One of the first phrases that Washoe, a chimpanzee who was taught sign language, and Alex, a gray parrot capable of constructing simple expressions, learned was "you tickle me." Primates and some birds are not the only animals with whom we share this feeling. A study by the Neuroscience Center at Bowling Green University in Ohio State, in the US, revealed that laboratory rats literally squeal with pleasure when tickled and, like humans, use them in their games and to establish bonds social.
In the process they release dopamine , a neurotransmitter that is related to emotions and feelings of pleasure.
More questions in VERY: Can tickles kill?
