Johannesburg — By comparing the genetic information with historical records, four instances of 'non-paternity' were also discovered, which proved there were extramarital affairs among the islanders
THE saucy sexcapades on a remote island off South Africa's West Coast have been exposed in a spin-off of genetic research.
South African researchers have discovered a "hidden ancestor" from Eastern Europe.
They also blew the lid off several extramarital affairs among the seven founding families of Tristan da Cunha, some 2800km off the Cape coast.
Researchers behind the study stumbled upon the existence of a travelling "stranger" while tracing the founding fathers, who originated from Scotland, England, Holland, the US and Italy.
The island, which boasts rich and detailed historical and genealogical records, has a population of just 300, believed to have descended from 15 ancestors - seven men and eight women who arrived on the island between 1816 and 1908.
The genetic study conducted by Professor Himla Soodyall and colleagues at the National Health Laboratory Service, in conjunction with the University of the Witwatersrand and the South African Medical Research Council, was conducted to test the accuracy of the island's ancestry.
There are seven surnames in use on the island, and each of these can be traced to the original male founders.
But, as an unexpected bonus, researchers have uncovered two additional family lines. One came from a normal gene mutation which occurs randomly. The other showed evidence of an unknown man who left his genes, but not his surname, on the island.
Soodyall, who headed the research team, said the research - based on the Y chromosome DNA passed down by fathers to their sons through generations, like a surname, showed that the stranger probably came from Eastern Europe.
"It is well documented that many passenger ships, cargo vessels and whalers, some from Russia and Norway, used the island as a stopover port for trade and replenishing supplies," said the study, which was published in the European Journal of Human Genetics.
By comparing the genetic information with historical records, four instances of "non-paternity" were also discovered, which proved there were extramarital affairs among the islanders.
"In these four instances the child did not have the Y chromosome from the father linked with the presumed family surname, but had the pattern associated with another family surname on the island.
"If the Y chromosome lineage is different to that of the presumed father, non-paternity is suggested," she said.
She added that genetic evidence showed that the Y chromosome came from other island families.
"There are also indications in the [island's] records that would support this possibility," she said.
The DNA sample used was taken from 76 males in 1982 and has been used in various studies since then, including Soodyall's research.
Soodyall said the Y chromosome passed on uniquely from father to son is a reliable method of "testing history".
Thus far, attempting to trace ancestors and distant relatives has mainly relied on oral traditions, church records and other documents, but these methods were limited, said Soodyall.
"Our genetic material is inherited from our parents, and their parents before, and so on. By examining transmission of genes in living people, we can study the genetic trails of our ancestors back to about 100000 to 150000 years ago," she added.
The Tristanians have yet to be told of the findings.