June 08, 2009

mtDNA of Native Mexicans

Human Genetics doi:10.1007/s00439-009-0693-y

Linguistic and maternal genetic diversity are not correlated in Native Mexicans

Karla Sandoval et al.


Mesoamerica, defined as the broad linguistic and cultural area from middle southern Mexico to Costa Rica, might have played a pivotal role during the colonization of the American continent. The Mesoamerican isthmus has constituted an important geographic barrier that has severely restricted gene flow between North and South America in pre-historical times. Although the Native American component has been already described in admixed Mexican populations, few studies have been carried out in native Mexican populations. In this study, we present mitochondrial DNA (mtDNA) sequence data for the first hypervariable region (HVR-I) in 477 unrelated individuals belonging to 11 different native populations from Mexico. Almost all of the Native Mexican mtDNAs could be classified into the four pan-Amerindian haplogroups (A2, B2, C1, and D1); only two of them could be allocated to the rare Native American lineage D4h3. Their haplogroup phylogenies are clearly star-like, as expected from relatively young populations that have experienced diverse episodes of genetic drift (e.g., extensive isolation, genetic drift, and founder effects) and posterior population expansions. In agreement with this observation, Native Mexican populations show a high degree of heterogeneity in their patterns of haplogroup frequencies. Haplogroup X2a was absent in our samples, supporting previous observations where this clade was only detected in the American northernmost areas. The search for identical sequences in the American continent shows that, although Native Mexican populations seem to show a closer relationship to North American populations, they cannot be related to a single geographical region within the continent. Finally, we did not find significant population structure in the maternal lineages when considering the four main and distinct linguistic groups represented in our Mexican samples (Oto-Manguean, Uto-Aztecan, Tarascan, and Mayan), suggesting that genetic divergence predates linguistic diversification in Mexico.



Kepler said...

This is fascinating and it makes us wonder how fast so diverging languages can appear.
But then Greenberg was putting all those languages into one bag already decades ago.

I don't know about American languages of Mexico but I have read a little bit about the structure of a couple of fAmerican languages spoken in Venezuela: Pemon, Warao and Yanomami. They are so incredibly different.
I read a lot of Warao but also Yanomami have the same type of C (C1, I think)...and yet: is this different from languages spoken in Europe and the Mediterranean area?

I wonder if something more can be found from the Y chromosomes. I remember some stories about many groups were women in one tribe spoke a different languages from men as they were all kidnapped and the pattern had been kept for generations...

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eurologist said...

This is fascinating and it makes us wonder how fast so diverging languages can appear.

I don't think 20,000 years (or 40,000, if you count Beringia) is a short amount of time...

I am not saying the Aztec - Mayan separation is that old, and surely it isn't. Just that there was plenty of time.

Actually, I am one of the few people who think many language groups are much older than current estimates. So, for example, I see many good reasons to put the origin of a "recognizable" Indo-European at around 6,500 to 5,000 BCE - quite a bit earlier than mainstream.

(And even that language IMO was simply related to mainstream Central European dialects of the time, which had their origin in the Ice Age... - but I won't mention this, since the Kurgan supporters will quickly come and chastise me ;))