Scientists Create “Woolly Mice” in a Step Toward Reviving Mammoths
Researchers have genetically engineered “woolly mice” with fur resembling the thick, shaggy coat that helped woolly mammoths survive the Ice Age. The breakthrough, unveiled by Colossal Biosciences on March 4, marks a major milestone in the company’s ambitious project to bring mammoths back to life by 2028.
A First Step Toward Woolly Mammoths
Colossal’s scientists aim to resurrect the woolly mammoth (Mammuthus primigenius) by editing the DNA of its closest living relative, the Asian elephant (Elephas maximus). But before attempting such complex modifications in elephants, the team first tested their genetic engineering techniques in mice, which breed rapidly and are easier to study.
“A mouse model is super useful in this case, because unlike elephants [whose gestation lasts about 22 months], mice have a 20-day gestation,” said Beth Shapiro, Colossal’s chief science officer. This allowed researchers to design, clone, and grow the woolly mice in just six months.
How Scientists Engineered Woolly Mice
To create these fluffy rodents, scientists modified seven genes linked to fur texture, length, and color. Instead of inserting mammoth genes into mice, they identified and altered mouse genes that perform similar functions to those in mammoths.
One key change involved blocking the FGF-5 gene, which regulates hair length, resulting in fur three times longer than normal. Additionally, mutations affecting TGF-alpha and KRT27 genes—both present in woolly mammoths—gave the mice wavier fur.
Researchers also attempted to modify a gene responsible for fat metabolism, mimicking the thick fat deposits that helped mammoths survive extreme cold. However, the physical effects of this change remain unclear.
Next Steps: Testing Cold Resistance
While the woolly mice resemble mini-mammoths in appearance, it’s still unknown whether they can tolerate colder temperatures. Scientists plan to conduct cold-resistance tests in the coming months to determine the effects of the genetic modifications.
The Challenge of Scaling Up to Elephants
Despite the success with mice, reviving woolly mammoths remains a formidable challenge. Unlike mice, elephants have naturally sparse hair, so achieving a dense, woolly coat would require even more advanced genetic engineering.
“You’d need additional genome editing to somehow find a way to increase the density of the hair,” said Vincent Lynch, an evolutionary biologist at the University at Buffalo.
Still, the woolly mice serve as an important proof of concept, demonstrating that multiple genetic mutations can be successfully combined to recreate mammoth-like traits. While there’s still a long road ahead, scientists are one step closer to bringing Ice Age giants back to life.