It is a mystery why you laugh when someone tickles you. It is not that you find it funny, but that the laughter comes involuntarily. There are reasons why you can’t tickle yourself and some other facts about tickling that you probably weren’t aware of.

There are millions of tiny nerve endings beneath your skin that alert your brain to all types of touches and sensations, which are analysed by the nervous system. A light touch can cause a tickling sensation in your body that makes you laugh. This is due to the joint analysis of two regions of the brain that function together:

• The somatosensory cortex: This is the region of the brain that is responsible for analysing touch and the pressure associated with it.

• The anterios cingulated cortex: This region of the brain administers pleasant feelings, which cause laughter.

Tickling sensations are caused by a light touch, so if a person is tickled too hard the anterios cingulated cortex registers it as pain rather than laughter, which is why some people don’t laugh when they are tickled.

Here are a few facts about tickling:

• It is impossible for a person to tickle their own body as the cerebellum located at the back of the brain predicts a self-tickle and alerts the rest of the brain, which mutes the sensation.

• The laughter from tickling is part of defence mechanism that signals submissiveness. It is a coincidence that the most vulnerable areas of the body are also the most ticklish, such as the stomach, neck, armpits and feet.

• Tickling is a product of socialisation. It builds relationships, like when a mother tickles her new born, the baby laughs, forming a communication between them.

• Human beings are not the only species to experience this phenomenon, since great apes and rats also laugh when they are tickled.

• Tickling alerts our body by drawing attention to external stimuli like parasites or predators.

• Ticklish spots are universal, like the area from the neck to the waist and the soles of the feet.

• During the 16th century, tickling was used as a form of corporal punishment. Ancient Romans punished their prisoners by tying them up and soaking their feet in salt water, and then letting goats lick it off.

• The most common reason for tickling is to show affection. People in adolescence are seven times more likely to get tickled by a member of the opposite  sex.

• You can trick your brain into avoiding laughter when you are being tickled. Place your hand on the face of your tickler and tell your brain that you are the one who is doing it and you will feel no sensation at all.

• Men are more sensitive to tickling than women, which is most likely a result of higher non-reciprocal sexual touching in women.