Dog Bark Gets A Science Definition (And It Doesn't Involve Communication With Humans)
    By News Staff | July 15th 2009 12:00 AM | 4 comments | Print | E-mail | Track Comments
    Dogs aren't the only animals that bark, they are just the most famous. Deer, monkeys and even birds also bark but what makes dogs different is a subject of interest in a new evolutionary biology study.

    In a recent Behavioural Processes paper, researchers have provided scientific literature with what they say is the first consistent, functional and acoustically precise definition of this household animal sound.

    Kathryn Lord, a graduate student in organismic and evolutionary biology at University of Massachusetts Amherst, says, “We suggest an alternative hypothesis to one that many biologists seem to accept lately, which seeks to explain dog barking in human-centric terms and define it as an internally motivated vocalization strategy.”

    But barking is not a special form of communication between dogs and humans, the authors state. “What we’re saying is that the domestic dog does not have an intentional message in mind, such as,‘I want to play’ or ‘the house is on fire,'” explains Lord.

    Don't tell Lassie that. Timmy would never have gotten out of that well.

    Instead, the researchers say barking is an auditory signal associated with an evolved behavior known as 'mobbing', a cooperative anti-predator response usually initiated by one individual who notices an approaching intruder. For example, A dog barks because it feels an internal conflict, an urge to run, as well as a strong urge to stand its ground and defend pups. When the group joins in, the barks intimidate the intruder, who often flees.

    “We think dogs bark due to this internal conflict and mobbing behavior, but domestic dogs bark more because they are put, and put themselves into, conflicting situations more often,” she says.

    They say the reason traces back to the first dogs that started hanging around human food dumps, 8,000 to 10,000 years ago. They would have experienced a serious disadvantage if they had run a mile away every time a human or other animal approached.

    According to Lord, “In evolutionary terms, dogs self-selected the behavior of sticking around, overcoming their fear and being rewarded by getting to eat that meal before some other dog got it. Thus these animals allow people to get unusually close. The scared ones die while those less scared stay, eat, survive and reproduce. So they inherit the tendency.”

    She adds, “By contrast, wild animals like wolves have a very long flight distance. They hear something and they run before you'd ever see them. Dogs hang around, but now they have committed to holding their ground and the closer an ‘intruder’ gets, the more likely mobbing is to occur rather than running away.”

    An example of the domestic environment (rather than the dog’s own behavior) that increases barking is the animal stuck behind a fence with a person approaching, says Lord. “The dog may either feel anxiety or excitement at seeing a stranger but in either case the dog is prevented from approaching or fleeing. This creates conflict, and thus barking.”

    They identify eight different parameters in three categories which must be met in order to classify a given vocalization as a bark. These include tonality, noise, pitch, volume or amplitude, abrupt onset and pulse duration, for example.

    In their view, barking is not self-referential communication to convey a message, but a short, loud sound characterized by combining both noise and tonal sounds, which is unusual in animal calls.

    This definition widens the bark’s usefulness as a functional behavior seen in many animals, though domesticated dogs display it more often. “Using this definition, even birds bark, and certainly many mammals besides canines, including baboons and monkeys, rodents and deer also bark,” Lord explains. “In a whole bunch of mammals and birds, what they do in such conflicted situations is bark.”

    You think some segments of the religious community have a problem with evolution? Wait until pet owners who think their dog 'communicates' with them by barking read this article.

    “We understand the objection when people say their dogs bark for supper or to get out and play,” Lord says. “Dogs do quickly learn the simple cause-and-effect relationship between their bark at 10 p.m. and the fact that you’ll get right up and take them outdoors. It’s true, but in our view it’s going too far to suggest the animal is intentionally referring to a specific activity. Rather, it has just learned cues, as it does when it learns to sit or beg for a treat.”


    without claiming there is deliberate communication from dogs to humans, it can be seen that the two species co-evolved. dogs got scraps, humans got warnings, especially at night. cute puppies got befriended. pariah dogs got rocks thrown at them, but still ate.
    the dogs bark because the other dogs bark. even a small barking dog can drive away a bear, because of the pack effect. what thoughts prevail matters little. nature rules.

    Gerhard Adam

    I'm not sure why the special connotation of "dogs to humans" is even being considered.  If the dogs and the humans are part of the "same pack", then the communication is intended to convey an overall message. 

    I can tell when dogs are barking because they detect another dog moving around.  The closer it approaches the more directed the barking becomes.  Similarly when another animal is moving around the property, the form of barking invariably serves to bring notice to that fact.  This is an especially noticeable attribute of such a bark, because when it is clear that the other animal is seen by all the "pack" members, the dogs lose interest in barking (except for perhaps one that will keep up a half-hearted harassing kind of bark). 

    If another human approaches, the dog's barking is notably more pronounced and aggressive (especially if this is around unusual times and the individual isn't known to them).  To contrast this with the previous example, all one has to do is to see how many dogs are participating in the barking and where they are standing.  If they aren't ALL together, then you know there is no one approaching.

    Overlooking the fact that barking is often used as a warning to strangers or as play among other dogs misses another element of communication.  Whatever "conflict" is generated, it is equally important to note that many dogs do NOT bark when someone comes close.  Once warning is given, many dogs will simply attack an intruder with no additional warning.

    The simple fact is that any dog owner that ignores his dog's barking, invariably does so at their own peril, because it usually means that dog is trying to "tell you something".

    Mundus vult decipi
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    I recently came across your blog and have been reading along. I thought I would leave my first comment. I don't know what to say except that I have enjoyed reading. Nice blog. I will keep visiting this blog very often.