The Tibetan Plateau, known as the "third pole", or "roof of the world", is one of the most inhospitable environments on Earth. While positive natural selection at several genomic loci enabled early Tibetans to better adapt to high elevations, obtaining sufficient food from the resource-poor highlands would have remained a challenge.
Now, a new study in the journal Science Advances reveals that dairy was a key component of early human diets on the Tibetan Plateau. The study reports ancient proteins from the dental calculus of 40 human individuals from 15 sites across the interior plateau.
[...] Ancient protein evidence indicates that dairy products were consumed by diverse populations, including females and males, adults and children, as well as individuals 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. Early pastoralists in western Tibet seem to have had a preference for goat milk.
"The adoption of dairy pastoralism helped to revolutionize people's ability to occupy much of the plateau, particularly the vast areas too extreme for crop cultivation," says Prof. Nicole Boivin, senior author of the study.
[...] "We were excited to observe an incredibly clear pattern," says Li Tang. "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."
Surprisingly, all the individuals with evidence for milk consumption were recovered from sites higher than 3700 meters above sea level (masl); almost half were above 4000 masl, with the highest at the extreme altitude of 4654 masl.
"It is clear that dairying was crucial in supporting early pastoralist occupation of the highlands," notes Prof. Shargan Wangdue. "Ruminant animals could convert the energy locked in alpine pastures into nutritional milk and meat, and this fueled the expansion of human populations into some of the world's most extreme environments." Li Tang concludes.
Journal Reference:
Li Tang, Shevan Wilkin, Kristine Korzow Richter, et al., Palaeoproteomic evidence reveals dairying supported prehistoric occupation of the highland Tibetan Plateau [open], Sci. Adv., 2023. DOI: 10.1126/sciadv.adf0345 [doi.org]