for National Geographic News
Rare DNA previously found only in people from West Africa has turned up in white males from northern England, a new study reports.
The surprising discovery was made during a survey of genetic diversity in the United Kingdom based on the male Y chromosome.
This sex-determining chromosome is copied from father to son, providing a record of male ancestry.
The uncommon DNA, a chromosome called hgA1, had previously been detected only in a region of West Africa that includes Mali, Senegal, and Guinea-Bissau, the team says (Africa map).
"It's a really special chromosome, one that's only been reported before in a handful of men in Africa," said Mark Jobling, a genetics professor from the University of Leicester who led the research team.
The hgA1 chromosome lies near the root of the family tree of Y chromosomes in Africa, Jobling added.
"It's an ancient type that's African specific."
But the team found hgA1 in one white British male who took part in the survey, despite the man having no known African family connection.
According to the research, published online this week in the European Journal of Human Genetics, the unusual DNA has been present in Britain for at least 250 years.
After making the surprising find, Jobling's team tested other British men who shared the same east Yorkshire surname as the original man found with the African chromosome.
(The researchers haven't revealed the surname, which is derived from a Yorkshire place name, to preserve the anonymity of the study participants.)
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