A fully preserved body of a European man was found on top of an icy mountain in Austria in 1991. The "Iceman" is one of a handful of humans to have their entire genetic code sequenced. During the genetic autopsy there was an incredible finding:

"Perhaps most surprising, researchers found the genetic footprint of bacteria known as Borrelia burgdorferi, in his DNA—making the Iceman the earliest known human infected by the bug that causes Lyme disease."

This incredible piece of news was buried deep in the article from National Geographic:

http://ngm.nationalgeographic.com/2011/11/iceman-autopsy/hall-text

I think you'll enjoy the full article. Early human life is fascinating to me, like how the Iceman had brown hair, brown eyes, and was lactose intolerant. 

Other than mummies, the Iceman is the oldest preserved human. The finding of Borrelia burgdorferi means that Lyme disease is the oldest known human pathogen! Holy cow!! Geneticists believe that the modern form of Borrelia diverged 10,000 years ago from its most common predecessor. In bacterial terms, 10,000 years is an incredibly long time.  Some conspiracy theorists believe that Lyme disease was engineered but I think these new findings are more mysterious and more plausible. Lyme disease is caused by an ancient pathogen that has survived the ages. It will take all of modern human ingenuity to rid the earth of the plague.