Overview
- A peer-reviewed study in Scientific Reports led by the University of Cambridge documents deliberate soil eating in Gibraltar’s free-ranging macaques as a response to digestive stress from tourist snacks.
- Human food made up about 18.8% of what some macaques ate, and geophagy was highest in busy tourist zones and during peak visitation.
- Researchers saw episodes after bread or ice cream, foods that can upset lactose-intolerant primates and trigger stomach pain or diarrhea.
- The practice appears socially learned, with groups favoring specific soils that may supply minerals, helpful microbes, or a mild protective lining in the gut.
- Feeding is banned and authorities provide fruit, vegetables, and water, yet tourists still feed animals or lose snacks to theft, which keeps the behavior going.