Andean Leaf-Eared Mouse Thrives at Record Elevations

On July 24, researchers reported that the Andean leaf-eared mouse inhabits an elevation span from the desert coast of northern Chile to the summits of the Andes, reaching peaks of roughly 22,000 feet (6,700 meters). Whole-genome analysis of 167 captured individuals revealed a suite of metabolic and genetic changes that enable survival where oxygen is less than half of sea-level levels and temperatures are almost always below freezing. No other mammal is known to occupy such a broad high-altitude range.

Reuters

High-elevation mice maintain superior thermogenic capacity, producing body heat more efficiently despite scarce oxygen. Their skeletal muscle mitochondria show an enhanced ability to generate energy, while brown-fat tissue is better equipped to oxidize fats for warmth. Genomic signals point to selection on genes linked to antioxidant defence and the metabolism of dietary toxins, reflecting the need to process toxic secondary compounds from the limited high-altitude flora. The study also noted that diet may play an unexpected role in coping with extreme altitude, though the specific plants remain unidentified.

Reuters

The findings suggest that mammals can evolve coordinated physiological and genomic strategies to thrive under chronic oxygen deprivation—a condition that mirrors certain human cardiorespiratory diseases. Understanding these adaptations could inform future research on treatments for patients with impaired oxygen delivery at sea level.

Reuters

University of Nebraska evolutionary biologist Jay Storz emphasized that the mouse’s ability to balance heat production with limited oxygen showcases a “metabolic adjustment” unseen in long-term human exposure to such heights. Co-author Guillermo D'Elía of the Universidad Austral de Chile highlighted the discovery of toxin-metabolizing capacity as “unexpected” and called for further study of the species’ diet, lifespan, and reproduction on summit habitats. Biologist Zachary Cheviron (University of Montana) stressed that even the most barren mountain zones host unique life forms that merit protection.

Reuters

• “On the summits of approximately 22,000 feet (6,700 meters) peaks where we have trapped these mice, there is less than half the oxygen that is available at sea level, and temperatures are almost always below freezing,” — University, of Montana

Reuters

• “When a mammal is challenged by extreme cold, it relies on metabolic heat production to maintain a constant body temperature. This ... requires oxygen as fuel. Since there is less oxygen at high elevation, mammals that live in such environments make metabolic adjustments to use oxygen more economically,” — Jay Storz, nebraska evolutionary biologist

Reuters

• “The discovery that the mice have evolved the ability to metabolize dietary toxins was unexpected,” — Jay Storz, nebraska evolutionary biologist

Reuters

• “High-elevation mammals have evolved the ability to survive and function under conditions of chronic oxygen deprivation that mimic disease states in humans,” — Jay Storz, nebraska evolutionary biologist

Reuters

• “We now have a good basis of the physiological aspects allowing those mice to live at 6,700 meters above sea level. We also have some understanding on the genomic basis of some of these adaptations. But there's much to learn,” — Guillermo D'Elía, of the Universidad Austral de Chile, another of the study's co-authors

Reuters