Romulus and Remus — represent a step toward bringing dire wolves back from extinction, claims Colossal Biosciences. The company tweaked the DNA of gray wolves to create embryos (based on what had been learned from reconstructed ancient dire wolf DNA). See how the pups grew from howling, milk-guzzling 15-day-olds to bounding 5-month-olds.

Pups born in captivity were later released to the wild. But they struggled to survive. Fewer than 20 roam North America today. All descend from only about a dozen animals. They lack enough genetic diversity to help them withstand environmental stresses, says Matt James. He’s Colossal’s chief animal officer.

But Colossal found some wolves on the Gulf Coast of Texas and Louisiana that seem a genetic match to red wolves. (They’re not officially recognized as such, however.) The genomes of these red “ghost” wolves, as Colossal calls them, carry some red-wolf genes that have been largely lost in wild populations.

In the lab, Colossal cloned four animals from red-ghost-wolf cells. These pups might one day be released into the wild to increase the genetic diversity of other wolves, James says. Or scientists could edit ancestral variants of red-wolf genes into today’s red wolves. That might help “make them more adaptable to climate change and disease and all the challenges that wild species face,” he says.

“Conserving species that are critically endangered is fantastic,” says Huson at Cornell. “These animals are already in the ecosystem. And we know their role.” That’s not true, she points out, for animals that have been extinct for thousands of years.

When animals disappear, other species fill gaps they leave in the ecosystem. Along the way, living animals can change these ecosystems in ways that may no longer support the lost species.

That’s why Huson wonders: Might bringing back an extinct species affect those living today? This, she explains, “makes me very cautious” about bringing back dire wolves, woolly mammoths or other long-extinct animals. “There could be unintended consequences.”