For the first time, a date has been identified when the elite of the Mongol Empire drank yak milk, specifically the 13th century, thanks to an aristocratic cemetery preserved in permafrost.
By analyzing proteins found in ancient dental calculus, an international team of researchers provides direct evidence for milk consumption from multiple ruminants, including the yak. In addition, they discovered milk and blood proteins associated with both horses and ruminants. The team's results are published in Communications Biology.
The study presents new protein findings from an elite Mongol-era burial ground with exceptional preservation in permafrost. This is the first example of yak milk recovered from an archaeological context.
Previous research indicates that milk has been a critical resource in Mongolia for more than 5,000 years. While the consumption of cow, sheep, goat, and even horse milk has been securely dated, until now, it has been difficult to pinpoint when people started drinking yak milk. Understanding when and where humans domesticated this iconic species has been limited to rarely recovered yak remains and artistic depictions of yaks. However, it is not clear if they are wild or domestic.
The discovery of an elite Mongol-era burial ground in northern Mongolia stunned researchers. "Our most important find was an elite woman buried wearing a birch bark hat called a bogtog and silk robes depicting a five-clawed golden dragon. Our proteomic analyzes concluded that she drank yak milk throughout her life," he said in a statement. Alicia Ventresca-Miller, an assistant professor of anthropology at the University of Michigan, said in a statement. "This helped us verify the long-term use of this iconic animal in the region and its links to elite rulers."
Located along a high-altitude ridge shrouded in mist, the location is named after Khorig, which means taboo. It may be that this burial ground was considered elite, as researchers recovered evidence of connections to the ruling elite, including a five-clawed dragon depicted on a Cizhou vessel and a traditional or deel robe.
"Ceramic vessels were turned into lanterns made of dairy products, revealing religious ideas and daily life for the elites of the Mongol empire," said J. Bayarsaikhan, a researcher at the Max Planck Institute for the Science of Human History and the National Museum of Mongolia.
Archaeologists have spent years collecting and preserving pieces of silk and leather scattered on the surface near burials. Unfortunately, in recent decades the permafrost has begun to thaw and the sites have been heavily looted. "The degree of looting we're seeing is unprecedented. Almost all of the burials we can locate on the surface have recently been destroyed by looting activity," said Julia Clark of Nomad Science.
Archaeologists have long suspected this area to be important and it remains one of the main yak grazing areas today. While much was lost to looters, what remained of the burials was still well preserved within the permafrost.
An international team of researchers used proteomic analysis of dental calculus to identify the diets of Mongol-era elites. They found proteins associated with milk, blood, and other tissues that had been consumed by different individuals.
"What's really exciting is that between cows and yaks, there is only one amino acid sequence difference in the most frequently recovered milk protein, and in this case, we were able to recover the part that is specific to the yak." yak, Bos mutus," said study co-director and paleoproteomic specialist Shevan Wilkin of the University of Zurich and the Max Planck Institute for the Science of Human History.
Due to the incredible preservation made possible by the environmental conditions of the permafrost, the team was able to identify intriguing proteins recovered from archaeological samples for the first time. These included mare's milk curd proteins, as well as caprine and equine blood proteins that had not previously been recovered from dental calculus.
