Scientists revive the dire wolf, or something close
TEXAS - For more than a decade, scientists have chased the idea of reviving extinct species, a process sometimes called de-extinction.
Now, a company called Colossal Biosciences appears to have done it, or something close, with the dire wolf, a giant, extinct species made famous by the television series Game Of Thrones.
In 2021, a separate team of scientists managed to retrieve DNA from the fossils of dire wolves, which went extinct about 13,000 years ago.
With the additional DNA, the Colossal researchers have now edited 20 genes of grey wolves to imbue the animals with key features of dire wolves.
They then created embryos from the edited grey-wolf cells, implanted them in surrogate dog mothers and waited for them to give birth.
The result is three healthy wolves – two males that are six months old and one female that is two months old, named Romulus, Remus and Khaleesi – that have some traits of dire wolves.
They are big, for one thing, and have dense, pale coats not found in grey wolves. Colossal, which was valued at US$10 billion (S$13 billion) in January, is keeping the wolves on a private 2,000-acre facility at an undisclosed location in the northern United States.
Dr Beth Shapiro, the chief scientific officer of Colossal, described the wolf pups as the first successful case of de-extinction. “We’re creating these functional copies of something that used to be alive,” she said in an interview.
The animals will remain in captivity. But the technology that the company has developed could potentially help conserve species that have not yet gone extinct, such as the critically endangered red wolf, which is largely limited to North Carolina.
In 2022, red wolf-coyote hybrids were discovered in Texas and Louisiana. On April 7, Colossal announced that it had produced four clones from the hybrids.
Hypothetically, introducing these clones to North Carolina could improve the genetic diversity of the red wolf population there and help the species avoid extinction.
Over the years, scientists have proposed various ways of reviving a lost species. Suppose, for instance, that they recovered an intact cell from the frozen carcass of a woolly mammoth. Perhaps the cell could be thawed and used to create a mammoth clone.
In 2023, the Colossal team began to focus on dire wolves as a potentially easier target species. Dire wolves are related to dogs, so scientists could take advantage of years of research on cloning dogs and implanting dog embryos.
“We’ve done a lot of work on dogs because people love everyone’s favourite domesticated grey wolf,” Dr Shapiro said.
Dr Shapiro, who joined Colossal in 2024, was part of the team that first retrieved dire wolf DNA from fossils in 2021. But that work recovered only traces of genetic material.
At Colossal, she and her colleagues decided to search for more dire wolf DNA, hoping to better understand the biology of the extinct species – and perhaps revive the animal.
“It was the simplest path to get a predictable result,” Dr Shapiro said.
The team took a fresh look at dire wolf fossils, using new methods for isolating DNA. This time they hit the jackpot, discovering a wealth of genetic material in two fossils – a 13,000-year-old tooth from Ohio and a 72,000-year-old skull from Idaho.
The dire-wolf genomes allowed Dr Shapiro and her colleagues to reconstruct the history of dire wolves in greater detail.
Dire wolves turned out to belong to the same lineage that gave rise to the wolves, jackals and African wild dogs living today.
The dire wolf split off from the main branch about 4.5 million years ago. Subsequently, about 2.6 million years ago, dire wolves interbred with other species, including the ancestors of today’s grey wolves and coyotes.
Dire wolves dominated southern Canada and the US, according to paleontologist Julie Meachen at Des Moines University who worked on the ancient DNA project.
And they outcompeted grey wolves, being 25 per cent bigger and possessing massive teeth and jaws. They hunted horses, bison and possibly mammoths.
When many of those prey species became extinct – probably in part because of human hunters – the dire wolf may have been doomed, and the grey wolf swept down from northern Canada and Alaska to fill the ecological void.
Dire wolves and grey wolves are more than 99 per cent genetically identical, Prof Meachen and her colleagues found. Eighty genes were dramatically distinct; some are known to influence the size of living dogs and wolves – suggesting that they were responsible for the big bodies of dire wolves.
More surprising was the discovery that dire wolves carried genes for a light-coloured coat, and the hair was probably thick and dense. Dr Shapiro and her colleagues are preparing a paper describing those results.
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Recipe for a dire wolf
With a list of dire wolf genes in hand, the scientists at Colossal started their de-extinction project.
First, they isolated cells from the blood of grey wolves and grew them in a dish. There, they tinkered with the wolf DNA.
Ten years ago, scientists altered a single gene in beagles to give them big muscles. Since then, researchers have learnt how to edit several genes at once in mammal DNA. For the dire wolf project, the Colossal team set out to edit 20 genes, pushing the technology to its current limits.
The scientists introduced dire wolf mutations to 15 genes. But they did not introduce the remaining five because previous studies had shown that those five mutations cause deafness and blindness in grey wolves.
So the Colossal team found mutations to those five genes that are present in dogs and grey wolves without causing diseases. They introduced those five backup mutations into the grey wolf cells.
“It’s a fine line you have to walk,” Dr Shapiro said. “You want to be able to resurrect these phenotypes, but you don’t want to do something that’s going to be bad for the animal.”
The researchers then transferred the edited DNA from the grey wolf blood cells into an empty dog egg. They created dozens of these eggs, which they implanted into large dogs that served as surrogate mothers.
Most of the embryos failed to develop, but four pups were born. One died from a ruptured intestine after 10 days, but an autopsy showed that the death was not the result of a harmful mutation.
The researchers are waiting to see just how big the wolves get and have an eye out for any unexpected changes to their biology. “I’m fascinated to see what happens,” Dr Shapiro said.
She added that the animals were unlikely to reveal much about the behaviour of dire wolves, given their captive rearing.
“I would love to know the natural behaviour of a dire wolf,” she said. “But they are essentially living the Ritz-Carlton lifestyle of a wolf. They can’t get a splinter without us knowing about it.”
Colossal has been collaborating with a number of Native American communities in the US. The MHA Nation in North Dakota has expressed interest in the dire wolf project.
“Its presence would remind us of our responsibility as stewards of the Earth,” Mr Mark Fox, MHA Nation tribal chair, said in a statement released by the company.
But if animals with dire wolf DNA were introduced into the wild, they would have to survive in a world that is drastically different from the ice age.
The huge animals that dire wolves specialised in hunting are either extinct or surviving in small populations. Any resurrected, free-roaming dire wolves would have to turn to smaller prey – and potentially would have to compete with grey wolves.
Grey wolves and red wolves face threats, including hunting, that no amount of genetic wizardry can address.
In March, 60 environmental organisations protested against a Bill introduced in Congress that would remove grey wolves from the endangered species list, a change that could lead to more deaths by hunting, the groups warned.
“If signed into law, the Bill would effectively sign death warrants for thousands of wolves across the country,” they wrote.
Prof Meachen, who was not involved in the creation of the wolf pups, said that she had mixed feelings about the de-extinction effort.
“All the little-kid feelings in me say that I want to see what they look like,” she said. “But I have questions. We have trouble with the wolves we have today.” NYTIMES
