The barren, wind-driven volcanic peaks of Puna de Atacama, which straddles Chile and Argentina, bear a striking resemblance to the surface of Mars, which is characterized by a sparse atmosphere and frigid environment. Located at staggering heights of more than 6,000 meters above sea level, these peaks were previously thought to be unsuitable for mammals. However, in a recent study published in a journal, current biology announces a breakthrough discovery. Mummified rats are discovered in these harsh landscapes, pushing the known limits of vertebrate survival on Earth.
“The most surprising thing about our discovery is that mammals can live at the top of volcanoes in such poor conditions. Mars,” said lead author Jay Stoltz, a biologist at the University of Nebraska-Lincoln. “Well-trained climbers can endure such extreme altitudes for a day’s ascent, but the fact that rats actually live at such altitudes suggests that we are a small mammal. This shows that we have underestimated the physiological tolerance of
Storz and his colleagues discovered the first mouse mummified body at the top of the Sarin volcano when they stumbled upon a desiccated corpse on the edge of a rocky mountain. But now that they knew what to look for, they quickly started looking for others.
“My climbing partner and I started exploring the remaining rocks and found seven more mummies on the same summit,” Storz recalls.
Then they began to systematically explore all the volcanic peaks of the Andes. So far, they have searched 21 volcanic peaks, including 18 volcanic peaks over 6,000 meters above sea level. In all, 13 mummified rats were found atop volcanoes over 6,000 meters above sea level. In some cases, the mummies were accompanied by the skeletons of numerous other rats.
A video showing the site where four mummies were excavated from an archaeological site atop Chile’s Pular Volcano (6,233 m).Credit: Jay Stolz
Radiocarbon dating and genetic analysis
Radiocarbon dating has revealed that the mummified rats found atop two volcanoes are at most several decades old. Those from the third site were even older, estimated to be up to 350 years old.Genetic analysis of the mummies at the summit reveals that they seed of the scissor mouse called Philotis Vacalumis known to occur at lower elevations in this region.
“It was a big surprise to find a rat mummy on the top of a wind-swept, frozen volcano,” Storz said. “Combined with live trapping records of rats on the summits and flanks of other high-elevation Andean volcanoes, there is increasing evidence for the existence of long-term settled populations of rats at extreme elevations.”
Exploring the mysteries of mammalian life at high altitudes
The discovery raises important questions, including how mammals can survive in a barren world of rock, ice, and snow, where temperatures never fall below freezing and available oxygen is at about half the ocean surface. There is. It is unknown why the rat climbed to such a height. More than 500 years ago, the Incas were known to perform human and animal sacrifices atop the Andes mountains. However, researchers say the mummified rats found at the top of the volcano could not have been transported by the Incas, and that no rat species is old enough to coexist with the Incas.
In ongoing studies, researchers are investigating whether high-altitude mice have special physiological characteristics that allow them to survive and function under hypoxic conditions. To find out, they are conducting physiological experiments on farmed mice collected from high altitudes. They also continue to conduct mountaineering surveys of small mammals in the high Andean peaks of Argentina, Bolivia, and Chile.
“With mountaineering biology research in the Andes, we continue to make surprising new discoveries about the ecosystems of extreme high-altitude environments,” Storz said.
Reference: “Genomic Insights into the Mystery of the Mouse Mummy on the Summit of Atacama Volcano” Jay F. Storz, Schuyler Liphardt, Marcial Quiroga-Carmona, Naim M. Bautista, Juan C. Opazo, Timothy B. Wheeler, Guillermo D’Elia and Jeffrey M. Good, October 23, 2023 current biology.
DOI: 10.1016/j.cub.2023.08.081
This research was funded by grants from: National Institutes of HealthNational Science Foundation, Geographical Society, FONDECYT.