Genome Scan Shows Polynesians Have Little Genetic Relationship To Melanesians
(1/19/2008)
-United States
Tags:
genomics, polynesians, humans, melanesians
Women dancers in a village on Ontong Java, an Atoll that is the
northernmost tract of land in the Solomon Islands. (Credit: Photo courtesy of
Jonathan Friedlaender)
The origins and current genetic relationships of Pacific Islanders have
generated interest and controversy for many decades. Now, a new comprehensive
genetic study of almost 1,000 individuals has revealed that Polynesians and
Micronesians have almost no genetic relation to Melanesians, and that groups
that live in the islands of Melanesia are remarkably diverse.
The researchers analyzed more than 800 genetic markers (highly informative
microsatellites) in nearly 1,000 individuals from 41 Pacific populations, as
opposed to prior small-scale mitochondrial DNA or Y chromosome studies, which
had produced conflicting results.
"The first settlers of Australia, New Guinea, and the large islands just to the
east arrived between 50,000 and 30,000 years ago, when Neanderthals still
roamed Europe," says Jonathan Friedlaender, professor emeritus of anthropology
at Temple and the study's lead author. "These small groups were isolated and
became extremely diverse during the following tens of thousands of years. Then,
a little more than 3,000 years ago, the ancestors of the Polynesians and
Micronesians, with their excellent sailing outrigger canoes, appeared in the
islands of Melanesia, and during the following centuries settled the islands in
the vast unknown regions of the central and eastern Pacific.
"Over the last 20 years there have been many hypotheses concerning where the
ancestors of the Polynesians came from in Asia, how long it took them to
develop their special seafaring abilities in Island Melanesia, and how much
they interacted with the native Melanesian peoples there before they commenced
their remarkable Diaspora across the unexplored islands in the Pacific," he
adds.
According to Friedlaender, one scenario called the 'fast train hypothesis,'
which is supported by the mitochondrial evidence, suggests that ancestors of
the Polynesians originated in Taiwan, moved through Indonesia to Island
Melanesia, and then out into the unknown islands of the Pacific without having
any significant contact with the Island Melanesians along the way.
A counter argument called 'slow boat hypothesis,' which the Y chromosome
evidence supports, suggests that the ancestors of the Polynesians were
primarily Melanesians, and that there was very little Asian or Taiwanese
influence. A third position, called the "entangled bank hypothesis," suggests
these ancient migrations simply can't be accurately reconstructed by looking at
the genetics of today's populations, even in the context of the available
archaeological evidence.
In their paper, the researchers state that their analysis is consistent with
the scenario that the ancestors of Polynesians moved through Island Melanesia
relatively rapidly and only intermixed to a very modest degree with the
indigenous populations there.
"Our genetic analysis establishes that the Polynesians' and Micronesians'
closest relationships are to Taiwan Aborigines and East Asians," says
Friedlaender. "Some groups in Island Melanesia who speak languages related to
Polynesian, called Austronesian or Oceanic languages, do show a small
Polynesian genetic contribution, but it is very minor -- never more than 20
percent.
"There clearly was a lot of cultural and language influence that occurred, but
the amount of genetic exchange between the groups along the way was remarkably
low," he says. "From the genetic perspective, if the ancestral train from the
Taiwan vicinity to Polynesia wasn't an express, very few passengers climbed
aboard or got off along the way."
Friedlaender adds that this study also confirms and expands their findings from
previous studies about the genetic diversity of Island Melanesians--among the
most genetically diverse people on the planet, showing further that their
diversity is neatly organized by island, island size, topography and language
families.
The study, "The Genetic Structure of Pacific Islanders," is published in the
January issue of PLoS Genetics. It involved researchers from Temple University,
University of Maryland, Yale, Binghamton University, the Marshfield Clinic
Research Foundation, Victoria University in New Zealand, Mackay Memorial
Hospital in Taiwan, and the Institute for Medical Research in Papua New Guinea.
The study was funded by grants from the National Science Foundation, the
Wenner-Gren Foundation for Anthropological Research, the National Geographic
Society, The National Institutes of Health, Taiwan National Science Council,
and Temple, Binghamton, and Yale Universities.
Note: This story has been adapted from a news release issued by Temple
University
www.geneticarchaeology.com
http://reddit.com/goto?rss=true&id=t3_65z48
mediacare
http://www.mediacare.biz
[Non-text portions of this message have been removed]
