Ancient lava tubes offer glimpse into Neolithic Arabia

Recent archaeological research, deep within ancient lava tube caves in northern Saudi Arabia, has thrown up the interesting information that people who lived in the Arabian Peninsula thousands of years ago went underground when they wanted to beat the heat. Possibly stopping there as they travelled between oases and pastures, they ducked into vast subterranean tunnels where molten lava had once flowed millions of years earlier. The study, led by researchers with Griffith University’s Australian Research Centre for Human Evolution (ARCHE) and an international team of collaborators, was reported April 17 in the journal PLOS One.Umm Jirsan (the longest tunnel system in the region, located in the Harrat Khaybar lava field, about 125km to the north of Medina), is an underground archaeological site that dates from the Neolithic to the Chalcolithic/Bronze Age periods, roughly between around 10,000 to 3,500 years ago. The site has revealed numerous periods during which humans occupied the area, revealing pastoralist activities that once provided sustenance to the ancient dwellers within vast, cavernous lava tubes or tunnels in the region.Scientists haven’t yet confirmed the age of the lava that formed this system, but a 2007 study suggested it was around 3mn years old. Umm Jirsan spans nearly 1.5km, with passages that are up to 39ft tall and as much as 148ft wide. Beginning in the Stone Age, Neolithic herders descended into and occupied these tunnels, archaeologists have discovered. Cooler air underground would have provided a welcome respite from the sun and wind, and for thousands of years, humans sheltered with their livestock in the tunnels. The herders left behind objects and even carved pictures on the rocky walls, researchers reported.Lava tubes are caves created when lava passes through natural channels and eventually cools into dark-coloured stone. Over long periods, as the rock above the hardened lava gradually widens, it forms a roof over the molten rock beneath it, which eventually exits and leaves behind a cave tunnel. These caves formed from ancient lava flows would naturally have been attractive to ancient residents of the region for the shelter they provided. Fortunately for archaeologists, these caves also preserve the rich heritage of the ancient people who inhabited Arabia far better than the arid landscape above."Our findings at Umm Jirsan provide a rare glimpse into the lives of ancient peoples in Arabia,” said Dr Mathew Stewart, lead researcher and a Research Fellow at ARCHE, in a statement. Among the evidence of ancient human activity at the site are rock art depictions of animals, as well as the actual remains of fauna hunted in the region, which reveal the presence of sheep, goats, and cattle, all pointing to the likely herding of livestock by the ancient residents of the area. Over time, the region’s protein-rich diets began to be increasingly complemented by vegetation consumption, coinciding with the prehistoric emergence of oasis agriculture.The researchers found at Umm Jirsan animal bones dating from 400 years to more than 4,000 years ago, and human remains ranging from 150 years to about 6,000 years ago. They also found cloth fragments, pieces of carved wood and dozens of stone tools — the first evidence that humans were using the tunnels, starting at least 7,000 years ago.Although similar information has long existed for other surrounding regions, Stewart and his colleagues say the recent studies at Umm Jirsan and nearby areas represent a new milestone in the archaeology of Arabia and present the first comprehensive investigation focusing on underground archaeology in Saudi Arabia. "These findings underscore the immense potential for interdisciplinary investigations in caves and lava tubes, offering a unique window into Arabia’s ancient past,” said Professor Michael Petraglia, director of ARCHE. These sites have tremendous potential to fill in some of the gaps in the natural and cultural archives that persist in the Arabian archaeological record.