If you’ve ever lived with dogs, or raised a puppy, you’ve probably seen them excitedly sink their teeth into a stick. Traditionally, we’ve brushed it off as just another canine instinct or behavior, much like shooting us puppy dog eyes or licking themselves. But what if chewing on sticks is actually a sign of dogs’ intelligence?

For a long time, scientists assumed that just a handful of animals, including many primates and crows, used tools. In fact, tool use was seen as a marker of advanced evolution, a sign that we are smart enough to adapt our environment to our needs. A pair of researchers at Kyoto University want to include dogs among the ranks of toolmakers, and their findings have the potential to change how we think about animal intelligence.

James Brooks and Shinya Yamamoto carefully observed dogs chewing on sticks, and asked themselves why this behavior is so common. They posit that dogs purposefully use sticks to clean their teeth, and that stick chewing could relieve teething pain in puppies, much like we humans give our babies teething rings, and note that the way dogs hold their sticks in their paws suggests they’re potentially thinking through how to manipulate objects in space. This fits the definition of tool use.

Brooks and Yamamoto recommend further studies to see if dogs seek out sticks to chew on more often when they have other indicators of tooth pain or after different kinds of meals, and if more frequent stick-chewers have better dental health later in life. They also suggest we view tool use in animals as a spectrum, and their research raises questions about animal behaviors that might otherwise be overlooked as mere instinct. In other words, dogs and their sticks might just be showing us that animals are deliberate in their interactions with their environments.