While UV rays can cause skin cancer, because skin cancer usually affects people after they have had children, it likely had little effect on the evolution of skin color because evolution favors changes that improve reproductive success.
The only problem was that I couldn't remember where I had heard that. In fact, I wasn't all that sure that I was right. I know that the Roman Empire lasted rougly 500 years but how about the Egyptians, the Chinese, the Ottomons, etc. I thought that it would be interesting to explore different empires and see how long they lasted. In another article, I talk about the definition of civilization..
The Roman Republic was gone. In its place, the government was now a dictatorship, under the leadership of an emperor. The first Roman emperor was Augustus, the adopted son of Julius Caesar. He was emperor for 45 years. This was the beginning of the Pax Romana or Roman Peace. This is a very misleading title. There wasn't really peace. Rome continued to expand the empire, mostly through conquest. Rome itself was still beset by criminals and sometimes riots. It is called the Pax Romana because the empire itself was stable. The people knew that there was an emperor to run things and Roman legions to take care of wars and riots. They didn't have to worry about somebody coming in and conquering Rome and destroying their beautiful city.