[Paleopsych] ABC: Ancient DNA may be misleading scientists
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Wed Dec 7 01:24:48 UTC 2005
News in Science - Ancient DNA may be misleading scientists - 18/02/2003
Tuesday, 18 February 2003
Ancient DNA in skeletons has a tendency to show damage in a particular
region, resulting in misleading genetic data and mistaken conclusions
about the origin of the skeleton, British scientists said.
A group of researchers at the Henry Wellcome Ancient Biomolecules
Centre of the University of Oxford, in Britain, made the finding while
studying Viking specimens. They found that about half of the specimens
had DNA that suggested they were of Middle Eastern origin.
But more detailed analysis revealed that many of the genetic sequences
in the double helix molecule, which carries the genetic information of
every individual, were damaged at a key base that separates European
sequences from Middle Eastern genetic types - damage which made the
skeletons appear to have originated in the Levant.
The results are published in the February 2003 issue of the
American Journal of Human Genetics.
Damage events appear to be concentrated in specific 'hotspots',
indicating that a high proportion of DNA molecules can be modified at
the same point. These hotspots appear to be in positions that also
differ between different human groups. In other words, the DNA damage
discovered affects the same genetic positions as evolutionary change.
"Now that this phenomenon has been recognised, it is possible to
survey the ancient sequences for damage more accurately, and determine
the correct original genetic type - open the way for more reliable
future studies," said Professor Alan Cooper, director of the centre.
Cooper has hopes the finding may have implications for future
research. "It also appears that we can use damage cause after death to
examine how DNA damage occurs during life - a completely
unanticipated, and somewhat ironic result," he said. "Potentially this
allows us to get uniquely separate views of the two major evolutionary
processes, mutation and selection."
Danny Kingsley - ABC Science Online
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