YORKSHIREMEN have been accused of having many traits over the years, from being miserly, to dourness, to blunt-speaking.

Now, researchers at English Heritage have added a new characteristic to the list - having a round head.

Studies on nearly 700 skeletons recovered from the deserted medieval village of Wharram Percy, near Malton, North Yorkshire, revealed Yorkshiremen living between the 11th and 13th centuries had rounder, rather than longer and narrower heads.

Similar trends have been found at sites throughout Western Europe during the same period.

The change that followed has been linked with an influx of immigrants, such as Vikings or Normans, who introduced different racial characteristics.

But Wharram Percy is unique in that the trend has been identified in an isolated and dwindling population.

The village was crippled by both the plague and sheep blight, which combined to spell its doom as potential newcomers gave it a wide berth.

However, female skulls do not show the same change.

The evidence is presented in the latest volume of the Wharram Percy Project, the results of 40 years of archaeological excavations at the Yorkshire Wolds village between 1950 and 1990.

Fourteen separate volumes are planned on what was the longest-running dig in British archaeological history.

The new study focuses on the 14th Century ruined church of St Martin's and its graveyard, where the skeletons were found.

Simon Mays, human skeletal biologist for English Heritage, said: "Our work has yielded few clues on why skulls changed, but we have cast serious doubt on some of the current theories.

"Despite the best efforts of science, we're still in the dark to explain why it happened. If immigration was responsible, we would expect both sexes to be affected.

"We do know that male skulls shapes eventually reverted back, becoming similar to those we have today."

The new volume also sheds unprecedented light on the lives of the peasants who lived at Wharram Percy. Researchers found the proportion of left-handed people in medieval times was higher than it is today - about 15 per cent compared with a modern figure of about eight per cent.

Infant mortality was high by modern standards, but low compared with other historic populations, possibly because illness and poor diet only tended to kick-in after children were weaned off breast milk.