Gibraltar Monkeys Eat Soil to Soothe Junk-Food Stomachs
Gibraltar Monkeys Eat Soil to Soothe Junk-Food Stomachs
Researchers say Barbary macaques in Gibraltar chew dirt to calm their stomachs after tourist junk food—a surprising, city-wide wildlife adaptation.
Gibraltar’s Barbary macaques are turning to soil to soothe their stomachs after eating junk foods left by visitors. A Cambridge-led study observed the behavior across the Rock of Gibraltar, noting that the monkeys often opt for dirt when their meals are high in calories, sugar, salt and dairy. Geophagy, the practice of eating earth, appears to help buffer the digestive system against the gut upset caused by these calorie-rich snacks. The researchers describe the behavior as both functional and cultural, likening it to nut-cracking in other primates, but driven entirely by close proximity to humans.
Across the study period, about 18.8% of all food consumed by the macaques came from junk food provided by tourists. Even though local authorities run feeding stations with fruit, vegetables and water, the macaques frequently pilfer human snacks. The findings suggest a notable shift in the species’ diet, away from their traditional fare of herbs, leaves, seeds and occasional insects, toward easier, human-sourced calories.
The emergence of this behavior underscores how wildlife can adapt to tourist activity in real time. While geophagy may offer short-term stomach relief, researchers warn about the broader implications of relying on human foods and the potential health consequences for the animals. The study highlights a complex interaction between wildlife, culture, and human presence on Europe’s only wild monkey population.
