In March 2025, Colossal Biosciences, a Dallas-based biotechnology company, announced the successful creation of genetically engineered “woolly mice,” marking a significant milestone in their ambitious de-extinction project aimed at reviving the woolly mammoth.

The woolly mouse project represents a crucial step toward Colossal’s goal of reintroducing mammoth-like traits into living organisms. By focusing on mice, which have a short gestation period of about 20 days, the researchers could rapidly test and observe the effects of multiple genetic modifications.

To develop the woolly mice, scientists employed advanced genome-editing techniques, including CRISPR, to simultaneously modify seven specific genes associated with hair characteristics and fat metabolism. Six of these genes were related to hair texture, length, and color, while the seventh influenced lipid metabolism, a trait linked to cold adaptation. The modifications led to mice exhibiting longer, thicker, and curlier fur with a golden-brown coloration, closely resembling the woolly coats of mammoths.

The success of the woolly mouse project serves as a proof of concept for Colossal’s broader de-extinction efforts. By demonstrating the feasibility of introducing multiple mammoth-like traits into a living organism, the company has laid the groundwork for future endeavors involving larger mammals, such as Asian elephants. Colossal aims to produce the first genetically modified elephant calf with mammoth characteristics by the end of 2028.

However, the project has garnered mixed reactions from the scientific community. While some experts acknowledge the technical achievements, others express skepticism regarding the practicality and ethics of de-extinction. Concerns include the complexity of replicating such genetic modifications in larger animals and whether resources might be better allocated toward conserving existing species.

In summary, the creation of woolly mice by Colossal Biosciences represents a noteworthy advancement in genetic engineering and de-extinction research. By successfully introducing mammoth-like traits into mice, the company has demonstrated the potential of their approach, bringing them closer to their goal of reviving the woolly mammoth. As the project progresses, it will be essential to address the scientific, ethical, and ecological considerations associated with de-extinction and the reintroduction of modified species into modern ecosystems.