No sand on this tomato.
No sand on this tomato. Pixabay/CC0 1.0

Western lowland gorillas, according to a study published yesterday, don’t like their food to be dirty. That’s a no-brainer. But researchers from Britain and Germany discovered that when given peeled apples covered in sand, gorillas would clean them before eating. What’s intriguing is that they did so without any human or gorilla teaching them how.

In at least 75% of trials, gorillas Bebe, Gorgo, Kibara, Louna, and Viringika, who are residents of the Leipzig Zoo in Germany, cleaned their apples before eating them. Since most of the gorillas were born and fed their whole lives in captivity, they wouldn’t have been exposed to the food-cleaning practices of wild gorilla populations.

Western lowland gorillas apparently don’t need to learn this behavior from parents or peers. Human parents have to wrestle dirty food away from their children, but western lowland gorillas figure out how to clean their treats. Those cognitive abilities may be genetic. Dirty food can have deadly parasites, after all.

For the study, researchers watched as Bebe and the other primates figured out how to clean their food. Gorillas sat in observation rooms and were offered peeled apples dusted with sand. Gorillas used their fingers, forearms, and sometimes the floor to wipe off the sand before eating. (The study also says that the gorillas were never deprived of food or water, and the sand was non-toxic and treated for bacteria.)

While culture plays a role in popularizing practices in wild gorilla groups, food cleaning, says the study, “is not heavily reliant on social learning.” So the next time you call on the five-second rule, you have no one to blame but yourself.

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