Effects of Purifying and Adaptive Selection on Regional Variation in Human mtDNA

Science Magazine | 2004-01-09

[Lessismore]

Eduardo Ruiz-Pesini,1 Dan Mishmar,1 Martin Brandon,1,2 Vincent Procaccio,1 Douglas C. Wallace1*

Abstract

A phylogenetic analysis of 1125 global human mitochondrial DNA (mtDNA) sequences permitted positioning of all nucleotide substitutions according to their order of occurrence. The relative frequency and amino acid conservation of internal branch replacement mutations was found to increase from tropical Africa to temperate Europe and arctic northeastern Siberia. Particularly highly conserved amino acid substitutions were found at the roots of multiple mtDNA lineages from higher latitudes. These same lineages correlate with increased propensity for energy deficiency diseases as well as longevity. Thus, specific mtDNA replacement mutations permitted our ancestors to adapt to more northern climates, and these same variants are influencing our health today.

1 Center for Molecular and Mitochondrial Medicine and Genetics, University of California, Irvine, CA 92697-3940, USA.
2 Information & Computer Science, Institute for Genomics & Bioinformatics, University of California, Irvine, CA 92697-3425, USA.

Excerpted from text ...

To further clarify the role of arctic selection, we examined only those haplogroups found primarily in the arctic. Haplogroups A, C, D, and G are highly enriched in northeastern Siberia, comprising 75% of arctic versus 14% of temperate Asian mtDNAs. Haplogroups A, C, and D arrived first in northern Siberia and thus were in a position to colonize the Americas when the Bering land bridge appeared. Haplogroup G arrived in Siberia after the bridge submerged. Haplogroup B joined A, C, and D in the Americas via an independent migration. Because B is absent in northern Siberia and rare in northwestern North America, it appears to have arrived by a more southerly route. Haplogroup X is found in the Great Lakes region of Central Canada, and is more prevalent in Europe than Asia. Hence, X has also persisted in the northern latitudes for prolonged periods (1).

[Lessismore]

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[billorites]

Well, I'm glad to have this cleared up.

[LiteKeeper]

YEC INTREP

[SauronOfMordor]

Translated into english: they've discovered that people who're adapted to Arctic conditions (Eskimoes) have differences in the DNA that governs their cells mitochondia (the part of the cell that generates energy from metabolizing glucose + oxygen). This difference allows Eskimos to better function in Arctic environments. The USA Today version may better explain it to non-biologists:

The change occurs in the mitochondria, the parts of human cells that burn fuel to produce heat and energy, according to the team of researchers led by Eduardo Ruiz-Pesini of the University of California at Irvine.

The scientists analyzed mitochondria from 1,125 people ranging from Africa to Europe and Arctic Siberia. They found that that mutations in mitochondria DNA, increasing production of heat, though reducing energy production, rise in people living closer to the pole, compared to tropical residents.

The change results in an increase propensity for energy deficiency diseases, but also in increased longevity and resistance to aging, they report in Friday's edition of the journal Science.

"Our observations support the hypothesis that certain (mitochondrial DBA) variants permitted humans to adapt to colder climates," the researchers concluded.

The variants continue to produce differences in energy production and affect health, they said.

DNA provides the blueprint for the development of the body, combining information from the separate DNA of each parent. However, mitochondrial DNA directing the energy production in cells is inherited only from the mother, unlike the DNA that provides the body's primary set of instructions for operation.

Racially-based genetic differences that effect such a fundamental characteristic as metabolism may have non-PC implications

[blam]

I think this is a translation of the same data. Am I correct?

Ice Age Ancestry May Keep Body Warmer And Healthier

GGG

[Lessismore]

The NY Times article doesn't mention the points made in the excerpted paragraph -- specifically that Haplogroup B appears to "have arrived by a more southerly route". Unfortunately, the article does not provide any information about the ethnicity of the subjects tested. I wonder whether Haplogroup B would be associated with Na-Dene Native Americans.

The other tantalizing bit is the Haplogroup X, which is characterized as more European that Asian and is said to have "persisted in the northern latitudes for prolonged periods". Since Haplogroup X is found around the Great Lakes, it may have arrived in the US via the North Atlantic.

I found the Paleohistory bits more interesting that the main content of the article.

[aruanan]

They found that that mutations in mitochondria DNA, increasing production of heat, though reducing energy production, rise in people living closer to the pole, compared to tropical residents.

This has to do with uncoupling proteins in the electron transport chain. Instead of producing ATP, it produces heat. This is the characteristic of mitochondria in brown fat. Infants have greater quantities of brown fat than do adults. Also, small animals such as mice rely on brown fat to keep warm. It's not surprising that increased levels of UCP would be a selective advantage in cold climes.

[SierraWasp]

"Also, small animals such as mice rely on brown fat to keep warm."

Sounds like Liberal Demicrats to me!!!

[blam]

"The other tantalizing bit is the Haplogroup X, which is characterized as more European that Asian and is said to have "persisted in the northern latitudes for prolonged periods". Since Haplogroup X is found around the Great Lakes, it may have arrived in the US via the North Atlantic."

I'm anxiously awaiting an explanation on this 'little secret' that has not gotten any 'press.'

European DNA Found In 7-8,000 Year Old Skeleton Found In Florida (Windover)

It'll probably change everything we believed before if it turns out to be true.

[blam]

If you have some time for reading, go to this site, The Neanderthal Theory, and read this article. I found it intriguing.

[farmfriend]

Gods, Graves, Glyphs
List for articles regarding early civilizations , life of all forms, - dinosaurs - etc.

Let me know if you wish to be added or removed from this ping list.

[Kenuchelover]

Far from being just a "European" haplogroup, it should be noted that it is found at HIGHER levels in the Near East & among certain American Indian tribes than it is in Europe... and that it is found at the same ("European") level among the Altai ethnic group in Siberia, and among American Indians in general. Additionally, it is present (at lower levels) in India & North Africa.

Detailed analysis has shown that the American Indian X lineages CANNOT be descended from those in Europe (but that BOTH European & American Indian X lineages could be descended from the Siberian X lineages).

As far as Haplogroup X's distribution in North America, X lineages are ALSO found at fairly high levels on the Great Plains AND in the Pacific Northwest, and lower levels in other parts of the continent.... so there is NO reason to assume it arrived from the Atlantic. (It should be noted that it has ALSO been reported from prehistoric remains in Brazil).

Bluntly, the reason that "this little secret" hasn't gotten any press, is that the scientific community already knows that haplogroup X is NOT indicative of prehistoric Europeans in the Americas. Try searching PubMed for scientific journal articles next time, rather than relying on fluff articles in the popular press.

[blam]

"Try searching PubMed for scientific journal articles next time, rather than relying on fluff articles in the popular press."

You signed onto FRee Republic to tell me this? This is the only entry/post you have ever made on FR.

I'm a retired chip-maker...I don't claim to have any special knowledge/expertise in this area...everyone on FR knows that. I post my opinions and ask questions. That's all.

[Kenuchelover]

Don't trust television specials, nor the popular press, to get scientific details correctly.

Haplogroup X is NOT "more European than Asian". It is found at the SAME level among American Indians as it is among Europeans(& is higher among certain tribes than it is among any European ethnic group) as well as among at least one Siberian group (Altai).... and it's both more common and more diverse in the Near East.

It should also be pointed out that Europe has been much more widely DNA tested, that MANY Asian populations have not been mtDNA tested at all, and that virtually none of the latter have been tested for X. (Tests are SPECIFICALLY for each haplogroup, so budget concious researchers test for common, "expected" haplogroups..... and samples that don't match are lumped together as "other"). X lineages in Asia weren't found UNTIL researchers actually tested for them (duh!).... in particular, they tested unidentified "other" lineages among the Altai & found it immediately (it's also been recently found at a lower level among several other Siberian groups). It's also been found at low levels in India & North Africa.

Since phylogenetic analysis of the various X lineages has revealed that the European lineages CANNOT be ancestral to the Native American ones (different branch in the tree), but that the Siberian (& some Near Eastern) sequences COULD be, the only rational assumption is that X started out either in Africa or Asia Minor, migrated up into Siberia & over into the Americas.... and SEPERATELY migrated from either Siberia or Asia Minor into Europe.

BTW, Haplogroup B is VERY rare among the NaDene.... it's highest frequency in North America is centered in the Southwest (or actually, radiating outwards from Baja California).... and it's found in South America, which indicates an EARLY arrival. (Analysis of the various American haplogroups indicate that they likely all arrived at about the same time, roughly 20,000-40,000 years ago.... or earlier, depending on what the actual mutation rate turns out to be & how much selection culled lineage diversity).

[Kenuchelover]

Dear Blam,

Yes, I came across Free Republic by chance & signed on to give you relevant information that you showed no signs of possessing (you asked a question & posted some misinformation you'd come across, hence...) I also gave a piece of good advice concerning credibility of sources (MUCH garbage has been printed on this, mostly in the popular press) & offered a place to obtain hard scientific data on issues. No hostility existed on my part, I assumed you were actually interested in the truth..... aren't you? Whether or not your past history has any bearing on this, this was my first post on Free Republic... as you noted, I'm surprised you didn't also realize that this means I wouldn't know or care about any such history. Or do you have a problem with being told scientific facts that counter pseudoscientific fluff?

[blam]

I'm sensing that you have an ax to grind, huh?

Are you an American Indian/Native American?...Cherokee perhaps?

What do you think of the recent court decision to allow the scientists to examine the skeleton of Kennewick Man?

Connuche (Kenuche)
Cherokee
A Recognized Dish of Honor

[MenomineeMiss]

*Im absolutely interested in this haplo X "thing" pardon my lack of wording on it.Im just amazed and flabbergasted at the same time. Im Menominee indian of Wisconsin and this stuff kind of hits home for me.Seeing as my people are to some degree if not more "great lakes people". Im not a "fullblood" IF one goes by that moronic term both my parents are mixed blood but my mother is menominee for the most part and her mother is and her mother.. etc..
*In a way though it makes me feel bad to read these things and suddenly be reduced down to micro minis and then feel I am being judged by it.
I am not much for all this stuff when all I ever see come out of the testing of us native people is disrespect,people who arent exactly up front about what they are testing for and worst of all these tests no matter how ill gotten or well meaning all serve in undermining native's rights to exist AS native in one way or another. Understand we only want to live out our lives in a manner we feel suits us and die and be put to rest in a manner we also feel suits us. All this testing violates the living and dead to some degree.
Kennuche this is how I feel about the Kennewick man testers..Why cant they just leave well enough alone..that is someone's ancestors being disrespected in death all for some tests that will just be used later to undermine natives living now. All this scientific testing of natives is highly political in nature and harsh on us because of the whole origination theories that abound whilest testing is going.By my people's oral tradition I am Menominiwatok and we originated in the place now known as Wisconsin and michigan.. not Europe, not Siberia, not Mongolia or anywhere else..We are who we are..our ancestors have said so and they were here in this land long before any dna testers.Whose words should I believe my ancient Elders who were living here and had no reason to fib about such things or some dna testers who werent even living then....