Animal laughter may shed light on human illnesses

CHICAGO – Tickling rats to make them chirp with joy may seem frivolous as a scientific pursuit, yet understanding laughter in animals may lead to revolutionary treatments for emotional illness, researchers suggest.

Studying such sounds of joy may help us understand the evolution of human emotions and the brain chemistry underlying such emotional problems as autism and attention-deficit/hyperactivity disorders, said Jaak Panksepp, a neuroscientist who discovered rat laughter.

Biologists suggest that nature apparently considers sounds of joy important enough to have conserved them during the evolutionary process.

Panksepp, of Bowling Green University in Ohio, tried tickling rats gently around the nape of ther necks and found it made them chirp happily. Rats that were repeatedly tickled would seek out tickles. Researchers also found that rats would rather spend time with animals that chirp a lot than with those that don’t.

During human laughter, the dopamine reward circuits in the brain light up. When researchers neurochemically tickled those same areas in rat brains, the rats chirped.

Rat humor remains to be investigated, but Panksepp said that laughter, at least in response to a direct physical stimulus such as tickling, may be a common trait shared by all mammals.