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 history of the Roman Empire covers the history of Ancient Rome from the fall of the Roman Republic in 27 BC until the abdication of the last Western emperor in 476 AD. Rome had begun expanding shortly after the founding of the Republic in the 6th century BC, though it did not expand outside of the Italian Peninsula until the 3rd century BC.