Scientists at Colossal Laboratories and Biosciences, which calls itself the world’s only de-extinction company, recently genetically engineered artificially fluffy mice. Colossal calls these mice “woolly mice.”
Colossal scientists introduced various genetic mutations into mice, focusing on broadly mammoth-like traits: fluffy golden coats of fur, and — perhaps less adorably — changes to fat metabolism. To change hair texture, the scientists changed a mouse gene to a different allele, or gene variant, that impacts keratin, the hair and nail protein.
Many genetically engineered fertilized mouse eggs failed to be born, with the least successful experiment having an 11 percent birth rate. Yet birth rates were still higher than many other genetic experiments in mice. All mice born still appear fully healthy, several months after their Oct. 2024 births.
The only unintended side effect in live mice Colossal has noticed so far? They’re unexpectedly cute, Colossal cofounder and CEO, Ben Lamm, told various publications including Wired and Nature.
But there’s more behind Colossal’s success in raising $400 million of funding. Their ultimate goal is to create an approximate version of the woolly mammoth. Colossal hopes to genetically modify its closest living relative, the Asian elephant, to have the woolly mammoth’s trademark fur and cold resistance — similar to the modifications Colossal achieved in mice. The resulting animal would be genetically nearly identical to the Asian elephant, but with distinct woolly mammoth traits.
Colossal hopes a resurrected woolly mammoth could help restore ecosystems like tundras to their states before woolly mammoths went extinct 4,000 years ago. Furthermore, this research in gene editing has implications for healthcare; in fact, Colossal has already spun off two healthcare companies.
Moving forward for Colossal, however, may not be that simple. First, many scientists say woolly mice are of limited help in creating a woolly mammoth. Many of the genetic modifications Colossal introduced into mice were entirely different from modifications compatible with Asian elephants. Colossal chief scientist, Beth Shapiro, says the mouse-specific mutations were necessary because Asian elephants are genetically very different.
Editing mice is playing the gene-editing game in easy mode. There is a plethora of past research to reference. Mice have 20-day gestation periods, as opposed to the lengthy 22 months Asian elephants require. All of the traits Colossal achieved in mice already exist in other mice, just not all together in a single mouse.
Also, unlike mice, these elephants are endangered, have intricate social hierarchies, and are cognitively advanced. This creates stronger ethical concerns than those in place for Colossal’s mice, who received a typical 12-hour light/dark cycle and oversight from the UT Southwestern Institutional Animal Care and Use Committee.
But Colossal maintains experimenting on mice is useful for their end goal.
“While mice cannot fully replicate elephant physiology, mouse models provide valuable insight into the functional consequences of mammoth-specific adaptations and will help prioritize genetic modifications likely to confer desired traits in proboscideans,” says the paper that Colossal published on its mouse experiments. The paper has not yet been peer-reviewed or published in an academic journal. Additionally, Colossal researchers now plan to study cold resistance and hair development in their woolly mice to probe the impacts of their genetic modifications.
Not only is there disagreement about these results’ utility, but scientists are also heavily divided on whether Colossal should even try to recreate woolly mammoths at all. Philosophy professor Craig Callender, who studies science ethics, told Scientific American that Colossal is performing a “stunt,” and vice president of international policy at the Wildlife Conservation Society Sue Lieberman in the same article called the project “arrogance.”
Many scientists question the environmental benefits of creating new woolly mammoths, noting woolly mammoths’ ecosystems are long gone and do not need resurrection or maintenance. Furthermore, woolly mammoths, if reintroduced to the wild, would lack one major advantage: learning from other animals of the same species. Yet another concern is that projects like these divert attention and money from areas in conservation where they could arguably be more useful.
Although the future is uncertain and the project controversial, one thing is clear: Colossal considers their woolly mice a success and is currently working on extending their research. They hope that soon, woolly mammoths will come back to roam the tundras of Earth.
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