IT'S dirty work...but somebody's got to do it.

Archaeologist Andrew Jones believes centuries-old human and animal excrement can help unlock the secrets of how our ancestors lived more than 1,000 years ago.

Where there's muck there may well be brass. But the academic reckons historic rubbish should not just churn stomachs - it can be archaeological gold.

He says York's run-of-the-mill hospitals and factories are as important a source of evidence as great historical landmarks, like York Minster.

The down-to-earth boffin has been kicking up a stink about excrement studies and grubbing around in old filth for more than 30 years.

Dr Jones, of the York Archaeological Trust, told the Evening Press it was time to take heritage studies back to its everyday every sense.

"Heritage has normally been concerned with fine art or obscure pieces of archaeology, hard to see in the landscape," he said.

"It's been the territory of scholars and connoisseurs: highly-educated people.

"In today's world there's a much greater awareness that heritage is for everybody. It's not just about great cathedrals and wonderful stately homes, but more humble domestic buildings."

He admitted that his subject was seen as "amusing and slightly unpleasant". But he added: "You don't need a PhD in Gothic architecture to understand how a drain works."

He said it was becoming increasingly clear that human faeces and animal manure were important in dissecting the past.

They still underpin many British cities, including York, London, Edinburgh and Carlisle. Riverside build-ups of damp organic deposits now prove particularly useful for archaeologists.

Deposits help experts learn about diets - from Viking to the mid Twentieth Century when most modern sewer systems were developed - and the often squalid conditions our ancestors lived in, like in the Hungate area of York.

Recent work on the subject has found peach stone remains going back to Viking times and Roman-era fish bones.

"In the modern world we get quite spoilt," said Dr Jones. "But for most of human history, people have lived in conditions we see today in most developing countries."

Down to earth Dr Jones, who is based at Bradford University, was speaking ahead of a series of free public lectures on York's Grimy Heritage, organised by York University.

Forthcoming lectures include Ancient Excrement with Dr Jones (February 17), Filth Of Ages (February 24) and Molecular Secrets In The Earth (March 3). All take place at 7pm in the physics block at the Heslington campus.

Updated: 10:00 Saturday, February 12, 2005