A researcher and a guide were heading towards the summit of the Llullaillaco volcano when a surprising discovery took place. The sleeping volcano can be found on the western side of the Andes Mountains while the southern part meets the Atacama Desert. The guide pointed out a mouse, which was quite surprising since the pair was at the height of 22,000 above the sea level. At first, the researcher did not observe the mouse, which rushed to hide under a rock. While mice may not seem to be something special at first sight, the yellow-rumped leaf-eared mouse represents an important milestone for biology since it the first mammal spotted at such a height. Scientists Discovered A Mammal That Lives At The Highest Elevation In The World With the help of trained reflexes, the scientist managed to catch the mouse in a few minutes. The spectacular rodent is quite sturdy as it leaves in an area where the concentration of oxygen reaches 45% of the one found near the sea-level and temperatures that can fall below 75 degrees Fahrenheit. Another mystery is represented by the diet that is consumed by the petite creature since the vegetation encountered at such heights tends to be close to nonexistent. It is worth noting that the discovery of the mouse may force researchers to alter the current elevational limits for mammals, as it is clear that they are quite resilient. New data could also be obtained by performing more studies on summits, which remain relatively unexplored across the world. Their potential to host animal life has been deemed to be quite low from a theoretical point of view due to the harsh environmental conditions that can be encountered. The expedition was inspired by a video shared by an explorer who visited the summit and spotted a mouse in 2013. Future research will explore the physiological adaptations which allow the mouse species to survive at such heights.