Why are the palms of our hands so much lighter than the rest of our hand?
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The skin has 5 layers. At the bottom is the “basal” layer where your skin reproduces. At the basal layer your skin cells are yet to be melanated/ produce melanin so they are pale or white. As your skin matures and rises to the surface layers it will produces melanin respective to what your body instructs it to. Creating your natural skin tone.
The palms of our hands and the bottoms of our feet are covered with a special type of skin layer called “lucidum” which is see through. In Latin it literally means “clear layer.” So we can see the yet to be melinated skin cells in the palms of our hands at that basal layer but the back of our hand can be much darker.
The easy answer is because we have less melanin in our palms (and soles), but you’re probably asking for an evolutionary explaination.
We aren’t sure.
One theory is about communication, humans naturally gesticulate and it’s a large part of communication, which was even larger before the invention of language. White palms would stand out and make it easier to read body language at distance or in dim light. You may notice that showing palms is usually a friendly/submissive gesture.
I lkie that one, but that doesn’t mean it’s correct.
What? Color wise? I assume? Melanin is what determines our skin color. By being exposed to sunlight, out skin produces more melanin temporarily, which makes us tan. Tanning is a reaction to avoid damage to the skin. Melanin protects against UV rays. (Debated) Melanin is produced at a ratio based on genetics as well (black and brown people have an initial ratio that is higher than Caucasians.) Also Melanin is produced (debated) based on Vitamin B — folate. And that is dependent on sunlight. And when humans migrated away from the equator, a Vitamin deficiency arose over thousands of years and dozens of generations.
In addition Vitamin D is mostly produced by Sunlight. So skin farther from the equator was slowly adopted to be more translucent. This allows Vitamin D to be absorbed quicker. Those closer to the equator have less need of lighter skin and therefore have darker skin.
And now back to the question. I assume it is.. why is the palm of the hand not as dark as the rest of the skin… This is conjecture, but it is because there is no need for melanin in this area because of less access to sunlight. Other areas do this — especially areas without hair (or fur for animals.) Backsides of joints like underarms and knees and feet and even genitals are usually lighter colored. For the previous reason of sunlight and a second reason of nerves. Hands have evolved to have more nerve endings as have elbows and knuckles. Penises and Vaginas also have more nerve endings than most skin. You will notice the areas that are lighter also have less hair. This is another proof of the nerve theory.
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