Colossal Biosciences genetically engineered a ‘woolly mouse’ with mammoth traits. The milestone could inform human gene therapy.

The biotech company Colossal Biosciences has long aspired to bring back the extinct woolly mammoth, which roamed the Northern Hemisphere thousands of years ago, during the last ice age. But for now, as a step along the way, the company has come up with something decidedly less mammoth: meet the woolly mouse.

The journey to the woolly mouse began with the woolly mammoth. Scientists at Colossal examined more than 100 genomes of Asian elephants and woolly mammoths. They lined up those genomes side by side and compared them to find the parts which are crucial for making a mammoth.

The de-extinction company Colossal Biosciences wants to bring back the woolly mammoth—starting with a very furry mouse.

Using DNA and genomics technologies, scientists have modified the mice to have longer, thicker hair and an altered metabolism expected to allow them to tolerate colder temperatures, Colossal Biosciences said.

While the Colossal Laboratories and Biosciences project to bring back extinct species has been compared to “Jurassic Park”, it has started at a much smaller scale than a T. Rex: woolly mammoth mice.