March 20 (UPI) -- A Philadelphia Zoo gorilla going viral after showing off his human-like method of walking doesn't like to get his hands dirty, officials said.
Zookeepers at the facility said Louis, a 14-year-old gorilla at the zoo, was holding tomatoes in his hands at the time of the video that spread rapidly across social media, but he has also been known to use his human-like walk just to keep his knuckles clean.
"In the video, he does have his hands full of tomatoes, which is one of his favorite treats, and I think he just doesn't want to crush them by knuckle-walking, so he stands up and walks. He'll also do it more if the yard is muddy. For whatever reason, he does not like the feel of mud on his hands and he just likes to stand up and walk sometimes," zoo curator Michael Stern told CBS News.
"Gorillas will occasionally stand up for a few seconds or walk a couple of steps, but what we see Louis doing is really walking clear across the yard, and that's quite special," Stern said.