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Angela
15-05-14, 23:48
I just saw this on my feed...
Late Pleistocene Human Skeleton and mtDNA Link Paleoamericans and Modern Native Americans Because of differences in craniofacial morphology and dentition between the earliest American skeletons and modern Native Americans, separate origins have been postulated for them, despite genetic evidence to the contrary. We describe a near-complete human skeleton with an intact cranium and preserved DNA found with extinct fauna in a submerged cave on Mexico’s Yucatan Peninsula. This skeleton dates to between 13,000 and 12,000 calendar years ago and has Paleoamerican craniofacial characteristics and a Beringian-derived mitochondrial DNA (mtDNA) haplogroup (D1). Thus, the differences between Paleoamericans and Native Americans probably resulted from in situ evolution rather than separate ancestry.


http://www.sciencemag.org/content/344/6185/750
The full text isn't there.

See also:
http://www.bbc.com/news/science-environment-27432234

Fire Haired14
16-05-14, 03:36
There are other ancient north American mtDNA and Y DNA samples(some even pre-clovis), which prove early Americans are the ancestors of modern Americans. Amerindians are a very distinct and uniform people genetically, there is no doubt in my mind all of their genetic markers are descended of pre-clovis Americans.

LeBrok
16-05-14, 04:55
It will be a great study case, how much genom can "float"/mutate away from the source in 12 thousand years, without third party admixtures, when compared to current Native Americans.

bicicleur
16-05-14, 17:41
It will be a great study case, how much genom can "float"/mutate away from the source in 12 thousand years, without third party admixtures, when compared to current Native Americans.

I agree, this is interesting.

And I see allready some comments about backmigrations from America to Siberia or mixing with later migratons from Siberia to America.
I don't beleive in all this.
The Saqqaq, Inuits, Yupiks etc. who stayed around Bering Strait for the last 8000 years or so ago are from different clades than the Native Americans, they never mixed with them.

bicicleur
16-05-14, 17:42
There are other ancient north American mtDNA and Y DNA samples(some even pre-clovis), which prove early Americans are the ancestors of modern Americans. Amerindians are a very distinct and uniform people genetically, there is no doubt in my mind all of their genetic markers are descended of pre-clovis Americans.

do you have a list of those?

Angela
16-05-14, 18:16
It will be a great study case, how much genom can "float"/mutate away from the source in 12 thousand years, without third party admixtures, when compared to current Native Americans.


It's also quite interesting how much the phenotype has changed in those 12,000 years without any additional gene flow (although some did reach the most northernmost areas, I think).

I'm not sure if this is a direct quote from the paper, but...

"They have longer, narrower crania than later Native Americans, and smaller, shorter faces, too - more closely resembling modern peoples of Africa, Australia, and the Southern Pacific Rim."

ebAmerican
16-05-14, 21:45
The continuity angle is stretching it. There are five mtDNA groups found in the Americas A, B, C, D, and X. D is the oldest mtDNA which is probably Clovis (D1) and the other's are probably later migrations. This would explain the phenotype differences in Paleo-Amerindians compared to modern Amerindians. D1 could be a remnant of the Clovis migration in modern Amerindians. There are some pheno-characteristics that sexual selection could attest, but Paleo-Amerindians being Sinodonty and some pre-Columbian Mesoamericans being Sundadonty in their dental patterns is not one of them. If there were continuity wouldn't we see only Sinodonty and possibly something else, and not the other Asian dental characteristic of the Jamon and Indonesians? It is more accurate to say that multiple migrations and mixed ancestry led to phenotypes of modern Amerindians, then to say that it was in situ.

Aberdeen
16-05-14, 22:03
The continuity angle is stretching it. There are five mtDNA groups found in the Americas A, B, C, D, and X. D is the oldest mtDNA which is probably Clovis (D1) and the other's are probably later migrations. This would explain the phenotype differences in Paleo-Amerindians compared to modern Amerindians. D1 could be a remnant of the Clovis migration in modern Amerindians. There are some pheno-characteristics that sexual selection could attest, but Paleo-Amerindians being Sinodonty and some pre-Columbian Mesoamericans being Sundadonty in their dental patterns is not one of them. If there were continuity wouldn't we see only Sinodonty and possibly something else, and not the other Asian dental characteristic of the Jamon and Indonesians? It is more accurate to say that multiple migrations and mixed ancestry led to phenotypes of modern Amerindians, then to say that it was in situ.

I agree, but I think there's a desire to argue for continuity in order to shut up folks with strange theories about Europeans preceding Native Americans to the Americas. But one doesn't need to argue that there could only have been one migration from Siberia 15 thousand years or more in the past in order to debunk such ideas. All the major inflow that can be measured in terms of mtDNA appears to have arrived from Siberia, and the most recent Siberian migration would still have happened a few thousand years ago.

Fire Haired14
17-05-14, 00:49
The continuity angle is stretching it. There are five mtDNA groups found in the Americas A, B, C, D, and X. D is the oldest mtDNA which is probably Clovis (D1) and the other's are probably later migrations. This would explain the phenotype differences in Paleo-Amerindians compared to modern Amerindians. D1 could be a remnant of the Clovis migration in modern Amerindians. There are some pheno-characteristics that sexual selection could attest, but Paleo-Amerindians being Sinodonty and some pre-Columbian Mesoamericans being Sundadonty in their dental patterns is not one of them. If there were continuity wouldn't we see only Sinodonty and possibly something else, and not the other Asian dental characteristic of the Jamon and Indonesians? It is more accurate to say that multiple migrations and mixed ancestry led to phenotypes of modern Amerindians, then to say that it was in situ.

D1 is found throughout north and south America, plenty of mtDNA and two Y DNA samples have been taken of ancient Americans some even older than the one from this study and all have native American-specific haplogroups, Ameridians are a unfirom population(North or south doesn't matter), and that a genome of a Clovis individual can be defined as an Amerindian(no differnt from modern ones). So, Ameridian's ancestors probably arrived in north America admixed.

There are obvious phenotype differences with modern Ameridian people, and i think the PalaeoAmericans difference with modern ones is exaggerated.

Sile
17-05-14, 01:02
D1 is found throughout north and south America, plenty of mtDNA and two Y DNA samples have been taken of ancient Americans some even older than the one from this study and all have native American-specific haplogroups, Ameridians are a unfirom population(North or south doesn't matter), and that a genome of a Clovis individual can be defined as an Amerindian(no differnt from modern ones). So, Ameridian's ancestors probably arrived in north America admixed.

There are obvious phenotype differences with modern Ameridian people, and i think the PalaeoAmericans difference with modern ones is exaggerated.

but how old is D1 ?

Fire Haired14
17-05-14, 01:11
This study from 2008 (http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0001764) estimated D1 to be 18.6±2.3 ky years old. mtDNA haplogroups that take up the vast majority of modern Ameridian mtDNA were all estimated to be 18,000-21,000 years old, and are exclusive to Ameridians, which is evidence of their ancestors arrived admixed around that time.

Aberdeen
17-05-14, 15:13
This study from 2008 (http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0001764) estimated D1 to be 18.6±2.3 ky years old. mtDNA haplogroups that take up the vast majority of modern Ameridian mtDNA were all estimated to be 18,000-21,000 years old, and are exclusive to Ameridians, which is evidence of their ancestors arrived admixed around that time.

That's an over-simplification. Although most Native Americans have an mtDNA subclade unique to the Americas, D2 is a specifically Inuit and Aleut subclade in the Americas and is also found in Siberia. Although C* is found in northwestern South America, subclades C1b, C1c, C1d and C4c are found in North America (mostly in the northern and western part) and not in South America, suggesting that they represent a late entry into the Americas. Subclade X2a is not found in South America, and in fact is found mainly among a few North American tribes, mainly Dene and Ojibwe, where it's often a very common haplotype. To me, this definitely suggests a late entry into the Americas. To say that these are minority haplotypes ignores the fact that they're frequent in the limited areas in which they're found. Some geneticists estimate that the Dene are descended from people who arrived in North America only about 8000 years (and I think that applies to the Ojibwe as well), and that's long after the original colonization of the Americas from Siberia. And the Inuit appear to be mostly descended from people who only arrived in North America about 4000 years ago, with the Thule component being in the Americas perhaps only about 1000 years. So, while the mtDNA from the bulk of Native Americans indicate an arrival date probably prior to 15000 years BP, that's not the whole story.

Fire Haired14
17-05-14, 16:05
Aber, i never said northern native Americans who look very east Asian also descend 100% from the Clovis people. mtDNA C1 is found throughout North and south America, so your wrong saying it is exclusive to a specific region. C4c and X2a may be from other migrations since they are not found in all Ameridians, but besides them pretty much 100% of Ameridian mtDNA no matter where you go north or south falls under the same mtDNA clades. Autosomal DNA and Y DNA tell the same story, Ameridians are a very uniform population.

Your argument for D1 being from earlier migrations is incorrect, and i don't understand why you are pushing diversity in Ameridians so much.

Aberdeen
17-05-14, 18:28
Aber, i never said northern native Americans who look very east Asian also descend 100% from the Clovis people. mtDNA C1 is found throughout North and south America, so your wrong saying it is exclusive to a specific region. C4c and X2a may be from other migrations since they are not found in all Ameridians, but besides them pretty much 100% of Ameridian mtDNA no matter where you go north or south falls under the same mtDNA clades. Autosomal DNA and Y DNA tell the same story, Ameridians are a very uniform population.

Your argument for D1 being from earlier migrations is incorrect, and i don't understand why you are pushing diversity in Ameridians so much.

Fi, you're wrong, as usual. Bisso-Machado et al (2012) reported that all C among South American populations is C*. And no, Amerindians are not a very uniform population and no, it isn't true that pretty much 100% of Ameridian (?) mtDNA no matter where you go north or south falls under the same mtDNA clades. There are important regional differences, and the most important one is that X2 makes up close to 25% of Algonquin/Ojibwe mtDNA but it's completely absent from South American populations.

I'm not pushing diversity, I'm explaining the facts. The two major population movements into the Americas after the initial settlement pretty much impacted only North America, but the impact is noticeable and important. However, it's not as if these groups arrived in the Americas recently (unless you count the Thule portion of Inuit DNA, which probably arrived 1000 or less years ago). And although X2 is the only major Amerindian mtDNA not strongly associated with east Asia, it has been found at low levels in Siberia, so I still think a Siberian explanation is the most probable one for X2. But if it had arrived with the original founding population, we could expect to find it all over the Americas, and that's not the case.