Watch the video
A Mouse in Mammoth’s Clothing: The Genetic Experiment Turning Heads
In a breakthrough that seems straight out of science fiction, Colossal Biosciences — the biotech company aiming to resurrect extinct species like the woolly mammoth, dodo, and Tasmanian tiger — has unveiled its latest creation: the "woolly mouse." This genetically engineered rodent, sporting a shaggy, golden coat reminiscent of its ice-age predecessor, marks a significant step in the company's controversial quest for "de-extinction."
The Woolly Mouse: A Miniature Mammoth?
The woolly mouse, announced by Colossal on Tuesday, is not a mere curiosity. It represents what the company's chief science officer, Beth Shapiro, calls "an important step toward validating our approach to resurrecting traits that have been lost to extinction." While it lacks the tusks and towering presence of a mammoth, the mouse displays thick, wavy fur and other cold-adapted traits engineered into its DNA.
To achieve this feat, Colossal's team combed through ancient mammoth genomes — extracted from preserved skin, bones, and hair — and identified genes responsible for the animals' distinctive woolly coats and cold tolerance. These genes were then carefully edited into lab mice, creating what the team describes as a "superfuzzy" rodent with long hair, curly whiskers, and a unique coat texture.
Science at the Genetic Frontier
The genetic engineering process involved targeting several genes simultaneously — a complex maneuver using a blend of three advanced gene-editing technologies. The researchers made eight precise tweaks to the mouse genome, altering seven key genes. For example, disabling the FGF5 gene resulted in longer hair, while changes to FAM83G, FZD6, and TGM3 gave the mice their characteristic wavy fur. A modified version of a melanin-related gene also turned the mice's coats golden, adding to their mammoth-like appearance.
Beth Shapiro emphasized that this work not only showcases the potential to drive physical changes using ancient DNA but also confirms that the edited mice remain healthy. "Our goal is to ensure that these genetic alterations produce the desired traits without compromising the well-being of the animals," Shapiro said.
A Steppingstone to Mammoths — or a Sideshow?
While Colossal views the woolly mouse as a crucial step toward reviving the mammoth — with hopes of birthing a mammoth-elephant hybrid by 2028 — many scientists remain skeptical. Critics argue that reintroducing extinct species into modern ecosystems is fraught with both ethical and practical challenges.
Evolutionary biologist Tom Gilbert, an advisor to Colossal, praised the genetic work as "a superexciting proof of principle," but other experts voiced concern. "It’s an impressive technical achievement," said Louise Johnson from the University of Reading, "but only a few of the engineered mutations actually move the mouse genome closer to a mammoth’s."
Furthermore, the ecological justification for bringing back extinct species remains hotly debated. Colossal claims that woolly mammoths could help slow climate change by trampling Arctic permafrost, reducing methane release. But critics like Douglas McCauley, an ecologist at the University of California, Santa Barbara, counter that the effort feels more like "making monsters in the lab" than a genuine climate solution.
Ethical Quandaries and the Road Ahead
Beyond the scientific hurdles, the woolly mouse raises pressing ethical questions. Gene editing has a high failure rate, often resulting in unsuccessful pregnancies or unhealthy offspring. While Colossal reports that all of their woolly mice — born in mid-October 2024 — are alive and under veterinary care, bioethicists like Robert Klitzman question whether the project's "wow" factor outweighs its scientific or environmental value.
Critics also highlight the potential dangers of releasing genetically modified animals into the wild. Even though Colossal has no plans to breed the woolly mice — all of them are male — concerns linger about future projects involving larger animals like mammoths.
In response, Colossal's CEO Ben Lamm remains steadfast. "Our work draws attention from kids, students, and the public, inspiring the next generation of scientists," he said. Shapiro adds that gene editing could become a vital tool in conservation, helping species adapt to changing habitats or resist disease.
Conclusion: Fluffy Fascination or Genetic Gimmick?
The woolly mouse may be tiny, but it has sparked a mammoth-sized debate about the intersection of science, ethics, and conservation. Whether this fuzzy rodent represents a meaningful step toward reviving extinct species or an expensive stunt remains to be seen. One thing is certain: Colossal Biosciences' work — and its woolly mouse — have captured the world's imagination, for better or for worse.