Last Updated: 12:01am BST 23/05/2008
A new study on ancient human migrations suggests that Orcadians and
Siberians are closely related, writes Roger Highfield.
Orkney Islanders are more closely related to people in Siberia and in
Pakistan than those in Africa and the near East, according to a novel
method to chart human migrations.
advertisement
The surprising findings come from a new way to infer ancient human
movements from the variation of DNA in people today, conducted by a
team from the University of Oxford and University College Cork, which
has pioneered a technique that analyses the entire human genetic
makeup, or genome.
Although it provides relative genetic contributions of one group to
another, rather than timings, it confirms how the first modern humans
came out of Africa 50,000 years ago, mostly from a group in southern
Africa called the San.
But the subsequent movements around the world, via the near east,
central Asia and then Europe, turned up some surprises including a
strong similarity between the Sindih, a people who once lived in
Pakistan, and Orkney Islanders, or Orcadians.
In turn, the Orcadians are closely related to the people who first
colonised Siberia.
"Reindeer herders (a people called the Yakut) are indeed unexpectedly
related to British, because one of their strongest signals of ancestry
is from Orcadians, the only British population in the sample" says Dr
Daniel Falush of University College Cork, a co-author on the paper in
the journal PLoS Genetics.
The Orcadians, or those closely related to them in central/northern
Europe, also contribute to two other North East Asian populations, the
Hezhen and Han from Northern China.
"Humans like to tell stories and amongst the most captivating is the
story of the global spread of modern humans from their original
homeland in Africa," says Dr Falush.
"Traditionally this has been the preserve of anthropologists but
geneticists are now starting to make an important contribution."
Previous methods have either concentrated on one part of the human
genetic code (for example, just the Y-chromosome) or a greatly
oversimplified model of heredity.
"Our technique enables us to identify more subtle details about
genetic contributions than other methods," says Dr Garrett Hellenthal
of the University of Oxford, a co-author.
"By incorporating the inheritance of 'blocks' of DNA between
generations, rather than just individual genes, it captures a
panoramic view of the sharing of patterns of DNA across the entire
human genome," he says.
"This allows us to consider a vast number of possible colonisation
scenarios - not just the ones people have already thought of - and use
an algorithm to determine the most likely migration routes."
The new technique was used to analyse 2540 genetic markers using DNA
data from 927 individuals of diverse ethnicity whose DNA was collected
by the Human Diversity Project.
The researchers believe their method can cope with much larger
datasets with over 500,000 genetic markers and are now working on a
detailed picture of migrations into Europe.
Source Article
No comments:
Post a Comment