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..
Timeline of the Roman Empire. This is not a timeline of the history of the Roman Empire and only includes important legal and territorial changes and political events in the Empire from its founding in 27 BC by the Roman Emperor Augustus until the fall in the West in 476 AD and the transition in the East in 610.