PHILADELPHIA (AP) — A gorilla at the Philadelphia Zoo decided to stroll upright like humans do to avoid getting his hands dirty.

Apparently, 18-year-old Louis is a clean freak.

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When Louis has his hands full of tomatoes or other snacks, he walks upright like a human to keep food and hands clean, rather than the typical gorilla stance of leaning forward on his knuckles.

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Michael Stern, curator of primates and small mammals, says workers had to install a fire hose over a mud puddle in the yard. The nearly 500-pound, 6-foot-tall primate crosses it like a tight rope to avoid getting dirty.

Stern says it’s “pretty unusual” for gorillas to walk around upright. In the wild, Western lowland gorillas like Louis might do it for a few seconds to reach food or wade into swamps.

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