Researchers have confirmed through a new study that the treacherous, snow-capped tops of volcanoes in the Andes Mountains are home to the world's highest-dwelling vertebrates. This groundbreaking finding challenges previous assumptions about the limits of vertebrate life, according to an article on Live Science.

Scientists, curious about the presence of mummified mice on the peaks, have long wondered if these small mammals actually lived in the hostile environments or if they merely visited. Previous discoveries showed mummified mice near Incan ceremonial sites and burial sites at or near the summits of Andean volcanoes, leading to speculations that the animals may have been used in sacrificial rituals.

However, a recent study published in the journal Current Biology shed new light on these mysterious creatures. By dating the mummified leaf-eared mice found at high altitudes, researchers discovered that even the oldest specimens were only a few centuries old, ruling out the theory that the Incas had transported them there. This finding suggests that the mice actually lived in these extreme conditions and were naturally preserved by the cold and dry climate.

The breakthrough came in 2013 when scientists scaling the Llullaillaco volcano, situated on the border between Argentina and Chile, observed live mice scurrying across a snow field at the astounding altitude of 20,360 feet. Subsequent expeditions in 2020 confirmed that live mice were not only present at such heights but also managed to thrive at the summit, reaching an elevation of 22,100 feet. This was the highest elevation ever recorded for a vertebrate species, surpassing even birds that may soar higher but do not inhabit these heights.

The daunting conditions on the volcano's wind-whipped summit, where oxygen levels are 40% lower than at sea level, present numerous challenges for life. Nevertheless, over the past three years, researchers have gathered hundreds of mummified and live leaf-eared mice from not only Llullaillaco but also other volcanoes in the Puna de Atacama region that are taller than 19,700 feet.

The study's authors highlighted that such extraordinary elevations were previously believed to be entirely inhospitable to mammals. To confirm that the mice truly thrived at these heights, scientists compared the genomes of the high-altitude mice with those of their lower-altitude counterparts. They discovered that the high-dwelling rodents were closely related to each other, albeit slightly different. This genetic similarity suggests that breeding and long-term residence at these extreme altitudes were possible for these tiny mammals.

Further evidence supporting this revelation was the discovery of rodent burrows above 19,700 feet. The fact that the genetically similar specimens from the same volcano were evenly split between males and females indicated that these "summit mice" were permanent residents rather than transient visitors, as emphasized by the study authors.

While the mystery of the mummified mice has been partially unraveled, there are still unanswered questions regarding the diet and survival mechanisms of the leaf-eared mice in their frigid habitat. Researchers are hopeful that a colony of high-altitude mice recently established in Chile will provide insights into these fascinating adaptations.

The study's findings represent a remarkable discovery in our understanding of the limits of vertebrate life and the resilience of seemingly delicate organisms in extreme environments. These high-living mice challenge our preconceived notions and expand our knowledge of the diverse ways in which life can adapt and persist against all odds.

For more information on this extraordinary study, visit Science.