Some of the stones are round and white, resembling bird eggs. Others are scarlet red like a living piece of flesh. Others yet are shiny and multicolored, crisscrossed by translucent mineral veins. The one thing these pretty pebbles found in the prehistoric site of Qesem in central Israel have in common is that they have no apparent use, and their presence has bedeviled researchers for nearly a decade.

Open gallery view Red but non-utile pebbles found at the prehistoric site of Qesem cave, central Israel Credit: Pavel Shrago

Now archaeologists have concluded that these 17 stones were collected by prehistoric hominins 300,000 years ago simply for their aesthetic value: that is, because they were pretty to the eye of the beholding caveman or cavewoman. Fact is, we all like a pretty stone and it seems, so did the early humans.

“When we were digging through the sediments of the cave these stones immediately caught our attention, and surely something similar happened back then,” says Ella Assaf, an archaeologist and PhD candidate at Tel Aviv University who authored the study published earlier this month in the Journal of Lithic Studies. “There is something very special about them because of their small size, the variety of color, and their round or symmetrical shape,” she adds.

The pile of aesthetically pleasing but useless flint stones adds to the growing body of evidence that our early ancestors created much more complex societies than previously believed and shared with us sophisticated features that were once thought to be unique to anatomically modern humans, which the Qesem cave dwellers were not.

Discovered in 2000 during road works east of Tel Aviv, Qesem has yielded hundreds of thousands of flint tools, animal bones and other items left by generations of hominins who intermittently inhabited the cave between 420,000 and 200,000 years ago. The mysterious pebbles were found between 2009 and 2016 in layers that were dated to around 300,000 years ago, Assaf says.

Open gallery view The collection of pebbles found at the prehistoric site of Qesem cave, central Israel. Credit: Pavel Shrago

Oooh, shiny

Flint does not occur naturally in karstic caves like Qesem and researchers had previously determined that its prehistoric inhabitants had to bring in the raw material for their tools from different sites, some up to 30 kilometers away. Since the unusual pebbles were all flint stones, this means they had also been brought to the cave purposefully. But why?

The pebbles are smaller than the smallest stones used at Qesem to produce tools and, unlike other flint cores found at the site, they show no signs that any flakes were chipped off to make utensils. Microscopic analysis did not find residues that would have indicated the stones might have been used to grind softer materials.

This process of elimination led Assaf to conclude that the eye-catching pebbles were collected for a cultural rather than functional purpose, and were selected on the basis of aesthetical criteria.

“A sense of aesthetics is part us from the dawn of our history, it’s a very basic human trait,” Assaf argues. “Today, when I take a walk in nature with my children and some special stone catches their eye, they will hold it up and say ‘Mommy, look what I found’ – there is no reason to believe this was not the case with prehistoric humans.”

In fact, she notes, there are studies that show that all primates can be attracted to unusual, non-utilitarian objects – orangutans for instance are intrigued by shiny colorful stones too. But humans – including archaic ones - are the only ones who like to collect them.

Open gallery view Qesem Cave Credit: Ran Barkai

As for any meaning and purpose that the hominins of Qesem assigned to those stones, we will probably never know. The stones were collected at different times and were found mainly in the southern part of the cave, suggesting this area may have been devoted to whatever use the stones were dedicated to, the archaeologist says. Perhaps it was just the spot where kids stashed the Paleolithic equivalent of a stamp collection.

Even if the pebbles were gathered by curious children and used as toys, that still shows the existence of aesthetical preferences in this hominin population, Assaf notes. But ethnographic studies of hunter-gatherer groups suggest the objects could have also served a more complex social purpose, she says.

Open gallery view A range of pretty but non-utile stones found at Qesem Credit: Pavel Shrago

Because flint was used to make tools that were essential for survival, it was a huge part of the lives of prehistoric people, just like plants and animals. Prehistoric humans may have endowed stones with spiritual energies or other symbolic meanings, possibly using them in rituals or to attract a mate.

Open gallery view Qesem cave. Credit: Tel Aviv University

And why would some stones be considered more attractive than others? This might have to do with evolutionary advantage. Attraction to shiny (or glossy) objects could be based on the inborn need for fresh water, some have suggested. Perhaps the reason we like warmer colors, such as red and yellow, from an early age is because they remind us of lovely ripe fruit.

Open gallery view Humans like warm-colored fruits so maybe they have a predilection for warm-colored rocks too Credit: Doram Gaunt

Qesem cave lies at a key juncture in human evolution. It marks a turn toward more sophisticated tool-making and may be the earliest example of the use of controlled fire.

We don’t know exactly who were the inhabitants of the cave, as only a handful of human teeth have been recovered there. Anthropologists say the teeth display a mix of features typical of Neanderthals and Homo sapiens, suggesting that the Qesem people were not anatomically modern humans.

Still, the study of the Qesem pebbles highlights how our ancestors were far from being primitive quasi-apes, and shared many of the characteristics we list when we try to answer the question of "what makes us human."

Open gallery view Some of the remains of flint tools found in Qesem cave. Credit: Ariel David

“We shouldn’t assume that their lives were just about hunting, eating and making tools: they had a rich cultural life, of which we know almost nothing,” says Assaf. “While we don’t know the specific significance of these finds, they certainly reflect part of this cultural world.”

The face of Australopithecus

While it is rare to find such a relatively large number of collected items in the same prehistoric site, the Qesem pebbles are probably not the oldest case of hominins displaying aesthetic sensibilities. As early as the 1960s, the renowned paleoanthropologist Mary Leakey identified unmodified stones that were collected by hominins one to two million years ago at sites in Olduvai Gorge, Tanzania.

Researchers speculate that an even older find, the Makapansgat pebble from South Africa, may have been collected three million years ago by an Australopithecus Africanus because it resembled a face, representing the earliest example of symbolic and aesthetic thought. It bears adding that the Makapansgat pebble consisted of jasperite and was found next to some Australopithecus remains, dozens of kilometers from where it could have originated naturally.

The debate over these pretty-but-useless objects and what they might represent is fierce, and researchers often hesitate to interpret them as the result of a conscious aesthetical choice, mainly because we will never know what was going on through the mind of our distant ancestors when they picked up that weird-looking pebble.

The Makapansgat ‘pebble of many faces’ Credit: Wits University, YouTube

“It’s definitely not a mainstream idea,” says Prof. Ran Barkai, a Tel Aviv University archaeologist who directed the Qesem dig together with Prof. Avi Gopher. “We tend to focus on items that had a functional use. We are not used to analyzing this kind of find so we just put it in a box somewhere and forget about it.”

Perhaps because of this caution, Assaf’s own study was rejected 10 times before being accepted for publication, she says. But studies like hers can help open up new avenues of research into understanding when and how humans first developed what appears to be a universal code of aesthetics embedded in our biology, Barkai says.

“This kind of objects appears in prehistoric sites all over the world,” he concludes. “And now we are getting reactions from colleagues who say: we also have something like this and we didn’t pay attention to it.”