Mysterious Mouse Mummies Unearthed in Mars-like Conditions of Andes Mountain Peaks
Thirteen mouse mummies, an intriguing find in the Andean mountains, have defied expectations by thriving at extreme elevations once considered inhospitable to mammals
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The summits of the Andes mountains endure an incredibly severe environment, with frigid temperatures plunging as low as minus 40 degrees Celsius (minus 40 degrees Fahrenheit) and vegetation thriving hundreds and even thousands of meters below.
The researchers from Argentina, Chile, Bolivia, and the United States are investigating how a particular species of leaf-eared mouse adapted to live in this desolate area. Their investigation was sparked by the discovery of 13 mummified mice at elevations above 6,000 meters (19,685 feet) on the Atacama Plateau in Chile and Argentina. This finding reinforces the fact that this species is the highest dwelling mammal in the world, as stated in the study published in Current Biology.
The mice, known as Phyllotis vaccarum, are typically found inhabiting the Andes mountains, ranging from lower altitudes to sea level. In 2020, a live mouse was observed at the peak of Llullaillaco, a volcano reaching 6,739 meters (about 22,110 feet) in elevation on the Chilean border. It currently holds the record for being the highest living mammal, as disclosed by Jay Storz, co-author of the new and 2020 studies.
Upon the discovery of the living mouse, Storz initiated expeditions to 21 different volcanoes. During these endeavors, 13 mummified mice were discovered on the Salín, Púlar, and Copiapó volcanoes.
The summits of the Andes mountains are harsh environments with no vegetation, freezing temperatures and winds at over 100 miles per hour.
Jay Storz, a biology professor at the University of Nebraska-Lincoln, expressed astonishment at the discoveries made at these exceptionally high altitudes. He emphasized the incredibly harsh conditions of these environments, stating that it is difficult to fully convey their hostility.
Atop these volcanoes, the air offers a mere 40% of the oxygen found at sea level, noted Storz. Additionally, temperatures seldom reach above freezing, and the wind gusts are immensely powerful, reaching a recorded speed of over 116 miles per hour at a 6,505-meter (21,342-foot) National Geographic weather station.
Moreover, this environment has been likened to that of Mars. In 2021, NASA scientists examined this setting to gain insights into "how the fundamental components of life could withstand and adapt to Martian conditions over an extended period," as stated on the organization's website.
Freeze-dried mouse mummies are created due to the unfavorable living conditions, which, in turn, provide optimal conditions for preservation, according to Storz. Typically, it's difficult to find mummified mice due to predator-related deaths. However, in the mountains' higher altitudes, these mice lack natural predators.
Following the Chicxulub impact several weeks or months ago, the surviving non-avian dinosaurs are struggling to survive. The intense heat generated by the falling debris initially caused such a drastic rise in temperature that numerous animals perished within mere days. As time passed, our planet's atmosphere became filled with soot, dust, and other deposits, blocking out the Sun and causing global temperatures to plummet. Without sunlight for photosynthesis, plant life across the globe gradually withered away, resulting in the collapse of the entire food chain. In this desolate landscape, a solitary, wounded Dakotaraptor carefully surveys the remnants of her territory, which will later be notoriously known as Hell Creek, 66 million years into the future.
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The researchers used radiocarbon dating, a method that estimates the age of organism material by measuring its carbon content, to determine the age of the mummies. The results showed that the oldest mummies were no more than 350 years old, suggesting that some may have recently died. This contradicts previous theories that the mice were used in Incan rituals, as they are not as old as the Inca civilization.
"It remains a perplexing enigma as to the reasons behind their presence - why they would willingly scale such unfathomable heights. However, one thing is certain - they achieved this feat unaided," stated Storz. He further added that the team had also stumbled upon proof of burrows actively inhabited at these dizzying altitudes.
Currently, the team of researchers is engrossed in studying 31 mice, all captured alive, which encompasses the mouse that holds the record for such extraordinary survival. Storz mentioned that their objective is to comprehend how this species manages to endure in such extreme circumstances. The investigation will also involve scrutinizing the contents of their digestive tracts to ascertain their dietary habits.
Courtesy ZSL
The giant chicken frog is facing extinction due to a deadly fungus that affects amphibians. According to one theory, mice consume lichens, which are a combination of fungus and algae. These lichens are also a common part of the diet for some Arctic mammals, highlighting the challenging conditions of their environment. Mosses and small arthropods also thrive in this environment, developing from the vapor and hot gases emitted by volcanic soil crusts, as explained by Emmanuel Fabián Ruperto, an ecologist at the Argentine Institute for Dryland Research in Mendoza, Argentina, via email to CNN.
According to Fabián-Ruperto, there is another theory suggesting that plant fragments, small insects, and other food sources are transported to the mountain peaks by the wind. Fabián-Ruperto, who was not part of the study, stated that living at such extreme elevations was previously believed to be impossible for mammals. These recent observations exceed previous records in the Himalayas and other mountains, questioning our understanding of species' ability to survive in these conditions.
In extreme environments, life adapts and thrives. Researchers are particularly interested in the leaf-eared mouse, which weighs around 55 grams (approximately 1.9 ounces). They are studying how this small mouse manages to regulate its body temperature effectively at high altitudes. Despite the risk of rapid heat loss, which could lead to hypothermia and death within minutes, the mouse survives. Further investigation is needed to understand this phenomenon.
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The species' adaptability in higher altitudes, where the mice are active during the daytime, instead of at night like their counterparts at lower altitudes, could be a key factor contributing to their success, according to Storz. "No matter how hostile the environment may be, life always manages to find a way," Storz noted. He hopes this discovery sheds light on how animals can evolve to thrive in environments that were previously considered uninhabitable.
