Did you ever wonder why Timmy and Lassie were such good friends? 

It turns out our ability to understand dogs peaks at right around 10 years old. According to a new study, published in the journal Applied Animal Behavior Science, humans and canines have spent so long living side by side, that we’ve developed a basic understanding of canine language. In fact, the vast majority of us can tell a dog’s mood just by the tone of its bark. However, the study suggests that we don’t gain that ability until we’re about 10, which explains why younger kids can never tell when it’s time to stop yanking the puppy’s tail!