Humans Have Hung Out in Saudi Arabia's Longest Lava Tube Over the Last 7,000 Years

Archaeologists found the first evidence of Human occupation in lava tubes

Hiya!

It seems to me that, likely without realizing it, we’ve embraced the same strategy as Nature to survive as a species. When Nature finds something that works, it repeats and diversifies it. Patterns are everywhere in nature — in every shape, form, and timeframe — and every living thing on Earth is subject to them. Nay, we require them for survival.

It seems that our species, perhaps more than most, has instilled the same strategy, which may be why we’ve achieved so much. Take the wheel, for example, one of our earliest inventions that we likely created after observing nature. We still utilize the wheel today and have only improved it over hundreds of thousands of years, maybe longer. Now, it seems we’re doing the same thing with lava tubes.

What’s a Lava Tube

Lava Tubes are just what you’d imagine — tubular caves formed by lava. During a volcanic eruption, lava flows from its underground chambers and creates passages. The surface, exposed to cooler elements, solidifies while hot molten rock flows beneath. As the eruption ends, the lava drains out, leaving behind a tunnel.

Umm Jirsan

Saudi Arabia’s largest volcanic field, Harat Khaybar, is about 78 miles (125 kilometers) north of Medina. Inside is the reigon’s longest lava tube, Umm Jirsan, which is almost a mile (1.5 km) long.

While Harat Khaybar last erupted in the 7th century C.E., it’s challenging to pinpoint when Umm Jirsan last flowed with lava, especially since the area has long experienced intermittent volcanic activity for over a thousand years.

Lead author of the study I’ll tell you about soon and research fellow at Griffith University’s Australian Research Center for Human Evolution (ARCHE), Mathew Stewart, explained to Live Science’s Owen Jarus that,

"There have been some 1500 volcanic eruptions in Arabia over the past 1500 years, and many more in antiquity.”

Yet, despite the high number of eruptions, ancient humans decided the shelter Umm Jirsan provided was worth the danger.

The Discovery

Stewart and his colleagues have explored the Saudi Arabia region for over 15 years and discovered many signs of human habitation, including stone structures on its surface. But these finds are rare and challenging to find thanks to the hot and arid desert climate, which breaks down organic material.

But then, they thought, perhaps people went underground to escape the conditions on the surface. Stewart explained to James Woodford of New Scientist, that the landscape’s surface is a:

“hot, dry and flat basalt desert. But when you are down in the lava tube, it’s much cooler. It’s very sheltered and it would have been a great place of refuge.”

So Stewart and his colleagues at ARCHE led an excavation of Jumm Jirsan with the help of the Saudi Heritage Commission, the Saudi Ministry of Culture, and the Saudi Geological Survey. Their findings were published in the journal PLOS One in April 2024.

What They Found

Stewart and his colleagues discovered a plethora of artifacts in parts of Umm Jirsan’s vast underground network, including animal bones, fragments of cloth, pottery, and stone tools. They also found human skeletal remains, though the researchers believe hyenas likely dragged the bones in due to previous research by Stewart.

In 2021, Stewart coauthored a study detailing evidence of striped hyenas stockpiling hundreds of thousands of bones in the Umm Jirsan’s tunnels over thousands of years. The researches counted at least 14 species, including humans.

In other lava tubes around the area, the researchers found rock art depicting domestic goats, sheep, and dogs, supporting the idea that prehistoric people kept livestock. In a statement, Stewart said:

“This site likely served as a crucial waypoint along pastoral routes, linking key oases and facilitating cultural exchange and trade.”

Ancient humans during the Neolithic and Bronze Ages — between about 7,000 and 10,000 years ago — weren’t the only ones taking advantage of this naturally formed shelter.

Radiocarbon dating and optically stimulated luminescence dating, which analyzes when certain minerals were last exposed to heat or sunlight, suggest that the tubes continue to be used in modern times.

Experts performed isotopic analysis on the remains of human and (other) animal remains in the tunnel and learned that the animals mostly grazed on shrubs and grasses. In contrast, the humans had a more protein-rich diet, including dates, wheat, figs, and wheat.

Additional chemical analysis of the human remains showed they ate more cereals, fruits, and other plants over time, which the researchers believe may have been due to the rise in “oasis agriculture in the Bronze Age.” Oasis agriculture is a farming method used on fertile lands near a body of water in otherwise arid regions.

However, it appears humans didn’t live in lava tubes for extended periods. In their study, the researchers explain:

"The lava tube does not appear to have served as a permanent habitation location, but rather as a site that likely lay on herding routes and that allowed access to shade and water for passing herders and their animals."

"Prior to this, as well as during pastoral periods, the lava tube was likely also linked with hunting activities, which probably remained a cornerstone of local economies into the Bronze Age."

Stewart told Woodford in an email that people still use lava tubes like Umm Jirsan for temporary shelter, “whether it was for corralling animals, accessing water resources, or simply for leisure.”

Perspective Shift

The fact that modern humans still use the region's caves to escape brutal heat and arid climate conditions is a nice reminder that despite being separated by thousands of years and unimaginable technological advancements, there’s something timeless in our humanity.

Considering that lava tubes seem to provide such great shelter for such an extended period, it only makes sense that we’d recycle the idea — which is exactly what astronauts are doing.

NASA has suggested that lava tubes could be a place for humans to shelter on Mars, and scientists at Japan’s space agency, JAXA, proposed the same thing as a way for astronauts to live on the Moon.

See? It's like how Nature repeats what works. We’ve realized the value of lava tubes as temporary safety and shelter, so we've continued to utilize them for millennia. And now, we’re using our knowledge to help us survive an alien atmosphere.

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Photo by Mick Haupt on Unsplash