Diversity and age of the four major mtDNA haplogroups in native America

Diversity and age of the four major mtDNA haplogroups, and their implications for the peopling of the New World.
S L Bonatto and F M Salzano,Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.  

Despite considerable investigation, two main questions on the origin of Native Americans remain the topic of intense debate-namely, the number and time of the migration(s) into the Americas. Using the 720 available Amerindian mtDNA control-region sequences, we reanalyzed the nucleotide diversity found within each of the four major mtDNA haplogroups (A-D) thought to have been present in the colonization of the New World. We first verified whether the within-haplogroup sequence diversity could be used as a measure of the haplogroup’s age. The pattern of shared polymorphism, the mismatch distribution, the phylogenetic trees, the value of Tajima’s D, and the computer simulations all suggested that the four haplogroups underwent a bottleneck followed by a large population expansion. The four haplogroup diversities were very similar to each other, offering a strong support for their single origin. They suggested that the beginning of the Native Americans’ ancestral-population differentiation occurred approximately 30,000-40,000 years before the present (ybp), with a 95%-confidence-interval lower bound of approximately 25,000 ybp. These values are in good agreement with the New World-settlement model that we have presented elsewhere, extending the results initially found for haplogroup A to the three other major groups of mtDNA sequences found in the Americas. These results put the peopling of the Americas clearly in an early, pre-Clovis time frame.

It’s nice to see a study that agrees with the older (40,000 years plus) dates that are seen in some American sites like Topper. Why the recent entry (13k) date is clung onto so fiercely by some I’ll never know.

3 responses to “Diversity and age of the four major mtDNA haplogroups in native America

  1. Why the recent entry (13k) date is clung onto so fiercely by some I’ll never know.

    A couple of reasons spring to mind. The first is that an accepted model within the scientific community tends to be conserved, often in spite of emerging contradictory evidence, until that model’s proponents have passed on to their reward. It’s just the way of things.

    The second reason is pressure from the Native American community. “Clovis First” is simple and easily understood. It establishes that the indigenous inhabitants of the Americas constitute one people and implies that people enjoys an indisputable prior claim to the New World. Now that some tribes operate gambling casinos on their reservations, the community has the monetary and legal power to press that claim in the courts, especially with regard to indigenous cultural and physical remains. The upshot is that, at least potentially, a scientist that openly challenges “Clovis First” could find themselves without access to important archaeological sites.

    Some indication of this dynamic was evident during the “Kennewick Man” fiasco:

    http://en.wikipedia.org/wiki/Kennewick_Man

  2. Yes, I heard about that from an American archaelogist friend. Silly really,they are still their ancestors.

    Although; the whole ‘genocide of the Australoids’ might raise some interesting points.

  3. The Native American cultural and socio-political landscape is a minefield, something not easily navigated even for those of Native American descent. Somehow, I don’t think injecting a phrase like ‘genocide of the Australoids’ into the discourse, even politely, is going to result in fruitful discussion.

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