Aug. 9 (UPI) -- Archaeologists have found a 30,000-years-old rock shelter in Ethiopia. The ancient site is the earliest evidence of high-altitude living, according to a new study published in the journal Science.
The newly discovered shelter housed foragers during the Middle Stone Age, a period of African prehistory dating from 280,000 years ago to approximately 25,000 years ago. Scientists found the rock shelter in Ethiopia's Bale Mountains.
Given the physiological challenges of life at high altitudes, researchers assumed high altitude living was a rather recent phenomenon. The latest discovery suggests early humans were venturing above 11,000 feet as early as 30,000 years ago.
The Bale Mountains shelter is the oldest high-altitude shelter in the world, but in recent years, scientists have found a number prehistoric shelters in Andean and Tibetan plateaus.
But while early hunter gatherers began exploring higher elevations earlier than scientists thought, these high elevation sites remain rare. And just as they did for these early humans, the sites presented numerous challenges for archaeologists. Excavation tools had to be brought in with the help of mules.
The high-elevation dig revealed locally collected stones, animal bones and fire hearths. Scientists also found what they estimated to be human feces, as well as an "abundance of lithic artifacts and human-accumulated fauna," as they detailed in their paper.
Researchers dated the artifacts to the Late Pleistocene, between 47,000 and 31,000 years ago.
Though scientists can't say whether the shelter was permanently occupied, the evidence suggests it was at least periodically in use for several thousand years.
In an accompanying "perspective" published in the journal Science, anthropologist Mark Aldenderfer questioned the dating efforts used at previous high-elevation excavations and criticized the certainty with which the interpretations of previous high-elevation excavations have been presented.
"Words matter, and it's time for archaeologists working on the world's high plateaus to be more deliberate about the terms they use to describe and frame their findings," Aldenderfer wrote.
Aldenderfer was complimentary of the latest study, calling the restraint in not overstating their findings "admirable."