What Causes Humans to Be Ticklish?

Fabian van den Berg:

There are several theories on why we feel ticklish, and two distinct types of tickling exist. One of them serves as a defensive mechanism, alerting us to something moving on our skin, like parasites. This is known as knismesis. It's the sensation you get when something soft brushes against you, often causing goosebumps and a sense of discomfort rather than laughter.

The second type of tickling involves specific areas of the body, and it's called gargalesis. This form is more intense and results in uncontrollable laughter. Unlike knismesis, gargalesis likely plays a role in social bonding, helping to strengthen connections between individuals.

Certain ticklish spots play an important role in bonding between parents and children. As we age, these same areas turn into erogenous zones, aiding in mating, a key social activity.

The fact that these sensitive areas are also vulnerable likely isn't accidental. Some experts believe tickling serves to teach children how to protect their most delicate spots.

Other animals, like chimpanzees, also engage in tickling. During play, they make a panting, breathless sound when they laugh. They enjoy it so much that they persist in the activity, wanting to keep it going.

Elephants can also be tickled, but my favorite is still the rat.

There was a study where someone's job was to tickle rats (that must look fantastic on a resume). The researchers said, "Come join me in tickling rats." While fun, this was legitimate research. It was known that rats emit high-pitched sounds when they play or engage in mating—sounds of enjoyment (similar to laughter). When they tickled the rats, they made the same noises, suggesting they enjoyed the tickling, much like humans. It activates brain regions linked to joy (at least, those corresponding to ours).

However, it's important to note that we often project human emotions onto animals, which can be misleading. While animals like chimps and rats appear to enjoy being tickled, it's not certain they actually do, as we can't ask them directly. Not all animals respond the same way, so experts aren't entirely sure they enjoy it as much as we think.

A heartbreaking example of misunderstanding involves the slow loris. While these creatures can be tickled, they definitely don’t enjoy it. What humans see as pleasure is actually fear, turning what appears to be playful behavior in humans or primates into actual torment for this seemingly adorable animal.

Tickling likely acts as both a warning signal and a way to teach us to protect ourselves. In humans, other primates, and rats, it seems to also help in building social bonds. But be mindful who you tickle—not all animals experience it as pleasure (and some humans don’t like it either).

This post originally appeared on Quora. Click here to view.