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..
Julius Caesar's appointment is a core component of the Roman Empire's history. The Roman Empire is not just one of the most famous in history; it's also the longest-lasting. It spanned several different eras, but essentially lasted from 27 B.C. to 1453 A.D. -- a grand total of 1,480 years [source: Daniels]. The republic that preceded it was brought down by civil wars, which led to the appointment of Julius Caesar as dictator.