Why should we use sunscreen?
When summer arrives, the warmth begins to increase, and when we see the sun, we feel like going to the beach or the park, so that the sun bathes our skin to grab that golden color that everyone is looking for.
But in reality there is nothing healthy in that little color, because it is actually an inflammatory response of our body, caused by the massive self-destruction of cells that prefer to die to kill us from skin cancer, it is your body trying to repair your carelessness.
The sun bathes us with many forms of energy such as heat, visible light and ultraviolet radiation, which is a very energetic type of invisible light, it comes in three types UVA, UVB and UVC, UVC which is more energetic due to its wavelength. short wave can interact with the very small ozone molecules in the atmosphere and does not reach where we are.
UVB is mostly absorbed by oxygen and ozone molecules in the atmosphere, but a small part reaches us and burns the most superficial layers of our skin, UVA, which has the longest wavelength, is able to cross the atmosphere without problems, even through window glass and penetrate our skin deeper into the dermis, both UVA and UVB radiation can cause burns and skin cancer.
But sunbathing can't be that bad after all you don't see an iguana slathering on sunscreen before spending hours basking in the sun, in fact no other animal apart from us uses sunscreen, well elephants get covered in mud and hippos secrete a reddish-colored sweat that acts as a sunscreen, but apart from those cases, no one else, actually all vertebrates, that is, birds, fish, reptiles and amphibians, naturally produce compounds that protect them against the damaging effects of ultraviolet light on their cells They are called mycosporin-like amino acids, or MAAs.
It is an ability that vertebrates inherited from algae or bacteria by horizontal genetic transfer, that is, they did not inherit it from a common ancestor, but at some point they ate someone with that gene and the gene became part of their genetic material, in a spectacular demonstration of the saying you are what you eat and it doesn't work that easily eating spiders isn't going to turn you into spider-man it doesn't work like that, you have to think that the tree of life is more like a river where a channel can be separate, but can later come back together in unexpected ways.
So because if all vertebrates are born with sun protection, because we must buy sunscreen containers that are very expensive, the fault lies with our ancient predators; In the beginning, all vertebrates shared the gene that allows them to produce MAAs, natural sun protection, but our group, the small and vulnerable mammals, spent too much time hiding from predators like carnivorous dinosaurs in dark places like caves and holes in the ground. places where sunlight does not reach so easily.
It is believed that at some point this gene that protected them from ultraviolet light was lost in random mutations because living in dark places they did not need it to survive, if you did not have the gene you could survive just like the individuals that did have it and therefore So there was no evolutionary advantage, so the gene was lost.
When the dinosaurs died and our mammalian ancestors came out of hiding they had to evolve their own ways to protect themselves against ultraviolet light, the most common solution was fur, mammals aren't furry just to look cute and huggable it's a defense against cold and heat sun, everyone has some form of fur with a few exceptions like elephants, rhinoceroses, hippos and humans.
The only primate that is not covered in hair and that has to slather on sunscreen every time they go out in the sun is man; we should have kept our fur or acquired that valuable gene.
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