Mysterious rat mummies found in Mars-like conditions on Andes peaks

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With temperatures reaching freezing point -40°C (minus 40 degrees Fahrenheit) and vegetation Hundreds and sometimes thousands of meters below the mountaintops, the peaks of the Andes maintain an extremely harsh environment.

So how did a species of leaf-eared mouse make this barren land its home?

This is the question posed by a team of scientists Argentina, Chile, Bolivia and the United States They are looking for an answer after discovering 13 mummified mice at altitudes of more than 6,000 meters (19,685 feet) in… Atacama Plateau in Chile and Argentina. Their discovery also proves that this species is the highest living mammal in the world, according to the study Recently published in Current Biology.

The mice, called Phyllotis vaccarum, are commonly found living in the Andes at lower elevations, along the Down to the sea level. In 2020, A live mouse has been recorded at the summit of Llullaillaco, a high volcano 6,739 metres (about 22,110 feet) on the Chilean border. He currently holds the world record for The highest living mammalssaid Jay Stowers, co-author of the new study and the 2020 study.

The discovery of the living mouse prompted Storrs to conduct expeditions to 21 different volcanoes. The 13 mummified mice were found at the Saline, Polar and Copiap volcanoes.

“Every time we find anything at those extremely high altitudes, we’re completely blown away,” Stowers said. Professor of Biology at the University of Nebraska-Lincoln. “It’s really hard to overstate how harsh these environments are.”

At the top of these volcanoes, each breath of air contains only about 40 percent of the oxygen available at sea level, Stowers said. Temperatures rarely rise above freezing, and wind forces are so strong, they were once recorded at speeds exceeding 116 miles per hour from the National Weather Station at an elevation of 6,505 meters (21,342 feet).

Furthermore, the environment has been described as being Mars-like. In 2021, NASA researchers studied the environment in an attempt to “understand how the building blocks of life might respond to Martian conditions over time.” According to its website.

Freeze-dried rat mummies

Although the conditions are not ideal for the organisms, they create ideal conditions for preservation, as the mice are essentially freeze-dried, Stowers said. Under normal circumstances, stuffed mice are difficult to obtain because most deaths occur due to predators. But high in the mountains, mice have no predators.

The researchers conducted Radiocarbon – a method that uses the amount of carbon from an organism’s material to estimate its age – which indicated that the oldest mummies are no more than 350 years old, while some may have died more recently, according to the study.

Storz pointed to previous reports of rodents, where archaeologists believed that rats were used as part of… Inca rituals. Since the samples are not as old as the Inca civilization (More than 500 years), this theory has been ruled out.

“It’s still a mystery as to why they’re there — why they ascend to such extreme altitudes — but it’s also clear that they got there on their own,” Stowers said, noting that the team also found evidence of active burrows at high altitudes.

Stowers said that the research team is currently conducting research on 31 live trapped mice, including the record-holder, to try to understand how this species can survive in harsh conditions. The research will also include analyzes of their gut contents to find what the mice were eating.

One theory is that mice eat lichens, which are a combination of the two Mushrooms and algaeThis is also a common part of, Stowers said Some diets of arctic mammalsAnother example of a harsh, arid environment. Lichens, as well as other algae and small arthropods, develop from the flow of water vapor and hot gases from the volcano’s soil crust. Emmanuel Fabian Roberto, Environmental scientist in Argentine Institute of Dryland Research in Mendoza, Argentina, told CNN in an email.

The second theory is that plant remains, small insects and other food resources are carried by the wind to the mountaintops, Fabian Roberto said.

“It was thought that life at such high altitudes was impossible for mammals,” said Fabian Roberto, who was not involved in the study. “These observations exceed previous records in the Himalayas and other mountain ranges, challenging what we thought we knew about species’ abilities to survive.”

Life finds its way in harsh environments

The leaf-eared mouse weighs Average 55 grams (about 1.9 ounces). As more research is done, scientists hope to learn how the tiny mouse can maintain a constant body temperature at such high altitudes, when the rate of heat loss can lead to hypothermia and death within minutes, Fabian Roberto said.

Stowers said that one of the main reasons for the species’ success could be its ability to adapt to higher altitudes, as rats have been observed to be active during the day, rather than at night like their counterparts at lower altitudes.

“Life always seems to find a way no matter how hostile the environment,” Storz said. He hopes this discovery will shed light on how evolution has equipped animals to live in environments that were originally thought to be uninhabitable.