Biologist Dr Harry Kenward was itching with excitement when he realised the creature on his microscope slide was the oldest body louse known to exist.

Dr Kenward, English Heritage senior research fellow in the department of biology at the University of York, was sifting through remains excavated from a Roman tip when he made the discovery.

The next oldest body louse was discovered in Iceland and dates back just 300 years but the Roman louse, which is approximately 1,800 years old, proves that along with cockroaches, grain weevils and other pests, the Romans were responsible for bringing lice to Britain.

Dr Kenward said: "I was commissioned by English Heritage to do some work to try and throw light on what was going on at these sites in terms of vegetation and human activity.

"I was looking at what it would have been like to walk out through the yard in a Roman settlement. Would you get wet feet, would your nostrils have been assaulted by the smell of dung?

"This louse looked identical to a modern louse and because these deposits are so rich in organic matter they use up all the oxygen and do not experience much decay."

Dr Kenward said the louse is a major find which furthers his work to try and reconstruct past human life. He said: "I jumped up and down and got very excited when I found it because I knew the next oldest recorded in Britain dated back to the 18th century. These lice were real pests for Second World War soldiers. They got them in a big way and called them crab lice because they looked like crabs.

"The Romans probably had the same problem with them because they tend to be worse when people are wearing their clothes for a long time - it provides a good breeding ground."

Dr Kenward found one Roman louse and one Norman louse but he said both finds were extraordinary. He said: "When you think of something that lives in such a private place the chances of finding it are very small."

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