These Tiny Mummies Reveal the Unexpected Survival Abilities of Mice

Rising miles above sea level, the peaks of Andean volcanoes are extremely hostile to life. Temperatures never rise above freezing, the air is so thin it’s difficult to breathe, and the wind is constantly blowing.

But life has found a way: Researchers who climbed the peaks of three volcanoes in Chile and Argentina found more than a dozen naturally mummified leaf-eared mice (Phyllotis vacarum), some of them may be centuries old1. The presence of the freeze-dried creatures and analysis of their genome suggests that leaf-eared mice spend long periods of time in these hostile locations.

“This is really surprising and challenges our previous assumptions about the adaptability of species to extreme environments,” says Emmanuel Fabián Ruperto, a behavioral ecologist at Argentina’s Arid Zone Research Institute in Mendoza.

The discovery is reported today in Current biology.

Brown mountains under a blue sky, with a person in the middle.

A researcher descends the Salín volcano, near the Argentina-Chile border, where the team found the mummies of two pairs of closely related mice.Credit: Jay Storz

Study co-author Jay Storz, an evolutionary biologist at the University of Nebraska-Lincoln, and his colleagues had previously captured a live leaf-eared mouse at the summit of a fourth Andean volcano, 6,739 meters above sea level. ‘altitude.2. It remains the highest-altitude living mammal ever reported. But the discovery of mummies over an extended period of time shows that the lone mouse was not a “one-off” discovery, Storz says.

Genome analysis of the mummies showed that there were equal numbers of males and females, and that one peak was home to two pairs of closely related mice. This suggests that the mice did not occasionally wander up to the peaks; instead, communities of mice have taken up residence at the tops of volcanoes.

Like the living mouse, the mummies were found more than 6,000 meters above sea level, more than 1,000 meters above the highest flora in the region.

Curled up, desiccated body of a mouse on a white surface next to a metal ruler for scale.

A mouse mummy discovered at the summit of the Salín volcano, culminating at 6,029 meters.Credit: Marcial Quiroga-Carmona

“At such altitudes, food availability is practically non-existent,” explains Fabián-Ruperto. “So, what do these animals feed on? »

The authors hope to answer this question by analyzing the contents of the rodents’ stomachs. Why animals choose to live so high may remain a mystery, but one thing is clear, Storz says: “We have underestimated the abilities of mammals to survive and function in these extreme conditions. »


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