Overview
- In experiments, chimpanzees quickly picked out quartz, calcite and pyrite from ordinary stones and focused their attention on the crystals.
- They inspected the pieces by turning them in their hands and holding them to eye level, carried some to sleeping areas, hid them in the mouth, sorted them by type and traded them for food.
- The authors propose that transparency, geometric regularity and shine drive the attraction, aligning with archaeological finds of hominins collecting small crystals up to about 780,000 years ago without obvious practical use.
- The peer‑reviewed study by García‑Ruiz and colleagues appears in Frontiers in Psychology (doi: 10.3389/fpsyg.2026.1633599) and tested two groups of captive chimpanzees in Spain.
- The researchers caution that captivity and prior exposure to human objects may have influenced behavior and they urge larger studies, especially with wild apes, to assess how broadly the findings apply.