Newswise — The Tibetan Plateau, often referred to as the "third pole" or the "roof of the world", is a hostile and inhospitable environment on Earth. Despite early Tibetans evolving through positive natural selection in certain genomic loci to better cope with the high altitudes, obtaining enough food from the scarce resources of the highlands would have remained a formidable challenge.

A recent study published in the journal Science Advances has shed light on the dietary habits of early humans living on the Tibetan Plateau. The study utilized ancient proteins extracted from the dental calculus of 40 human individuals from 15 different sites across the interior plateau.

The findings of the study suggest that dairy played a significant role in the early human diets of the region. The presence of dairy-related proteins in the dental calculus of these ancient individuals indicates that they likely consumed dairy products, such as milk and cheese, as a substantial part of their diet. This discovery challenges the previous notion that early humans in this harsh environment had limited access to food resources and were primarily dependent on hunting and gathering.

“We tried to include all the excavated individuals with sufficient calculus preservation from the study region,” states Li Tang, lead author of the study. “Our protein evidence shows that dairying was introduced onto the hinterland plateau by at least 3500 years ago,” states Prof. Hongliang Lu, corresponding author of this study.

The ancient protein evidence from the study suggests that dairy products were consumed by various populations on the Tibetan Plateau, including both females and males, adults and children, as well as individuals from different burial contexts, including elite and non-elite contexts. This indicates that dairy consumption was not limited to a specific group, but was a widespread practice among diverse populations in the region.

Furthermore, the study reveals that different types of animals were utilized as sources of dairy, including goats, sheep, and possibly cattle and yak. This suggests that early pastoralists on the Tibetan Plateau made use of a variety of domesticated animals for their dairy needs. Interestingly, the research also indicates that there was a preference for goat milk among early pastoralists in western Tibet.

“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. 

Tracing dairying in the deep past has long been a challenge for researchers. Traditionally, archaeologists analyzed 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. 

Dr. Shevan Wilkin, co-author of the study, emphasizes the significance of palaeoproteomics as a new and powerful tool for investigating Tibetan diets in unprecedented detail. The analysis of proteins in ancient human dental calculus has provided direct evidence of dietary intake and has enabled researchers to identify the species of milk consumed.

Palaeoproteomics, which involves the analysis of ancient proteins, has emerged as a cutting-edge technique that allows researchers to gain insights into the diets of ancient populations with high precision. By examining proteins preserved in dental calculus, researchers can directly determine the types of food consumed by individuals in the past, including the identification of specific animal species from which the milk originated.

This breakthrough in the field of palaeoproteomics has provided valuable information about the ancient diets of Tibetan populations, shedding light on the consumption of dairy products and the species of animals that were utilized as sources of milk. It demonstrates the power of innovative scientific techniques in uncovering new details about past human cultures and lifestyles, and highlights the importance of interdisciplinary approaches in advancing our understanding of human history and evolution.

"We were thrilled to discover a remarkably distinct trend," exclaimed Li Tang. "All the milk peptides we analyzed originated from ancient individuals in the western and northern steppes, where agricultural cultivation was exceptionally challenging. Surprisingly, we did not detect any milk proteins from the southern-central and south-eastern valleys, where more fertile land for farming was abundant."

Astoundingly, every individual with compelling evidence of milk consumption was unearthed from sites situated at an elevation higher than 3700 meters above sea level (masl). Nearly half of them were found above 4000 masl, with the most astounding discovery made at the extreme altitude of 4654 masl.

"Undoubtedly, it is evident that dairying played a pivotal role in sustaining early pastoralist communities in the highlands," remarked Professor Shargan Wangdue. Li Tang further concluded, "The ability of ruminant animals to efficiently convert the energy stored in alpine pastures into nutritious milk and meat fueled the expansion of human populations into some of the most challenging environments on Earth."

Journal Link: Science Advances