The color of human skin is largely to do with exposure to our suns rays, I'm sure it is tied primarily to a specific frequency that of ultraviolet. The colors of skin varies throughout the peoples of the earth from the whitest of white to the blackest of black and everything in between. There are many variables to consider when approaching this, obviously the natives of Africa are some of the darkest because historically they have been the last culture to put cloths on, and many live on or near the equator, where the suns rays are more intense. Some people have a problem with the fact that Eskimos (extreme northern peoples) are brown and see this as a problem, but all one has to realize is that the most reflective color there is, is flat white, which the arctic and antarctic regions is full of. in addition consider that Aurora Borealis and Aurora Australis are a result of the earths magnetic field allowing solar radiation to more readily penetrate our atmosphere such the people of extreme north or south would be more exposed to solar radiation.
Here's something from the US FDA (http://www.fda.gov
) that I just found.
"Many factors determine how much UV you are exposed to, including:
* Time of year
* Time of day
* Weather conditions
UV rays are strongest in areas close to the equator. Because the sun is directly over the equator, UV rays only travel a short distance through the atmosphere to reach these areas. UV radiation is also the strongest near the equator because ozone15 in these areas is naturally thinner, so there is less to absorb the UV radiation.
UV exposure is lower in areas further from the equator because the sun is farther away. Exposure is also decreased because UV rays must travel a greater distance through ozone-rich portions of the atmosphere to reach the earth’s surface.
UV exposure is also greater in areas of snow, sand, pavement, and water due to the reflective properties of these surfaces.Altitude
Altitude is another contributing factor to the amount of UV. Higher altitudes have greater UV exposure because there is less atmosphere to absorb UV rays.Time of Year
The sun’s angle in relation to the Earth varies according to season. During the summer months the sun is in a more direct angle, resulting in a greater amount of UV radiation.Time of Day
UV is most intense at noon when the sun is at its highest point in the sky, and UV rays have the least distance to travel through the atmosphere. Especially in the hot summer months, it is a good idea to remain indoors during the peak sun hours of 10am and 4pm.Weather Conditions
Many people believe that you cannot get sunburned on a cloudy day; this is simply not the case. Even under cloud cover it is possible to damage your skin and eyes, and cause long-term damage. It is important that you protect yourself with sunscreen, even in cloudy weather.Reflection
Some surfaces, such as snow, sand, grass, or water can reflect much of the UV radiation that reaches them. Sunglasses rated for 100% UV protection, a wide-brim hat, and broad-spectrum sunscreen can help protect your eyes and skin from reflected UV rays."
The point is, that there are many variables to consider.
They mention clouds as not being the protector that many think they are, but I'm sure they're not speaking of kumulonimbus or nimbostratus as these varieties are extremely dense, dark and deep (depth of altitude spanned), such that any geographic area at a given altitude and latitude that historically experiences greater than average rainfall would provide more protection than that of a drier climate, and would tend to produce whiter people.
Frequency of being outdoors verses indoors also plays a part. Construction of the homes also plays a part. The amount of electromagnetic energy that is reflected indoors also plays a part. And since communities (cultures) of people tend to construct homes and use them similarly, at any particular latitude, altitude, climate, and that they are typically participants in the same gene pool, one can easily see the likelihood of a particular shade of skin to be predominate, over the longer tern of similar conditions.
Finally, anyone that sees that the basic premise of Darwin's Theory of Evolution as to natural selection, as the truth that it is, and fails to except the differences between us humans, as anything other than environmental, as through the new understanding of epigenetics, does not understand the full truth of Darwin's Theory of Evolution.
Of course there's a lot more that I could say to keep barracuda's such as Arising_UK away from my jugular, but as I know, and she fails to consider, I'm a lazy fuck, and sometimes just don't care to spend all the inordinate amount of time required, to formulate a truly solid argument, I expect you all to be capable of filling in the blanks of knowledge that I've taken for granted, during my assertion, which is usually done on the fly. Of course those that are naturally adversarial and come here more for the argument than they do the sharing, such as Arising_UK, shall be more prone to try and tear my assertion apart, instead of applying their mental prowess to fill in the blanks that my laziness and complacency has afforded. I can't type for crap, and only have so much time to share.