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From Viking sailors to New Age spiritualists, people have always been slightly obsessed with crystals, and it turns out that chimpanzees are no different. Observing our simian cousins go absolutely bananas over these shiny minerals, researchers believe they may now be able to explain the magpie-like behaviors of prehistoric humans who lived around 800,000 years ago.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.It’s at this point in our history that the first collection of crystals appears in the archaeological record. Discovered at the famous Zhoukoudian site in China in 1931, this assemblage of 20 small quartz crystals was accumulated by Homo erectus and marks the beginning of humanity’s long love affair with sparkly rocks.
Other similar finds from 500,000 years ago have since been unearthed in South Africa, while six quartz prisms from India were stockpiled by one of our ancestors around 300,000 years ago. Importantly, none of these items display signs of having been modified, which means they weren’t used as weapons, tools, or personal adornments – all of which leaves a massive, glimmering question mark hanging over their function.
To gain new insights, researchers decided to study the behavior of our closest living relatives when encountering crystals. They therefore conducted a series of experiments with chimpanzees housed in a sanctuary.
Chimpanzees' interest in crystals goes beyond mere curiosity.
Juan Manuel García-Ruiz
Given that chimps and humans diverged from their last common ancestor between 6 and 8 million years ago, the discovery of any shared behaviors between us and them would suggest that these traits are at least that old. Describing his team’s observations, study author Juan Manuel García-Ruiz from the Donostia International Physics Center told IFLScience that “there were three moments that were absolutely astonishing.”
The first of these occurred when the chimps were presented with a large, Kubrick-esque crystal “monolith” alongside a normal rock of similar size. Ignoring the duller object, a chimp called Yvan picked up the monolith and carried it to the apes’ sleeping area, where the group spent almost two days actively exploring this unfamiliar object.
“The way they "studied" it there, turning it over to observe it from different angles, was amazing,” says García-Ruiz.
A second unexpected moment occurred when the chimps were given a pile of stones that contained a mix of quartz crystals and regular pebbles. Amazingly, the animals were able to immediately tell the difference between the two types of stone, and consistently chose to pick up the crystals.
Yvan held one of these quartz pieces close to his eye in order to examine its transparency. “This obvious and persistent behavior went beyond anything I could have ever anticipated,” says García-Ruiz. “It means that chimpanzees' interest in crystals goes beyond mere curiosity.”
If our results are correct, then we have had crystals on our minds for at least 7 million years.
Juan Manuel García-Ruiz
Finally the chimps were presented with a pile of regular stones that also contained three types of crystal, each of which differed in shape, luminosity and transparency. One chimp, named Sandy, immediately separated all three crystal types from the pebbles, demonstrating a clear ability to distinguish between normal stones and crystals.
“We could not believe it because that was proof of the ability to relate crystals of different properties as singular objects,” explained García-Ruiz.
Overall, the researchers conclude that chimpanzees are attracted to crystals because of their shape and transparency, which set them apart from everything else in the natural landscape. From trees to clouds, primates evolved in a world characterized by rounded edges and fractal patterns, yet crystals boast straight lines and are the only see-through solid that our primordial ancestors would have encountered – which may explain why they fascinate us so.
Moreover, because this penchant for crystals is present in chimpanzees, it must also have been a trait of extinct human species like Homo erectus. This explains why prehistoric hominins were such avid collectors of these eye-catching items.
“If our results are correct, then we have had crystals on our minds for at least 7 million years,” says García-Ruiz.
The study is published in the journal Frontiers in Psychology.
