Table of contents:
- If the whole body is submerged, why are only the palms and feet wrinkled?
- Wrinkled fingers after lingering in the water are the work of the nervous system, not the influence of water
- Wrinkled finger shape adaptation technique?
After a relaxing evening soak to relieve a tired day of work or a relaxing weekend swim in the pool near your home, you may notice that your palms and feet are wrinkled - just like raisins. These wrinkled fingers will not last long, but are you curious about why your skin can become wrinkled after lingering in the water?
If the whole body is submerged, why are only the palms and feet wrinkled?
Some researchers argue that this wrinkled finger phenomenon is the result of a biochemical reaction, an osmosis process in which the moving water also pulls a number of compounds from the skin, leaving the skin layers dry and wrinkled afterwards.
Human skin is like a protective armor which functions to protect the inside of the body from germs and bacteria, while keeping body fluids inside. Unfortunately, leather is not waterproof.
The outermost layer of the skin, the epidermis, is responsible for this wrinkling reaction. The epidermis contains keratinocyte cell clusters, the skeleton that makes up the intracellular skeleton made of keratin protein, which strengthens your skin and keeps it moisturised. These cells then divide rapidly at the bottom of the epidermis, pushing the taller cells further up. Halfway through the journey, this cell group will then die. The dead keratin cells then create their own layer of the epidermis, which is called the stratum corneum.
When hands are immersed in water, keratin absorbs water. However, the inside of the finger does not swell. The dead keratin cells swell and begin to "colonize" the remaining surface of the skin, but these cells are still connected to the cells on the inside of the finger that are still alive but are pushed back by the swelling. As a result, the lining of the stratum corneum then shrinks, much like a skirt that is creasingly creased, to provide temporary space for this swelling.
Tangling only occurs in the fingers and toes because the epidermal layer on this part of the body is thicker than the rest of the body - hair and nails also contain a different type of keratin which also absorbs water, this is the reason why nails become soft after showering or washing. plate.
Wrinkled fingers after lingering in the water are the work of the nervous system, not the influence of water
Quoted from Scientific AmericanScientists have found out that wrinkled fingers after lingering in the water are not just a simple reflex or the result of the osmosis process, but the role of the nervous system.
The reason is, surgeons have revealed that if some of the nerves in the finger are cut or damaged, this wrinkled response will not occur. This suggests that this change in skin condition is a forced reaction released by the body's autonomic nervous system - the system that also controls breathing, heart rate and sweating. In fact, these distinctive wrinkles, which you only find on the palms of the hands and feet, are caused by narrowing blood vessels just below the surface of the skin.
Wrinkled fingers, according to surgeons, are a sign of an intact nervous system. And sure enough, the wrinkled response seen on each of the finger pads has been used as a method of determining whether the sympathetic nervous system is still working properly in a patient who is otherwise unresponsive.
Uniquely, the wrinkles on the fingers will not appear until about five minutes of being in the water continuously, which means that brief, accidental contact with water is not enough to produce wrinkles. Therefore, you have never experienced your fingers shrink when exposed to rainwater or in a humid and dewy place. Furthermore, finger wrinkles will occur more rapidly in response to fresh water than to seawater, which may reflect conditions that may have originally developed only in primates.
Wrinkled finger shape adaptation technique?
Apart from humans, there is one primate so far that can exhibit a wrinkled finger response after lingering in the water: the long-tailed macaque Makaka (Macaque). The finger-wrinkling response shown by the Makaka macaques is considered an adaptation technique, designed in such a way that these monkeys can grip objects more securely in dry and wet conditions.
However, to prove whether this response also acts as a similar adaptation technique in humans is still a matter of debate. Although there are a number of studies that show that wrinkled fingers can help humans to grip more firmly, such as the Makaka macaque, there are also many studies that doubt it. This is because the research test method only takes into account the grip on small objects, such as marbles and dice.
A group of researchers from Taiwan, quoted from BBC Future, conducted an experiment comparing wrinkled and normal finger grips on an iron bar, and the results showed no significant difference. In fact, wrinkled fingers show less than optimal performance. In addition, Mark Changizi, a 2AI Labs neurobiologist, argues that behavioral tests like this should be done for gripping large and heavy objects to prove the benefits of wrinkled fingers in supporting body weight, not fine motor movements such as lifting marbles. According to Changizi, the key to assessing the impact of wrinkled skin is in movement, not dexterity testing.
It is very difficult to prove the assumption that any biological feature is an adaptation, let alone why it evolved. However, researchers can look for clues that suggest this feature in humans may have evolved as an adaptation technique. We'll just wait for the development.
