By Tilottama Shrinivasa
Over at Dark is Beautiful there is a spirited campaign on that we at the Finger fully support. We also want to add our nerdy contribution.
You know how all those cosmetics people keep telling you that the key to a happy life is fair skin…uh…everywhere? Well, they couldn’t be more wrong about this because they all seem to forget that we live in the tropics. In the tropics, dark skin is very cool. And it is very cool because it is very hot. Literally. Let me start at the untangled beginning.
Skin is dark because of a pigment in your skin called melanin (I know you know that but stay with me). Melanin is produced when UVB radiation (UV rays are further divided into C, B and A versions in increasing order of wavelength) damages the DNA of the skin cells (you know that too as cosmetics people don’t forget to tell you this, all the time, but skip the next 3 paragraphs for the truth)…(the next 3 paragraphs are also true of course).
UVB radiation is a big nuisance in general because while UVC is absorbed by the atmosphere, almost all the UVB lands right on top of us tropic-dwellers! Why specifically tropical-dwellers you ask? Well, UVB is what is supposed to get absorbed by the very famous ozone layer and it does get absorbed very nicely in the temperate zone.
However while all the atmosphere’s ozone is produced in the tropical belt, the winds in the stratosphere carry it away from this region and into the temperature region. The amount of ozone above our heads is measured in Dobson Units (DU) which is how many micrometres of ozone would one have if one brought the entire column of ozone to the earth’s surface (where it compresses into a smaller space due to the higher pressure so 1 DU is 10 micrometres of the gas under standard temperature and pressure).
Anything under 220 DUs of ozone is considered a hole. As figure 1 below shows you, the tropics always have between 200 and 275 DUs of ozone up there so we are always getting a severe dose of UVB which would mean we would all die of skin cancer really, really quickly, but we don’t! And the reason we don’t is because of this ultra-cool superheroine – Melanin.
|Figure 1: Ozone layer distribution across the globeSource: www.esrl.noaa.gov/csd/assessments/ozone/2010/twentyquestions/Q4.pdf (Figure Q4-1)|
Now, because of UVB’s wavelength, it can go through pretty much everything.
a. Should you wear a white tent from top to bottom to avoid skin damage?
Ans: Sorry, the white doesn’t always reflect UVB and it goes right through the gaps between the cloth-fibers because of its short wavelength…
b. Should you paint your face white with sunscreen/sunblock to avoid skin damage? Ans: Nope, those golems can get through that as well (see table here). In fact sun screens (all that SPF, UVA PF jazz) are only tested in the temperate region (where there isn’t much of an issue to begin with) or sometimes on a few white skinned people from Australia (whose genes aren’t very good at producing melanin at will) and do more damage than good to everyone else by preventing melanin formation with lousy chemicals that increase your chances of (guess?) skin cancer! Also underweight babies, breast cancer, infertility (in men) and god knows what else (the best ones still use nasty things like zinc and titanium oxides ground to nano particle levels without enough research to prove they don’t enter the blood stream at that size).
c. Should you stay indoors all day to avoid skin damage?
Ans: You will end up with Vitamin D deficiency and have severe arthritis by the time you hit 40!
There is hope though, because UVB meets its match in melanin. What melanin does is to quickly absorb (not try to reflect) UVB rays and convert it to heat then and there (99.9% of UVB is converted in a process imaginatively labelled ultrafast internal conversion)! So you might get, slightly, more hot under the skin but skin cancer? No! Melanin decreases your chances of having disastrous mutations to a negligible amount (this phenomenon is aptly called photoprotection)!
Not only that, in parts of you that don’t see the sun under normal circumstances, melanin also prevents bacterial infections by surrounding the bacteria and heating the hell out of it! Or maybe it just chokes them to death. Anyway, to summarise, here is what Melanin does…
1) Decreases your chances of getting skin cancer from the Sun to next to nothing.
2) Prevents you from getting nasty infections (bacterial, fungal, any other parasites that crawl all over the tropics) in certain places just because it is a beautiful result of evolution and really cares for you.
Unlike the cosmetic companies that only want your money and don’t give a damn if you get cancer or not. In fact, since most of them are owned by pharmaceutical companies, I am not saying they hope you will get cancer, but if you do, they can sell you even more stuff.
So what should you do? Embrace the melanin! Understand that you are dark (or you should hope you are as otherwise you have a big problem) because it is the optimised colour for the tropics that keeps your skin (and you) healthy and there is nothing more beautiful than healthy skin!
Skin tip: If you have the misfortune of being fair out here, we advise you to follow the ancient Indian practice of rubbing oil all over yourself and doing 24 Surya Namaskaras in the early morning Sun. This will help you get darker in a safe way and if it doesn’t, the yoga will help you come to terms with your fate…
Tilottama Shrinivasa is a mechanical engineer who is especially interested in mathematical modelling, structural analysis, biofuels, cats and dogs.
image credit: via papazimouris