Re: Americas Settled 15,000 Years Ago, Study Says

On Mar 14, 12:45 pm, Peter Alaca <p.al...@xxxxxxxxxxxxxx> wrote:
Jack Linthicum wrote: on, 14/03/2008 16:00:
On Mar 14, 8:41 am, Peter Alaca <p.al...@xxxxxxxxxxxxxx> wrote:
Jack Linthicum wrote: on, 14/03/2008 13:21:
On Mar 14, 8:00 am, Peter Alaca <p.al...@xxxxxxxxxxxxxx> wrote:
Jack Linthicum wrote: on, 14/03/2008 11:29:
Article from National Geographic with a series of contradictory
statements which the article doesn't seem to resolve.
Example: "And there are several possible reasons other than ice why
people did not venture south earlier, including a "ferocious army of
predators" living in North America that might have had a role in
keeping humans away."
This statement would imply that the humans encountered the "ferocious
army of predators" which would seem to say that they got down quite
far into North America at least.
Americas Settled 15,000 Years Ago, Study Says
Stefan Lovgren
for National Geographic News
March 13, 2008
A consensus is emerging in the highly contentious debate over the
colonization of the Americas, according to a study that says the bulk
of the region wasn't settled until as late as 15,000 years ago.
Researchers analyzed both archaeological and genetic evidence from
several dozen sites throughout the Americas and eastern Asia for the
paper.
"In the past archaeologists haven't paid too much attention to
molecular genetic evidence," said lead author Ted Goebel, an
archaeologist at Texas A&M University in College Station.
"We have brought together two different fields of science, and it
looks like they are coming up with the same set of answers."
The article, which is published in tomorrow's issue of the journal
Science, shows that the first Americans came from a single Siberian
population and ventured across the Bering land bridge connecting Asia
and North America about 22,000 years ago.
The group got stuck in Alaska because of glacial ice, however, so
humans probably didn't migrate down intRo the rest of the Americas
until after 16,500 years ago, when an ice-free corridor in Canada
opened up.
Clovis Not First
Scientists have long agreed that the first Americans came from
northeast Asia, according to Goebel.
But the new article--which analyzed genetic and archaeological evidence
from 43 sites, including a dozen sites in Asia--better pins down the
makeup of the first Americans.
Genetic evidence, for instance, points to a founding population of
less than 5,000 individuals.
Some geneticists had also previously suggested that the migration
across the land bridge could have occurred as early as 30,000 years
ago.
"Now there seems to be consensus among those studying mitochondrial
DNA and [chromosome records] of modern native Americans that it
happened pretty late, after the last glacial maximum, maybe as late as
15,000 calendar years ago," Goebel said.
Meanwhile, archaeologists for years had considered sites belonging to
the so-called Clovis culture, which dates back 13,000 years, to
represent evidence of the first Americans.
The Clovis culture was named after flint spearheads found in the 1930s
at a site in Clovis, New Mexico. Clovis sites have been identified
throughout the contiguous United States as well as in Mexico and
Central America.
But several sites, from Wisconsin to Monte Verde in Chile, have been
discovered in recent years that predate Clovis by at least a thousand
years.
"There probably has to have been some time before Clovis in which
people were here, but they didn't leave much of a record behind
because there just weren't that many people," Goebel said.
Coastal Route
Archaeological evidence shows that there were people occupying the
Asian side of the Bering land bridge area as early as 30,000 years
ago.
"That tells us that once early modern humans spread out of Africa
around 50,000 years ago and colonized temperate Eurasia, it wasn't
very long before they had developed the technology and the skills
needed to be able to make a go of it in the Arctic," Goebel said.
Modern humans spread across the land bridge about 22,000 years ago,
according to the new article.
But then the group got stuck for up to 5,000 years, blocked by thick
ice sheets across Canada.
It was only when the ice had melted sufficiently that humans began to
spread south, either along the coast or though an interior corridor in
western Canada, the authors say.
"That might have been the bottleneck that kept people from draining
south from Alaska into temperate North America," said Goebel, adding
that geological evidence suggests the Pacific coastal corridor would
have become ice-free perhaps as early as a thousand years before the
interior corridor.
"This suggests that the first Americans may have spread through the
New World along a coastal route," he said.
Henry Harpending is an anthropologist and population geneticist at the
University of Utah in Salt Lake City who was not involved in the
study.
He agreed that there is a consensus emerging among researchers
studying the first Americans.
"But there are still outstanding questions," he said.
For example, there are some "puzzling anomalies" in the Alaskan
archaeological record dating back to before the glacial melt, he
pointed out.
And there are several possible reasons other than ice why people did
not venture south earlier, including a "ferocious army of predators"
living in North America that might have had a role in keeping humans
away.
"We all have open minds, and we will leave them open," Harpending
said.
http://news.nationalgeographic.com/news/2008/03/080313-first-american...
What ferocous predators would that be?
I think you must have a very open mind to
regard this as an option.
You obviously have to buy the DVD for $17 National Geographic:
Prehistoric Predators (2007)
"Not available for shipment outside of the U.S. and Canada"

It's tigers, lions and bears, to do a switch on the Wizard of Oz.
In addition to the comedy above how are ferocious predators going to
keep a sea going migration of at most 5,000 people, say 10 to a canoe,
from succeeding?
I don't think it was a migration of 5000 people.
More likely it was an expanding of 'territory'
And the idea of armies of tigers, lions and
bears is ridiculous, as is the idea of such kind
of animals just south of the ice cap.

--
p.a.

Weller's cite gives the size of migrating groups as about 80, which
seems reasonable. The estimate for a self-regenerating group for the
Polynesian voyages was about 17, the capacity of one of their larger
canoes. The estimates are for several smaller boats, perhaps skin
boats over a frame, and probably much shorter time between stopovers.

The ability to build large boats when the supply of large trees, in
the area which is now Southeastern Alaska and British Columbia, became
available would increase the size of the migrant group or be able to
accommodate what several boats did before.

You don't need migration to settle a continent.
Just expansion of the hunting range and setting
up camp some kilometers further away.

--
p.a.

I see the word "migration" more than a dozen times on the first two
pages of Mitochondrial Report

Another frequent controversy is about the size of the founding
population during the peopling of the Americas. The initial results
showing the existence of few founder haplogroups for the mtDNA and Y
chromosome suggested a strong population bottleneck,6 although this
interpretation was not supported by further mtDNA studies.21 However,
a recent analysis of several genomic loci, including mtDNA, suggested
that the Americas could have been founded by as few as 80 effective
individuals, and even the largest values in the credible interval only
comprise a few hundred effective individuals.24 On the other hand, the
study of other single genetic systems does not seem to support much
loss of genetic diversity during the initial settlement of the
continent;25, 26, 27, 28 instead, it concludes that a moderate-
intensity bottleneck is the best scenario. Another recent genomic
study using exclusively autosomal intergenic markers also suggested
moderate values, with the Native American founding population
consisting of around 500 effective individuals (95% confidence
interval 74-1332).29

Footnotes at the cite
http://www.ajhg.org/AJHG/fulltext/S0002-9297(08)00139-0#
.

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