The dogs are barking--and sending a message.

• Position: Your Life

Dogs--they are loyal, loving, and always there to lend an ear when you need it most but, when it comes to understanding their vocalizations, let's just say it can get lost in translation.

Man's best friend seemingly barks at everything--from the television, to the neighbors, to ladybugs on the windowsill--so what does it mean? Your pooch may produce varying forms of "yelps," "woofs," and "cries" but, to a trained ear like that of Kathryn Lord, visiting assistant professor of biology at Gettysburg (Pa.) College, a bark is a distinct vocalization.

"It is a signal that is always abrupt in onset and short in duration," says Lord, a researcher of evolutionary and developmental behavior, specifically in dogs and wolves. Barking is common among both birds and mammals, including deer, seals, and monkeys, but is the hallmark of domesticated dogs since they bark more frequently than any other animal, even wolves, their closest cousin.

Lord theorizes barking is due to an evolved behavior known as mobbing, a response typically provoked by the approach of a threat. To understand the behavior, you need to look back 10,000 years to when our furry friends first started roaming human food dumps. Although it was a great way for dogs to score a free meal, it also forced them to compete against other predators.

At this...