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Out of Africa theory (Split)
Posted: 25 February 2011 08:30 PM   [ Ignore ]   [ # 16 ]
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asanta - 25 February 2011 03:15 PM
George - 25 February 2011 02:29 PM

As usual, a waste of my time.

LOL ...and still no citations!

Find your own citations. You can start with the Wiki page on Recent African origin of modern humans (a.k.a. “Out of Africa”):

“Genetic and fossil evidence is interpreted to show that archaic Homo sapiens evolved to anatomically modern humans solely in Africa, between 200,000 and 150,000 years ago, that members of one branch of Homo sapiens left Africa by between 125,000 and 60,000 years ago, and that over time these humans replaced earlier human populations such as Neanderthals and Homo erectus without interbreeding with them.”

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Posted: 25 February 2011 09:05 PM   [ Ignore ]   [ # 17 ]
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If you want to split this, Doug, go ahead.

citizenschallenge.pm - 25 February 2011 03:57 PM

Why would Out-of-Africa preclude interbreeding?

That’s a long story, CC, but Ill try to make it short. Anthropology is about two hundred years old and for most of that time the vast majority of anthropologists believed in what is known as Polygenism, where it was thought that different races evolved independently from seperate species of apes. Multiregionalism was viewed as another attempt to follow in the footsteps of polygenist evolution (which is certainly wrong) and was generally viewed as racist. Then came the Eve theory and thanks to people like Stephen Jay Gould, who sold his soul to his ideals, the theory became popular practically overnight. In order to see all humanity as one big happy family they decided to get rid of Polygenism for once and for all, and left no space in the new theory for any archaic humans. And then came 2010…

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Posted: 25 February 2011 09:26 PM   [ Ignore ]   [ # 18 ]
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From Dr Laden (anthropology):Fully modern humans are known in southern africa at about 120,000 years ago but probably predate that time. I’ve examined a skull with all the modern human traits and a very large brain case from about 360,000 years ago from near Kimberly SA. There are modern human skeletal remains from between those two dates elsewhere in Africa, including the Omo skull (southern ethiopia) and other ethiopian remains. The best evidence for behavior (in the stone tools) puts what might be modern human thinking and technology at either 250K (beginning of the middle stone age) or about 500K (the so called “Fauersmith” technology) though this is obviously much more speculative.

The question is not whether or not fully modern humans evolved in africa or elsewhere, but rather, when in Africa this happened (and exactly where/how and involving what details).

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Posted: 25 February 2011 09:56 PM   [ Ignore ]   [ # 19 ]
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Yes, Asanta, the “fully modern humans” were found in a cave closed to the Klaises river in South Africa. The problem here is that they merely show some “modern” characteristics which is very different from calling them modern humans. If you focus on a few selected features you will always some “modernity” since some individuals will always have some “modern” characteristics. Another problem is that when you compare them with specimens from a later period (even from the same region) they will appear archaic. Whatever these people were, they were certainly not modern. Even today there are some living people who appear more archaic than modern. Are they not modern?

None of this makes much sense when we look at it from from the perspective of recent origin of our species. Indeed, the answer Multiregional continuity can offer here sounds a lot more plausible.

[ Edited: 26 February 2011 06:47 AM by George ]
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Posted: 25 February 2011 10:40 PM   [ Ignore ]   [ # 20 ]
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George - 25 February 2011 09:56 PM

None of this makes much sense when we look at it from from the perspective of recent origin of our species. Indeed, the answer Multiregional continuity can offer here sounds a lot more plausible.

Both competing theories place the genesis of humankind, the difference is how the distribution occurred and the probability of interbreeding with subspecies. ‘Out of Africa’ does not mean those who stayed behind (i.e. modern Africans) did not continue to evolve. Evolution continues until a species becomes extinct.
Dogs evolved in Asia. No one believes that Asian breeds are less evolved than dogs from other parts of the world. For example the Dhole (Cuon alpinus),  a species of canid native to Southeast Asia and only existing member of the genus Cuon is a subspecies of canis, but no less evolved, it just took a slightly different pathway. There are bears all over the world, of the eight species,  the strangest are probably the Sloth Bear (Melursus ursinus) and Panda Bear (Ailuropoda melanoluca). No one would call them ‘less evolved’ than the Grizzly, Black or Polar bears.

[ Edited: 25 February 2011 11:26 PM by asanta ]
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Posted: 26 February 2011 05:37 AM   [ Ignore ]   [ # 21 ]
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Sorry, Asanta, I have no idea what “less evolved” means.

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Posted: 26 February 2011 06:54 AM   [ Ignore ]   [ # 22 ]
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NB: this thread has been split off from the ‘what are you reading’ thread, HERE at #174.

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Posted: 26 February 2011 09:00 AM   [ Ignore ]   [ # 23 ]
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am curious to know how the three theories (Leaky Replacement,Multiregionalism and Out of Africa) can explain the racial differences between races (hair color , skin color and eyes color).

@George: the burden of proof is on you ,so you are the one who is asked to substantiate your claim , don’t say “find your own citations”

[ Edited: 26 February 2011 09:03 AM by Phi- ]
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Posted: 26 February 2011 09:06 AM   [ Ignore ]   [ # 24 ]
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Phi- - 26 February 2011 09:00 AM

am curious to know how the three theories (Leaky Replacement,Multiregionalism and Out of Africa) can explain the racial differences between races (hair color , skin color and eyes color).

The differences are not difficult to explain: they reflect the geographic regions of the peoples. What is less clear is why people are so similar.

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Posted: 26 February 2011 09:11 AM   [ Ignore ]   [ # 25 ]
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George - 26 February 2011 09:06 AM

The differences are not difficult to explain: they reflect the geographic regions of the peoples.

I don’t think the geographic regions have any effect on these differences ,so because the Nordic people live in a cold area they have blue eyes .

George - 26 February 2011 09:06 AM

What is less clear is why people are so similar.

what kind of similarity are you talking about ?

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Posted: 26 February 2011 09:43 AM   [ Ignore ]   [ # 26 ]
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I guess I should have been more clear. (Sorry, it’s the weekend, and I am busy doing a million things at the same time.) The differences are easier to explain using the Multiregionalism model and the similarities using Out of Africa. Now, Out of Africa has a harder time explaining the differences than Multiregionalism explaining the similarities. (I hope it’s clear.)

And yes, the phenotypic differences (and similarities) would be things like eye and skin colour, the shape and size of the skull, etc. But we are now entering a new chapter in the search for our past, the chapter of genetics. This is where it gets more complicated. At least for now.

[ Edited: 26 February 2011 09:51 AM by George ]
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Posted: 26 February 2011 10:22 AM   [ Ignore ]   [ # 27 ]
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Maybe an explanation of what Multiregionalism actually represents is necessary here. Around two million years ago humans (whatever one chooses to call them, H. erectus or archaic H. sapiens—but it doesn’t really matter) left Africa and begun settling in different parts of the world. As these very small groups of people stayed isolated from each other for some time, they adapted to their environment. After some time they became to grow in size and interbreed with neighbouring tribes. IOW, they were now exchanging genetic information. These peoples kept their advantageous genes (according to their locations) but also added new advantageous genes from other peoples. There was never one big African exodus replacing Neandertals, H. erectus, Denisovans, etc. We “are” Neandertals, Denisovans and a number of other peoples, some more and some less than others.

We have been one species for almost two million years. Instead of seeing the human evolution as a branching tree (Out-of-Africa) or Polygenism (individually growing ladders), Multiregionalism represents a picture of a river with a number of smaller creeks flowing in and out of main stream. The main stream is the large genetic similarity we all share.

[ Edited: 06 July 2011 01:04 PM by George ]
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Posted: 26 February 2011 06:44 PM   [ Ignore ]   [ # 28 ]
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asanta - 25 February 2011 10:40 PM

the strangest are probably the Sloth Bear (Melursus ursinus) and Panda Bear (Ailuropoda melanoluca).
No one would call them ‘less evolved’ than the Grizzly, Black or Polar bears.

The hell they wouldn’t just ask DM   LOL
sorry red face I’ll get back to this fascinating text. I mean that too.

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Posted: 26 February 2011 06:53 PM   [ Ignore ]   [ # 29 ]
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This has been fascinating, nice explanations and I am a bit familiar with the outlines of the theory.
But, now I’m confused as to exactly what George and asanta disagree on, for a while it felt like you guys were doing a tag team…. in a good way.

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Posted: 08 March 2011 05:07 AM   [ Ignore ]   [ # 30 ]
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PNAS paper: humans may have originated in southern Africa. See HERE

Hunter-gatherer genomic diversity suggests a southern African origin for modern humans

Abstract

<snip>

The observed patterns are consistent with an origin of modern humans in southern Africa rather than eastern Africa, as is generally assumed. ... African hunter-gatherer populations continue to maintain the highest levels of genetic diversity in the world. ...

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