April 6, 2005
Animals laugh. Sort of. Rats, when tickled, emit sounds that sound like laughter. How do we know that? Scientists at Bowling Green State University in Ohio and Northwestern University in Illinois, tickled rats for science. Not only that, they got their research on rat-tickling published in "Science" this week. The article didn't say who funded the research but how expensive can it be to tickle rats? You take a rat, hold in your hands.... The reseachers concluded that humans are not the only species to laugh, although we may be the only ones to respond to verbal jokes. The neural circuits for laughter exist in very ancient regions of the brain, and therefore may precede the capacity to speak in evolutionary terms, the researchers wrote. Organisms can laugh before they can speak, which when you think about it, is a nice thing. According to Jaak Panksepp of Bowling Green, the capacity to laugh "emerges early in child development and perhaps in mammalian brain-mind evolution as well. Indeed, young children, whose semantic sense of humor is marginal, laugh and shriek abundantly in the midst of their other rough-and-tumble activities." Other mammals have play sounds, including a panting sound when you tickle them. Panksepp has "laughing rats," which emit “a cacophony of 50-kHz chirps when delighted, including when Panksepp (or more likely a graduate student) tickles them. The laughing rats also preferred the company of other rats that laughed a lot, forming a jolly band of rodents. The animal room must be a riot. When they laughed, they seemed to show that dopamine reward circuits in the brain fired off, just as happens when humans laugh, so the sounds have some biological basis. “The sources of play and laughter in the brain are instinctual and subcortical," he wrote. The research, he suggested, might lead to the discovery of molecules that could alleviate depression. The "Science" paper was notable for several reason, not the least of which it was politically incorrect enough to quote Charles Darwin, and contained part of a poem by William Blake (“...Under every grief and pine/ runs a joy with silken twine.”). You don’t get to see a lot of Blake in "Science," which is too damned bad. There is the Annals of Improbable Research, to think of, of course.