Stone Age humans once sought refuge in lava tube caves

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People who lived in The Arabian Peninsula Thousands of years ago they went underground when they wanted to beat the heat. They likely stopped there as they moved between oases and grasslands, then delved into vast underground tunnels where molten lava flowed millions of years ago, according to a recent study.

The beginning in stone AgeArchaeologists have discovered that Neolithic herders descended and occupied these vast tunnels, known as lava tubes. The cool air underground would have provided respite from the sun and wind, and for thousands of years, humans took shelter with their livestock in tunnels. The researchers reported April 17 in the magazine that the shepherds left behind items and carved images into the rock walls One plus.

In the Harrat Khaybar lava field, about 78 miles (125 kilometers) north of Medina in Saudi Arabia, there is a tunnel system called Umm Jarsan, which is the longest in the region. Scientists have not yet confirmed the age of the lava that formed this system, but A 2007 study It has been suggested that it is about 3 million years old. Umm Jarsan extends over a mile (about 1.5 km), with walkways up to 39 feet (12 m) high and up to 148 feet (45 m) wide.

Archaeologists in Umm Jarsan recently found animal bones dating back to between 400 years and more than 4,000 years old, and human remains ranging in age from 150 years to about 6,000 years. The research team also found pieces of cloth, pieces of carved wood and dozens of stone tools, the first evidence that humans have been using tunnels for at least 7,000 years.

“From previous reports we knew that fossils were preserved at the site,” said the study's lead author. Dr. Matthew Stewarta research fellow at the Australian Research Center for Human Evolution at Griffith University in Australia.

“However, we did not expect to find evidence of human presence in the form of rock art, stone artefacts, stone structures, and pottery,” Stewart told CNN via email. “People have used and occupied these lava tubes for thousands of years. While most research in the Arabian Peninsula focuses on surface sites, underground sites like Umm Jarsan offer huge potential to fill some of the data gaps.”

He said that this discovery highlights the importance of Umm Jarsan and other tunnels for understanding human spread in the region Guillaume CharlotArchaeologist at the French National Center for Scientific Research. Overall, knowledge about ancient climate and humans in northwest Arabia is limited, “particularly during the transitional phase between the Neolithic and the beginning of the second millennium,” said Charlox, who studies ancient sites in Saudi Arabia but was not involved in the new study. research. .

Around this time, local people were settling around the recently formed oases; The emergence of these desert refuges will shape human migration patterns in the region for thousands of years, he said via email. “It seems to me that the main contribution of this innovative and major research project is that it highlights the long-term use – and perhaps temporary occupation – of this type of cave, which has remained unstudied, and its enormous potential, particularly for understanding ancient ecological contexts.”

For nearly 15 years, Stewart and his colleagues have been compiling evidence of ancient human life in the Arabian Peninsula, mostly from sites around lake deposits, Stewart said. About 400,000 years ago, recurring wet periods saturated the Arabian deserts with rainfall. During the “Green Arabia” phases, lakes and ponds abounded and the landscape flourished with lush vegetation, leading to waves of migrating humans who spread across southwest Asia, Stewart and other researchers reported earlier in the journal. nature.

But the last phase of green Arabia was about 55,000 years ago, and the harsh desert environments do not match the archaeological evidence. Stewart noted that while stone tools are well preserved in dry deserts, bones and other organic materials are easily decomposed and destroyed by abrasion and extreme heat and cold, leaving little for researchers to interpret.

“To this end, in 2019 we decided to investigate underground places where organic materials and sediments could be better preserved,” he said.

So the scholars turned their attention to Umm Jarsan. A map of the site was previously drawn by the Saudi Geological Survey a report It was described in 2009 as a refuge for wild animals such as foxes, wolves, birds and snakes. The caches of bones in the tunnels included parts of a human skull estimated at the time to be about 4,000 years old. But until 2019, archaeologists had not closely studied the tunnel system, Stewart said.

“We were able to date the animal bones and sediments, which told us that people began occupying the cave 7,000 years ago and perhaps 10,000 years ago,” Stewart said.

Compared to other sites where humans once lived, the amount of archaeological material at Umm Jarsan was “extremely small,” suggesting that people were visiting the tunnels as temporary shelters rather than living there permanently, the study authors reported.

In another tunnel near Umm Jarsan, researchers found 16 panels of engraved rock art. The carvings appear to have been grazing scenes, with implement-wearing humans standing next to domesticated animals such as dogs, cows, goats, and sheep. Other carvings showed animals with highly arched horns similar to those of ibex. However, these horned animals could represent a different breed of domesticated goat, according to the study. The subjects and varnish of the sculptures indicate that they date from a regional period known as the Chalcolithic Age (ca. 4500 to 3500 BC), which preceded the advent of the Bronze Age.

“Collectively, archaeological finds at the site and in the surrounding landscape paint a picture of repeated use of the Umm Jarsan lava tube over thousands of years,” Stewart said. The site – which lies along a known migration route of Bronze Age shepherds – “may have served as a stopping point, a place of refuge protected from the elements.”

Stewart added that this unprecedented evidence of human presence in ancient Arabian lava tubes highlights how people adapted to living in arid landscapes, and further investigations at Umm Jarsan and other lava tubes promise to add more details.

“These sites have enormous potential to fill some of the gaps in natural and cultural archives that remain in the Arab archaeological record.”

Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American, and How It Works.