How/why do we develop freckles on parts of our body that aren’t exposed to sunlight?
In: Biology
i think what you mean are birthmarks. as the name implies, you are born with them usually, but they can still develop over the years. while freckles will vanish over time if you avoid the sun, birthmarks dont. they are less dependent on sunlight, too, i know because i developed a tiny birthmark in my teens on my bellend.
another one would be skin cancer, but i hope you’re not talking about that, eventhough many people confuse them and birthmarks. i would advise you to check out online if you have any suspicious birthmarks and if you do, go see a doc. skin cancer can be treated exremely well if noticed in an early stage.
sorry if this isnt the most scientifically proven and sourced answer, it’s just my life experience (and that of my parents who go get skin cancer treatment on a yearly basis and get them frozen off, lasered away or even cut out by the dozens if not hundreds.)
Why do black and brown people have brown skin in regions not exposed to sunlight?
Same thing. Freckling is just a particular skin types ‘strategy’ for distributing melanin. Freckling is more prominent in areas exposed to sun because exposure to UVB stimulates melanin production, but everyone has some baseline level of melanin production.
Alternatively, what *you* may be seeing and calling freckles are in fact nevi or moles. Some families carry a trait that causes the expression of dozens of moles all over the skin with such a broad distribution they can look a bit like freckles, but upon closer inspection you’ll see that they’re raised instead of flat like freckles. Moles are melanocyte dysplasia or irregular growth. Melanocytes make melanin and dysplasia is called dysplasia because it happens whether exposed to stimulus (sunlight) or not. The melanin makes them dark, but they show up with or without sun because that’s just how those cells are programmed. They are not all cancerous or even mostly but people with this condition need to be screened yearly by a dermatologist because any of these moles can transform .
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This isn’t a comprehensive answer, but maybe a piece of the answer. When you wear clothing outside on a sunny day, it dramatically reduces but does not completely eliminate exposure to UV on those parts of the body. Some light and UV does penetrate and hit your skin, dependent on the material, thickness, and color of the clothing.
Just going to earn people that moles in areas that have never seen the sun can still be cancerous. Just had one removed. The ones on my arms over the years were all fine but it was the one on my stomach that was pre-melanoma.
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