Scientists Create Woolly Mice. Next up is the Mammoth That Went Extinct Around 4,000 Years Ago

Animals belonging to past periods always invite fascination, like dinosaurs and woolly mammoths. A company went one step ahead in its fascination when it decided to resurrect some of these beings, stated CNN.  Despite multiple evidence of progress showcased by the company, several scientists still doubt whether the endeavor is meaningful.

The company in question is Colossal Biosciences. The experts associated with the company have created what they call a 'woolly mouse.' Researchers think it brings them one step closer to their aim to ‘de-extinct’ woolly mammoths. The mouse in this examination had its genes edited to be closer in characteristics to woolly mammoths (Mammuthus primigenius).  "The Colossal Woolly Mouse marks a watershed moment in our de-extinction mission," said Ben Lamm, Colossal’s co-founder and chief executive, stated Nature.

The company claimed that the creation would allow experts to test their theories regarding links between certain DNA sequences and physical traits possibly exhibited by woolly mammoths that lived around 4,000 years ago. "It is an important step toward validating our approach to resurrecting traits that have been lost to extinction and that our goal is to restore," said Dr. Beth Shapiro, chief science officer at Colossal, stated CNN.

For creating the 'woollly mouse' experts identified the genetic variants that made woolly mammoths different from their closest living relative: the Asian elephant. The team was able to determine ten variants in total. These variants were associated with aspects like texture, thickness, hair length, color, and body fat. In terms of function, the corresponding DNA variants were spotted in the lab mouse. The team focused on a gene known as FGF5 (fibroblast growth factor 5) to encourage longer and shaggier hair growth in the mouse. Three genes were targeted to ensure that the hair growths had a wooly texture. 

In total, eight edits were made in the lab mouse. "I think that the ability to edit multiple genes at the same time in mice, and to do so and obtain the expected woolly appearance, is a very important step,” said Love Dalén, a professor of evolutionary genomics at Stockholm University. "It is a proof-of-principle that Colossal has the know-how to do this kind of gene editing, including to insert mammoth gene variants into a different species."

Though several scientists were impressed by the work, several had reservations. Some felt that despite having similar physical features, there was no proof that the mouse would react in the same way as woolly mammoths did. "My biggest problem with the paper is that there is nothing addressing whether the modified mice are cold-tolerant — through introducing traits that are apparent in mammoths — which is the justification given for carrying out the work," Robin Lovell-Badge, head of the Stem Cell Biology and Developmental Genetics Laboratory at The Francis Crick Institute in London said. "As it is, we have some cute-looking hairy mice with no understanding of their physiology, behavior, etc. It doesn’t get them any closer to know if they would eventually be able to give an elephant useful mammoth-like traits, and we have learned little biology."

Many scientists also felt the knowledge about woolly mammoths was not enough to conduct this experiment. "While we know a lot about mouse genetics, we know much less about mammoths and elephants. It isn’t yet known which sections of the genome are vital for achieving the characteristics (needed) to make an elephant fit for life in the Arctic Circle. Genes that are linked to fur and fat in well-studied animals like mice are obvious targets, but the devil is in the detail," said Tori Herridge, Senior Lecturer, School of Biosciences, University of Sheffield. "Unless you decide to make EVERY edit necessary … in the genome, you are only ever going to create a crude approximation of any extinct creature, based on an incomplete idea of what it should look like. You are never going to ‘bring back’ a mammoth," she added.

The company is also committed to resurrecting other extinct species like the dodo and Tasmanian tiger, or thylacine. Since its inception, the company has raised $435 million for its ambitious project.