Ancient Genetic Flow North America-South America

The Western Hemisphere. General term for the Americas following their discovery by Europeans, thus setting them in contradistinction to the Old World of Africa, Europe, and Asia.

Moderators: MichelleH, Minimalist

shawomet
Posts: 381
Joined: Tue Jul 10, 2012 9:14 am

Ancient Genetic Flow North America-South America

Post by shawomet » Fri Nov 09, 2018 6:26 pm

https://www.inverse.com/article/50624-g ... th-america

"We report genome-wide ancient DNA from 49 individuals forming four parallel time transects in Belize, Brazil, the Central Andes, and the Southern Cone, each dating to at least ∼9,000 years ago. The common ancestral population radiated rapidly from just one of the two early branches that contributed to Native Americans today. We document two previously unappreciated streams of gene flow between North and South America. One affected the Central Andes by ∼4,200 years ago, while the other explains an affinity between the oldest North American genome associated with the Clovis culture and the oldest Central and South Americans from Chile, Brazil, and Belize. However, this was not the primary source for later South Americans, as the other ancient individuals derive from lineages without specific affinity to the Clovis-associated genome, suggesting a population replacement that began at least 9,000 years ago and was followed by substantial population continuity in multiple regions."

Highlights


Genome-wide analysis of 49 Central and South Americans up to ∼11,000 years old

Two previously unknown genetic exchanges between North and South America

Distinct link between a Clovis culture-associated genome and the oldest South Americans

Continent-wide replacement of Clovis-associated ancestry beginning at least 9,000 years ago

If you google the journal Cell, and name of paper is "Reconstructing the Deep Population History of Central and South America", first two authors are Posth and Nakatsuka, you should find the paper. The link will not paste in this forum.

https://www.cell.com/cell/fulltext/S009 ... all%3Dtrue

shawomet
Posts: 381
Joined: Tue Jul 10, 2012 9:14 am

Re: Ancient Genetic Flow North America-South America

Post by shawomet » Fri Nov 09, 2018 6:57 pm

The Extremely Fast Peopling of the Americas: a second genetic study, which both supports and differs from the findings described in the previous link:

https://www.theatlantic.com/science/arc ... as/575335/

kbs2244
Posts: 2469
Joined: Wed Jul 12, 2006 12:47 pm

Re: Ancient Genetic Flow North America-South America

Post by kbs2244 » Tue Nov 13, 2018 1:57 pm

If I read it correctly, they are saying it was a fast moving, costal migration?
Then inland from the first settlements?
What about the mountains.
What drove them to attempt to cross that barrier?

Those mountains are high and very cold, and the Pacific coast is a pretty nice place to live.

User avatar
circumspice
Posts: 943
Joined: Sat Dec 19, 2009 7:10 pm

Re: Ancient Genetic Flow North America-South America

Post by circumspice » Tue Nov 13, 2018 5:00 pm

kbs2244 wrote:If I read it correctly, they are saying it was a fast moving, costal migration?
Then inland from the first settlements?
What about the mountains.
What drove them to attempt to cross that barrier?

Those mountains are high and very cold, and the Pacific coast is a pretty nice place to live.


Human curiosity. It's a huge part of the human psyche.

The need to know what is on the other side... There were probably a few hardy explorers who made the trek, then came back & told everyone of the wonders they saw 'over there'. Think about it... Once you clear the mountains & foothills, there are open plains as far as the eye can see. Large rivers too... They probably saw vast herds of horses, camels, elk, deer, bison, mammoths & mastodons...

Who could resist the urge to carve out & claim territory in such an environment? I would have been among the first to volunteer to go.
"Damn with faint praise, assent with civil leer, and, without sneering, teach the rest to sneer." ~ Alexander Pope

Simon21
Posts: 525
Joined: Fri Jan 03, 2014 4:40 am

Re: Ancient Genetic Flow North America-South America

Post by Simon21 » Wed Nov 14, 2018 9:17 am

kbs2244 wrote:If I read it correctly, they are saying it was a fast moving, costal migration?
Then inland from the first settlements?
What about the mountains.
What drove them to attempt to cross that barrier?

Those mountains are high and very cold, and the Pacific coast is a pretty nice place to live.
It is generally presumed that human beings followed coastal paths and went inland much later. As to what motivated them is anyone's guess, food, escaping from disease.

Why did the original Koories mount their frail craft, sail the seas to end up in a country that was largely desert?

Or the polynesians crossing vast distances in the Pacific to find small islands


User avatar
Cognito
Posts: 1606
Joined: Fri Jul 28, 2006 10:37 am
Location: Southern California

Re: Ancient Genetic Flow North America-South America

Post by Cognito » Fri Apr 26, 2019 1:57 pm

Pre-dating the genetic timeframe in the article is the iron oxide mine (i.e. red ochre) found in Chile and dating from 12,000 years before present: https://www.eurekalert.org/pub_releases ... 051811.php

Assuming that it would take some time before anyone would discover iron ore in the mountains with the perceived need being material for burial customs, etc. (which requires a population base), then I would be looking at genetics earlier than Clovis. Then again, I'm a trouble-maker. :D
Natural selection favors the paranoid

kbs2244
Posts: 2469
Joined: Wed Jul 12, 2006 12:47 pm

Re: Ancient Genetic Flow North America-South America

Post by kbs2244 » Fri Apr 26, 2019 3:29 pm

I enjoy the trouble maker remark.

One thing I missed in the original news release is that they are basing a hemispheric theory on 49 samples.

I am reminded of my great grand uncle’s poem concerning the group of blind men describing an elephant.

https://en.wikisource.org/wiki/The_poem ... e_Elephant

User avatar
Cognito
Posts: 1606
Joined: Fri Jul 28, 2006 10:37 am
Location: Southern California

Re: Ancient Genetic Flow North America-South America

Post by Cognito » Mon Apr 29, 2019 12:35 pm

One thing I missed in the original news release is that they are basing a hemispheric theory on 49 samples.
Statistics, KB:

A population sample size of 49 will return a margin of error of 14% at a 95% confidence level. That's appears to be a decent point at which to submit a hypothesis.
Natural selection favors the paranoid

kbs2244
Posts: 2469
Joined: Wed Jul 12, 2006 12:47 pm

Re: Ancient Genetic Flow North America-South America

Post by kbs2244 » Mon Apr 29, 2019 1:03 pm

Where does the 95% come from?

User avatar
Cognito
Posts: 1606
Joined: Fri Jul 28, 2006 10:37 am
Location: Southern California

Re: Ancient Genetic Flow North America-South America

Post by Cognito » Mon Apr 29, 2019 8:09 pm

Where does the 95% come from?
KB, in statistics the confidence level is a measure of the reliability of a result. A confidence level of 95% means that there is a probability of at least 95 per cent that the result is reliable. This is a standard when calculating a margin of error. Margin of Error = 1.96 x √((p(1-p)/n)).

I learned to use the above in graduate school at the University of Washington in Seattle as something useful to determine the best fit for a population size to return a decent result. A sample size of 49 is good. Take a statistics class and you will have a better understanding of where the authors are coming from.
Natural selection favors the paranoid

User avatar
circumspice
Posts: 943
Joined: Sat Dec 19, 2009 7:10 pm

Re: Ancient Genetic Flow North America-South America

Post by circumspice » Tue Apr 30, 2019 11:07 am

Cognito wrote:
Where does the 95% come from?
KB, in statistics the confidence level is a measure of the reliability of a result. A confidence level of 95% means that there is a probability of at least 95 per cent that the result is reliable. This is a standard when calculating a margin of error. Margin of Error = 1.96 x √((p(1-p)/n)).

I learned to use the above in graduate school at the University of Washington in Seattle as something useful to determine the best fit for a population size to return a decent result. A sample size of 49 is good. Take a statistics class and you will have a better understanding of where the authors are coming from.


If kbs educated himself on everything he wishes to cast doubt upon, he'd have nothing to naysay. Education is his kryptonite. Just sayin'...
"Damn with faint praise, assent with civil leer, and, without sneering, teach the rest to sneer." ~ Alexander Pope

kbs2244
Posts: 2469
Joined: Wed Jul 12, 2006 12:47 pm

Re: Ancient Genetic Flow North America-South America

Post by kbs2244 » Tue Apr 30, 2019 12:32 pm

I have read your posts on a minimum self sustaining population size and they make sense to me.

But if...

"A confidence level of 95% means that there is a probability of at least 95 per cent that the result is reliable"

How do you establish that "probability"
This is starting to sound like circular reasoning.

User avatar
Cognito
Posts: 1606
Joined: Fri Jul 28, 2006 10:37 am
Location: Southern California

Re: Ancient Genetic Flow North America-South America

Post by Cognito » Tue Apr 30, 2019 3:30 pm

How do you establish that "probability"
This is starting to sound like circular reasoning.
KB, as opposed to taking you through introductory statistics on this forum, I suggest you pick up a book on the topic and self educate since my recommendation about taking a class obviously went by the wayside. If you are concluding that statistics involves circular reasoning, then study really hard.
Natural selection favors the paranoid

kbs2244
Posts: 2469
Joined: Wed Jul 12, 2006 12:47 pm

Re: Ancient Genetic Flow North America-South America

Post by kbs2244 » Wed May 01, 2019 3:01 pm

I am sorry if I offend.
It is not my intention.

But; "confidence level" and "probability" do not raise my confidence level in the probability of a correct answer to an important problem. (Which, in the end, this is not.)

Good enough for a pitching change or for a horse race perhaps.
I am sure money has been made on decisions based on them.

But fail to see a good reason to study something with such a weak foundation.

Post Reply