New DNA Study Helps Explain Unique Diversity Among Melanesians

Eureka Alert ^ | 2-28-2007 | Temple University - Preston Moretz

[blam]

Contact: Preston M. Moretz
pmoretz@temple.edu
215-204-7476
Temple University

New DNA study helps explain unique diversity among Melanesians

Small populations of Melanesians — among the most genetically diverse people on the planet — have significant differences in their mitochondrial DNA that can be linked to where they live, the size of their home island and the language they speak, according to a study being published in the new online journal, Public Library of Science ONE (http://www.plosone.org).

The study, "Melanesian mtDNA complexity," was lead by Jonathan Friedlaender, emeritus professor of anthropology at Temple University. The study appears in the Feb. 28 issue.

Friedlaender and his collaborators from Binghamton University, the Institute for Medical research in New Guinea and the University of Pennsylvania, examined mitochondrial DNA sequences from 32 diverse populations on four Melanesian islands, an island chain north and northeast of Australia that includes Fiji, New Caledonia, Vanuatu, the Solomon Islands, and New Guinea. The islands that were intensively covered were Bougainville, New Ireland, New Britain and New Guinea. "Mitochondrial DNA has been a focus of analysis for about 15 years," says Friedlaender. "It is very interesting in that it is strictly maternally inherited as a block of DNA, so it really allows for the construction of a very deep family tree on the maternal side as new mutations accumulate over the generations on ancestral genetic backgrounds.

"In this part of the world, the genealogy extends back more than 35,000 years, when Neanderthals still occupied Europe," he adds. "These island groups were isolated at the edge of the human species range for an incredible length of time, not quite out in the middle of the Pacific, but beyond Australia and New Guinea. During this time they developed this pattern of DNA diversity that is really quite extraordinary, and includes many genetic variants that are unknown elsewhere, that can be tied to specific islands and even specific populations there. Others suggest very ancient links to Australian Aborigines and New Guinea highlanders."

Friedlaender also says that the study gives a different perspective on the notion of the "apparent distinctions between humans from different continents, often called racial differences. In this part of the Pacific, there are big differences between groups just from one island to the next — one might have to name five or six new races on this basis, if one were so inclined. Human racial distinctions don’t amount to much."

### The study was funded by grants from the National Science Foundation, the Wenner-Gren Foundation for Anthropological Research, the National Geographic Society Exploration Fund and the Penn Faculty Research Fund.

[Pharmboy]

Yes...but you said above that Cavalli Sforza had the Melanesians the farthest away from the Africans. THAT doesn't seem to make sense if they are also old--they should be closest to the originals, the Africans.

[Varda]

Genetic distance is a measure of the dissimilarity of genetic material. The more dissimilar, the further away (in time) from the point of divergence. For this to work, you have to believe that there is a constant rate of mutation that can be translated into time.

[Pharmboy]

I understand that...but it still makes NO sense that two populations considered VERY old would be VERY distant from each other.

[Sam Ketcham]

"New Guinea highlanders" I'll bet they look cute in their plaid grass skirts.

[blam]

"I was told that Africa has more genetic diversity than the rest of the world combined."

The Toba eruption 75,000 probably is responsible for killing most of the other genes outside Africa. Albeit, the Neanderthals and apparently the 'Hobbits' on Flores suevived that eruption. It was the 'nuclear-winter' effect that did the killing, btw.

[Varda]

One is the founding population and the other is maybe the first daughter population. Both populations continue evolving, accumulating mutations. Over time they become more and more different. Because of the early split, this first daughter population doesn't contain the entire catalog of mutations of the founder population. The population with the most unique mutations compared to another population is the most distant from that population.
More recent daughter populations will contain the recent mutations and will not have had enough time to accumulate many unique mutations of it's own. These populations are considered closer in genetic distance.

[Varda]

The human race seems to have had some really close calls. I think it's possible other Homo erectus populations survived too (New World maybe).

[Pharmboy]

OK--so what you're saying is that the population closest to the original differs the most from it based on mutations occurring since the fission. These suppose different mutation rates of different populations and would then throw out the biogenetic clock.

[Dustbunny]

Interesting

[To Hell With Poverty]

"I'm not physically or mentally deficient. Nor am I Muslim. But genealogy is fun for me because so many of my lines converge on common ancestors. Us Southerners had ancestors who lived in rural areas with limited access to new blood. We did ok."

LOL, maybe you should change your FReeper name to "Twig" then, as in "if your family tree doesn't fork...." ;-)

[SunkenCiv]

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