Like simian Nolan Ryans, chimpanzees have garnered a reputation among the rest of the animal kingdom for their pitching prowess. Unfortunately, it’s not baseballs they’re tossing. Chimps have a habit of attacking bystanders by throwing their own feces, tossing poop around like relief pitchers at the bottom of the ninth. It's yet another reason they will never make a good pet.

Why do they do this? And could turd-tossing actually be a sign of intelligence?

According to the Jane Goodall Institute of Canada, this type of behavior isn’t usually seen in free-roaming chimps in the wild. While the species is still prone to throwing things, they usually stick to rocks or branches when they want to express their annoyance. In captivity, foreign objects are not usually in abundance, and chimps that are feeling frustrated or anxious will instead opt to toss the one thing that’s in plentiful supply: poop.

Ease of access is not the only reason a chimpanzee will launch feces. When a chimp is in captivity, throwing poop is likely to cause a reaction—either from zoo employees or guests. Chimps will begin to associate the act (throwing fecal matter) to a response (usually surprise or horror). Though this behavior isn’t limited to them—howler monkeys in Belize also do it—chimps are probably the most well-known example. In tossing their crap, chimps realize that they can control the behavior of others to some degree. If they throw an overhand turd, people will run.

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While it would be easy to associate throwing poop with limited intelligence, the opposite might be true. In a 2012 study published in Philosophical Transactions of the Royal Society B, researchers at Emory University found that chimpanzees who had good aim when throwing things had more development in their motor cortex, where physical actions are coordinated. They also had better communication between the cortex and Broca’s area, a portion of the frontal cortex that helps process language in humans. Their left brain hemispheres, which control right-handed behavior, demonstrated more development. The rocket-armed chimps were also typically better communicators within their social groups.

Another indication that hurling poop fastballs is for intellectuals: It might be premeditated. A 2009 article published in Current Biology described a chimp named Satino, a resident of Sweden’s Furuvik Zoo in the 1980s and 1990s, who demonstrated real scheming. Satino was an aggressive chimp (he eventually killed a fellow male chimp) who often tossed rocks at visitors watching him from behind a fence. Because Santino always seemed well-armed, zookeepers investigated his enclosure and found that Santino had been stockpiling rocks from the moat that separated him from the fence. Santino made sure to do this before the zoo opened so he would have ammunition at the ready. He even chipped away at big concrete rocks to craft dinner plate-sized projectiles. Other chimps have been observed to poop in their hands and then wait for an annoying human to pass by.

Lots of things might cause chimps to feel disgruntled. In the wild, it might be having their buttons pushed by other primates. In zoos, they might be upset that people are staring at them and that they're limited in their movements. If you happen to be among those observing chimps in a facility, bear in mind that they might get a little upset. And depending on their aim, so will you.

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