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Originally Posted by basmoq
Ok, speaking as a scientist myself, I must say that xepherys is completely wrong in his statement that we have evolved protection against UV (please take a course in basic genetics) UV rays cause Thymine Dimers to form in our DNA, which prevents DNA Polymerase from being able to read the strand of DNA beyond the dimer. Our cells have developed the ability to correct Thymine dimers, but it takes time, the more dimers you create (ie. the more time you spend in the sun), the more likely you are to not be able to keep up with the damage, leading to errors in the reading of your DNA. Now some errors make no difference to protien function, however, some cause cell death. Accumulate enough errors in a single cell and it can lead to skin cancer. Please do not use a rudimentary knowledge of scientific theory to prove your own theories, and don't believe anything you read on the internet, go to scientific journals if you want real science, it is very common for journalists to completely misstate the significance of a journal article. If you would like a more detailed description of the problem, PM me and I will dig up some info out of one of my medical texts. BTW, the statements about darker skin listed above are quite true  |
Interesting. First of all, most of my observations are not based on internet readings, but classes and book knowledge I've collected over the years. While I'm the first to admit I am not a geneticist, I do have a fundamental knowledge, on a larger scale, of how the human body operates and how evolution takes it's grip over time.
Yes, darker skin is better regarding exposure to sunlight, and most current data shows that humans BEGAN their existance as darker skinned people in northern Africa and the Mesopotamian areas. Lighter skin developed primarily in people who migrated north and began having seasons that kept them out of the sun year-round. This, already, signifies that our sun exposure is taken into consideration in our genetic makeup.
Your primary points regarding the dimers are absolutely correct. That does not, however, mean that our genetic makeup has not greatly improved our sunshine survivability over the course of thousands of years. As a scientist, I'm sure you understand that there is a difference between corresponding and causal factors when making such a statement. The same could be said for many things that are part of our daily lives. Please do not use a large vocabulary and a shield of science to bring about a facade of perfected knowledge. Since there are legitimate scientists on both ends of the spectrum regarding sunscreen and sun exposure, one would logically conclude that nobody knows with 100% certainty what the compound effect is. There are pros and cons, good and bad to just about everything in life. It's the overall compound nature of those effects, all added up (hence compound), that determine our views and knowledge.