Ancient humans survived on the Tibetan Plateau- the highest plateau on Earth-during the coldest period of the past 2.5 million years, showcasing their remarkable resilience and adaptability.
The last glacial maximum, which lasted from 26,500 to 19,000 years ago, was the most severe phase of the Late Pleistocene ice age. During this period, massive ice sheets and polar ice caps covered large portions of the Earth, while global temperatures remained approximately 4 degrees Celsius to 5 degrees Celsius lower than today's average, the New Scientist reported.
"The Tibetan Plateau was previously thought to be uninhabitable during the last glacial maximum," says Wenli Li of the University of Chinese Academy of Sciences in Beijing. "Extreme cold, sparse vegetation and low oxygen levels at high altitudes made survival incredibly difficult."
While evidence had shown that humans lived on the plateau before and after the last glacial maximum, no signs of occupation during this period had been found- until now. In 2019, Li and her team uncovered a site 3,800 meters above sea level in the Yarlung Tsangpo River valley on the southern Tibetan Plateau. The site contained numerous artefacts indicating human habitation.
The researchers unearthed 427 artefacts, including stone tools and the first ochre pieces- the red-coloured rock used in ancient art- ever discovered in Tibet.
Radiocarbon dating of ancient bones and charcoal from the site revealed three distinct periods of human occupation between 29,200 and 23,100 years ago. Two of these periods, around 25,000 and 23,000 years ago, coincide with the last glacial maximum.
"No archaeological site had previously been dated to this period," says Feng He of the University of Wisconsin-Madison, who was not involved in the study. "This discovery reinforces the idea that early humans were highly resilient and adaptable to extreme conditions."
To better understand the environment during these occupations, researchers analyzed nearby stalagmites and lake cores, which provide climate data through their chemical composition. Their findings suggest that the river valley had more moisture than expected for the harshly dry ice age in Tibet, allowing cold-tolerant plants and herbivores to persist.
"The valley likely provided essential resources- water, vegetation, and game needed for survival," says Li.
Stone tools found at the site resemble those from older sites farther north in the plateau's interior, suggesting that as the climate became colder and drier, people migrated into the river valley, Li explains.
Previous research had proposed that river valleys on the southern Tibetan Plateau may have served as refuges for Tibetans escaping the intensifying cold of the last glacial maximum, says He. "It's satisfying to see that this discovery supports that hypothesis."
Looking ahead, Li and her team plan to further investigate how climatic shifts during the last glacial maximum influenced human occupation and migration at the site, which they have named Pengbuwuqing after a nearby hill.
