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A company aiming to revive extinct animal species has unveiled genetically engineered “woolly mice” that it says are an important milestone in its quest to bring back mammoths.
US-based start-up Colossal Biosciences said the shaggy rodents show several traits similar to those that helped elephants’ ancient ancestors resist the cold.
Independent experts said the creation of the hirsute mice was intriguing but still far short of resurrecting a huge beast such as the mammoth — or, in the case of Colossal, an elephant engineered with its prehistoric predecessor’s biological characteristics.
Creating a woolly mammoth from scratch would require genetic samples and technology beyond what is available, so Colossal’s plan is to use Asian elephants as its basis organism.
“The Colossal woolly mouse marks a watershed moment in our de-extinction mission,” said company chief executive Ben Lamm. “We’ve proven our ability to recreate complex genetic combinations that took nature millions of years to create.”
Colossal said on Tuesday it had modified seven genes simultaneously to give the woolly mice luxuriant locks resembling the thickness, texture and colour of those found in mammoths.
The work was based on analysis of genetic data from 59 woolly, Colombian and steppe mammoths that lived between 3,500 and more than 1.2mn years ago.
The company’s work has captured imaginations while raising questions about the feasibility, desirability and ethicality of restoring extinct species or imitations of them. Colossal argues that its work is no Jurassic Park-style vanity project, but a valuable effort to restore beasts such as dodos and Tasmanian tigers to ecosystems where they once roamed — and make crucial scientific discoveries along the way.
Colossal and its partners are working on artificial womb technologies that could help efforts to protect existing endangered species threatened with extinction, as well as restore mammoths and other extinct animals.
The Colossal mice are a “living model for studying cold-climate adaptations in mammals”, the company said. The gene edits altered the mice’s hair to make it grow longer and with a woollier hair texture, giving them wavier coats and curlier whiskers, the company said.
They also had a mammoth-style truncated version of a gene that affects the metabolism of fats and thus helps regulate body weight in chilly conditions.
The technology used on the woolly mice offered an “exciting opportunity to test some of our ideas about extinct organisms”, said Louise Johnson, an evolutionary biologist at Reading university in the UK. But she added that most of the genetic alterations used were already known to change rodents’ coats, so “you could, in theory, produce mice like this by just breeding mice with weird hair together”.
Dusko Ilic, professor of stem cell science at King’s College London, said the refinement of the gene data to make the edits compatible with the mice was a “noteworthy milestone” but that translating the approach to elephants would pose “significant challenges”.
Elephants’ gestation periods of 18 months or more are the longest of any mammal. They generally give birth to a single calf and they take at least 10 years to become sexually mature.
“How many elephant cows would need to undergo experimental pregnancies to give birth to a ‘woolly elephant’?” Ilic asked. “And how long would it take before the first such hybrid is born?”
Colossal raised its latest $200mn in January in a funding round led by TWG Global that the group said valued it at $10.2bn.
TWG is co-led by Guggenheim Partners chief executive Mark Walter and Thomas Tull, founder of media company Legendary Entertainment and producer of several hit films, including Christopher Nolan’s Batman Begins and The Dark Knight.
Colossal’s private investors include Oscar-winning director, producer and screenwriter Sir Peter Jackson, best known for the Lord of the Rings films.
