>>10827427Summer and winter fur are also adaptions meant to protect against changing environmental conditions, but fur is moreso for cold temperatures than it is for anything to do with UV. Tanning is the same. You tan in the summer to protect yourself against the suns rays. Yes there is a genetic element, but you will only tan if exposed to sunlight or other UV light. If you spend the entirety of the summer indoors and in shade, you won't tan. You can even tan in the winter if the sun is out enough and you go out in it. So tanning is certainly more of an on the fly adaptation to current environmental conditions than anything else.
>It's genetic if you tan or not. You can be very white and tan or brown and not tan.Most people do tan to a degree. Very brown people might not tan as much because there is no need for them to do so, since their skin has the long term adaption of high melanin levels due to longterm evolutionary changes. White people have more of a need to tan if they go into a more UV exposed environment, and of course tanning on a white person is more noticeable. Inability to tan is pretty rare and is a form of albinism, a genetic defect, since this ability is actually pretty important for most humans on Earth.
I guess what I am rambling about is that tanning is a genetic but it is also a real time adaption to whatever level of UV you are currently exposed to. If the body decides to tan it is because you are in an environment that the body detects has a high level of UV. It is very likely that if you are tanning you are also accumulating cellular damage, which is why the body needs to react fast in order to protect itself against the sunrays.
