Overview
- The peer-reviewed study, published Wednesday in Scientific Reports, reports Gibraltar’s Barbary macaques deliberately eating soil and interprets it as self-medication for junk-food-related stomach upset.
- Over 98 observation days and more than 612 hours, researchers logged 46 soil-eating events in at least 44 of roughly 230 monkeys.
- Dirt eating was most common in troops that linger near tourists, increased in summer when visitors peak, and was absent in the only troop with little to no human contact.
- Many episodes occurred in view of other macaques, and troops showed distinct preferences, from red clay called terra rossa to tar-tinged grit from potholes, suggesting social learning.
- The team plans chemical and microbiome tests to confirm how soil might help, and wildlife managers are using the findings to push stricter enforcement of Gibraltar’s no-feeding rule.