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.

Dallas-based Colossal Biosciences announced the birth of the “Colossal Woolly Mouse,” genetically engineered mice that express certain