Comments on Mulligan et al.
"…We explicitly incorporated archaeological, geological, and
paleoecological constraints into our analyses to enhance the
anthropological relevance of the results and to provide a
comprehensive model for the initial settlement of the Americas…As in
our previous analysis, we evaluate the significance of our results in
concert with other non-genetic data…Prior to entry to the New World,
we propose a period of isolation…"
As we've discussed before, I think this weakens the independence of
the DNA evidence. I'd hazard a guess that the archeological
constraints include Monte Verde as the earliest occupation of the
Americas. Hence the proposed isolation prior to entry into the New
World.
"…In light of these facts, we have now analyzed the largest dataset
of Native American mitochondrial coding genomes using publicly
available sequences (n =148…"
Good to see the sample inching up from 68 to 148.
"…assume a single migration event, which makes the approach ideal for
questions concerning the peopling of the Americas since it is
generally agreed that there was a single migration…The three stages
remain; 1)divergence of Amerind ancestors from the Asian gene pool..."
A single migration event and gene pool is generally agreed upon by
whom?
"…suggests an entry to the New World that was coincident with the
retreat of the North American ice sheets, i.e. the opening of
an `icefree corridor' ,17–14 kya …"
The ice-free corridor was not open during this timeframe:
http://www.sfu.museum/journey/mod/03middle/maps/folder2/image1.jpghttp://www.sfu.museum/journey/03middle/index.php"…The variants that occur on the branch leading to each New World
founding haplogroup represent variation that evolved prior to
expansion into the Americas whereas variation within each founding
haplogroup, i.e. nucleotide diversity within a haplogroup,
represents variation that evolved after entry to the Americas –
we are interested in the variation that occurred prior to entry into
the Americas…"
See Gisele Horvat's comments:
--- In
HumanMigrations@yahoogroups.com, "Gisele Horvat" <g> wrote:
>
> --- In
HumanMigrations@yahoogroups.com, "Gisele Horvat" <g> horvat@> wrote:
>
> > Updated Three-Stage Model for the Peopling of the Americas
> > Connie J. Mulligan1*, Andrew Kitchen1, Michael M. Miyamoto2
>
> "The variants that occur on the branch leading to each New
> World founding haplogroup represent variation that evolved
> prior to expansion into the Americas ..."
>
> This is a reference to the evolution of New World-specific
> mutations. If all Native American sequences have all of them
> and no Asian sequences have any of them, then where did they
> occur? According to the authors of this and other articles
> - in Beringia and this is Mulligan et al's 'First Stage'.
>
> However, I'm not yet certain that all Native Americans
> have all of them as I know I have not yet seen a sufficient
> amount of *complete* Native American sequences. If or when
> sequences which fall in between those of Asians and Native
> Americans are located in the New World, then Mulligan's
> Stage 1 will dissipate.
>
> As an example from a well-studied population - after
> identifying haplogroups H and V in Europe, HV (sequences
> which came before H and V), pre-HV, etc. were discovered.
> We already are aware of Native American sequences which
> lack at least one Native American-specific mutation in
> hypervariable region I. These would be ideal ones to
> examine more carefully.
>
> Gisele
http://tech.groups.yahoo.com/group/HumanMigrations/message/3345http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0003199Mulligan CJ, Kitchen A, Miyamoto MM (2008) Updated Three-Stage Model for the Peopling of the Americas. PLoS ONE 3(9): e3199. doi:10.1371/journal.pone.0003199
