Extinction is still forever, but scientists at the biotech company Colossal Biosciences are trying what they say is the next best thing to restoring ancient beasts — genetically engineering living animals with qualities to resemble extinct species like the woolly mammoth.

Woolly mammoths roamed the frozen tundras of Europe, Asia and North America until they went extinct around 4,000 years ago.

Colossal made a splash in 2021 when it unveiled an ambitious plan to revive the woolly mammoth and later the dodo bird. Just last year, the company said they made a breakthrough in efforts to bring back the extinct Tasmanian tiger.

Colossal has focused on identifying key traits of extinct animals by studying ancient DNA, with a goal to genetically “engineer them into living animals,” said CEO Ben Lamm.

In a 2023 interview, CBS News correspondent Jonathan Vigliotti told Lamm, “I hear mammoth and dodo in the same sentence and, you know, it’s science fiction to me.”

“Yeah, I mean, it is,” said Lamm, “until it’s not.”

Outside scientists have mixed views about whether this strategy will be helpful for conservation.

“You’re not actually resurrecting anything — you’re not bringing back the ancient past,” said Christopher Preston, a wildlife and environment expert at the University of Montana, who was not involved in the research.

On Tuesday, Colossal announced that its scientists have simultaneously edited seven genes in mice embryos to create mice with long, thick, woolly hair. They nicknamed the extra-furry rodents as the “Colossal woolly mouse.”

Results were posted online, but they have not yet been published in a journal or vetted by independent scientists.

The feat “is technologically pretty cool,” said Vincent Lynch, a biologist at the University of Buffalo, who was not involved in the research.

Scientists have been genetically engineering mice since the 1970s, but new technologies like CRISPR “make it a lot more efficient and easier,” said Lynch.

The Colossal scientists reviewed DNA databases of mouse genes to identify genes related to hair texture and fat metabolism. Each of these genetic variations are “present already in some living mice,” said Colossal’s chief scientist Beth Shapiro, but “we put them all together in a single mouse.”

They picked the two traits because these mutations are likely related to cold tolerance — a quality that woolly mammoths must have had to survive on the prehistoric Arctic steppe.

Independent experts skeptical of “de-extinction”

Colossal said it focused on mice first to confirm if the process works before potentially moving on to edit the embryos of Asian elephants, the closest living relatives to woolly mammoths.

However, because Asian elephants are an endangered species, there will be “a lot of processes and red tape” before any plan can move forward, said Colossal’s Lamm, whose company has raised over $400 million in funding.

“We are in the world of synthetic biology. These tools exist. It’s hard to put the genie back in the bottle. We need to be really thoughtful about the intended and unintended consequences of our actions,” Lamm told CBS News Boston in 2022.

Independent experts are skeptical about the idea of “de-extinction.”

“You might be able to alter the hair pattern of an Asian elephant or adapt it to the cold, but it’s not bringing back a woolly mammoth. It’s changing an Asian elephant,” said University of Montana’s Preston.

Still, the refinement of precision gene-editing in animals could have other uses for conservation or animal agriculture, said Bhanu Telugu, who studies animal biotechnology at the University of Missouri and was not involved in the new research.

Telugu said he was impressed by Colossal’s technology advances that enabled scientists to pinpoint which genes to target.

The same approach might one day help fight diseases in people, said Lamm. So far, the company has spun off two health care companies.

“It’s part of how we monetize our business,” said Lamm.

Ben Mezrich, who authored the book, “Woolly: The True Story of the Quest to Revive One of History’s Most Iconic Extinct Creatures,” told CBS News in 2017 that reviving woolly mammoths could potentially facilitate medical breakthroughs.

“I mean, elephants don’t get cancer, which is very strange,” he told CBS News. “Elephants have thousands and thousands of more cells than us. And why they don’t get cancer is in their genes. If we can figure that out, we can use this genetic engineering to solve cancer.”