Everyone who has a dog wants to believe they have an amazing connection with their pooch. You know what they want and it seems as if they can read your heart, if not always your mind, right?

Well, read on to see if you’ve been interpreting those tail thumps correctly all this time.

If I had to guess, I would say most people agree that a wagging tail equals a happy dog.

Experts like Silvia Leonetti and Taylor Hersh (both bioacousticians) and Andrea Ravignani (an evolutionary cognitive scientist) say that tail wags can denote a much wider range of emotions than that, though.

The trio pulled together more than 100 studies about why dogs wag their tails and what those wags mean before giving Science an interview to parse it all out.

First, they asked Silvia Leonetti whether or not other animals wag to communicate.

“Many animals have a tail, and they use it for different reasons, like moving, balance, or removing flies from their bodies. One study that looked at more than 40 species over a 4-year time span found that the domestic dog was the species that wags its tail most.”

They also wag their tails at a younger age and more often that their wild counterpart, which are wolves.

Leonetti also believes that it’s more common in dogs than in wolves because it evolved along with other traits that humans valued in domesticated dogs.

“We were selecting dogs for docility and tamenes, but these traits were genetically linked to the tail-wagging behavior. A second hypothesis is that during the domestication process, humans consciously or subconsciously selected dogs that were wagging their tails more because we are very attracted to rhythmic stimuli.”

Taylor Hersh says we now know quite a bit about the different ways dogs communicate through tail wags.

“I think my favorite thing that I learned in reviewing all the studies is that tail wagging is an symmetric behavior. Often if there’s something a dog encounters that it wants to approach, it wags more to the right side of its body, whereas if there’s something it wants to withdraw from, it wags to the left side of its body. And they can perceive those asymmetries in other dogs.”

As for the assumption that a wagging dog is a happy dog, well, Hersch says it’s more complicated than that.

“One major takeaway that we saw in reviewing the research is that the links just aren’t as clear. There was a study, for example, that looked at shelter dogs and how the dogs wagged their tails before and after being pet by a human. Dogs that had been admitted as strays actually had their cortisol levels go down after they had been pet by a shelter volunteer. The dogs that had been surrendered by owners didn’t show that drop. In both cases, the dogs were wagging their tails more when they were being pet but their stress levels changed differently depending on their life history.”

The takeaway is, I think, that like with humans, a lot can be going on in a dog’s body that they’re not showing on the outside.

You know your dog best, and when it comes to strange dogs, well…as always, approach with glee (but also caution) until you get the lay of the land.

If you found that story interesting, learn more about why people often wake up around 3 AM and keep doing it for life.