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Out of Africa theory (Split)
Posted: 08 March 2011 06:51 AM   [ Ignore ]   [ # 31 ]
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dougsmith - 08 March 2011 05:07 AM

PNAS paper: humans may have originated in southern Africa. See HERE

Yes, it can be that they did originate there. But large genomic diversity can also simply mean a larger population. It really depends how you look at the data. You will always find a greater diversity in a habitat where the species is well adapted, as there is a greater chance for mutations and lower chance for a selective sweep and population bottlenecks.

[ Edited: 06 July 2011 01:06 PM by George ]
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Posted: 08 March 2011 07:19 AM   [ Ignore ]   [ # 32 ]
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And HERE is a response from one of the best known supporters of Out-of-Africa, Chris Stringer:

“I’d be cautious about localizing origins,” says Stringer.

[...]

Different populations in ancient Africa probably contributed various genes and behaviours to modern humans, says Stringer. “I don’t think there was a single Garden of Eden where it all happened.”

Of course, we still don’t know if the only populations who had contributed to the origin of our species were all African. But as said above, this is coming from Stringer, so it is to be understood.

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Posted: 16 March 2011 08:29 AM   [ Ignore ]   [ # 33 ]
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John Hawks comments on the southern African origin of “modern” humans.

Population structure within Africa: has “modern human origins” become a non sequitur?

[...]

The “southern African origins” conclusion of the paper comes out of a simple analysis that assumes that the best-fit maximum for genetic diversity (as assessed by linkage) is the most likely point of origin of the population. That would be true if the African population emerged by a series of founder effects from a single small ancestral population—the “serial founder effect” model that I have criticized here before. But of course in 2011, we know that model is false, because it is predicated on a lack of ancient mixture with Neandertals or other populations. If the serial founder model can’t work outside Africa, it certainly can’t work inside Africa, where populations were larger and regionally diversified during by the beginning of the Late Pleistocene. Without that false assumption, the “southern African origin” evaporates. The primary observation, a cline of linkage disequilibrium within sub-Saharan Africa, can be explained with reference to mixture of populations without assuming an origin and expansion from one geographic location.

[...]

Oh, and do you know who else is supposedly a multiregionalist? Dawkins! Go figure. That is, at least, what I heard in an interview with Milford Wolpoff (the leading proponent of multiregionalsim). So what the heck was Dawkins thinking when he wore the “We Are All Africans” t-shirt the other day? Well, now I know. He meant the same thing as Darwin did: humans come from Africa! Of course, humans here refers to the genus of Homo, not the species of H. sapiens. Good, I can keep liking Dawkins.  grin

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Posted: 06 July 2011 12:56 PM   [ Ignore ]   [ # 34 ]
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I am not sure if anyone here is following the Out-of-Africa vs. Multiregionalism debate, but according to THIS article from the Guardian, the most known opponent of Multiregionalism, Chris Stringer, now “embraces” the multi-regional hypothesis. Weird. It’s like Dawkins saying that he now embraces the punctuated equilibrium. No idea what to make of this…

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Posted: 06 July 2011 03:48 PM   [ Ignore ]   [ # 35 ]
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George - 06 July 2011 12:56 PM

I am not sure if anyone here is following the Out-of-Africa vs. Multiregionalism debate, but according to THIS article from the Guardian, the most known opponent of Multiregionalism, Chris Stringer, now “embraces” the multi-regional hypothesis. Weird. It’s like Dawkins saying that he now embraces the punctuated equilibrium. No idea what to make of this…

I always follow your posts with great interest George…. smirk

But this multiregional idea presents a problem to me using Ockham’s razor.  If it is agreed on that hominids originated in Africa, then how, when and where did Neanderthal originate? By the same process as the African hominid? In Europe? At the same time?
Seems to me that if Hominids originated in Africa, they are the parents of all subsequent Hominidae. True, Neaderthal may have developed after migration into Europe or Asia, or wherever, the fact remains they originated in Africa.

I believe we are in agreement there?

Then comes the question, at what point did Neanderthal split from its African ancestor and why? Another question did Neaderthals’ adaption to a different environment make it smarter than the earlier hominids? And also the question, in view of the great variety of habitats in Africa, why would Neaderthal not have also developed in Africa.

What creates a natural need for having to become smarter in order to adapt? Migration itself places a demand on inventing temporary shelters, transport vehicles, portable storage devices, transportation of fire, etc, etc .
But migration, started also in Africa, there are many tribes which are nomadic, each with specific skills adapted to their range.
http://en.wikipedia.org/wiki/Human_migration

IMO, Neaderthals may well have been the “most adventurous” of the African hominids and as thet migrated farther and farther away from “home” they acquired greater knowledge of climates, environmental challenges, animal diversity, etc. Thus “by exposure” they learned to adapt (artificially), wherever they went.

A famous architect once remarked that the “teepee” is an example of advance technology in a portable home. It has an adjustable chimney. which allow it to be warm in the winter and cool in the summer, the poles are not only the structural foundation but also the transport mechanism (portage) and it can be erected and taken down in a matter of minutes, yet house a large number of people.
These techinical requirement resulted in a variety of teepees, each ideally suited for their specific use.

Thus the question arises, do nomadic people become smarter than their cousins who stayed on the farm and developed their own advances in planting, harvesting, non destructive use of the forests, animal husbandry?

How can you possibly tell? Each sub-species developed their own unique skills in accordance to demand placed on them by their environment. 

IMO and I have stated it before, the brain’s potential, once it has acquired the ability to think and imagine, is almost limitless in ability to grow synapses and analytical powers when required by environmental pressures.

The concept of “smart” is a relative concept.

[ Edited: 06 July 2011 03:52 PM by Write4U ]
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Posted: 07 July 2011 07:08 AM   [ Ignore ]   [ # 36 ]
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Write4U,

The whole story on the classification of the Neadertal is a complicated subject and it would take me quite some time to write it all down. I suggest you start with the Wiki page and if you’re interested I can also recommend a few books on this topic.

I’ll tell you one thing, though. It is often very difficult to figure out who exactly was who, when looking at the archeological remains in Europe—and the same thing happens elsewhere around the world.

As far as the intelligence of each of the Homo species (or subspecies, or whatever they were) is concerned, I don’t want to go there. Not now.

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Posted: 07 July 2011 02:21 PM   [ Ignore ]   [ # 37 ]
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The one thing that stumps me, if there was an early split , then when and where did the “rejoining” occur?
Did we make a date, something like “in about a million years let’s meet up in Alsaka, or Mongolia?”
How did all these species get there in the first place?

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Posted: 07 July 2011 08:20 PM   [ Ignore ]   [ # 38 ]
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They couldn’t have been separated for too long otherwise they would have all become different species. From what the DNA is showing they never seemed to have been any significant genetic difference between the archaic homo subspecies.

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Posted: 07 July 2011 08:27 PM   [ Ignore ]   [ # 39 ]
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And just to add to my previous post, the genetic difference between the Neandertals and the Denisovans was about the same as today’s genetic difference between a person from Sub-Saharan Africa and a European.

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Posted: 09 July 2011 05:42 AM   [ Ignore ]   [ # 40 ]
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George - 06 July 2011 12:56 PM

I am not sure if anyone here is following the Out-of-Africa vs. Multiregionalism debate, but according to THIS article from the Guardian, the most known opponent of Multiregionalism, Chris Stringer, now “embraces” the multi-regional hypothesis. Weird. It’s like Dawkins saying that he now embraces the punctuated equilibrium. No idea what to make of this…

I found this particular link really slow to come up.

George if you have a link to summary of the debate {maybe this one works} would appreciate it. It does sound like the sort of thing Steven J. Gould would have done one of his monthly columns on if he were still with us.
Thanks!
Jackson

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Posted: 09 July 2011 06:34 AM   [ Ignore ]   [ # 41 ]
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Jackson,

I am not sure what you mean by the “summary of the debate.” The link was from an article in the Guardian saying that Stringer now seems to accept Multiregionalism—something, I find very hard to believe.

I am also not understanding your comment regarding Gould.

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Posted: 09 July 2011 07:32 AM   [ Ignore ]   [ # 42 ]
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George - 09 July 2011 06:34 AM

Jackson,

I am not sure what you mean by the “summary of the debate.” The link was from an article in the Guardian saying that Stringer now seems to accept Multiregionalism—something, I find very hard to believe.

I am also not understanding your comment regarding Gould.

Hi George.
a. if you come across a summary of this ‘debate’ could you put a link here—if you think you already posted one, could you repost it.  I kind of think that is not so much a debate as a discussion of details.  With more and more info about the human genome the discussion seems to get more complex but there might be certain points which are considered proven and which provide a simple framework.
b. An up-to-date discussion of the nuances of human evolution is something Gould wouuld have enjoyed summarizing in a readable essay.

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Posted: 09 July 2011 09:53 AM   [ Ignore ]   [ # 43 ]
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HERE is one link discussing the subject, between Rabiz Khan from the Gene Expression and the paleoanthropologist Milford Wolpoff.

Regarding Gould, he is one of the reasons why the multiregional hypothesis became unpopular and still suffers from that effect today. Gould is one the worst things that has ever happened to popularization of the study of human nature. He was certainly not an expert on the subject of human evolution. I know, now I am supposed to say that at least he was a good writer, but I never liked his writing either.

[ Edited: 09 July 2011 09:55 AM by George ]
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Posted: 09 July 2011 01:05 PM   [ Ignore ]   [ # 44 ]
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George - 24 February 2011 05:59 PM

There are actually three different scenarios here, Occam. The Out-of-Africa one is now officially dead as it didn’t allow for any interbreeding between the different human groups. Multiregionalism and the new “Leaky Replacement” are still possible but there are lots of problems with both theories.

I agree with that.

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Posted: 09 July 2011 01:05 PM   [ Ignore ]   [ # 45 ]
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George - 07 July 2011 08:20 PM

They couldn’t have been separated for too long otherwise they would have all become different species. From what the DNA is showing they never seemed to have been any significant genetic difference between the archaic homo subspecies.

I agree with that.

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