Apropos the recent discussion about human
adaptability between Harry and me, the following
piece will be of interest. (Be it noted, however,
that the Science Daily writer confuses his
latitudes with his longitudes in the 6th
paragraph, though he was correct in his fifth para.)
Keith
Did the Orientation of the Continents Hinder
Ancient Settlement of the Americas?
ScienceDaily (Sep. 21, 2011) - In an intriguing
original look at the history of the first
Americans, a new study finds evidence that the
north-south orientation of the American
continents slowed the spread of populations and
technology, compared to the east-west axis of Eurasia.
The research, published in the American Journal
of Physical Anthropology, is part of a special
section which explores who the first Americans
were and how they were able to settle in the last great unexplored habitat.
The research, by Sohini Ramachandran and Noah
Rosenberg, from Brown University and Stanford
University respectively, uses genetic information
to explore the effects of continental axes and
climates on human migration and adaptation across the Americas.
"It has been proposed that the east-west
orientation of the Eurasian landmass aided the
rapid spread of ancient technological
innovations, while the north-south orientation of
the Americas led to a slower diffusion of
technology there," said Ramachandran. "Our
research develops this idea, arguing that
continental orientation influenced migration
patterns and played an important role in
determining the structure of human genetic
variation and the distribution and spread of cultural traits."
The research supports the idea that technological
diffusion was accelerated across Eurasia because
populations with the same latitude experience
similar climates, making adaptation to new
locations easier for domesticated animals, plants
and consequently humans. Alternatively, migrating
along lines of longitude involves adapting to new climates.
"The idea that technology was diffused along
latitudinal lines was proposed by Jared Diamond
in 1997, but if this is correct and the spread of
technology was accompanied by human migrations it
follows that a comparative study into genetic
variation would reveal a signature of greater
genetic differences between populations along
lines of longitude in the Americas than that in
Eurasia along lines of latitude," said Ramachandran.
To test this hypothesis the team analysed genetic
variation data from 68 populations, 39 from
Eurasia and 29 from Native Americans. The data
were used to identify relationships between the
genetic and geographic distances between populations on each continent.
The results confirmed that the increase in
genetic distances along lines of longitude in the
Americas occurs over shorter geographic distances
than the increase in genetic distances in Eurasia along lines of latitude.
"For many years anthropologists have asked who
the first Americans were and how they were able
to settle in the last major habitat open to
humans," said Jeff Long, guest editor of the
special section. "These six papers use genetics
to answer these questions, not only confirming
the genetic signatures of historic relationships
between Native Americans and Eastern Asia, but
also providing evidence for prehistoric migration
and adaptation of settlers to the new world."
----------
Story Source:
The above story is reprinted (with editorial
adaptations by ScienceDaily staff) from materials
provided by
<http://onlinelibrary.wiley.com/>Wiley-Blackwell,
via <http://www.alphagalileo.org>AlphaGalileo.
----------
Journal Reference:
* Sohini Ramachandran, Noah A. Rosenberg. A
test of the influence of continental axes of
orientation on patterns of human gene flow.
American Journal of Physical Anthropology, 2011;
DOI: <http://dx.doi.org/10.1002/ajpa.21533>10.1002/ajpa.21533
Keith Hudson, Saltford, England http://allisstatus.wordpress.com/2012/08/
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