Tourist Snacks Have Triggered a Bizarre New Behavior
Gibraltar’s famous Barbary macaques have picked up an unusual habit — they are eating dirt after feasting on human junk food.
Scientists say the monkeys deliberately consume red clay-rich soil after eating snacks such as chips, biscuits, chocolates, and even ice cream, likely to calm stomach trouble caused by these processed foods. Since such salty and sugary treats are far removed from their natural diet, researchers believe the animals may have developed this behavior as a way to protect their digestive systems.
What makes the discovery especially striking is that the behavior appears closely linked to tourist activity.
Scientists Believe the Monkeys Are Self-Medicating
Researchers call this behavior geophagy, or the intentional eating of soil and clay. While scientists have documented geophagy in many animals before, this is the first time they have linked it so clearly to the consumption of human junk food in Gibraltar’s macaques.
During the study, researchers recorded 46 separate soil-eating incidents involving at least 44 monkeys. More importantly, they noticed that the behavior became far more common in areas with heavy tourist footfall and during the busy summer season, when visitors often feed the macaques or when the animals steal food directly from them.
As a result, scientists suspect the monkeys may be using dirt as a natural remedy.
Why Dirt Might Help
The red soil the macaques consume contains clay minerals such as kaolin, a substance long known for its stomach-soothing properties. In humans, similar clay-based compounds are often used to ease digestive discomfort.
Because of this, experts believe the soil may help neutralize stomach acids, absorb toxins, and restore balance in the gut after the monkeys eat highly processed foods.
In short, the macaques may be self-medicating in response to an unnatural diet created by human interaction.
A Bigger Warning for Wildlife
However, the discovery is more than just a fascinating animal behavior story. It also serves as a warning about how human habits can reshape wildlife.
Tourist snacks now form a noticeable part of the monkeys’ diet, pushing them to develop unusual coping mechanisms. Over time, researchers warn, continued feeding could harm their health and permanently alter their natural behavior.
In other words, these monkeys may be adapting — but their adaptation is also a sign of how deeply human influence is changing life in the wild.
