LAB Biology - file 01
Your wrinkled fingers in water are an ingenious heritage
Do you like bathing? It’s perfect and comfortable to wash away everyday stress at once. Moreover, in modern life, you can enjoy TV programs, YouTube videos, or singing Karaoke while immersing in your bathtub. By the way, when you have forgotten the time and are staying for a long time in a bath, do you notice that your fingers, and toes, too, have wrinkled up? Don’t worry, but this doesn’t ruin your beauty at all!
This biological response is NOT Osmosis, which is a passive result of water soaking into the outer layer of your skin, but in fact, an active biological process.
The Mechanism: How do our fingers and toes wrinkle?
First, the most important fact to understand is that skin wrinkling is controlled by your Autonomic Nervous System (ANS). This system is better known for handling essential unconscious tasks to sustain our life, such as heart rate and breathing, even during sleep.
When your hands or feet are submerged in water, your nervous system sends a signal to the blood vessels underneath the skin to constrict. Because the volume underneath the skin decreases due to the water pressure, but the surface area of the skin remains the same. So the skin should be pulled inward as much as the decrease. This causes to create the ridges on your skin.
This process has been proven by the fact that if the nerves in a person’s finger have been damaged, that finger will NOT wrinkle, even if it stays in water for a long time.
The Rain Tread Theory: Why does this response happen?
In biology, this response is believed to be one of the Evolutionary Adaptations. Actually, the wrinkles act like the treads on a tire.
1. Water displacement
The channels created by the wrinkles allow water to be squeezed out from between your finger and the object you are grabbing.
2. Better grip
By channeling the water away, more of the skin's surface can make direct contact with the object. This significantly improves grip in wet conditions. In laboratory experiments, participants with wrinkled fingers proved to be able to pick up wet slippery marbles significantly faster than those with dry fingers.
3. Evolutionary advantage
This adaptation is thought to have helped our early ancestors survive with foraging tasks such as gathering food from wetlands or streams, and securing a better footing when walking on slippery rocks in the rain.
These are really similar to the treads on a car tire, channelling water away to increase traction on the road and reduce the risk of hydroplaning.
Biomimetics is a field of biological engineering that learns and emulates the models, systems, or elements of nature to apply to engineering. The Rain Tread Theory is an interesting example of how a biological design by nature functions similarly to a human-engineered design.
In addition, another interesting fact: The wrinkling process in water takes about 5 minutes of immersion to start. Think if it happened instantly, our hands would be changing the texture every time we washed them!
A Survival Strategy: Let’s take a look further in light of evolution
Looking through a lens of evolution, the Rain Tread Theory is a survival strategy for human beings. This is NOT merely a random quirk, but just an active adaptation in evolution that was very significant to give our early ancestors a secure grip on survival in wet environments.
The Survival Advantage: How had the wrinkling response worked for our early ancestors?
In principle, evolution doesn’t keep sustaining traits that don’t offer any benefit, but rather gets rid of those that are useless in the way of Natural Selection. So naturally, wrinkles on our fingers and toes should have advantages.
1. Foraging
Our early ancestors had been foraging, searching for food in the wild. They would have been much more efficient at gathering wet food, such as shellfish from tide pools or plants from slippery riverbeds, with their puckered fingers and toes.
2. Locomotion
Animals use a variety of methods to move. In Ethological terms, this method is called Locomotion. Since the wrinkling also occurs on our toes, it would have provided a significant advantage for the Bipedal Locomotion, walking and climbing on mossy rocks in the rain, or across wetlands without slipping, secured by a better grip under a pair of their wrinkled toes.
How about other species?
Is this response unique to Humans? No, evidences show that this trait is shared with our Primate cousins, most notably Macaques. This fact suggests that the Adaptation had likely evolved in our common ancestor millions of years ago, long before modern human races had emerged. It could be said that this survival strategy was a Primate-wide solution for living in environments with frequent rain and plentiful water sources.
The Cost of the Wrinkles: Why don't our fingers and toes wrinkle all the time?
The fact that the wrinkled fingers and toes are so good for grip is true. If so, why don't our fingers and toes wrinkle as default initially?
In fact, there are some costs to having wrinkled skin that make it a temporary tool to adapt to specific environments rather than an inherent permanent feature.
1. Reduced sensitivity
Smooth fingertips are just suitable for sensing fine textures. Permanent wrinkles would likely make it hard to perform delicate tasks and even detect small changes in surface quality.
2. Marred skin integrity
Wrinkled skin can be more vulnerable to harm. It would be prone to being torn, cleft when catching on a dry, rough surface.
3. Broken tactile precision
As for dry objects, wrinkles on your fingertips provide NO advantage, but instead, they can render it hard to grasp and hold something steadily due to the thick-skinned sense of touch.
This systematic process is an ingenious evolutionary legacy on a long way back before our human species had emerged on the earth. And in a modern context of the age, this example shows a specimen of Biological Engineering (or simply Bioengineering) that our body functionally transforms itself into a high-performance multi-terrain machine to switch to the water mode, essentially for our survival strategies.
Further reading (sponsored by Amazon):
This “Biomimetics: Nature-Inspired Design and Innovation” provides a professional, contemporary, and concise review of the current knowledge and advances in Biomimetics!
Table of Contents
This “Bioengineering: A Conceptual Approach” explores critical principles and new concepts in bioengineering, integrating the biological, physical, and chemical laws and principles that provide a foundation for the field!
Table of Contents
