Overview
- A multi‑institution study published in Nature reports deliberate soil‑eating, or geophagy, in Gibraltar’s free‑ranging Barbary macaques linked to access to tourist food.
- Researchers observed the behavior during fieldwork and found the same individuals with greatest access to chips, sandwiches and sweets were most likely to eat soil while a group with no visitor contact showed none.
- Authors say tourist food high in sugar, salt and dairy is poorly digested by the macaques and likely causes stomach upset that the animals try to soothe by eating soil.
- The team hypothesizes the soil may act as a physical antacid and could introduce microfungi or microbes that help rebalance a disrupted gut microbiome, but they stress that microbiological and health tests are needed to confirm this.
- About 230 macaques live on the Rock of Gibraltar and feeding is legally banned with fines up to £4,000; authorities and researchers say enforcing the ban during peak visitor months is difficult and raises animal‑welfare and management questions.