FROM ICE AGE TO MICE AGE

Scientists have declared a 'watershed moment' in their quest to bring back the woolly mammoth... by successfully breeding genetically engineered long-haired rodents

- Hanna Geissler

AT FIRST glance, you would be forgiven for thinking these shaggyhaired mice are nothing special. Their fur is a little lighter in colour, longer and more wavy than usual, but a mouse is a mouse - or is it? According to the world's leading deextinction experts, the birth of these rodents marks a "watershed moment" in the quest to bring back animals that last roamed the Earth thousands of years ago.

The mice have been genetically engineered by Colossal Biosciences to express traits of the woolly mammoth, which make them better adapted to survive in cold climates. Changes to their DNA have resulted in coats that resemble their namesakes' in colour, length, texture and thickness. And genes controlling lipid metabolism - the process of absorbing and synthesising fats to store energy have been altered so they store more fat just beneath the skin.

The company's ambitious chief executive Ben Lamm, who co-founded Colossal in 2021, says this murine milestone "brings us a step closer to our goal of bringing back the woolly mammoth".

"By engineering multiple cold-tolerant traits from mammoth evolutionary pathways into a living model species, we've proven our ability to recreate complex genetic combinations that took nature millions of years to create," he says.

Once considered fanciful, de-extinction is a branch of research that aims to resurrect past species by editing the DNA of modern animals. The process begins with identifying observable characteristics or traits, known as phenotypes, that you want to recreate.

A genome contains all the DNA in an organism, with the information needed for it to function. Colossal used computer science analysis to select targets in the genomes of 59 woolly, Columbian and steppe mammoths ranging from 3,500 to 1.2 million years old. Researchers also looked at data from Asian and African elephants to see which genes drive key differences between the closely related animals.