Mice, according to The Hitchhikers Guide to the Galaxy, are not actually of the Earth, but instead hyper-intelligent beings searching for the meaning of life, the universe and everything.
“The whole business with the cheese and the squeaking is just a front,” writes Adams in the cult science fiction book and radio play.
New research suggests Adams wasn’t far wrong.
Publishing in Current Biology, American mountaineer-researchers have demonstrated mice are capable of survival in “Mars-like” extremes akin to outer space.
The authors Professor Jay Storz from the University of Nebraska-Lincoln and fellow mountaineer-researcher Mario Pérez Mamani found mummified and living mice at the summits of volcanos above 6000 metres in altitude.
The team captured living proof – a live specimen of leaf-eared mouse (Phyllis vaccarum) – from the peak of the Llullaillaco volcano (6,739 metres high), in the Puna de Atacama region on the border of Chile and Argentina.
They also discovered mouse burrows and 13 other mummified leaf-eared mice from three neighbouring volcanoes, Salín, Púlar and Copiapó.
Apart from the mice, no other mammal has ever been found surviving at such extreme altitudes.
In the 1970s and 80s mice cadavers had been found on Andean peaks, but archaeologists thought the rodents had most likely hitched a ride with Incas.
However, the new evidence suggests it is more likely the mice reached the summits by themselves, and continued to survive there.
Storz says the high-altitude environments the mice have been found in rank among the most inhospitable on the planet. The environment is so arid, cold and oxygen-poor that NASA has visited the Atacama to practice searching for life on Mars.
“Even at the base of the volcanoes, the mice are living in an extreme, Martian environment,” he says. “And then, on the summits of the volcanoes, it’s even more so. It feels like outer space.
“It just boggles the mind that any kind of animal, let alone a warm-blooded mammal, could be surviving and functioning in that environment.”
The researchers wondered whether the mummified mice might be a distinct sub-population of the leaf-eared rodent, with a different evolutionary history. But by comparing the mummified mice DNA with that of other leaf-eared mice (from different altitudes in the Atacama Desert) shows the genomic data is all very similar.
“All are one big happy family,” says Storz. While further evidence – such as the equal ratio of males to females among the mouse mummies – suggests the mice were mountaineers rather than hitchhikers.
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