Re: Polynesian canoes (Re: Rat genes solve mystery of great Pacific odyssey

From: G Horvat (g-horvat_at_shaw.ca)
Date: 07/28/04 

Date: Wed, 28 Jul 2004 04:57:30 GMT

On Tue, 27 Jul 2004 18:40:33 -0400, Yuri Kuchinsky <yuku@trends.ca>
wrote:

>G Horvat wrote:
[...]
>> It is implied,
>> for instance, in some craniometric articles that Polynesian-like
>> Paleoindians were replaced by more recent Native American who (1/4 of
>> them), according to their mtDNA sequences, shared a common ancestry
>> with Polynesians. While, I suppose, this is possible, it does not
>> seem like the most logical conclusion to me.
>
>Can you clarify this for me a bit, Gisele? What is the most
>logical conclusion here, in your view?

If I have to explain it, maybe it isn't so logical? :-) Geneticists
maintain that there is continuity in the mtDNA sequences of past and
present Native Americans but physical anthropologists recognize
differences between early and later crania. If both are right, then
1) the physical differences must be due to admixing which occurred
within the New World and 2) admixture must adversely affect physical
anthroplogist's abilities to connect past and present Native
Americans. Solution: compare the Paleoindian crania to those of an
Old World population which displays little evidence of admixture (in
their mtDNA sequences at least) and who is genetically related to 1/4
of Native Americans hence Polynesians (93% haplogroup B) to determine
what the earliest harborers of haplogroup B sequences looked like (if
contemporaneous measurements are not available).

Longer Explanation:

All non African mtDNA sequences cluster into 2 groups - M & N.

Haplogroup cluster M contains the majority of the Asian sequences
(Asian C, D, E, G, M7, M8, M9, M10, Z, Melanesian Q, some Australian
haplogroups, many Asian Indian haplogroups, etc.). New World
haplogroups C & D belong to this cluster.

Haplogroup cluster N has also been divided into 2 groups:

1. Group R - the majority of the European haplogroups, Asian F,
Asian/Polynesian/Micronesian/New World B, Melanesian P and many of the
Australian sequences which can be typed thus far.

2. Remainder of N (phylogenetically precedes R) - Asian/New World A,
haplogroup X, Europe & area I, W & N1, Asian N9, Ainu/Nivkhi Y and
several Australian aborigine types of sequences.

In my last count, 37% of Native Americans had haplogroup A sequences,
23% had haplogroup B, 1% - haplogroup X, 18% - haplogroup C, 18% -
haplogroup D and 3% "other" (probably recent admixture that I should
have excluded). 61% of their sequences, therefore, currently belong
to group N and 36% to group M. At the time that the haplogroups
diverged from each group, what *should* the harborers of each type of
sequence looked like? We will probably never know but based upon the
locations of the related haplogroups, we can probably summon up some
type of hazy picture. How closely does this "hazy picture" resemble
physical anthropologists' descriptions of Paleoindians?

"The Paleoindian samples from North and South America are quite
distinct (with a few exceptions) from late Holocene American Indian
populations. Paleoindians appear as multivariate outliers in our
analyses, and fall closer to the regional centroid of Polynesian and
even Australian populations than to modern American or northeast Asian
populations." (Powell & Neves, 1999)

"The first entrants to the Western Hemisphere of maybe 15,000 years
ago gave rise to the continuing native inhabitants south of the
U.S.-Canadian border. These show no close association with any known
mainland Asian population. Instead they show ties to the Ainu of
Hokkaido and their Jomon predecessors in prehistoric Japan and to the
Polynesians of remote Oceania" (Brace, 2001)

"These [11] crania [Spirit Cave,Wizards Beach, Browns Valley, Pelican
Rapids, Prospect, Wet Gravel male, Wet Gravel female, Medicine
Crow,Turin, Lime Creek, and Swanson Lake] were also compared to
Howells’ worldwide recent sample, which was expanded by including six
additional American Indian samples. None of the fossils, except for
the Wet Gravel male, shows any particular affinity to recent Native
Americans; their greatest similarities are with Europe, Polynesia, or
East Asia." (Jantz & Owsley, 2001)

"While in North America the early human remains are, in general, but
not exclusively, more similar to South Asians, Ainu/ Polynesians or
Europeans (Steele and Powell, 1992, 1994, 1999; Chatters et al., 1999;
Brace et al., 2001; Jantz and Owsley, 2001), in South America they are
closer to Australians and sub-Saharan Africans (Neves and Pucciarelli,
1989, 1990, 1991; Munford et al., 1995; Neves et al., 1998, 1999a,b)."
(Neves et al., 2003)

>> Haplogroup B was often described as if it was a northern Asian
>> haplogroup. Haplogroup A still is ...
>
>But both of these haplogroups have a much wider
>distribution, right?

Yes. With regards to haplogroup A - in nearly every corner of
Asia, this haplogroup has been described by someone as admixture -
even in Central Asia (where Native Americans have often been traced
back to):

Proc. R. Soc. Lond. B (2004) 271, 941-947
Unravelling migrations in the steppe: mitochondrial
DNA sequences from ancient Central Asians
C. Lalueza-Fox1,2*, M. L. Sampietro2, M. T. P. Gilbert3†, L. Castri4,
F. Facchini4, D. Pettener4 and J. Bertranpetit2

at least one haplogroup A sequence was described as resembling one
obtained from a Chukchi and, therefore, the authors concluded:

"In addition, the presence of a haplogroup A sequence found
in Siberia (Starikovskaya et al. 1998) and a G2 sequence
found in Chinese Han (Yao et al. 2002) points to Siberia
and Mongolia as a possible source of such migrations."

The Chukchi haplogroup A sequences, however, can be traced back to the
New World.... I'm still working on it. Certain central or southern
Chinese Tibeto-Burmese populations have much higher frequencies of
these sequences than most Siberian.

Gisele

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