Conditions on the peak of Llullaillaco, 6739 above sea level, are cold, dry and hostile – but some mice somehow survive there

A leaf-eared mouse (Phyllotis vaccarum) found near the summit of Llullaillaco
Marcial Quiroga-Carmona
The environment near the summit of Llullaillaco — a massive Andean volcano straddling the border of Argentina and Chile — is hostile to animal life: perpetually frigid, exceptionally dry and oxygen poor. But scientists found mice there in 2020, and their latest research adds to evidence that the tiny rodents may actually make the highest reaches of the volcanic peak their home.
A couple of years ago, Jay Storz at the University of Nebraska in Lincoln and Thomas Bowen at California …