Lead: Researchers led by crystallographer Juan Manuel García-Ruiz published a study on March 4, 2026, reporting that rescued chimpanzees at a rehabilitation center near Madrid showed sustained interest in quartz, calcite and other crystals. In controlled tests at Rainfer Fundación Chimpatía, apes repeatedly manipulated the shiny minerals and sometimes refused to relinquish them, forcing researchers to trade large quantities of bananas and yogurt to recover the largest specimen. Some stones were never retrieved. The findings, appearing in Frontiers in Psychology, are presented as a window onto why both humans and their closest relatives might find certain minerals compelling.
Key Takeaways
- The study was published on March 4, 2026, in Frontiers in Psychology (peer-reviewed academic journal).
- It was led by Juan Manuel García-Ruiz of the Donostia International Physics Center and conducted at Rainfer Fundación Chimpatía, a chimpanzee rehabilitation facility near Madrid, Spain.
- Researchers offered multifaceted quartz, calcite and other crystals to two separate groups of chimps; a sandstone rock served as a non-shiny control object.
- Chimpanzees handled and retained the crystals more persistently than the control rocks; the largest quartz required substantial food trades (bananas and yogurt) to be returned.
- Several crystals were never recovered from the animals during the observation period, indicating strong and sometimes exclusive possession behavior.
- Archaeological finds of quartz and other crystals at prehistoric sites date back as far as 700,000 years, though there is no clear evidence those stones were made into tools or ornaments.
Background
Humans have a long-documented fascination with shiny minerals: quartz and related stones appear in archaeological records stretching into the Lower Paleolithic, with discoveries as old as about 700,000 years. Archaeologists have repeatedly found raw crystals in and around habitation sites, but there is limited evidence that early hominins modified those minerals into functional tools or decorative objects. That ambiguity leaves open questions about motive—whether crystals were collected for practical use, sensory appeal, symbolic meaning, or other reasons.
Modern popular culture and some contemporary communities assign healing or metaphysical properties to crystals, a practice that sits uneasily alongside mainstream scientific views. Juan Manuel García-Ruiz, a crystallographer by training, framed the new chimpanzee work as an empirical step toward separating material causes of attraction (color, reflection, geometry, hardness) from cultural or symbolic explanations. To investigate innate or perceptual drivers of interest, his team chose to test a nonhuman primate species that shares close evolutionary ties with humans and that displays complex object-manipulation behaviors.
Main Event
The experiments took place at Rainfer Fundación Chimpatía, a Spanish rehabilitation facility that cares for chimpanzees rescued from a range of adverse situations. García-Ruiz and colleagues installed two pedestals in the outdoor yards used by two different social groups of chimpanzees. On one pedestal the researchers placed a roughly one-foot-tall, multifaceted quartz crystal; on the other they placed a sandstone rock of comparable size and shape to serve as a dull, non-reflective control.
Chimpanzees approached, inspected and handled the quartz far more frequently than the sandstone. Individual apes carried crystals away, kept them in sleeping areas or otherwise treated them as items of interest. One chimp—identified in images as Toti—was photographed examining a quartz specimen with sustained attention. The apes’ behavior included visual inspection, hefting, rubbing and caching, behaviors the team logged and quantified during observation periods.
In several instances the animals resisted returning a crystal to researchers. Recovering the largest specimen required the team to offer repeated exchanges of food rewards, notably bananas and yogurt, until an animal would relinquish it. Other crystals were not recovered during the observation window and remained in the possession of the animals, underscoring a level of attachment or exclusive use in some cases.
Analysis & Implications
The chimpanzees’ preferential interest in crystals suggests that basic sensory features—gloss, internal reflections, faceted geometry and tactile feedback—can attract nonhuman primates independently of cultural narratives. If such perceptual attractions are widespread in primates, they could help explain why early hominins sometimes collected crystals without converting them into tools: the stones might have been attention-grabbing items with no immediate utilitarian function.
That hypothesis does not resolve whether humans later layered symbolic, social or ritual meanings onto crystals. The presence of crystals at very ancient sites could reflect repeated, simple behaviors (collecting shiny things) that became incorporated into cultural practices only later. The new study therefore argues for parsing perceptual predispositions from learned or culturally transmitted value when interpreting archaeological patterns.
There are research limitations to note: the study was conducted with captive, rehabilitated apes accustomed to human-provided rewards and enrichment, which can shape object interest and exchange behavior. The authors caution against directly equating captive chimp behavior with that of wild chimpanzees or Pleistocene hominins. Future work should test wild populations, expand the range of tested minerals and measure which physical properties (e.g., reflectance, symmetry, hardness) most strongly predict ape interest.
Comparison & Data
| Object | Key properties | Typical outcome in study |
|---|---|---|
| Quartz (multifaceted) | High luster, internal reflections, geometric facets | High interest; some items carried or retained; largest required food trades |
| Calcite (various forms) | Variable luster and crystal faces | Marked interest; handled frequently |
| Sandstone (control) | Dull surface, no strong reflections | Lower sustained interaction; less often retained |
The table summarizes qualitative outcomes rather than exact counts because the published report emphasizes behavioral patterns—sustained attention and retention—over simple frequency tallies. Those patterns align with the idea that optical and tactile characteristics correlate with chimp interest, while non-reflective rocks elicited comparatively little persistent handling.
Reactions & Quotes
“Some colleagues say, ‘We have to tell people that this is completely ridiculous,’”
Juan Manuel García-Ruiz, lead author and crystallographer
The comment appears in the study’s public explanation of motive: García-Ruiz emphasized that he seeks to understand why crystals attract attention, not to validate supernatural claims. The research team framed their work as a step toward distinguishing perceptual drivers from cultural belief.
“The animals showed sustained interest and in some cases exclusive possession of these stones,”
Rainfer Fundación Chimpatía (staff observation)
Rainfer staff provided caregiving context and helped run the experiments; their observations underscore that the chimps sometimes treated crystals differently than ordinary enrichment objects, prompting the exchange behavior reported by researchers.
Unconfirmed
- Whether chimpanzees experience any symbolic or aesthetic appreciation for crystals analogous to human cultural meanings is not established by this study.
- It remains unproven that prehistoric humans collected crystals for the same perceptual reasons observed in chimps rather than for social, ritual or unknown cultural purposes.
- Whether wild chimpanzee populations display the same degree of interest in crystals as rehabilitated, human-habituated individuals is not yet confirmed.
Bottom Line
The study provides controlled evidence that chimpanzees can be strongly drawn to crystals and may even retain them preferentially compared with non-reflective rocks. That attraction appears tied to sensory properties—shine, geometry and tactile quality—that make certain minerals attention-grabbing for primates.
These results suggest a plausible, non-cultural explanation for some ancient occurrences of crystals in archaeological contexts: early hominins may have repeatedly collected striking minerals because they were perceptually compelling. However, the research does not resolve how or when perceptual interest could have become cultural symbolism; further comparative and field work is needed to connect perceptual tendencies with long-term human practices.
Sources
- The New York Times (news report summarizing study and interviews)
- Frontiers in Psychology (peer-reviewed academic journal where the study was published)
- Donostia International Physics Center (DIPC) (research institute; lead author affiliation)
- Rainfer Fundación Chimpatía (rehabilitation facility and study collaborator)