We've had crystals in our minds for at least six million years.
Long before humans assigned meaning or utility to crystals, something in the primate mind was already reaching for them. Researchers in Spain observed chimpanzees consistently selecting crystals from ordinary stones, rotating them, studying their transparency, and in one case hoarding them as if they were precious — behavior that mirrors humanity's own 780,000-year fascination with these geometric anomalies. The findings suggest that our attraction to crystals is not a cultural inheritance but an evolutionary one, rooted in a shared ancestor six to seven million years ago and encoded in the primate perception of a world otherwise dominated by curves and chaos.
- A chimpanzee named Yvan walked off with a research crystal and had to be bribed back with bananas and yogurt — the pull was that immediate and that strong.
- Another chimpanzee, Sandy, sorted crystals from pebbles into separate groups on a wooden platform, distinguishing between quartz, pyrite, and calcite with a precision that suggested she regarded them as categorically different — and possibly valuable.
- The tension at the heart of this research is ancient: if our closest living relatives share our fixation on crystals, then human crystal collection predates culture, religion, and even practical knowledge of what crystals are.
- Crystals' flat surfaces and straight edges make them geometric outliers in a natural world of curves — and that strangeness, researchers believe, is precisely what arrests primate attention.
- The study's open question now points toward wild and less enculturated chimpanzee populations, where the same attraction, if confirmed, would extend this shared inheritance across six million years of divergent evolution.
In a laboratory in Spain, researchers placed a crystal beside an ordinary rock and watched chimpanzees choose. The crystal won, immediately and completely. That small moment opened into a much larger question: why have humans collected crystals for hundreds of thousands of years, long before finding any practical use for them?
Crystallographer Juan Manuel García-Ruiz and his team at the Donostia International Physics Center suspected the answer might lie not in human culture but in primate biology. Working with two groups of chimpanzees at the Rainfer Foundation, they ran a series of experiments. In the first, animals examined a large crystal with deliberate care — rotating it, tilting it, studying it from every angle. One chimpanzee carried it away. The researchers paid in bananas and yogurt to get it back.
In a second experiment, smaller crystals hidden among twenty rounded pebbles were identified within seconds. The chimpanzees held them up to eye level and studied their transparency for hours. One animal, Sandy, went further — she transported both pebbles and crystals to a wooden platform and sorted them into separate groups, distinguishing three crystal types from all ordinary stones. Chimpanzees do not normally move objects this way in the wild. The researchers read it as possible concealment, as if Sandy considered the crystals worth protecting.
The explanation García-Ruiz offers is geometric. In a natural world of curves — trees, rivers, clouds, animals — crystals are singular. They are flat-surfaced, straight-edged, the only naturally occurring polyhedral solids. That distinctiveness, paired with transparency, appears to arrest primate attention in a way nothing else does. Early humans may have been drawn to the same qualities, collecting crystals not for use but for the simple fact that they were strange.
The chimpanzees in this study are enculturated, comfortable around humans and unfamiliar objects. Whether wild populations show the same pull remains to be tested. But the core finding is striking: the attraction to crystals may be something written into the primate mind at least six million years before we ever thought to ask why.
In a laboratory setting in Spain, researchers placed a large crystal beside an ordinary rock and watched what happened next. The chimpanzees noticed both objects. Within moments, the crystal became the object of their complete attention. The rock was forgotten.
This simple observation launched a larger question: Why are we drawn to crystals? Why have humans collected them for hundreds of thousands of years, long before we found any practical use for them? A team led by crystallographer Juan Manuel García-Ruiz at the Donostia International Physics Center decided to investigate whether the answer might lie in our shared ancestry with chimpanzees, our closest living relatives. Humans and chimpanzees diverged from a common ancestor somewhere between six and seven million years ago. If chimpanzees showed the same pull toward crystals that humans do, it would suggest the attraction runs deeper than culture or learned behavior—it would point to something written into our evolutionary past.
The researchers worked with two groups of chimpanzees at the Rainfer Foundation, animals accustomed to living around humans and encountering objects that do not exist in nature. In their first experiment, they presented the animals with a large crystal alongside a regular stone of similar size. The chimpanzees examined the crystal with deliberate care, rotating it, tilting it, studying it from every angle. One chimpanzee named Yvan picked it up and carried it back to the dormitories. The researchers had to trade bananas and yogurt to get it back. The curiosity was strongest immediately after discovery and gradually faded, much like how novelty wears off in human minds.
The second experiment tested whether the chimpanzees could recognize smaller crystals buried in a pile of twenty rounded pebbles. They could. The animals selected the crystals within seconds. Even when the researchers added different types of crystals—pyrite and calcite alongside quartz—the chimpanzees still identified and selected the crystal stones. They held them up to eye level and looked through them, studying their transparency with what García-Ruiz described as extreme curiosity. Hours passed. The animals kept examining them.
One chimpanzee named Sandy displayed behavior that particularly intrigued the researchers. She carried both pebbles and crystals in her mouth to a wooden platform and sorted them into separate groups. She separated the three different crystal types from all the ordinary pebbles, distinguishing between them despite their differences in transparency, symmetry, and luster. Chimpanzees do not normally transport objects this way in the wild. The researchers interpreted this as possible concealment behavior—Sandy may have regarded the crystals as valuable.
What emerges from these observations is a pattern. Crystals possess qualities that stand out in nature. Unlike trees, mountains, rivers, clouds, and animals—all dominated by curved and branching forms—crystals are defined by flat surfaces and straight edges. They are the only naturally occurring polyhedral solids, geometric objects that appear almost nowhere else in the landscape. This geometric distinctiveness, combined with their transparency, seems to be what captures attention. Early humans may have been drawn to these same qualities as they tried to make sense of the world around them, collecting crystals not because they were useful but because they were strange and beautiful.
The study raises questions for future work. The chimpanzees tested here are enculturated, accustomed to human environments. Do wild chimpanzees show the same attraction? Do individual personalities shape how much interest an animal takes in crystals? García-Ruiz noted that some individuals might be idealists fascinated by transparency, while others are pragmatists more interested in whether something is edible or smells interesting. These variations matter. But the core finding stands: an attraction to crystals appears to be something we share with our closest living relatives, something that may have been part of our minds for at least six million years, long before we understood what crystals were or what we might do with them.
Citas Notables
We were pleasantly surprised by how strong and seemingly natural the chimpanzees' attraction to crystals was. This suggests that sensitivity to such objects may have deep evolutionary roots.— Prof Juan Manuel García-Ruiz, lead researcher
She separated the three crystal types, which themselves differed in transparency, symmetry, and luster, from all the pebbles. This ability to recognize crystals despite their differences amazed us.— Prof Juan Manuel García-Ruiz, on chimpanzee Sandy's sorting behavior
La Conversación del Hearth Otra perspectiva de la historia
Why would chimpanzees care about crystals at all? What's the evolutionary advantage?
That's the puzzle. There may not be one—not in the traditional sense. The researchers think the attraction is about the crystals' geometry. In nature, almost everything is curved or branching. Crystals are the exception: flat surfaces, straight edges, perfect angles. That difference alone might be enough to capture attention.
So it's novelty? They're drawn to things that look unusual?
Partly. But it's more specific than that. When the researchers mixed small crystals into a pile of twenty pebbles, the chimpanzees found them in seconds. They weren't just picking up anything different—they were recognizing something particular about the crystal structure itself.
The chimpanzee Sandy sorted them. That seems almost deliberate, almost like she understood something.
It does. She separated three different crystal types from ordinary stones, even though the crystals looked different from each other. She was making distinctions based on properties we associate with crystals—transparency, symmetry, luster. And she carried them in her mouth to a platform, which is unusual behavior. The researchers think she may have been treating them as valuable.
But these are enculturated chimpanzees, right? They live around humans. Could that change how they respond to objects?
Yes, and that's why the researchers want to test wild populations next. These animals are used to encountering things that don't exist in nature. But even accounting for that, the consistency of the response is striking. Every group showed the same preference, the same careful examination.
If this goes back six million years, what does that tell us about ourselves?
It suggests that our fascination with crystals—collecting them, displaying them, finding them beautiful—isn't something we invented. It's something we inherited. We've been drawn to these geometric forms for longer than we've been human.