Tickling is no laughing matter. Many great scientists, including Plato, Darwin and Galileo, have tackled tickling, and much about it remains a mystery. However, research has revealed that tickling has some important defensive, social and health functions.
When people think about being tickled, they often recall a parent or relative moving their finger or a feather lightly across their foot’s sole. The same sensation occurs when a spider, scorpion or other insect scurries across our foot, leading scientists to believe ticklish feet are an evolutionary defense against insect bites. Given that our feet are close to the ground, often exposed, and are among our most ticklish body parts, this explanation makes sense.
For us to be tickled, we cannot know where the object touching our foot’s sole will move. This is why we cannot tickle ourselves. It also furthers the creepy-crawly tickling theory, since bugs move unpredictably and cause a great tickle response.
Another support for the bug-related theory is that tickling stimulates nerves connected to both pain and touch, which is why most people consider it simultaneously pleasant and unpleasant. Our first reaction is to pull our foot away from the tickling source. Interestingly, a similar tickle response occurs in many animals, including monkeys, cats, and even rats, presumably as a way to avoid bug bites.
Not only do insects tickle, but people also like to tickle each other. Tickling is one of the most common human behaviors, and Darwin believed a link existed between tickling and social bonding. This is why, he said, children laugh when their parent tickles them, but if the child doesn’t expect to be tickled, they respond with displeasure.
Today, psychologists believe tickling helps establish trust between a child and mother. Even people that believe they don’t like to be tickled, may actually enjoy it. In one study, adults who claimed they did not like being tickled smiled more when tickled than those people who said they found tickling pleasant. Perhaps all this childhood tickling played a subconscious role in Americans’ bond with Tickle Me Elmo, 1996’s most popular toy.
In my practice, I often ask patients if their feet are ticklish because it can reveal information about their health. If they’re not, it either means their feet never were ticklish or the patient may have neuropathy, a disease where nerves deteriorate. The first sensation patients that have neuropathy often lose is the ability for their feet to be tickled. Discovering neuropathy early is important because a more serious disease, such as diabetes, thyroid disorders, a vitamin deficiency or certain kinds of arthritis, often causes it.
When patients with neuropathy come to me with an open sore on the sole of their foot, I am not surprised when an x-ray reveals a pin, tack or nail inside the foot. Because these patients’ feet are numb, they don’t experience pain when they step on something sharp.
Without pain, these patients tend to let their foot problems persist longer than they should before seeking medical care. Recently, a woman with neuropathy who had an infected sore between two toes waited so long before coming to me that when I spread the toes apart to examine the sore, I saw maggots crawling around. Eventually, she needed several toes amputated.
When patients that don’t have neuropathy complain about foot pain, I often tell them to be happy their feet can experience pain; it alerts them to problems and they want to seek help. People that have lost sensation in their feet, whether due to neuropathy or other diseases, need to be especially vigilant and examine their feet regularly for problems.
If your feet are no longer ticklish or you notice other changes in their sensation, see a podiatrist. Otherwise, the next time someone tickles your foot, don’t just laugh, be happy.