Friday, January 26, 2007
Study provides first genetic evidence of long-lived African presence within Britain
Genetics: January 24th, 2007 - New research has identified the first genetic evidence of Africans having lived among 'indigenous' British people for centuries. Their descendants, living across the UK today, were unaware of their black ancestry.
The University of Leicester study, funded by the Wellcome Trust and published today in 'European Journal of Human Genetics' (see below), found that one-third of men with a rare Yorkshire surname carry a rare Y-chromosome type previously found only among people of West African origin.
The researchers, led by Professor Mark Jobling of the Department of Genetics at the University of Leicester, first spotted the rare Y-chromosome type, known as hgA1, in one individual, Mr X. This happened while PhD student Ms Turi King was sampling a larger group in a study to explore the association between surnames and the Y chromosome, both inherited from father to son. Mr X, a white Caucasian living in Leicester, was unaware of having any African ancestors.
"As you can imagine, we were pretty amazed to find this result in someone unaware of having any African roots," explains Professor Jobling, a Wellcome Trust Senior Research Fellow. "The Y chromosome is passed down from father to son, so this suggested that Mr X must have had African ancestry somewhere down the line. Our study suggests that this must have happened some time ago."
Although most of Britain's one million people who define themselves as 'black or black British' owe their origins to immigration from the Caribbean and Africa from the mid-20th century onwards, in reality, there has been a long history of contact with Africa. Africans were first recorded in the north 1800 years ago, as Roman soldiers defending Hadrian's Wall.
To investigate the origins of hgA1 in Britain, the team recruited and studied a further 18 males with the same surname as Mr X. All but one were from the UK, with paternal parents and grandparents also born in Britain. Six, including one male in the US whose ancestors had migrated from England in 1894, were found to have the hgA1 chromosome.
Further genealogical research to identify a common ancestor for all seven X-surnamed males suggests that the hgA1 Y chromosome must have entered their lineage over 250 years ago. However, it is unclear whether the male ancestor was a first-generation African immigrant or a European man carrying an African Y chromosome introduced into Britain some time earlier, or even whether the hgA1 Y chromosome goes back as far as the Roman occupation.
"This study shows that what it means to be British is complicated and always has been," says Professor Jobling. "Human migration history is clearly very complex, particularly for an island nation such as ours, and this study further debunks the idea that there are simple and distinct populations or 'races'."
In addition, Professor Jobling believes that the research may have implications for DNA profiling in criminal investigations.
"Forensic scientists use DNA analysis to predict a person's ethnic origins, for example from hair or blood samples found at a crime scene. While they are very likely to predict the correct ethnicity by using wider analysis of DNA other than the Y chromosome, finding this remarkable African chromosome would certainly have them scratching their heads for a while."
Background Info: 8 per cent of the UK's 54 million inhabitants belong to ethnic minorities, and over one million classify themselves as 'black or black British' according to the 2001 census. Most owe their origins to immigration from the Caribbean and Africa beginning in the mid-20th century. However, in reality, there has been a long history of contact with Africa.
Africans were first recorded in the north 1800 years ago, as Roman soldiers defending Hadrian's Wall. Some historians suggest that Vikings brought captured North Africans to Britain in the 9th century. After a hiatus of several hundred years, the influence of the Atlantic slave trade began to be felt, with the first group of West Africans being brought to Britain in 1555. African domestic servants, musicians, entertainers and slaves then became common in the Tudor period, prompting an unsuccessful attempt by Elizabeth I to expel them in 1601. By the last third of the 18th century, there were an estimated 10 000 black people in Britain, mostly concentrated in cities such as London.
Source: Wellcome Trust
Based on the paper:
Africans in Yorkshire? The deepest-rooting clade of the Y phylogeny within an English genealogy
Turi E King, Emma J Parkin, Geoff Swinfield, Fulvio Cruciani, Rosaria Scozzari, Alexandra Rosa, Si-Keun Lim, Yali Xue, Chris Tyler-Smith and Mark A Jobling
Eur J Hum Genet advance online publication, January 24, 2007; doi:10.1038/sj.ejhg.5201771
The presence of Africans in Britain has been recorded since Roman times, but has left no apparent genetic trace among modern inhabitants. Y chromosomes belonging to the deepest-rooting clade of the Y phylogeny, haplogroup (hg) A, are regarded as African-specific, and no examples have been reported from Britain or elsewhere in Western Europe.
We describe the presence of an hgA1 chromosome in an indigenous British male; comparison with African examples suggests a Western African origin. Seven out of 18 men carrying the same rare east-Yorkshire surname as the original male also carry hgA1 chromosomes, and documentary research resolves them into two genealogies with most-recent-common-ancestors living in Yorkshire in the late 18th century. Analysis using 77 Y-short tandem repeats (STRs) is consistent with coalescence a few generations earlier.
Our findings represent the first genetic evidence of Africans among 'indigenous' British, and emphasize the complexity of human migration history as well as the pitfalls of assigning geographical origin from Y-chromosomal haplotypes.
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