Why the humble lab mouse is the most important mammal in modern science

Nature · Published 3 October 2026 Swipe more like this →

In short: As our closest non-primate relatives, mice are the backbone of biomedical discovery. From mapping the human genome to testing life-saving treatments, these small rodents provide a controlled biological canvas. Yet, behind their standardized strains lies a complex history of artificial selection that has fundamentally reshaped their behavior and physiology.

The laboratory mouse, Mus musculus, has been a fixture of scientific inquiry since the 17th century. Early researchers like William Harvey and Robert Hooke utilized them to probe blood circulation and air pressure, while Gregor Mendel’s 19th-century experiments with mouse coat color inadvertently laid the groundwork for modern genetics. Today, their utility stems from high genetic homology with humans, rapid reproduction, and ease of handling. They are members of the Euarchontoglires clade, sharing a deep evolutionary history that makes them uniquely suited for modeling human disease.

The modern era of mouse research began in the early 20th century, catalyzed by Clarence Cook Little. By 1909, Little produced the first inbred strains, a process requiring at least 20 generations of brother-sister mating to ensure near-identical genetics. This consistency allows scientists to isolate specific variables, such as the function of a single gene, without the interference of genetic variation. The Jackson Laboratory now maintains over 8,000 genetically defined strains, ranging from 'Doogie' mice with enhanced memory to 'Oncomice' engineered to develop cancer.

Despite their utility, these animals are far from uniform. Strains like C57BL/6—which accounted for an estimated 83% of U.S. laboratory rodents in 2011—exhibit distinct traits, such as voluntary alcohol consumption and heightened sensitivity to pain. Researchers must also account for stress-induced behaviors like barbering, where mice pluck their own or others' fur. As genomic tools evolve, projects like the Diversity Outbred program are now reintroducing genetic variation to better map complex conditions like obesity and alcohol use disorder, proving that the future of the lab mouse lies in both extreme precision and renewed diversity.

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