Colossal Biosciences, the Texas-based company leading the way in the science of de-extinction technology, has genetically engineered a “woolly mouse,” a significant achievement toward its goal of resurrecting extinct species like the woolly mammoth.
The tiny mammal, engineered to express multiple mammoth-like traits, was created by Colossal scientists who successfully edited seven genes associated with cold adaptation, creating mice with altered coat color, texture, and thickness.
A Platform for Mammoth De-Extinction
“The Colossal Woolly Mouse marks a watershed moment in our de-extinction mission,” said Ben Lamm, Co-Founder and CEO of Colossal Biosciences. “By engineering multiple cold-tolerant traits from mammoth evolutionary pathways into a living model species, we’ve proven our ability to recreate complex genetic combinations that took nature millions of years to create. This success brings us a step closer to our goal of bringing back the woolly mammoth.”
Colossal’s research team, using a dataset of 121 mammoth and elephant genomes, identified key genes responsible for hair length, thickness, and metabolic adaptations to cold. Through an innovative combination of gene-editing techniques, they successfully altered the mouse genome, achieving high efficiency in the expression of cold-adapted traits.
Why Start with a woolly Mouse?
Before being able to successfully de-extinct a woolly mammoth, the team wanted to start with something that would have a shorter gestational timeline.
“Right now, Colossal has three flagship de-extinction projects – woolly mammoth, thylacine, and dodo,” Lamm told the Debrief. “The gestational time for elephants and mammoths is around 22 months while the gestational time for a mouse is around 20 days. It makes the most sense for Colossal to test our end-to-end process from computational analysis to multiplex editing to a living animal in a mouse model that is a fraction of the time it takes to grow an elephant through gestation.”
Additionally, Colossal scientists plan to use fat-tailed dunnarts—a close relative of the extinct thylacine—for similar phenotype testing in their thylacine de-extinction efforts.
Future Cold Testing and Applications
Though the woolly mice display mammoth-like fur characteristics, testing their actual cold resilience remains an ongoing effort.
“We need to have age-matched mice that are behaviorally acclimated to these sorts of tests in order to get statistically robust data, and so are planning these experiments for later in the year,” Beth Shapiro, Colossal’s Chief Science Officer told the Debrief.
Despite the novelty of their achievement, Colossal insists that science rather than commercial applications—such as mass-producing woolly mammoth fur—are not the focus of their work.
“The purpose of Colossal is to bring back extinct species while developing tools and technologies to help conservation and advance human health care,” Lamm stated. “We are not focused on producing woolly mammoth fur for commercial means.”
A Mouse-Size Step Forward for De-Extinction
For Colossal, the most exciting takeaway from this project is the validation of their approach.
“I mean, the mice are adorable, which was a surprise to me,” Shapiro said to the Debrief. “But the most exciting thing about it is the demonstration that our pipeline for de-extinction—from identifying DNA sequences to modify using computational biology and ancient DNA, to designing experiments to make multiple edits at a time, to editing cells and using surrogates to give birth to genetically modified animals—works.”
The company’s achievement follows news earlier this year that it had reached a new funding milestone that is expected to accelerate its pioneering de-extinction efforts and advancements in genetic engineering.
As Colossal continues refining its techniques, the woolly mouse stands as proof that their vision for de-extinction is not just theoretical but achievable. With continued advancements, the dream of resurrecting the woolly mammoth may soon become a reality.
Kenna Hughes-Castleberry is the Science Communicator at JILA (a world-leading physics research institute) and a science writer at The Debrief. Follow and connect with her on BlueSky or contact her via email at kenna@thedebrief.org