On the tourist-packed Rock of Gibraltar, one of the most common sights are monkeys begging for food – and sometimes stealing sweet and salty snacks from unsuspecting visitors.
Scientists have now documented an unusual behavior among these macaques that may help them avoid stomach aches from this junk food.
The researchers said the monkeys were seen eating soil frequently, a behavior they said may help the monkeys avoid stomach upset from eating human snacks.
They found that soil eating was more common in monkey groups that consumed more food from tourists, including chocolate, crisps and ice cream – high in sugar, fat and milk, and low in fibre.
“We propose the idea that human food, without changing according to their natural diet, causes intestinal upset, and the possibility of disruption of the microbiome, the effects of which are caused by soil elements,” said Sylvain Lemoine, a biological anthropologist at the University of Cambridge in England and the lead author of the study published on Wednesday in the journal Scientific Reports.
Compared to something in humans, eating clay “probably acts like antacids”, Lemoine said, adding that more research is needed to understand its effects on gut bacteria.
