This dog-exhalation study reopens many questions about whether animals laugh, comments Brian Knutson of the National Institutes of Health in Bethesda, Md. He has recorded chirps that laboratory rats give as they wrestle with each other. Rats also chirp before receiving morphine or having sex. He interprets the sound as indicating "the rat expects something rewarding." ... He says he's unsure about how to compare the chirp of a romping rat to the guffaw of a person. "I think we've done a decent job of figuring out what it means in the rat," he says. "Now the onus is on the human researchers."Another analyst of rat chirps, Jaak Panksepp of Bowling Green (Ohio) University, has recorded the animals' ultrasonic squeaks while he tickled them. "Of course, you have to know the rat," he cautions.
Yet another student of play, Marc Bekoff of the University of Colorado in Boulder, says he thinks he knows the panting sound Simonet describes. "When I get down on all fours and go up to dogs and go 'hhuhahhuhahhuh,' they get very solicitous," he says.
Now what am I doing when I do this?
They're probably just humoring the poor lunatic . . .