Chimpanzees at a Spanish rehabilitation center have shown an intense fascination with crystals, offering clues about human attraction to shiny minerals. Researchers from Donostia International Physics Center conducted experiments where apes repeatedly handled quartz crystals, carried them in their mouths, and even refused to return them without extensive negotiations involving bananas and yogurt.

Led by crystallographer Juan Manuel García-Ruiz, the study published in Frontiers in Psychology involved two separate chimpanzee groups at Rainfer Fundación Chimpatía near Madrid. The apes consistently preferred quartz over sandstone rocks of similar size, with one alpha female removing a one-foot-tall crystal from its pedestal and keeping it in constant sight. Some smaller crystals remain unretrieved after the experiments ended.

The research suggests chimpanzees are drawn to crystals' transparency and geometric properties, potentially mirroring the same attraction that drew early humans to these minerals 700,000 years ago. While outside experts caution against overgeneralizing from a small sample of rescued animals, the findings support García-Ruiz's theory that crystals may have helped humans develop abstract thought and geometry by being "the only Euclidean object in nature."