Rat mummies are found in a hostile environment on the top of the Andes mountains

With freezing temperatures of up to 40 degrees Celsius Negatives and vegetation hundreds and sometimes thousands of meters below the mountain tops, the Andes mountain tops maintain an extremely hostile environment.

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

This is the question that a team of scientists from Argentina, Chile, Bolivia and the United States is trying to respond after discovering 13 mummified rats at altitudes above 6,000 meters in the Atacama plateau, in Chile and Argentina.

The discovery further proves that the species is the highest living mammal in the world, according to the study recently published in Current Biology.

The mice, called Phyllotis vaccarumare commonly found living in the Andes mountains, at lower altitudes, up to the level from the sea.

In 2020, a live rat has been recorded at the summit of Llullaillaco, a volcano with 6,739 meters of altitude on the border with Chile. He currently holds the world record for mammal living in a higher placesaid Jay Storz, co-author of the new and 2020 study.

The discovery of the live mouse spurred Storz to undertake expeditions to 21 different volcanoes. The 13 mummified rats were found on the Salín, Púlar and Copiapό volcanoes.

“Every time we find something at these extreme altitudes, we are completely amazed,” said Storz, professor of biology at the University of Nebraska-Lincoln. “It’s really hard to overstate how inhospitable these environments are.”

At the summit of these volcanoes, each breath of air contains only about 40% of the oxygen available at sea level, Storz said. Temperatures also rarely rise above freezing and wind forces are extremely strong, once recorded at more than 116 miles per hour from a National Geographic weather station at 6,505 feet.

Furthermore, the environment has been described as similar to that of Mars. In 2021, NASA researchers studied the environment in an effort to “understand how the building blocks of life may respond to Martian conditions over time,” according to your website.

Freeze-dried rat mummies

While the conditions are not ideal for living creatures, they create perfect conditions for preservation, as the mice are essentially freeze-dried, Storz said. Under normal circumstances, it is difficult to find mummified rats since most deaths are caused by predators. But high in the mountains, rats have no predators.

The researchers carried out radiocarbon dating — a method that uses the amount of carbon in an organism’s material to estimate its age — which indicated that the oldest mummies were no more than 350 years old, while some could have died recently, according to the study.

Storz pointed to previous accounts of the rodent, where archaeologists thought rats would be used as part of inca rituals. As the samples are not as old as the Inca civilization (more than 500 years), this theory was discarded.

“It’s still a mystery why they’re there — why they would rise to these extreme elevations — but it’s also clear that they got there on their own,” said Storz, who also noted that the team has found evidence of active burrows at high elevations. altitudes.

The team of researchers is currently conducting research on 31 mice trapped in live traps, including the record-breaking mouse, to try to understand how the species can survive in extreme conditions, Storz said. The research will also include analysis of intestinal contents to find out what the rats have been eating.

One theory is that rats eat lichens, a combination of a fungus and an algasaid Storz, which is also a common part of diet of some Arctic mammalsanother example of an arid and sterile environment.

Lichens, like other mosses and small arthropods, develop from the release of water vapor and hot gases from the volcano’s soil crust, the ecologist said. Emmanuel Fabián Ruperto, of Argentine Dry Land Research Institute in Mendoza, Argentina, at CNN by email.

A second theory is that plant fragments, small insects and other food resources are carried by the wind to mountaintops, Fabián-Ruperto said.

“It was believed that life at such high altitudes was impossible for mammals,” said Fabián-Ruperto, who was not involved in the study. “These observations surpass previous records in the Himalayas and other mountain ranges, challenging what we thought we knew about the species’ survival capabilities.”

Life in extreme environments

The leaf-eared mouse weighs in average 55 grams. With more research, scientists hope to learn how the little mouse manages to maintain a stable body temperature at such high altitudes, when the rate of heat loss could lead the mouse to hypothermia and death within minutes, Fabián-Ruperto said.

One of the main reasons for the species’ success may be its adaptability to higher altitudes, where the mice have been observed to be active during the day, rather than nocturnal like their low-altitude counterparts, Storz said.

“Life always seems to find a way, no matter how hostile the environment may be,” Storz said. He hopes this discovery will illuminate how evolution can equip animals to live in environments originally considered uninhabitable.