Overview
- The Science paper, published Thursday, July 9, 2026, reports whole-genome and physiological data from 167 Andean leaf-eared mice sampled from sea level to more than 6,700 meters.
- High-elevation mice produce more body heat than lowland conspecifics through increased shivering in skeletal muscle and more active brown fat, helping them maintain temperature in subfreezing, low-oxygen conditions.
- Laboratory tests show highland mice have greater maximal oxygen consumption and enhanced mitochondrial respiratory capacity that sustain tissue energy use under hypoxia.
- Genomic scans found selection on genes for energy metabolism, vascular regulation and biotransformation of plant toxins rather than on classic hemoglobin changes.
- Populations across elevations show little overall genetic differentiation, researchers are expanding geographic sampling and lab mechanistic work, and any human medical implications remain hypothetical at this stage.