BY Steve Connor
London - A fishy diet has blown a hole in the theory that a group of 14th century English monks died of syphilis, long before Christopher Columbus was supposed to have brought the veneral disease to Europe from the New World.
Scientists have found that the original estimates of the ages of skeletons found at the site of a monastery in Hull failed to take into account the fact that the monks lived on a diet rich in fish.
The skeletons were thought to date back between 1300 and 1450, long before Columbus discovered America in 1492, when his sailors were supposed to have contracted the disease during sexual trysts with the local natives.
The dating of the skeletons, and the presence of marks on the bones indicating the terminal stages of syphilis, were thought to be incontrovertible evidence that the disease was present in Britain well before Columbus discovered America.
However, another chemical analysis of the skeletons has found that the monks's diet was at least 30 per cent fish. Their bones would therefore have contained a high proportion of "old" carbon from the sea, which can make their skeletons appear older than they really are in radiocarbon dating.
When the fish diet is taken into account, the age range of the skeletons falls within the period when Columbus and his men had already returned to Europe, said Anthea Boylston, a palaeopathologist at the University of Bradford.
"A diet rich in fish is not really surprising in a medieval period when they ate fish every Friday. After all it was a Catholic country in those days," Boylston said.
"Clearly the marine correction is critical. Without it the calibrated date appears unquestionably pre-Columbian. The correction places the age of the individual within a century either side of the discovery of the New World," she said.
Scientists at Oxford University's Radiocarbon Accleration Unit are about 92 per cent certain that the skeletons date to between 1410 and 1530.
Several scientists in the United States have produced convincing evidence that syphilis was present in America long before Columbus arrived. The work relies mainly on the presence of syphilitic marks on bones that are reliably dated.
It is also well established that Europe suffered an epidemic of venereal syphilis at the turn of the 15th and 16th centuries, around the time that Columbus and his crew returned home.
Bruce Rothschild, of Northestern Ohio Universities College of Medicine, has also found evidence of syphilis among the natives living in the region of the Dominican Republic at the time when Columbus first landed there 500 years ago. "That's the smoking gun," he said.
Dr Rothschild has suggested that the monks of Hull may not even have been suffering from venereal syphilis but a closely related infection called yaws which is passed on by skin contact rather than sexual intercourse.
Dr Rothschild believes this and other evidence explains why the first epidemic of true venereal syphilis occurred in Europe only after America was discovered.
Some researchers, however, believe the case is far from closed. They say other work still points to a European origin of the first syphilis epidemic - the famous "pox" that the French, English and Italians blamed each other for.
"Certainly a new epidemic disease does seem to have arrived at the end of the 15th Century, about the time of the return of Columbus's ship," Boylston said. "But was there an endemic disease in the population before that? It's very difficult to know." - Foreign service