Melting ice reveals new clues to ancestors of ancient Asian empire
On top of the world mountain regions, life needs ice. From the Rockies to the Himalayas, glaciers and other accumulations of snow and ice persist year round. Often found on shady slopes protected from the sun, these patches of ice turn arid peaks into biological hotspots.
As an archaeologist, I appreciate these patches of snow and ice for the rare glimpse they can offer in time through the fog of prehistoric alpine times. When people lose things in the ice, the ice sheets act like natural freezers. For thousands of years, they can store snapshots of the culture, daily life, technology, and behavior of the people who created these artifacts.
Frozen heritage is melting mountain ice in all hemispheres. In doing so, small groups of archaeologists scramble to muster the funds and personnel necessary to identify, recover and study these objects before they disappear.
Along with a group of academics from the University of Colorado, the National Museum of Mongolia and partners around the world, I work to identify, analyze and preserve ancient materials emerging from the ice in the grassy steppes of Mongolia, where such discoveries have a huge impact on how scientists understand the past.
Life on the ice
During the hot summer months, unique plants thrive on the well-watered margins of the ice patches. Large animals like caribou, elk, sheep, and even bison seek ice to cool off or escape insects.
Because ice patches are predictable sources of these plants and animals, as well as fresh water, they are important to the livelihoods of neighboring populations almost wherever they are found. In the dry steppes of Mongolia, meltwater from mountain ice feeds summer pastures, and domestic reindeer seek ice in much the same way as their wild counterparts. Aside from global warming, the ice margins act as magnets for people – and deposits of the materials they leave behind.
It is not only their biological and cultural significance that makes patches of ice important tools for understanding the past. Tangible objects made and used by early hunters or herders in many mountainous regions were constructed from soft organic materials.
These fragile objects rarely survive erosion, weathering and exposure to the harsh elements that are common in alpine areas. If tossed or lost in ice, however, items that would otherwise degrade can be stored for centuries under freezing conditions.
But high mountains experience extreme weather conditions and are often far from urban centers where modern researchers are concentrated. For these reasons, the important contributions of mountain dwellers to human history are sometimes excluded from archaeological records.
For example, in Mongolia, the high mountains of Altai were home to the oldest pastoral societies in the region. But these cultures are only known through a small handful of graves and the ruins of a few windswept stone buildings.
More and more artifacts are melting ice
One of our findings was a piece of finely woven animal hair rope from a slab of melting ice on top of a mountain in western Mongolia. During the investigation, we spotted him lying among the exposed rocks at the edge of the receding ice.
The artifact, which may have been part of a bridle or harness, looked like it had been thrown in the ice the day before. Our guides even recognized the traditional manufacturing technique. However, scientific radiocarbon dating has revealed that the artifact is actually over 1,500 years old.
Objects like these provide rare clues to the daily life of the ancient shepherds of western Mongolia. Their excellent preservation allows us to perform advanced laboratory analyzes to reconstruct the materials and choices of the first livestock cultures that ultimately gave birth to pan-Eurasian empires like the Xiongnu and the Great Mongol Empire.
For example, scanning electron microscopy allowed us to determine that camel hair was chosen as the fiber to make this rope bridle, while the collagen retained in ancient tendons revealed that deer tissue was used for hanging a Bronze Age arrowhead at its shank.
Sometimes the objects that emerge end up overturning some of archaeologists’ most basic assumptions about the past. The locals have long been classified as herding societies, but my colleagues and I found that Mongolian glaciers and ice patches also contained hunting artefacts, like spears and arrows, and large skeletal remains. game such as the argali sheep spanning a period of more than three millennia.
These findings demonstrate that big game hunting on mountain ice has been an essential part of pastoral livelihood and culture in the Altai Mountains for thousands of years.
But time is running out. The summer of 2021 is shaping up to be one of the hottest on record, as scorching summer temperatures fry the rainforests of the Pacific Northwest and forest fires ravage the Siberian Arctic. The impact of escalating temperatures is particularly severe in cold regions of the world.
In the region my colleagues and I study in western Mongolia, satellite photos show that more than 40 percent of the ice cover has disappeared in the past three decades. Once each artifact is exposed to melting ice, it may only have a limited window of time for scientists to retrieve before it is damaged, degraded, or lost due to the combination of freezing, thaw, weather conditions and glacial activity that can affect previously frozen artefacts.
Due to the magnitude of modern climate change, it is difficult to quantify the amount of material lost. Most of the high mountains of Central and South Asia have never been systematically studied for molten artifacts.
In addition, many international projects have not been able to continue since the summer of 2019 due to the Covid-19 pandemic – which has also resulted in cuts, wage cuts and even complete closures of archeology departments. in major universities.
Revealed by warming, providing climatic clues
Ice sheet artifacts are irreplaceable scientific data sets that can also help researchers characterize ancient responses to climate change and understand how modern warming can affect the world today.
In addition to the man-made artifacts left in the snow, the ice patches also preserve “ecofacts” – natural materials that track important ecological changes, such as the shifting of the tree line or the modification of tree habitats. animals. By collecting and interpreting these datasets as well as ice artifacts, scientists can gather information about how people have adapted to significant ecological changes in the past, and perhaps expand the toolkit for tackle the climate crisis of the 21st century.
Meanwhile, plant, animal and human communities that depend on shrinking ice sheets are also at risk. In northern Mongolia, my work shows that summer ice loss is detrimental to the health of domestic reindeer.
Local ranchers are concerned about the impact of the loss of ice on the viability of pastures. Melting ice is also converging with other environmental changes: in western Mongolia, animal populations have declined dramatically due to poaching and poorly regulated tourist hunting.
As the rising heat exposes artifacts that provide insight into ancient climate resilience and other important scientific data, the loss of ice itself is reducing humanity’s resilience for years to come.
This article originally appeared on The Conversation by Guillaume Taylor to University of Colorado Boulder. Read the original article here.