We too easily forget that modern east asians are all local varients
that had population booms because of really good luck and local
agricultural success. The bad news is that all our speculation
regarding an european influx in the last three thousand years has
just become more speculatative. All such overlays were ultimately
onto a first population that likely is best described as Ice Age
steppe eurasian from which sucessor populations arose including
european, chinese and all other asian tribal groups that may be
identified.
We still have cultural sources and better DNA resolution to attend
to, but reading much into the european component found in Native DNA
is seriously premature.
We do have extended evidence of an Ice Age hunting population that
spread worldwide including the Americas with major hybridization and
likely coastal populations on the continental shelf to interact with.
The survivors of the Pleisrtocene Nonconformity then rebounded and
were then overlain by deliberately implanted colonies of
agriculturists with which they traded and intermarried.
I think that this working conjecture holds up well and remains an
ongoing source of stress as the non agriculturalists appear to remain
resistent. Intermarriage has diluted that tenency but we need to
discover any DNA linkage in particular.
"Great
Surprise"—Native Americans Have West Eurasian Origins
Oldest human genome
reveals less of an East Asian ancestry than thought.
Brian Handwerk
National Geographic
PUBLISHED NOVEMBER 20,
2013
Nearly one-third of
Native American genes come from west Eurasian people linked to the
Middle East and Europe, rather than entirely from East
Asians as previously thought, according to a newly sequenced genome.
Based on the arm
bone of a 24,000-year-old Siberian youth, the research
could uncover new origins for America's indigenous peoples, as well
as stir up fresh debate on Native American identities, experts say.
The study authors
believe the new study could also help resolve some long-standing
puzzles on the peopling of the New World, which include genetic
oddities and archaeological inconsistencies. (Explore an atlas
of the human journey.)
"These results
were a great surprise to us," said study co-author and
ancient-DNA specialist Eske Willerslev, of the University of
Copenhagen, Denmark.
"I hadn't
expected anything like this. A genome related to present-day western
Eurasian populations and modern Native Americans as well was really
puzzling in the beginning. How could this happen?"
So what's new?
The arm bone of a
three-year-old boy from the Mal'ta site near the shores of Lake
Baikal in south-central Siberia (map) yielded what may be the
oldest genome of modern humans ever sequenced.
DNA from the
remains revealed genes found today in western Eurasians in the Middle
East and Europe, as well as other aspects unique to Native Americans,
but no evidence of any relation to modern East Asians. (Related: "Is
This Russian Landscape the Birthplace of Native Americans?")
A second individual
genome sequenced from material found at the site and dated to 17,000
years ago revealed a similar genetic structure.
It also provided
evidence that humans occupied this region of Siberia throughout the
entire brutally cold period of the Last Glacial Maximum, which ended
about 13,000 years ago.
Why is it important?
Prevailing theories
suggest that Native Americans are descended from a group of East
Asians who crossed the Bering Sea via a land bridge perhaps 16,500
years ago, though some sites may evidence an earlier arrival. (See
"Siberian, Native American Languages Linked—A First [2008].")
"This study
changes this idea because it shows that a significant minority of
Native American ancestry actually derives not from East Asia but from
a people related to present-day western Eurasians," Willerslev
said.
"It's
approximately one-third of the genome, and that is a lot," he
added. "So in that regard I think it's changing quite a bit of
the history."
While the land bridge
still formed the gateway to America, the study now portrays Native
Americans as a group derived from the meeting of two different
populations, one ancestral to East Asians and the other related to
western Eurasians, explained Willerslev, whose research was published
in the November 20 edition of the journal Nature.
"The meeting of
those two groups is what formed Native Americans as we know them."
(Learn more about National Geographic's Genographic Project.)
What does this mean?
Willerslev believes
the discovery provides simpler and more likely explanations to
long-standing controversies related to the peopling of the Americas.
"Although we know
that North Americans are related to East Asians, it's striking that
no contemporary East Asian populations really resemble Native
Americans," he said.
"It's not like
you can say that they are really closely related to Japanese,
Chinese, or Koreans, so there seems to be something missing. But this
result makes a lot of sense regarding why they don't fit so well
genetically with contemporary East Asians—because one-third of
their genome is derived from another population."
The findings could
also allow reinterpretation of archaeological and anthropological
evidence, like the famed Kennewick Man, whose remains don't look
much like modern-day Native American or East Asian populations,
according to some interpretations.
"Maybe, if he
looks like something else, it's because a third of his ancestry isn't
coming from East Asia but from something like the western Eurasians."
(Read about history's great migration mysteries.)
What's next?
Many questions remain
unanswered, including where and when the mixing of west Eurasian and
East Asian populations occurred.
"It could have
been somewhere in Siberia or potentially in the New World,"
Willerslev said.
"I think it's
much more likely that it occurred in the Old World. But the only way
to address that question would be to sequence more ancient skeletons
of Native Americans and also Siberians."
Intriguing questions
also exist about the nature of the advanced Upper Paleolithic Mal'ta
society that now appears to figure in Native American genomes.
The Siberian child
"was found buried with all kinds of cultural items, including
Venus figurines, which have been found from Lake Baikal west all the
way to Europe.
"So now we know
that the individual represented with this culture is a western
Eurasian, even though he was found very far east. It's an interesting
question how closely related this individual might have been to the
individuals carving these figurines at the same time in Europe and
elsewhere."
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