Ancient Tibetans thrived in one of Earth’s most inhospitable environments with the help of dairy foods, new research suggests.

The Tibetan Plateau, also known as the third pole – or roof of the world, is one of the most inhospitable environments on the planet.

Researchers say that while positive natural selection enabled early Tibetans to better adapt to high elevations, obtaining sufficient food in that environment would have been a challenge.

However, a new study reveals dairy was a key component of early human diets on the Tibetan Plateau.

The scientists report on the ancient proteins from the dental plaque of 40 humans from 15 sites.

Professor Hongliang Lu, Centre for Archaeological Science at Sichuan University, China, said: “We tried to include all the excavated individuals with sufficient calculus preservation from the study region.

“Our protein evidence shows that dairying was introduced onto the hinterland plateau by at least 3,500 years ago.”

Data indicates dairy products were consumed by individuals of all ages across diverse populations, as well as people from both elite and non-elite burial contexts.

Additionally, prehistoric Tibetan highlanders made use of the dairy products of goats, sheep, and possibly cattle and yak, the researchers say.

Senior author of the study, Professor Nicole Boivin, Max Planck Institute of Geoanthropology, said: “The adoption of dairy pastoralism helped to revolutionise people’s ability to occupy much of the plateau, particularly the vast areas too extreme for crop cultivation.”

Tracing the consumption of dairy in the deep past has long been a challenge for researchers.

Traditionally, archaeologists analysed the remains of animals and the interiors of food containers for evidence of dairying, however the ability of these sources to provide direct evidence of milk consumption is often limited.

Li Tang, also of the Max Planck Institute of Geoanthropology, said: “We were excited to observe an incredibly clear pattern.

“All our milk peptides came from ancient individuals in the western and northern steppes, where growing crops is extremely difficult.

!However, we did not detect any milk proteins from the southern-central and south-eastern valleys, where more farmable land is available.”

The researchers said that surprisingly, all the individuals with evidence for milk consumption were recovered from sites higher than 3,700 metres above sea level –  almost half were above 4,000 metres, with the highest at the extreme altitude of 4,654 metres above sea level.

The findings are published in the Science Advances journal.