Macaques have learned to eat soil to avert gut irritation caused by salty and sugary snacks, researchers believe
Troops of monkeys living on the Rock of Gibraltar have learned to eat soil in what scientists believe is an effort to settle their stomachs after all the junk food they receive – and sometimes steal – from crowds of tourists.
Researchers spotted the intentional mud eating, known as geophagy, while observing groups of Barbary macaques in the territory. Monkeys that had the most contact with tourists ate the most soil and consumption peaked in the holiday season, they found.
About 230 macaques live on Gibraltar in eight distinct groups, and while local authorities provide them with daily helpings of fruit, vegetables and seeds, tourists routinely feed them snacks ranging from bags of chips and chocolate bars to M&M’s and ice-creams.
The observations don’t prove why the monkeys eat soil, but scientists suspect it has a protective effect on the digestive system. The only macaques on the rock that were not seen eating soil belonged to a group that is isolated from visitors and tourists.
