John Hopton for redOrbit.com – Your Universe Online
People certainly disagree about whether being tickled is funny or just plain awful, and we have all met that person who challenges our whole ethical core with an enticing “I am serious, do not do it.” It appears that science has not entirely agreed on the phenomenon of ticklishness either, though there are some prominent theories.
For instance, being ticklish is an evolutionary tool designed to prepare us for attack. The most ticklish parts of the body are also the most vulnerable: under the chin, around the ribs and stomach, near the groin and under the armpits.
A SciShow video tells us that there are two kinds of ticklishness. One is knismesis, where we get a bit of a shudder if something brushes our skin. If an insect lands on us we do a quick jolt to get rid of it, in the same way that a horse swats it with its tail. This applies more to ticklish feet because there are a lot of nerve-endings there.
The second is more difficult to understand: gargalesis. This is the full on belly laugh and wriggling we get from a harder touch, particularly in those tickling hotspots mentioned before. While knismesis is widespread in mammals, gargalesis only exists in primates. Apes are ticklish in the same spots as we are.
SciShow explains the reason we laugh when tickled is because, despite the confusing mix of fun and pain, it is actually good for us. It teaches us to wriggle and get away from predators–and about which areas to protect. Laughing encourages the tickler to do it more, and in this way our vindictive sibling or playful parent can teach us survival skills. It is the same reason that puppies play fight. If we reacted, instead, with anger, we wouldn’t do it to each other as often, and our life skills would suffer.
While they also believed that gargalesis was an evolutionary mechanism, researchers in Germany took a slightly different view and identified the laughter as displaying submissiveness. Scientists at the University of Tuebingen, the Daily Mail reported, “theorize that parents would have tickled their offspring to train them to react to danger and that the laughter of tickling is an acknowledgement of defeat.” Tuebingen scientists also suggested that ticklish laughter is different to other kinds of laughter in terms of brain activity and social response.
It is interesting that we can’t tickle ourselves. This fits in with the fight/flight evolutionary tool theory. It can also tell us a lot about how our brain distinguishes the self from others, including distinguishing our own touch from that of others. This is something that robots have not been able to achieve yet, but a better understanding of it within ourselves will help with the development of artificial intelligence.
Scientists have gone to extreme and comical lengths to try and make people tickle themselves, from having lucid dreamers tickle each other, using self-tickling devices with time delays, using magnetic brain stimulation and even trying to give people out-of-body or body-swap experiences using a virtual reality device. Most of the experiments failed, but like the poor little brother whose big brother just found out that tickling him is doing him a favor, they learned something along the way.
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