Amid all the panting, a dog at play makes a distinctive, breathy exhalation that can trigger playfulness in other dogs, says a Nevada researcher. Yes, it might be the dog version of a laugh.
"To an untrained human ear, it sounds much like a pant, 'hhuh, hhuh,'" says Patricia Simonet of Sierra Nevada College in Lake Tahoe. However, this exhalation bursts into a broader range of frequencies than does regular dog panting, Simonet discovered when she and her students analyzed recordings.
They observed the bursts during play but not in aggressive clashes, Simonet reported in Corvallis, Ore., last week at a meeting of the Animal Behavior Society.
Gordon Burghardt of the University of Tennessee in Knoxville, who theorizes about the evolution of play, says Simonet's p