Tuesday, May 22, 2007

Why We Have Greasy Skin: Hypothesis 2

A while back, I heard that the reason people develop greasier skin with then become teenaged is because in ancient times, our ancestors found shiny, greasy faces attractive. That doesn't make much sense. Why should looking greasy be considered attractive? Is there even any proof for that? Whose professional opinion was this?

However, consider this. Today I was working in a friend of the family's yard. I've been tilling up their lawn so they can put in a garden. There hasn't been much rain around here, so as a result, below the surface, the earth is very dry. As I till it up, it kicks up vast amounts of dust.

Now, knowing that I was going to be doing this sort of labor today, I didn't bother take a shower yesterday. As a result, my skin was exceptionally greasy. A lot of the dust I kicked up stuck to my skin. Plausibly, this is the very reason why we have greasy skin, or at least one of them--to collect dirt.

But why would it be advantageous to be dirty? If sunlight hits dirt, you don't get burned. It acted like sunblock. This is, perhaps, the same reason we have hair in the regions we do. Hair too blocks sunlight. Often, its pigments are lightened as the energy from the rays are absorbed.

If hair and greasy skin are helpful against sunlight, why don't kids have these things? Well, it's a tough to answer question. It's possible that in prehistoric societies, children were sheltered enough until puberty to not need this extra protection. The adults, on the other hand, needed it for when they spent time in the sun hunting/gathering.


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