If you plot various anthropometric (especially osteological and craniological) measurements of samples of human populations, you will find that Native Americans, Mongols, and indigenous North Asians occupy one extreme of the range of measurements. This is how races were defined in the first place.
No, it is not. Actually, it is the most likely of all. 
You shouldn't even need me to explain why, but I guess I'll have to give you a summary:
*Eastern Eurasians and Native Americans are closely related according to their physical anthropological characteristics
*Eastern Eurasians and Native Americans are closely related according to their autosomal genetic characteristics
*Eastern Eurasians and Native Americans are closely related according to their mitochondrial DNA
*Eastern Eurasians and Native Americans are not closely related according to the Y-chromosomal DNA of many of them, but some of them do share haplogroup C3-M217
What is the simplest explanation for these observations? You decide.
Native Americans do have haplogroup C in the form of its subclade, C3-M217, which they share with North Asians, East Asians, and Central Asians.
It is not really subjective. As I said before, if you graph various measurements of populations around the world and look at the results, you will find that North Asians and indigenous peoples of the Americas occupy one extreme in most of the graphs. In other words, they are the "most distinctive" or "most divergent" groups in regard to these traits; therefore, they are the most "Mongoloid" (or whatever name you want to choose as a label for that set of anthropometric values and ranges).
The haplogroup C found in Oceania consists mainly of two subclades: haplogroup C2 in Central-Eastern Malayo-Polynesian peoples, and haplogroup C4 in indigenous Australian peoples. These two subclades are not necessarily closely related to each other, nor are they necessarily closely related to the haplogroup C subclades that are found in Asian and American populations.
Haplogroup C is currently placed next to haplogroup F as a branch of haplogroup CF. Haplogroup C's subclades are limited to Mongoloid and Australoid populations. Its subclade C3-M217 is, in particular, shared among North Asians, Native Americans, Central Asians, East Asians, and some Southeast Asians, reflecting the relatively recent genetic links that exist among these populations.
Haplogroup O is ultimately a branch of haplogroup F, nearly all of whose subclades are found exclusively or most commonly in Caucasoid populations.
The fact of the matter is that it is much more likely that haplogroup C3 (and perhaps some other subclades of haplogroup C) should be "originally Mongoloid" than that a terminal branch of haplogroup F should be. If haplogroup O is so ancient and "originally Mongoloid," then why is it not found in the most extreme representatives of Mongoloid traits, i.e. indigenous Siberians and Americans?
O is the most common male Y chromosome in Asia.
Q and C are about the same age and they or branches are found in North
East Asia and also in the Americas.
First lets clear something up.
Terms like Mongoloid, I use for the sake of easy discussion but if you are
going to try to talk about "extreme Mongoloid", "True Mongoloid" etc.
These terms are defunct and no longer used by most anthropological
institutions or geneticists. These terms started going out of use about
15 years ago, at least in most of Western Europe and the U.S./Canada...
http://en.wikipedia.org/wiki/Caucasian_race#cite_note-17
http://en.wikipedia.org/wiki/Caucasian_race#cite_note-11
http://en.wikipedia.org/wiki/Caucasian_race#cite_note-10
The United States National Library of Medicine:
Other Notable MeSH Changes and Related Impact on Searching: Ethnic
Groups and Geographic Origins". NLM Technical Bulletin 335 (Nov-Dec).
2003.
http://www.nlm.nih.gov/pubs/techbull/nd03/...ta_changes.html. "The
MeSH term Racial Stocks and its four children (Australoid Race, Caucasoid
Race, Mongoloid Race, and Negroid Race) have been deleted from MeSH in
2004. A new heading, Continental Population Groups, has been created with
new indentions that emphasize geography.".
These type of things were based on measurements of "scientist" like Coon
who and his predecessors who were often trying to prove the innate
physical superiority of the "Aryan Race". For example, it was believed in
the 1800's that "Mongoloids" evolved from Orangutans and were not even
related to people in Europe or Africa but from some distant early ape-like
primate. This was not science as we know it today.
Humans exist in clines. Even in regions with great deserts /moutains/and
waterways there was often still gene flow and intermediate populations,
although they were so small it limited gene flow in such a way as to
maintain stronger phenotypical appearance on each side of the divide.
There has never existed a "pure Mongoloid".
As far as Native Americans...it is not true they represent "extreme
Mongonloid" features.
That is false.
Coon and others felt the most extreme Mongoloid features were in the
Tungustic and Northeast Asia in people like these:

The earliest Native Americans did not look like that.
They looked like Kinwick man, who looked like Ainu/Jomon, and more
distantly Austronesian.

It is likely when these type of people came to the americans, 20,000 years
ago the extreme phenotype we seen in Northeast Asia today did not exist,
if they did, they had no yet made it to that area of Asia (just like Yayoi
did not exist and Jomon lived all over Japan).
These people are usually considered "proto-Mongoloid" as they have some
proto-Caucasoid features as well.
I have said over and over again we can not look at Haplogroups and
origin and always attribute present phenotype to people who lived in the
past with those Haplogroups. That assumes evolution through natural
selection and genetic bottlenecks, intermarriage that lead to new gene
introduction, etc ALL STOPPED. IT DID NOT. Humans have never been
stagnant...we are not genetic deadends (no population).
A good example...Kets look like this and they are predominately (like over
70%) Q Y chromosone:
[img]http://upload.wikimedia.org/wikipedia/commons/9/91/Ket_shaman_1914.pn
g[/img
The vast majority of Native Americans look nothing like that.
They look like this:
Iraquois
[img]http://www.wheretheyplaygames.com/images/people01.jpg[/img]
Amazonian Indian
[img]http://www.publicanthropology.org/images/Faces/Yanomami%20portrait8(girl).jpg[/img]
Lakota
[img]http://www.buffalosoldier.net/Chief%20Victorio%20aka%20Apache%20Wolf.jpg[/img]
Shawnee
[img]http://www.rootsweb.ancestry.com/~ohgreene/Images/218.jpg[/img]
Mayan
[img]http://w0sd.com/mexico2004/0027.jpg[/img]
They obviously don't look like Kinwick men, Ainu,or Kets.
Some of them likely have C and Q though, no doubt.
In any case it is highly unlikely that people who originated from proto-Mongoloids (Native Americans/Amerids) represented what you are referring to as "extreme Mongoloids".
The "Mongoloid" phenotype did not exist in the Americans to our knowledge 20,000 years ago and likely did not exist in much of East Asia.
It was probably still evolving as it moved West into East Asia from Central Asia/Eurasian Steppes.
The people who look the most like "extreme Mongoloids" that live in large numbers are Tungustic and people who live South of them.
We know (or it is believed, even by many Chinese anthropologist) Han came out of North West China, near the foothills near Tibet and spread into East Asia...it is likely they were not alone in this migration or did not come first (possibly proceeded by proto-Turkic and Tugustic Altaic speakers into East Asia), but had the phenotype we consider "Mongoloid".
It is not shocking there is no firm lingustic connection between any Native American language (even Inuit whose ancestors were thought to have come from Asia last) and East Asian languages, only speculation, well but for people like Kets...but Kets are thought to be a member of the na-Dene language Supergroup, but that group doesn't extend far outside of Canada and Alaska but some isolated regions in the American Southwest, in groups like the Navajo and Apache, but this is still considered controversial.
Other languages like Ainu are isolates and so far removed from anyone...no one will likely ever know there connection. I would imagine most of the proto-Mongoloid type were absorbed or killed off and were likely never large in population to begin with because they were hunter gathers who live in low population density and are nomadic...
MtDNA is interesting in that...of
A, B, C, D, and X, only the last is associated with East Asia.
The others are
direct descendants from N (sometimes through R), which is 50,000 years old and thought to have evolved in the Middle East or Central Asia and are not found at all or only in trace amounts in East Asia.
In any case, much of that is neither here nor there.
First we have to consider that "Mongoloids" actually existed as a "distinct grouping".
Most people today (expert associations) say they do not and never have.
Even if we say they do, the most "extreme phenotypical cline" is not Native Americans or other "proto Mongoloids"... the idea it is proto, links directly to the features being pre-Mongoloid, therefore some mix of Caucasiod and Mongoloid.
That is not called "extreme" it is called "intermediate".
Native Americans are clearly derived from an Asian population with affinities to the Mongoloids.[18] However, Native Americans retain certain non-Mongoloid features.[18] These might represent the genetic legacy of a pre-Mongoloid, Australoid-Caucasoid population, swamped by a later Mongoloid immigration;[18] more likely, they reflect the broad range of physical variation found in early northern Asian populations, before Mongoloid traits became predominant."
http://en.wikipedia.org/wiki/Mongoloid_race#Native_Americans
The physical features of the "Proto-Mongoloid" were characterized as, "a straight-haired type, medium in complexion, jaw protrusion, nose-breadth, and inclining probably to round-headedness".[41] Kanzō Umehara considers the Ainu and Ryukyuans to have "preserved their proto-Mongoloid traits". [42]
http://en.wikipedia.org/wiki/Mongoloid_race#Proto_Mongoloids
Edited by LongMa, 10 December 2008 - 09:22 AM.