An ancient species of humans lived on the Tibetan Plateau before modern man, scientists believe.
Denisovans, an ancient ancestor of modern humans, may have inhabited the harsh environment tens of thousands of years before previously thought.
The Tibetan Plateau has an annual temperature around freezing and is 4,000 metres (12,000 feet) above sea level.
Extreme altitude at the plateau makes survival tough and modern-day Tibetans carry remnants of Denisovan DNA.
Previous research has claimed humans didn’t inhabit the inhospitable region until 3,600 years ago.
Analysis at an archaeological site called Nwya Devu provided evidence that the first traces of humanity at the site predate this considerably.
‘What we know is that the Denisovans left their homeland in the Altai Mountains of southern Siberia and eventually trekked all the way to Melanesia [the islands northeast of Australia], taking with them their signature genome,’ Dr John Olsen at the University of Arizona in Tucson told New Scientist.
‘One logical route for such a migration may have included passage up and over the Tibetan Plateau.’
The site has long been used by academics and has wielded several hauls of artefacts, including stone tools.
Dating techniques used by the researchers found the earliest tools date back to between 40,000 and 30,000 years old.
Most Tibetans carry a novel piece of DNA in their genome which is believed to originate from the interbreeding between Homo sapiens and members of the cousin species Denisovans.