Billboards are useful, at  least if you want to know whether you’re within two  hundred miles of a Buc-ee’s.

Thousands of years ago, some  people had a similar idea by carving a huge camel into a  rock in the Arabian peninsula. That camel wasn’t signaling the  location of gas and novelty foods, but rather, something even more important: water.

Today, that camel is still conveying  a surprising amount of information. Not only has it doubled the amount of time we think humans were living in the region… it might also help crack a  prehistoric climate mystery. [♪INTRO] The timeline of human habitation  on the giant peninsula southeast of the Fertile Crescent  is long, but it’s not continuous. Arabia has always experienced  wetter and drier periods, and there's evidence that humans have been taking advantage of the  grasslands these wet periods provide for hundreds of thousands of years.

But the dry periods have  rendered it pretty inhospitable. For instance, during the Last Glacial Maximum 25,000 to 20,000 years ago, the  entire globe got colder and drier. Conditions in Arabia became pretty  intolerable for prehistoric people.

When things got chilly and dry, humans skedaddled out of there for at least five thousand years. But eventually the glaciers  around the globe receded, and humans moseyed back in when  Arabia became a bit balmier. It's just that it’s difficult  for scientists to pinpoint when exactly this moseying took place.

Enter the life-sized camel murals, or petroglyphs. And keep in mind that camels are big, so these scale engravings are pretty striking. And it’s not just camels these people  were splashing across to cliffs.

They carved other stuff like  ibex, wild donkeys and aurochs – the extinct ancestors of modern cows. The camels truly are impressive, though. They can even be identified as  males during the breeding season, sporting furry coats only  seen in the wet wintertime when it’s time to make more camels.

One hundred and thirty of  these naturalistic animal engravings were found at three  sites around Saudi Arabia, including 18 in the Sahout area  south of Saudi Arabia’s Nefud desert. These animals marked important  desert water sources, and if we could date them, they  might even solve the question of when Arabia became habitable to humans and animals again after the climate temporarily  rendered it a wasteland. The thing is, it's really tricky to  determine the age of a rock carving.

Radiocarbon dating is a great  way to tell the age of a very old thing because carbon is  present in all living things, and it begins to decay at a  predictable rate once the thing dies. But you can’t really date  geological formations that way, because nothing's formerly alive. Previously, researchers dated  fireplaces to estimate human habitation in the region  went back about 7000 years, but they admitted that was a very rough estimate.

But before we get to how old the site actually is, here’s a quick break. This SciShow video is supported by

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In a 2025 paper, the same research team dated the carvings themselves and  almost doubled that figure. They found a little tool similar  to those found at petroglyph sites around the world, from Europe to South America. This engraving tool, called a pecking tool, was found directly beneath an  engraving of two giant camels.

Through a different technique  called luminescence dating, the tool was determined to be  used around 12,000 years ago. Luminescence dating works differently  from radiocarbon techniques because it measures the energy built up since the last time crystalline minerals like silica, found in quartz or feldspar  rock, were exposed to sunlight. The process can tell  researchers when that particular layer of sediment was last exposed to sunlight.

Of course, this tells us more  about the layer of sediment the pecking tool was found in than anything, but that layer did include other  trappings of human habitation, like arrowheads and beads made of stone and shell. And if you find rock art and also  a tool used to make rock art, it’s more likely than not that  those two things go together. Somebody was there -- most likely making rock art and wearing fabulous jewelry.

So, what does the discovery  of these camel billboards tell us about what was going  on in prehistoric Arabia? Well, a few things: For starters, it reinforces something researchers already had an inkling about:  that Arabia became warmer and wetter after the last  ice age, grasslands emerged on the peninsula, and that  attracted animals and people. Environmental conditions were likely  still pretty harsh, so these murals were carved into cliff faces to mark  important surface water sources.

However, this research suggests  that surface water sources, called playas, returned to the  peninsula much sooner after the last glacial maximum than previously assumed. And of course, where there is  water, there will be animals. But the figures of camels in  their wet season coats carved into the rock, as well as the  very presence of the aurochs, give clues as to exactly how wet it was.

Aurochs, like modern cows, were thirsty, so they'd need year-round access to water. It’s possible that this site  got wet enough that aurochs would have been okey-dokey during the wet season. But it’s also possible these murals were made by folks who migrated seasonally.

They could have carved aurochs they had seen on their journeys to wetter climes. Either way, it's an important clue as to how much water was available in the region. All because people carved  really accurate-looking animals!

Regardless, these rock art billboards seem to mark the presence of these watering spots, suggesting people followed a  prehistoric superhighway of ephemeral lakes, marking the route  with these animal jumbotrons. Now that researchers know what to look for, maybe they can use the carvings to look for more ancient water sources. Or use more ancient art to learn  more about our prehistoric climate. [♪OUTRO]