The desolate, wind-whipped peaks of the Puna de Atacama, spanning Chile and Argentina, resemble the harsh terrain of Mars with sparse atmosphere and freezing temperatures.
Standing over 6,000 meters high, these summits were once deemed inhospitable for mammals. However, a recent study in Current Biology challenges this notion, revealing a groundbreaking discovery of mummified mice on these volcanic peaks, expanding the known boundaries of vertebrate survival on Earth.
Senior author Jay Storz, a biologist at the University of Nebraska, Lincoln, expressed astonishment at the findings, stating, “The most surprising thing about our discovery is that mammals could be living on the summits of volcanoes in such an inhospitable, Mars-like environment.” This challenges previous assumptions about the physiological tolerances of small mammals in extreme elevations.
The first mouse mummy was stumbled upon by Storz and his colleagues on the summit of Salin volcano. Subsequent systematic searches across 21 volcano summits, including 18 exceeding 6,000 meters, unveiled a total of 13 mummified mice.
Radiocarbon dating revealed their ages, ranging from a few decades to an estimated 350 years. Genetic analysis identified them as Phyllotis vaccarum, a species known to inhabit lower elevations in the region.
Storz emphasized the surprise of finding mice thriving in freezing, wind-swept environments and highlighted the accumulating evidence of long-term resident mouse populations at extreme elevations. The discovery raises questions about how these mammals survive in a barren landscape with freezing temperatures and reduced oxygen levels. The researchers are conducting physiological experiments on captive mice from high elevations to explore special traits enabling survival in low-oxygen conditions.
The mystery deepens as researchers question why these mice would ascend to such heights. While historical accounts mention Incas conducting sacrifices on Andean peaks, the researchers argue that the mummified mice couldn’t have been placed there by the Incas due to their age.
Ongoing research involves investigating the physiological traits of high-elevation mice and continuing mountaineering surveys of small mammals in the Andes. Storz emphasized the continuous revelation of surprising discoveries about the ecology of extreme high-elevation environments through their mountaineering biological surveys.