Why do dogs bark?:
Dogs bark to say that there is something strange happening and to
be alert. In the wild the barking tells puppies to hide and calls
the adults over for action. At home, our dog may bark at us or at
a burglar. The barking signals that something is happening; once
the new arrival has been identified, either a greeting takes place
or an attack.
A fearless dog that is intent on attacking is silent. It doesn't
waste time barking, that is, sounding the alarm. It just rushes
over and bites. On the other hand, a dog that wants to flee instead
will also be silent as it runs away.
A more common occurrence is when a dog is not quite sure -- it is
feeling a little fear while it thinks about attacking. This dog
will snarl and retract its lips to reveal its teeth. It is the tinge
of fear that converts the silent attack into a snarling one. The
urge to attack is still strong, however, so this is not a dog to be
If the dog is more fearful, it will alternate barking with growling.
If fear gains the upper hand, the growling will stop, replaced by
loud barking, until either the threatening situation goes away or
Apparently, barking was improved during the process of domesticating
the dog. Wolves bark, but not as loudly as dogs, although they can
learn to bark more loudly if they live around domestic dogs. It seems
likely that humans bred the louder puppies to create better guard
dogs. All dogs bark, except the Basenji, which was bred thousands
of years ago as a silent hunting dog.
Source: Illustrated Dogwatching, by
Desmond Morris, Crescent Books, New York, 1996, pp. 30-34.