Colossal Biosciences engineers mice with woolly mammoth traits

The George Church–cofounded de-extinction company, Colossal Laboratories and Biosciences has announced that it has successfully engineered woolly mammoth hair traits into mice. The Colossal woolly mice, as the company calls them, have long, golden, and wavy hair thanks to the editing of seven genes related to hair growth in the mouse genome.

CEO and cofounder Ben Lamm says that Colossal is “the world's first de-extinction and species preservation company” and that creating the woolly mice is one of the first steps toward functionally bringing back the woolly mammoth from extinction.

It’s a mission straight out of Jurassic Park, a comparison the company isn’t shying away from. And though there’s no recovering of DNA from mosquitoes preserved in amber, many of the fundamental science concepts are similar to those that inspired the 1990 book and series of movies. The company’s chief science officer, Beth Shapiro, says that people have been working on sequencing DNA from ancient mammoth remains for decades. “We get little, tiny pieces of mammoth DNA out of mammoth bones, and then we use a computer to map those to an Asian elephant genome,” she says.

The team identified gene variants found in the mammoth and Asian elephant genomes that researchers hypothesized were involved in traits such as “hair color, the length of guard hairs, and the waviness and density and texture of that hair,” Shapiro says. Then they found three genes within the mouse genome involved in those same pathways in mice and modified them to give the mice woolly hair traits. They also found four additional genes in mice they thought would be involved in hair traits by searching previously published research and modified them, as well, to enhance the mice’s woolly appearance.

Eventually, the team plans to build on these results to modify the genomes of Asian elephants, the closest living relative of the mammoths, to give them the traits of woolly mammoths. “We call it functional de-extinction because it's not possible to clone an extinct species if you do not have a living cell,” Lamm says.

But the company has its critics. Vincent Lynch, an evolutionary biologist at the University at Buffalo, doesn’t think this counts as de-extinction in any respect. “They're making genetic changes in an Asian elephant that gives that Asian elephant the superficial appearance of being a mammoth,” he says. “That’s not de-extinction; that's genome engineering.”

Colossal intends to assess whether these woolly hair traits give the mice any cold-tolerance traits. “We have experiments planned for the next year or so where we're going to take age-matched, wild-type, and modified mice and put them in different temperature situations to assess whether their behaviors change or they seem happier,” Shapiro says.

As for the ethics of using genetic engineering to bring back the woolly mammoth from extinction, Shapiro says that there is a “tremendous risk in deciding that these technologies are too scary for us to move forward with. We know that in the next 50 to 100 years, more than half of the species that are alive today are projected to become extinct,” she claims. “So deciding that we don't want to at least give ourselves the freedom and the flexibility to assess the power of these tools is making a decision that I find to be unacceptably risky.”

Shapiro says that by bringing back the woolly mammoth or other extinct species, those species can fulfill an ecological role in the environment in which they once lived. But Lynch disagrees with that claim. “I call bullshit on that for lots of reasons,” he says. “Mammoths went extinct. So the ecosystem has adapted to their absence. What's going to happen when you put them back? That's not reintroducing something that is gone; that's putting an invasive species into an environment that it has never seen before."

Lamm says there was, however, one unintended consequence of the gene-editing project in mice: “adorability.” Colossal won’t be selling or rewilding their supercute mice, but instead, “these mice will live out their natural lives in our vivarium,” he says.

The technology Colossal has developed in pursuit of de-extinction has already been spun off into multiple companies, including Form Bio and Breaking, with a third company in stealth to be announced soon, Lamm says.