genetic facts [was: Ashby, botanical facts

Ross Clark drc at antnov1.auckland.ac.nz
Mon Oct 19 23:15:38 EST 1998


Bernard Ortiz de Montellano wrote:
> 
> > Peter Ashby (p-ashby at nimr.MAPS.mrc.ac.uk) wrote on 5 Oct 1998 21:03:48 GMT:
> >
> {Yuri said}
> > Rebecca L. Cann and J.K. Lum are the scholars who are supporting
> > Polynesian -- American links recently based on DNA. They have studied the
> > DNA of living Pacific populations and compared their findings to the DNA
> > of native Americans. They found that several mitochondrial DNA lineages
> > occur both in the Pacific area and among Amerindians.
> >
> > Bonatto et al. actually AGREE with Cann & Lum on this. So this is very
> > significant.
> 
> Yuri, I can make no judgement from this. References please. Title,
> Journal, date, volume, page number.
> 
> >
> > And thus, your game is up, Peter. Certainly the latest DNA finding cannot
> > be seen as contradicting Heyerdahl. Supporting him is more like it.
> 
> Yet again you demonstrate your fundamental misuderstanding of the nature
> of evidence and proof. You even admit yourself that they can be
> interpreted in more than one way. I really am almost ready to give up on
> you. I originally entered this debate because you cross posted to
> soc.culture.new-zealand and your use of science was so appalling I
> couldn't let it pass. I thought (naivly) that I could point out the error
> of your ways and improve your reasoning. It is obvious that my mission has
> been doomed from the start. There are none so blind as them who will not
> see.
> 
> Yours pessimistically
> 
> Dr. Peter Ashby
> 
> Peter,
> 
> Obviously Yuri did not want to give you a cite. I finally got connected
> again with a library.:
> 
> J. Lum, R.L. Cann, J.J. Martinson, and L.B. Jorde. 1998. ³Mitochondrial
> and Nuclear Relationships among Pacific Island and Asian Populations²
> *American Journal of Hman Genetics* 63:613-624.
> 
> The bottom line is that both mt-DNA and STR data support an Asian origin
> for Pacific Island (including Rapa Nui) populations. The end of the
> abstract says: ³These results are consistent with an initial settlement of
> Remote Oceania from island Southeast Asia [New Guinea, Australia] and with
> extensive postcolonization male-biased gene flow from Near Oceania.²
> 
> As usual it is always nice to read the original source rather than
> someone¹s tendentious summary. There is no evidence that Cann supports
> Amerindian migration to Oceania. What is needed is a direct quote to that
> effect from Cann.
> 
> --
> Bernard Ortiz de Montellano


Thanks for the more recent reference, Bernard. I've had a chance to look 
at a couple of the papers referred to earlier, and I thought I'd add some 
quotes since Yuri is now talking as if this research "supports 
Heyerdahl".

J.Koh Lum, Olga Rickards, Clara Ching and Rebecca L.Cann, Polynesian 
mitochondrial DNAs reveal three deep maternal lineage clusters. Human 
Biology, August 1994, vol.66, no.4, pp.567-590.

[From the Abstract] Major Group I lineages are common in Remote Oceania 
and include about 95% of the Native Hawaiians, 90% of the Samoan, and 
100% of the Tongan donors in our sample...This group also contains 
non-Polynesian individuals, such as Indonesians, Native Americans, 
Micronesians, Malaysians, Japanese and Chinese....Group II individuals 
are seen at low frequency (<10%) in Hawaii, Samoa and the Cook Islands 
and may represent the predominant maternal lineage group of Papuan 
Melanesia. Major lineage group III, not found in Hawaii, tentatively 
links Samoa to Indonesia. Our observation of deep maternal genetic 
branches in Polynesia today confirms the notion that during the 
colonization of the Pacific, mainland Asian immigrants mixed with 
Melanesian peoples already inhabiting Near Oceania and carried a complex 
assortment of maternal genotypes derived from two distinct geographic 
sources to isolated island archipelagoes.

[And an interesting passage from the text:]

Finally, the South American sweet potato is found throughout Polynesia, 
raising the question of two-way voyaging from Polynesia or drift voyaging 
from the west coast of South America.... The presence of flotsam from 
North America in Polynesia and demonstration rafting from South America 
indicate that some limited contact may have been possible between eastern 
Polynesia and the Americas. Currently, there is a lack of compelling 
evidence from archeology, linguistics, or genetics that supports this 
idea. (582)

J.Koh Lum and Rebecca L.Cann, mtDNA and language support a common origin 
of Micronesians and Polynesians in Island Southeast Asia. Am.J. Phys. 
Anthro. 105:109-119 (1998)

We interpret these results as support of a rapid colonization of Remote 
Oceania by a closely related group of Austronesian-speaking populations 
from Island Southeast Asia. Following this initial settlement extensive 
gene flow occurred between these recent migrants and neighboring people 
from Island Southeast Asia and Papuan speaking Melanesians without major 
impact on the established linguistic relationships. (117)


Sandro L.Bonatto, Allan J.Redd, Francisco M.Salzano and Mark Stoneking, 
Lack of ancient Polynesian-Amerindian contact, Am.J.Hum.Genet. 59:253-256 
(1996).

Therefore, all the shared sequences between Polynesians and Amerindians 
are much more likely explained as a retention of ancestral Asian 
sequences by both descendant populations than by an ancestral or recent 
post-divergence admixture.
...
In conclusion, the presence of the B lineage and the matching of three 
other sequences between Polynesians and Amerindians probably reflect a 
shared Asian origin rather than direct contact. Nevertheless, these 
results do not rule out the possibilities of still-undetected minor 
contact and nonmaternal genetic exchange. (255)

R.L.Cann and J.K.Lum, Mitochondrial myopia: Reply to Bonatto et al. 
Am.J.Hum.Genet. 59:256-258 (1996)

...the question of whether there was limited gene flow between Native 
Americans and Oceanic populations is unresolved. Rather than make 
dogmatic statements, we feel that it is better to encourage the open 
exploration of this debate, with more genetic markers and the use of data 
already in the literature. (258)

-------------------------------------------

To sum up what Cann & Lum and the other researchers seem to be saying: 
- The mtDNA studies support the conventional view of Polynesians as 
coming from SE Asia with some Melanesian genetic input. 
- Connections between Polynesian and Amerindian groups most likely 
reflect their common Asian origin rather than recent contact.
- The possibility of more recent contact cannot be absolutely ruled out, 
but at the moment it is not clearly supported by any positive evidence.

Ross Clark



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