Mammal documented living at record altitude of 6,700 meters in the Andes

Researchers have documented a leaf-eared mouse inhabiting an Andean volcano summit at 6,700 meters, the highest altitude known for any mammal, with specific physiological and genetic adaptations.

• The study, published July 9 in Science, found the mouse (Phyllotis xanthopygus) living on Llullaillaco volcano in the Atacama Desert.
• Lead author Jay Storz said the mice across altitudes still interbreed, meaning adaptations arose despite ongoing gene flow.
• Laboratory experiments showed high-altitude mice better maintain heat production than lowland mice under low-oxygen conditions mimicking 7,000 meters.
• Genetic analysis revealed adaptations related to detoxification of plant chemicals, suggesting dietary challenges at high elevations.