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Can someone PLEASE help explain the “Out of Africa” theory?
Posted: 14 March 2012 04:16 PM   [ Ignore ]
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Hi guys, I’m totally fresh here, I’ve been doing reading about human origin models, and have for some reason randomly developed enthusiasm for the subject.  I’ve don a few days of reading, so I don’t know if this is an obvious question… Seems like it should be.

Here we go…

Out of Africa Theory seems absolutely untenable based on this ridiculously obvious logic:

a.  It maintains that Homo Sapiens are separate species from Neanderthal.

b.  It maintains that Homo Sapiens emigrated from Africa genetically/genotypically complete.

c.  Native African Homo Sapiens do not claim ancestory from Neanderthals, whereas as everyone native north of the border does.

d.  Because said humans have Neanderthal blood, they were not Homo Sapien out of Africa, or else Neanderthals were Homo Sapiens, thus refuting points A and B.


Will somebody please explain this to me, I think i’m having an existential crises.

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Posted: 14 March 2012 06:33 PM   [ Ignore ]   [ # 1 ]
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Out of Africa is no longer an accepted theory. Some anthropologists now offer a new theory based on the previous one often reffered to as “Out of Africa with leakage.” In other words, everything remains the same except for Homo sapiens interbreeding with other ancient humans. Those would be the Neandertals, the Denisovans in Asia and some other ancient humans in Africa. There were probably many more, though.

The competing theory with Out of Africa is the Multiregional theory, proposing that human evolution happened due to the migration of genes. Some kind of a genetic Chinese Whispers. The truth most likely lies somewhere in between, with some groups of people migrating and interbreeding with other ancient humans at the same time.

I can’t provide any links at the moment, but if you are interested I can recommend a few books later on. Let me know.

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Posted: 15 March 2012 12:49 PM   [ Ignore ]   [ # 2 ]
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Of course there is always controversy in science. The dominant theory is still that of an exclusively African origin for humans, with multiple waves of migration over a prolonged period of time. The multiregional theory is less widely held. Here are a couple of rsources to start with.

Human Genome Project
This page is mostly links to articles with information about human origins, migrations, and other issues illuminated in part by genetic information.

National Geographic Society Genographic Project
This is a project collecting DNA from ethnic groups around the world and trying to use genetic information to clarify the migration patterns of humans.

Smithsonian article on the subject

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Posted: 15 March 2012 01:08 PM   [ Ignore ]   [ # 3 ]
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mckenzievmd - 15 March 2012 12:49 PM

The dominant theory is still that of an exclusively African origin for humans

But what does that mean? Certainly all ancient humans’ roots can be traced back to Africa, but who and when left Africa and how their genes are distributed among today’s population is still a puzzle. Actually the puzzle is becoming more and more complicated as new data keep appearing. The genomes of New Guineans contain almost five percent of Denisovan DNA, for example. That’s a significant amount. What else is in their genome? We have no idea. We are only at the beginning of this new chapter in anthropology and the one thing we now know WITH CERTAINTY is that Out of Africa is simply wrong. And there are even problems with “Out of Africa with leakage,” as one big exodus around 70,000-50,000 years back seems more and more unlikely.

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Posted: 15 March 2012 04:14 PM   [ Ignore ]   [ # 4 ]
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George - 15 March 2012 01:08 PM
mckenzievmd - 15 March 2012 12:49 PM

The dominant theory is still that of an exclusively African origin for humans

But what does that mean? Certainly all ancient humans’ roots can be traced back to Africa, but who and when left Africa and how their genes are distributed among today’s population is still a puzzle. Actually the puzzle is becoming more and more complicated as new data keep appearing. The genomes of New Guineans contain almost five percent of Denisovan DNA, for example. That’s a significant amount. What else is in their genome? We have no idea. We are only at the beginning of this new chapter in anthropology and the one thing we now know WITH CERTAINTY is that Out of Africa is simply wrong. And there are even problems with “Out of Africa with leakage,” as one big exodus around 70,000-50,000 years back seems more and more unlikely.

To confuse the issue further, check this out:

http://news.yahoo.com/mysterious-chinese-fossils-may-human-species-150805074.html

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Posted: 15 March 2012 04:54 PM   [ Ignore ]   [ # 5 ]
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Yeah, I found the red deer cave people on another site. I wonder how many more offshoots will be found in the near future? The DNA projects seem to be helping too. I’m signing up for the 23andMe genome project as well.

Cap’t Jack

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Posted: 15 March 2012 05:50 PM   [ Ignore ]   [ # 6 ]
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Yes, this a significant and very exciting news indeed. As usual, Out-of-Africa seems again just a bit less credible. And Jack is right to wonder what else the future may bring us. What will we learn from these humans’ DNA once they succeed at extracting it? As new “species” of humans keep popping up like mushrooms after rain, the more puzzling (and fun!) the whole human evolution story gets.

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Posted: 23 March 2012 06:53 PM   [ Ignore ]   [ # 7 ]
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pranatron - 14 March 2012 04:16 PM

c.  Native African Homo Sapiens do not claim ancestory from Neanderthals, whereas as everyone native north of the border does.

d.  Because said humans have Neanderthal blood, they were not Homo Sapien out of Africa, or else Neanderthals were Homo Sapiens, thus refuting points A and B.

Statement (c) is the source of the muddle. There seems some Neanderthal strain in human beings, but all humans, no matter their race, derive their DNA mostly from Homo Sapiens, from Africa:

The Neanderthal mtDNA sequences were substantially different from modern human mtDNA (Krings et al. 1997, 1999). Researchers compared the Neanderthal to modern human and chimpanzee sequences. Most human sequences differ from each other by on average 8.0 substitutions, while the human and chimpanzee sequences differ by about 55.0 substitutions. The Neanderthal and modern human sequences differed by approximately 27.2 substitutions. Using this mtDNA information, the last common ancestor of Neanderthals and modern humans dates to approximately 550,000 to 690,000 years ago, which is about four times older than the modern human mtDNA pool. This is consistent with the idea that Neanderthals did not contribute substantially to modern human genome.

(From The Smithsonian’s website http://humanorigins.si.edu/evidence/genetics/ancient-dna-and-neanderthals)

since (c) is so muddled, (d) doesn’t follow.
inthegobi

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Posted: 24 March 2012 12:52 PM   [ Ignore ]   [ # 8 ]
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I think the term “Out of Africa” can by used in a simplistic way, as your a-b-c-d summarizes, and also in this more nuanced/complex way (mentioned by other posters) where there might have been multiple waves of migration and intermingling with other ‘branches’. 

I also think it is understood that the ancestors of Neanderthals also came from Africa—
http://en.wikipedia.org/wiki/Neanderthal


In your original a-b-c-d, does it agree with the Wikipedia summary or do you see a hole in that discussion?
http://en.wikipedia.org/wiki/Recent_African_origin_of_modern_humans

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Posted: 24 March 2012 02:04 PM   [ Ignore ]   [ # 9 ]
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Could all this not mean the DNA which eventually produced a hominid was present much earlier than originally estimated? Even before the continents split apart. In such a scenario it is very possible that different hominids evolved in the seperated continents, but still shared a fundamental ancient common ancestor.
This seems to have happened with many other species, why not hominids?

Imagine No. Africa still attached to Europe

[ Edited: 25 March 2012 03:09 AM by Write4U ]
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Posted: 25 March 2012 08:17 AM   [ Ignore ]   [ # 10 ]
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Write4U, might have a point, but I’m not sure, because if Write4U is referring to Pangaea, I think that is a little too far back for humanoid species or even ancestors there of in this case.

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Posted: 25 March 2012 11:03 AM   [ Ignore ]   [ # 11 ]
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No, it’s not possible because when Pangaea began to break apart, mammals were not around, much less hominids.

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Posted: 25 March 2012 02:29 PM   [ Ignore ]   [ # 12 ]
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George - 25 March 2012 11:03 AM

No, it’s not possible because when Pangaea began to break apart, mammals were not around, much less hominids.

Actually that would support the notion view that similar species can evolve independently. It speaks of the incredible flexibility of the gene structure. A few million years of evolution in the gene patterns and presto….hominid.

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Posted: 25 March 2012 03:44 PM   [ Ignore ]   [ # 13 ]
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I guess it would support it if it actually happened, which it didn’t. Except for the Star Trek universe and its humanoids, of course.  grin

[ Edited: 25 March 2012 03:46 PM by George ]
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Posted: 25 March 2012 03:59 PM   [ Ignore ]   [ # 14 ]
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George - 25 March 2012 03:44 PM

I guess it would support it if it actually happened, which it didn’t. Except for the Star Trek universe and its humanoids, of course.  grin

Well, as Mriana questioned, what about Pangaea?

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Posted: 25 March 2012 04:25 PM   [ Ignore ]   [ # 15 ]
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Write4U - 25 March 2012 03:59 PM
George - 25 March 2012 03:44 PM

I guess it would support it if it actually happened, which it didn’t. Except for the Star Trek universe and its humanoids, of course.  grin

Well, as Mriana questioned, what about Pangaea?

At the time, if any creature existed, I don’t think they were mammals yet, but may have been on the way to eventually being mammals- after a long period of time.

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