Burghardt's research illustrates how play is embedded in species' biology, including in the brain. Play, as much of animals' psychology including emotions, motivations, perceptions and intellect, is part of their evolutionary history and not just random, meaningless behavior, he said.
"Play is an integral part of life and may make a life worth living."
And then from the article science daily links to.....
For years, neuroscientist Jaak Panksepp had been watching rats play at the College of Veterinary Medicine at Washington State University, and recording some extremely high-pitched vocalizations they made as they did so. Then one morning in 1996, it hit him. Maybe, he thought, the bizarre sounds his lab rats made while they played were something akin to human laughter.
“I just walked into the lab and [said], ‘Let’s go tickle some rats,’” he recalls. Sure enough, flipping the rats on their backs and giving them a good belly tickle elicited a response that “was so wonderfully strong and powerful,” he says—the rats just couldn’t stop “laughing.”
Panksepp saw great value in studying rat laughter (technically termed ultrasonic vocalizations, or USVs). He suspected that the sound could be used as an objective measure of the animals’ positive affect, or pleasure, as it was produced most consistently during playtime, which was known to be a pleasurable and rewarding activity. Sure enough, as he and his colleagues began to work out the brain circuitry underlying the vocalization, they found that it overlapped with a reward pathway in the brain known to be activated during feelings of enthusiasm, joy, anticipation, and eagerness.
“Every place in the [pathway] that we stimulated, we got a chirp,” Panksepp says. “That’s the gold standard that [this vocalization] is [associated with] a big reward.” As the laughter is heard robustly during playtime, it indicates that play is in and of itself rewarding, or fun. But more important, rat laughter itself could provide the first objective measure of positive affect in nonhuman animals. This finding could lead to greatly improved animal models for psychiatric disorders, which currently rely on indirect measures such as sugar intake.
“If we take animal feelings seriously and develop ways to measure [them], [we can] profoundly increase our understanding of ourselves, especially at the lower levels where we’re so similar,” Panksepp says. “This is the first deep neuroscience of the mind.”
Read more: Recess - The Scientist - Magazine of the Life Sciences http://www.the-scientist.com/2010/10/1/4...z13NHrYqKl