US scientists have created a "woolly" mouse by expressing genetic information gathered from woolly mammoths and elephants, which they see as a step toward bringing the extinct species back to life.

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Woolly mouse – click to enlarge ( Image © Colossal Biosciences )

The lab-created rodents were engineered to express a number of mammoth-like traits that researchers say provide adaptation to colder climates.

By successfully modifying seven genes simultaneously, genetic engineering company Colossal Biosciences created mice with altered coat color, texture, and thickness in line with the extinct woolly mammoth's core phenotypes. The team used information from the computational analysis of 59 woolly, Columbian, and steppe mammoth genomes extracted from samples from 3,500 to over 1,200,000 years old.

Ben Lamm, co-founder and CEO of Colossal Biosciences, said: "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. This success brings us a step closer to our goal of bringing back the woolly mammoth."

The company's researchers used a dataset of 121 mammoth and elephant genomes, including Colossal-created high-quality reference genomes for Asian and African elephants, to pick out the genes necessary to influence hair and other cold-adaptation traits. They then refined the list to ten genes related to hair length, thickness, texture, and color as well as lipid metabolism that were compatible with expression in a mouse.

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George Church, professor of genetics at the Wyss Institute and Harvard Medical School and co-founder of Colossal, said: "The Colossal Woolly Mouse demonstrates remarkable progress we've made in precise genome engineering, including optimized delivery methods, innovative multiplexing, and combinations of gene-targeting strategies. We are showing that we can now rationally design and construct complex genetic adaptations, with profound implications for the future of multi-gene de-extinction and engineering."

Colossal Biosciences sees the woolly mouse experiment as a way of confirming genetic pathways necessary for its plans for the "de-extinction" of the woolly mammoth.

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The company was founded by technology and software entrepreneur Lamm and Church to apply CRISPR gene editing to enable so-called "de-extinction." It has discussed the extinct woolly rhino (Coelodonta antiquitatis), the dodo, and the Tasmanian tiger (or thylacine) as other candidates for the process. The company claimed that its woolly mouse is the first living animal engineered to express multiple cold-adapted traits using mammoth gene orthologs, while future research will help show how multiple genes work together to manifest physical traits. ®

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[1] https://regmedia.co.uk/2025/03/04/colossal_biosciences_wooly_mouse2.jpg

[2] https://www.theregister.com/2022/03/02/us_patent_crispr/

[3] https://www.theregister.com/2022/01/19/ai_motor_neuron/

[4] https://www.theregister.com/2020/10/08/nobel_prize_chemistry/

[5] https://www.theregister.com/2015/03/23/scientists_splice_mammoth_genes_into_elephant/

[6] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2Z8cxtEx1tDYrMVKhYc62hgAAAQM&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0

[7] https://whitepapers.theregister.com/