Dana asks: Why does tickling make us laugh and why can't we tickle ourselves? Evolution gives an answer to this question as well
Contrary to popular opinion, laughter is not unique to humans: chimpanzees and other monkeys make sounds similar to our laughter and in similar social situations. Chimpanzees in the wild will make such sounds when another member of the group tickles them or chases them in a game similar to "catch". The tickling or chasing monkey tends to continue this activity as it is reinforced by the laughter of its playmate.
Along with the social similarity between human laughter and that of chimpanzees, the difference can also be pointed out. The sound of our laughter is a series of "ha" syllables, each of which lasted about 0.07 seconds with intervals of about 0.2 seconds between two "ha". The monkey laugh is a kind of prolonged loud exhalation. This difference is important because it is related to the first steps in evolution that separated our ancestors from chimpanzees: standing upright. Walking on all fours requires coordination between breathing and walking so that the trachea is protected from the impact of the front limbs on the ground. Quadruped breathing is used as a 4:1 ratio between step duration and breath duration. When we straightened up on our feet, the way was opened for a separate control over the exhalation and therefore over the length of the syllables that can be produced. Compared to our relatives, the neck vertebrae that regulate breathing and standing are richer in nerve cells ("gray matter") which allows for a more coordinated and gentler muscle action in the systems that create the voice. The multiplicity of sounds on which human language was built was expressed for the first time in the unique syntax of laughter that first appears in the tickling between the parent and his baby.
The reaction of laughter and squirming as a response to gentle touch appears in babies and does not require learning. The source of the intense response to tickling originates from a reflex movement as a response to sudden contact common to many mammals, a shunning aimed at protection from reptilian creatures such as spiders or snakes.
But the importance of tickling for us humans and our relatives the chimpanzees is not in shedding scorpions but in strengthening social ties: children will respond with laughter to their parents' tickling but will not laugh at all if a stranger tries to tickle them. The baby learns to enjoy the touch of the caregiver's hand so that he also inherits a close touch that is unpleasant: treating a wound or moving away from danger. The mother's (or father's) tickling games begin around the age of six months and at about the age of one year they take on a playful and narrative nature (Grandma cooked porridge...) so they incorporate other modes of communication in addition to touch. Similarly, tickling is an activity that strengthens the bond between siblings and prevents violence. The importance of such gentle touch games was demonstrated in an experiment on macaque monkeys - the addition of tickling to infants led to the development of adult monkeys that were more inquisitive in a new environment and less timid in social situations than their brothers who were tickled less.
Why should we laugh when we are tickled?
According to one hypothesis, laughter is a response to the relaxation of stress: jokes are based on the gradual building of anticipation and tension that is resolved unexpectedly, the sound of laughter is a kind of "reassurance siren" intended to signal that the danger or conflict is not real. In the same spirit, tickling can be seen as an apparently threatening approach to sensitive body parts that ends in harmless contact. A "tickle fight" is the most primitive form of social play and a clear pattern can be identified: laughter, folding of the body, pushing away the tickling hand, then approaching again and tickling in response. This pattern is also observed in monkeys and is probably the first training in building social relationships when laughter signals that the contact is not hostile. In tickle games, laughter sometimes precedes the physical tickling: the tickled responds to the predicted feeling of the approaching stimulus and the tickle fights can be considered as a training of the information processing mechanisms that allow us to respond quickly and accurately to other stimuli.
Why can't we tickle ourselves?
Laughter can, as mentioned, appear in a variety of social situations, but while a written or drawn joke can make us laugh when we are alone, most people cannot tickle themselves. In order for a touch to make us laugh, it has to be non-threatening at the same time, that is, come from a familiar and unexpected person.
The reason lies in the brain mechanism that allows us to predict the sensations that will accompany the movement we initiate, this early prediction weakens the feeling.
The sensations from the skin, muscles, bones and joints are processed in a part of the cerebral cortex called the somatosensory cortex: this area is less activated when the source of the sensation is a voluntary action. It is hypothesized that the cerebellum - an area at the back of the brain responsible for the coordination of voluntary actions (coordination) is also responsible for predicting the sensation accompanying the action and therefore weakening it. If someone hits the foot with the same force exerted on it while running, the blow will be felt much more sharply than the feeling during actual running.
People whose ability to separate internal and external stimuli has been damaged: those suffering from auditory hallucinations or schizophrenia are sometimes able, therefore, to tickle themselves.
The inability to tickle oneself may be important in the development of the baby. The tickling game between the baby and its mother and the difference in sensation between self-touch and the mother's touch is the first training in the diagnosis of the self and knowing the boundary between "I" and the environment and others.
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More of the topic in Hayadan:
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Your comment is spot on only assuming the tickling is the action and not the result.
You claimed that most humans can tickle themselves, well the writer explained that while the *action* is possible, there will not be a *sensation* of tickling as a result. In this respect the wording is perfectly fine: humans can touch themselves but cannot tickle themselves.
Interesting and nice article,
Only that an error stands out in it that is common among many good people,
Error in understanding the difference between possible and permitted, between able and permitted.
When it is written: "Most people cannot tickle themselves"
This is a mistake since most people can tickle themselves.
The reaction will be different, but the ability is there.
The error is evident when talking about a criminal and saying
Because "he cannot do it" after he has already done it
While it is correct to say that it is forbidden or inappropriate.
A common error in communication and in general in understanding the difference
Between possible and permitted, between ability and possibility,
An error that deserves to be fixed…