Since I share a home with two Shetland Sheepdogs, barking is a part of my everyday life. While I enjoy hearing all the funny noises my pets make, barking can have serious consequences: It is one of the behavior problems that lands dogs in shelters. Ironically, humans may be responsible for the very barking we complain about.
Csaba Molnar, a former ethologist at Eotvos Lorand University, has been studying how barking evolved in the dogs we love. Barking is common in domesticated dogs, but not wild dogs.
Since barking is common in domesticated dogs, but not wild dogs, Molnar believes that the behavior is linked to selective breeding by humans. Molnar's studies have uncovered some interesting findings.
In terms of pitch, repetition, and harmonics, canine barks are fairly universal. In other words, one dog's alarm bark fundamentally resembled another dogs' alarm bark. Molnar found that even sheepherders, people who are certain in their ability to recognize their own dogs' vocalizations, couldn't distinguish their dogs' barks from others.
The most variation in barking is made by dogs at play. According to Molnar, this shows human influence. While warning barks are important for people to be able to identify, play noises are relatively unimportant.
People can reliably identify the context in which barks are made, by hearing audio clips of dogs in different situations (e.g., confronting a stranger, playing). In short, we have some ability to understand the canine language even without any visual clues.
Molnar is currently seeking funding to explore why humans might have selected for barking abilities, although another theory believes that it wasn't intentional. Eugene Morton, a zoologist and animal communication expert at the National Zoo, believes that in selecting for “friendly traits” in wolves, barking was a unintended byproduct. Barks are used by juvenile wolves, which also share many other traits with domesticated dogs, such as playfulness.
No matter how barking evolved, it's pretty cool that Molnar's study showed that we can understand dogs' vocalizations to some extent. We are closer to our pets than we think!