Anthropology assistant professor uncovers genetic patterns

I would like to see something more, I have an almost-Carl feeling that
this is wrong or that the interpretation of languages is not related
to genetics but linguistics. This is the kind of study that had better
be very accurate and not subject to internal interpretation of the
data.


Anthropology assistant professor uncovers genetic patterns
New reseach challenges previous theories of continent population

* Jared Rader/The Daily

Thursday, September 3, 2009



New questions of human origin could shed light on what makes groups of
people more or less prone to certain diseases, an OU researcher has
found.

Cecil Lewis, assistant professor of anthropology and director of the
OU Molecular Anthropology laboratory, studied genetic diversity among
American populations. His research is not only groundbreaking for
anthropology but it could also affect future health research.

“I made a number of surprising discoveries, some of which actually
applied to the Americas as a whole,” Lewis said.

Lewis’ research, which was recently published in the American Journal
of Physical Anthropology, focused on the genetic variations in the
Americas. What he found has challenged previous assumptions of the
human origins in the country.

The genetic evidence of Lewis’ research in South America suggests the
continent was populated first from the east to the west.

Lewis said this goes against the more common idea that North America
was populated first in the western coastal regions, with people then
migrating to South America and populating the continent from west to
east.

“When it comes to genetic data, there is an expectation for what area
of the Americas should have the largest genetic diversity,” Lewis
said.

This expectation is dependent on what population geneticists call the
“founder effect,” he said.

Lewis explained a founder effect occurs when there is a “parent
population” that has a lot of genetic diversity. If a small group of
the population moves away from the parent population to form a
“daughter population” in another area, that population would be
expected to only have less genetic diversity present in the parent
population.

Lewis’ research about South American genetic diversity challenges
those expectations. He said his data shows local populations in the
east of the continent, and when pooled together, yield a much greater
genetic diversity than in the west.

“Now the real story here is that when we look at the genetic data we
have to rethink our original idea for the peopling of South America,”
Lewis said. “There’s much more we need to look into before we can make
that kind of a strong statement, but it’s certainly true that the
genetic data is not fitting the pattern we would expect if the West
coast had the initial migration.”

Lewis said the founder effect could be traced back to the theory that
humans originated from Southern Africa. He said examination of the
genetic diversity of populations in Northern Africa and the Middle
East reveal smaller subsets of the genetic diversity found in South
Africa. European and Asian populations follow this trend, having
subsets of the genetic diversity found in the Middle East. North
American populations, in turn, have subsets of diversity found in
Asia.

Lewis’ study of founder effects and genetic diversity holds important
clues for disease risk and resistance among population groups.

“This history of founder effects helps us determine how well one local
population’s genetic risk factors might reflect the risk factors of a
larger community,” Lewis said.

He said this research is important because it will help determine
whether medical studies should focus on general populations or smaller
subsets of the population.

Lewis is currently leading a study to help answer this question. The
research involves the study of genes of blacks in Georgia and
comparing the results with the same study being done on blacks in
Oklahoma.


http://oudaily.com/news/2009/sep/03/anthropology-assistant-professor-uncovers-genetic-/


Research Article
Hierarchical modeling of genome-wide Short Tandem Repeat (STR) markers
infers native American prehistory
Cecil M. Lewis Jr. *
Department of Anthropology, University of Oklahoma, Norman, OK 73019
email: Cecil M. Lewis (cmlewis@xxxxxx)

*Correspondence to Cecil M. Lewis Jr., Department of Anthropology,
University of Oklahoma, Dale Hall Tower 521, Norman, OK 73019, USA

Keywords
human migration • American Indian

Abstract
This study examines a genome-wide dataset of 678 Short Tandem Repeat
loci characterized in 444 individuals representing 29 Native American
populations as well as the Tundra Netsi and Yakut populations from
Siberia. Using these data, the study tests four current hypotheses
regarding the hierarchical distribution of neutral genetic variation
in native South American populations: (1) the western region of South
America harbors more variation than the eastern region of South
America, (2) Central American and western South American populations
cluster exclusively, (3) populations speaking the Chibchan-Paezan and
Equatorial-Tucanoan language stock emerge as a group within an
otherwise South American clade, (4) Chibchan-Paezan populations in
Central America emerge together at the tips of the Chibchan-Paezan
cluster. This study finds that hierarchical models with the best fit
place Central American populations, and populations speaking the
Chibchan-Paezan language stock, at a basal position or separated from
the South American group, which is more consistent with a serial
founder effect into South America than that previously described.
Western (Andean) South America is found to harbor similar levels of
variation as eastern (Equatorial-Tucanoan and Ge-Pano-Carib) South
America, which is inconsistent with an initial west coast migration
into South America. Moreover, in all relevant models, the estimates of
genetic diversity within geographic regions suggest a major bottleneck
or founder effect occurring within the North American subcontinent,
before the peopling of Central and South America. Am J Phys Anthropol
2009. © 2009 Wiley-Liss, Inc.
Received: 15 December 2008; Accepted: 17 June 2009

Digital Object Identifier (DOI)

10.1002/ajpa.21143 About DOI

http://www3.interscience.wiley.com/journal/122541748/abstract
.

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