science facts

WTF Fun Fact 13344 – Humans Can’t Feel Wetness

The fact that humans can’t feel wetness seems ridiculous at first. You may have even read that it’s a misconception. But, technically speaking, we do not have the right “gear” to directly sense wetness – even though we all know when something is wet.

But how does that work?

Why humans can’t feel wet

Humans lack dedicated hydroreceptors – the specialized sensory receptors solely responsible for detecting wetness. As a result, wetness is not a distinct sensation for us, but rather an interpretation of multiple sensory inputs.

When a liquid, such as water, comes into contact with the skin, several different types of sensory receptors are activated. These include thermoreceptors, mechanoreceptors, and nociceptors. Thermoreceptors respond to temperature changes and can detect the cooling effect of the liquid on the skin. However, this response alone does not convey the specific quality of wetness.

Mechanoreceptors, responsible for sensing pressure and touch, provide information about the physical presence of the liquid. They detect the pressure exerted by the liquid and signal the brain accordingly. However, the activation of mechanoreceptors alone does not differentiate between wet and dry sensations.

Nociceptors, which detect pain and discomfort, may also play a role in the perception of wetness. If the liquid is extremely hot, cold, or otherwise causes discomfort, nociceptors are activated, contributing to the overall sensation. However, this response is not exclusive to wetness and can be triggered by other stimuli as well.

How we sense “wet”

Due to the absence of dedicated hydroreceptors, the brain must integrate and interpret these various signals to create the perception of wetness. It combines the inputs from thermoreceptors, mechanoreceptors, and nociceptors, along with other contextual cues, to generate the subjective experience of being wet.

While humans can recognize and differentiate wet sensations, it is important to note that wetness itself is not a distinct sensory modality. Rather, it is a perception resulting from the brain’s processing of multiple sensory inputs related to temperature, pressure, and even discomfort.

— WTF fun facts

Source: “Humans Technically Can’t Feel Wetness, And People Are Confused” — IFL Science

WTF Fun Fact 13338 – Monkey in the Mirror

It’s not until we’re around 2 years old that we figure out what the mirror is showing us. And not all animals can recognize their own reflections. But if you train a rhesus monkey in the mirror, it will the first thing it’ll do is check out its genitals.

The monkey in the mirror

A 2015 study found that rhesus monkeys are capable of recognizing themselves in mirrors and engaging in self-exploration behaviors, but only after some training. The research helps shed light on the cognitive abilities of non-human primates and their level of self-awareness.

The researchers trained a group of rhesus monkeys to touch a red dot on their faces after seeing it in a mirror. This task is commonly used to test an animal’s ability to recognize itself in a mirror and is considered a measure of self-awareness. It’s called the “standard mark test.”

It took several weeks of training for rhesus monkeys to pass the standard mark test. But, eventually, they were able to recognize themselves in the mirror and understand that the reflection was a representation of their own bodies.

The first thing the monkeys did after that? Umm. Let’s just say they engaged in a range of self-exploration behaviors.” And they started with their own genitals.

Monkey see

The rhesus monkeys didn’t spend all their time “down there” though. They eventually moved on to the nose and mouth, behavior similar to what has been observed in chimpanzees and orangutans.

The act of inspecting their own genitals may seem amusing, but it actually provides insight into the cognitive abilities of non-human primates. The ability to recognize oneself in a mirror is considered a measure of self-awareness. And that’s a crucial component of consciousness.

Self-awareness allows animals to engage in complex social behaviors, such as empathy, cooperation, and deception.

Rhesus monkeys’ ability to recognize themselves in mirrors and engage in self-exploration is significant because it suggests that they have a level of self-awareness that we previously thought unique to humans.

The study also has implications for our understanding of animal welfare. Animals that are self-aware are more likely to experience emotions, including pain, fear, and stress. This means that they may be more susceptible to negative welfare impacts, such as confinement and isolation.

If we understand the cognitive abilities of non-human primates, we can work towards improving their welfare.

— WTF fun facts

Source: “Monkeys Learn to Recognize Themselves in a Mirror – And Promptly Check Out Their Butts” — Discover Magazine