Scientists were surprised to find a smallpox DNA in a 17th-century child mummy.  It has long been believed that the disease has been around thousands of years ago.  The World Health Organization even stated that smallpox has existed for at least 3,000 years, but this new discovery proves that claim may be wrong.  Smallpox may only just be hundreds, rather than thousands, of years old.

Smallpox Virus Is The 'Oldest Human Virus Ever Sequenced'

Researchers were able to study samples of DNA of a mummified remains of a child who lived during 1650 AD - a time when smallpox was common in Europe.   Dr Edward Holmes of the University of Sydney told BBC news : "We managed to sequence the complete genome of the virus that causes smallpox, that's called variola virus.  It's the oldest human virus ever sequenced."

"This mummy allows us to calibrate very nicely the clock of evolution - it's a fossil, effectively.  This fossil tells us that in fact evolutionary history is much more recent than we thought before - it's actually only hundreds of years rather than thousands of years," Holmes said.

DNA From Lithuanian Child May Prove History Wrong

History claims smallpox is ancient, but this new discovery may just prove that wrong.  The common ancestor of the virus is fairly recent, from around 1588 to 1645.

Biologist at Northern Arizona University, Paul Keim, who has used DNA of ancient plague bacteria to help trace the history of that disease, told NPR.org that we really can't draw too many conclusions about the origin of the virus. 

"All we can really say is that the smallpox that was trafficking around the world at the end of its existence [in the 1970s] can be traced back to the 17th century," says Keim. "There were other models out there that were arguing that contemporary strains had gone back thousands of years, and that doesn't look like the case."