posted
Distance from Africa, not climate, explains within-population phenotypic diversity in humans
Lia Betti1, François Balloux2, William Amos1, Tsunehiko Hanihara3, Andrea Manica1
December 02, 2008
Abstract
The relative importance of ancient demography and climate in determining worldwide patterns of human within-population phenotypic diversity is still open to debate. Several morphometric traits have been argued to be under selection by climatic factors, but it is unclear whether climate affects the global decline in morphological diversity with increasing geographical distance from sub-Saharan Africa. Using a large database of male and female skull measurements, we apply an explicit framework to quantify the relative role of climate and distance from Africa. We show that distance from sub-Saharan Africa is the sole determinant of human within-population phenotypic diversity, while climate plays no role. By selecting the most informative set of traits, it was possible to explain over half of the worldwide variation in phenotypic diversity. These results mirror those previously obtained for genetic markers and show that ‘bones and molecules’ are in perfect agreement for humans.
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Of course, climate, environment, living conditions, random mutation and genetic drift, and globalization [inter-ethnic miscegenation as a consequence of immigration] chime in in varying forms and in complex ways in influencing cranio-morphometric variation, as I've noted here before, but what these folks seem to be observing, at least from the little mentioned in the abstract above, is more diversity in Africa, especially sub-Saharan Africa, vs. that elsewhere. It goes back to that old age basic lesson: non-African groups derived from a subset of Africans, and hence, loss of diversity or a fraction of diversity. Though variations would occur in OOA, as a result of a number of bottleneck events and elements of the aforementioned factors, the overall diversity within the population is very likely to be impacted by that of the "founding" population, notwithstanding subsequent expansion events. The pre-existing variation in the original OOA subgroups was already a fraction of that in the African homeland, and there is reason to suspect that a series of bottlenecks events, that marked the dispersal of OOA migrants, would have led to further losses in diversity along the way.
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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quote: but what these folks seem to be observing, at least from the little mentioned in the abstract above, is more diversity in Africa, especially sub-Saharan Africa, vs. that elsewhere. It goes back to that old age basic lesson: non-African groups derived from a subset of Africans, and hence, loss of diversity or a fraction of diversity.
New Research Proves Single Origin Of Humans In Africa
ScienceDaily (July 19, 2007) — New research published in the journal Nature (19 July) has proved the single origin of humans theory by combining studies of global genetic variations in humans with skull measurements across the world. The research, at the University of Cambridge and funded by the Biotechnology and Biological Sciences Research Council (BBSRC), represents a final blow for supporters of a multiple origins of humans theory.
Competing theories on the origins of anatomically modern humans claim that either humans originated from a single point in Africa and migrated across the world, or different populations independently evolved from homo erectus to home sapiens in different areas.
The Cambridge researchers studied genetic diversity of human populations around the world and measurements of over 6,000 skulls from across the globe in academic collections. Their research knocks down one of the last arguments in favour of multiple origins. The new findings show that a loss in genetic diversity the further a population is from Africa is mirrored by a loss in variation in physical attributes.
Lead researcher, Dr Andrea Manica from the University's Department of Zoology, explained: "The origin of anatomically modern humans has been the focus of much heated debate. Our genetic research shows the further modern humans have migrated from Africa the more genetic diversity has been lost within a population.
"However, some have used skull data to argue that modern humans originated in multiple spots around the world. We have combined our genetic data with new measurements of a large sample of skulls to show definitively that modern humans originated from a single area in Sub-saharan Africa."
The research team found that genetic diversity decreased in populations the further away from Africa they were - a result of 'bottlenecks' or events that temporarily reduced populations during human migration.They then studied an exceptionally large sample of human skulls. Taking a set of measurements across all the skulls the team showed that not only was variation highest amongst the sample from south eastern Africa but that it did decrease at the same rate as the genetic data the further the skull was away from Africa.
To ensure the validity of their single origin evidence the researchers attempted to use their data to find non-African origins for modern humans. Research Dr Francois Balloux explains: "To test the alternative theory for the origin of modern humans we tried to find an additional, non-African origin. We found this just did not work. Our findings show that humans originated in a single area in Sub-Saharan Africa."
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-------------------- The Complete Picture of the Past tells Us what Not to Repeat Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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posted
Hey whiskey, I wonder what ever happened to those OOA Chinese that populated Europe? Records show that the early people of Europe were Chinese. What happened to them? Ah, they lost their history so they died.... Posts: 4165 | From: jamaica | Registered: May 2008
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quote: Hey whiskey, I wonder what ever happened to those OOA Chinese that populated Europe?
False interpretations won't fly, you clown. Europe was populated from East Asia, as all geneticists state and Cavalli states, which is in line with OOA. At this time humans still resembled Oceanic's. Modern day Chinese and European pale phenotype is a recent evolutionary adaptation.
quote: What we know of the occupation of different continents (1) shows that West Asia was first settled around 100,000 years ago, although perhaps not permanently. Oceania was occupied first from Africa, more or less at the same time as East Asia (both probably having been settled by the coastal route of South Asia), and then from East Asia both Europe and America were settled, the latter certainly from the north, via the Bering Strait (then a wide land passage).---Sforza
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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quote: Hey whiskey, I wonder what ever happened to those OOA Chinese that populated Europe?
False interpretations won't fly, you clown. Europe was populated from East Asia, as all geneticists state and Cavalli states, which is in line with OOA. At this time humans still resembled Oceanic's. Modern day Chinese and European pale phenotype is a recent evolutionary adaptation.
quote: What we know of the occupation of different continents (1) shows that West Asia was first settled around 100,000 years ago, although perhaps not permanently. Oceania was occupied first from Africa, more or less at the same time as East Asia (both probably having been settled by the coastal route of South Asia), and then from East Asia both Europe and America were settled, the latter certainly from the north, via the Bering Strait (then a wide land passage).---Sforza
I'm just going to throw this out. What are his "core populations" his ancestral archetypes?
"The phylogenetic and spatial distribution of its equivalent in Europe (Cruciani et al. 2002), the R1-M173 (xM17) lineage for which considerable data exist (Semino et al. 2000a; Wells et al. 2001; Kivisild et al. 2003) implies that R1b3-M269 was well established throughout Paleolithic Europe, probably arriving from West Asia contemporaneous with Aurignacian culture.
Although the phylogeographic pattern of R1b3-M269 lineages in Europe suggest that R1-M173* ancestors first arrived from West Asia during the Upper Paleolithic, we cannot deduce if R1b3-M269 first entered Anatolia via the Bosporus isthmus or from an opposite eastward direction. However, archeological evidence supports the view of the arrival of Aurignacian culture to Anatolia from Europe during the Upper Paleolithic rather than from the Iranian plateau (Kuhn 2002)."
-------------------- The Complete Picture of the Past tells Us what Not to Repeat Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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posted
Yes, it was already known, which is why it says "recap" above.
On second thought, it had occurred to me that you might well be referring to the head post. Please clarify!
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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posted
Hope it stays that way, which is usually a daunting task these days.
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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posted
^ Then in answer to your question - 'already known'.
"We show that distance from sub-Saharan Africa is the sole determinant of human within-population phenotypic diversity."
^ No, I don't think most people know this.
Many people seem to think the diversity in Africa comes from admixture from Arabs and Europeans.
And diversity in Europe or Arabs would be indigenous.
Or perhaps I should say - 'that's what many people *want* to believe'.
However such wishful thinking makes no sense, and is close to being the exact opposite of what is true. Posts: 15202 | Registered: Jun 2004
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posted
It should be noted that Western anthropologists/geneticists continue to make the faux-race derived concept of "sub-Saharan Africa"--which in reality is a vast area with maximal genetic diversity.
I put it down to their naive and historic "phenotype explains all" mindset they don't ever seem capable of shaking off.
Posts: 5492 | Registered: Nov 2004
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quote:Originally posted by rasol: ^ Then in answer to your question - 'already known'.
"We show that distance from sub-Saharan Africa is the sole determinant of human within-population phenotypic diversity."
^ No, I don't think most people know this.
Many people seem to think the diversity in Africa comes from admixture from Arabs and Europeans.
And diversity in Europe or Arabs would be indigenous.
Or perhaps I should say - 'that's what many people *want* to believe'.
However such wishful thinking makes no sense, and is close to being the exact opposite of what is true.
Exactly, what this does is put yet another road block for those who want to promote that all Africans look alike(True Negroes), when in fact as shown, Africa is the continent with the most indigenous phenotypic diversity. The farther humans get from Africa the more those populations(non-Africans) tend to actually look like one another, instead of the falsely attributed and limited genetic and phenotypic diversity given to Africa. Africa, the cradle of mankind and civilization.
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posted
I don't think such a study would negate that back migration from Asia to Africa have influenced the phenotypes of some populations, specifically in northern africa. Perhaps that is why they specified Sub-Saharan.
I tend to think that certain extreme features actually do come from Arabs. Certain groups in Ethiopia actually look kinda like Arabs. I'm assuming that groups with the very light skin and the nearly straight hair have some sort of Arab influence, whereas aquiline features are not necessarily from Europeans or Arab influence.
Posts: 72 | Registered: Aug 2008
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quote:Originally posted by Boofer: I don't think such a study would negate that back migration from Asia to Africa have influenced the phenotypes of some populations, specifically in northern africa. Perhaps that is why they specified Sub-Saharan.
I tend to think that certain extreme features actually do come from Arabs. Certain groups in Ethiopia actually look kinda like Arabs. I'm assuming that groups with the very light skin and the nearly straight hair have some sort of Arab influence, whereas aquiline features are not necessarily from Europeans or Arab influence.
Please present this evidence for a back migration, as well as some pics clarifying exactly what you mean by extreme features. Thanks
Because according to genetic evidence, Arabs didn't invade and influence the north African gene pool until 7th century C.E.
In a recent publication, Bosch et al. (2001) reported on Y-chromosome variation in populations from northwestern (NW) Africa and the Iberian peninsula. They observed a high degree of genetic homogeneity among the NW African Y chromosomes of Moroccan Arabs, Moroccan Berbers, and Saharawis, leading the authors to hypothesize that “the Arabization and Islamization of NW Africa, starting during the 7th century ad, … [were] cultural phenomena without extensive genetic replacement” (p. 1023). H71 (Eu10) was found to be the second-most-frequent haplogroup in that area. Following the hypothesis of Semino et al. (2000), the authors suggested that this haplogroup had spread out from the Middle East with the Neolithic wave of advance. Our recent findings (Nebel et al. 2000, 2001), however, suggest that the majority of Eu10 chromosomes in NW Africa are due to recent gene flow caused by the migration of Arabian tribes in the first millennium of the Common Era (ce).
While you're at it, you can tell me if this guy has any extreme features that make him look non African?
Also of note is that from over 150kya Omo I from Ethiopia, resembles modern Ethiopians and Southern Sudanese today. So much for Ethiopians getting their features from people who weren't even around yet. Good luck explaining that.
quote:"From the size of the preserved bones, we estimated that Omo I was tall and slender, most likely around 5'10" tall and about 155 pounds," University of New Mexico anthropologist Osbjorn Pearson, who co-authored at least two of the new papers, told Discovery News.
Pearson said another, later fossil was also recently found. It too belonged to a "moderately tall -- around 5'9" -- and slender individual."
"Taken together, the remains show that these early modern humans were...much like the people in southern Ethiopia and the southern Sudan today," Pearson said.
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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1)The study was not intended to negate "back-migration". Whether potential back-migration has modified some Africans from a physiological standpoint, is trivial to and has no bearing on what the study is relaying -- greatest autochthonous diversity in Africa, especially sub-Saharan Africa, vs. elsewhere.
2)Likewise, it can be said that the regions you speak of, as original points of the said back-migration, have also been impacted by gene flow from mainland Africa.
3)Though the general idea of greatest diversity in Africa had been already known by some of us well-read and learnt ones, the pattern observed in this study, about the "progressive loss of diversity" in correlation to "progressive increase of distance" away from sub-Saharan Africa is necessarily new information. It ties into loss of diversity attained in bottlenecks that generally mark migration events. "Progressive loss of diversity" obviously speaks to additional bottlenecks linked to further dispersals of OOA migrants. Plus, Rasol makes a good point about persisting ignorance and/or wishful thinking on the matter of African diversity, especially in sub-Saharan Africa.
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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quote:Originally posted by rasol: ^ Then in answer to your question - 'already known'.
"We show that distance from sub-Saharan Africa is the sole determinant of human within-population phenotypic diversity."
^ No, I don't think most people know this.
Many people seem to think the diversity in Africa comes from admixture from Arabs and Europeans.
And diversity in Europe or Arabs would be indigenous.
Or perhaps I should say - 'that's what many people *want* to believe'.
However such wishful thinking makes no sense, and is close to being the exact opposite of what is true.
quote:I tend to think that certain extreme features actually do come from Arabs.
^ then you contradict your own disclaimer.
the study states: "We show that distance from sub-Saharan Africa is the *sole determinant* of human within-population phenotypic diversity."
^ you protest out of one side of your mouth that everyone knows this, and out of the other - you actually deny this - but based on no data.
Which proves, as I stated: 'that's what many people *want* to believe', even when study after study states the opposite.
Posts: 15202 | Registered: Jun 2004
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3)Though the general idea of greatest diversity in Africa had been already known by some of us well-read and learnt ones, the pattern observed in this study, about the "progressive loss of diversity" in correlation to "progressive increase of distance" away from sub-Saharan Africa is necessarily new information. It ties into loss of diversity attained in bottlenecks that generally mark migration events. "Progressive loss of diversity" obviously speaks to additional bottlenecks linked to further dispersals of OOA migrants. Plus, Rasol makes a good point about persisting ignorance and/or wishful thinking on the matter of African diversity, especially in sub-Saharan Africa.
more:
quote:Recent studies comparing craniometric and neutral genetic affinity matrices have concluded that, on average, human cranial variation fits a model of neutral expectation. While human craniometric and genetic data fit a model of isolation by geographic distance, it is not yet clear whether this is due to geographically mediated gene flow or human dispersal events. Recently, human genetic data have been shown to fit an iterative founder effect model of dispersal with an African origin, in line with the out-of-Africa replacement model for modern human origins, and Manica et al. (Nature 448 (2007) 346-349) have demonstrated that human craniometric data also fit this model. However, in contrast with the neutral model of cranial evolution suggested by previous studies, Manica et al. (2007) made the a priori assumption that cranial form has been subject to climatically driven natural selection and therefore correct for climate prior to conducting their analyses. Here we employ a modified theoretical and methodological approach to test whether human cranial variability fits the iterative founder effect model. In contrast with Manica et al. (2007) we employ size-adjusted craniometric variables, since climatic factors such as temperature have been shown to correlate with aspects of cranial size. Despite these differences, we obtain similar results to those of Manica et al. (2007), with up to 26% of global within-population craniometric variation being explained by geographic distance from sub-Saharan Africa. Comparative analyses using non-African origins do not yield significant results.
Am J Phys Anthropol. 2008 May;136(1):108-13 von Cramon-Taubadel N, Lycett SJ. Leverhulme Centre for Human Evolutionary Studies, University of Cambridge, The Henry Wellcome Building, Fitzwilliam Street, Cambridge CB2 1QH, UK.
Posts: 5555 | From: Tha 5th Dimension. | Registered: Apr 2006
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quote:Originally posted by akoben: Hey whiskey, I wonder what ever happened to those OOA Chinese that populated Europe? Records show that the early people of Europe were Chinese. What happened to them? Ah, they lost their history so they died....
quote:Originally posted by rasol: ^ Then in answer to your question - 'already known'.
"We show that distance from sub-Saharan Africa is the sole determinant of human within-population phenotypic diversity."
^ No, I don't think most people know this.
Many people seem to think the diversity in Africa comes from admixture from Arabs and Europeans.
And diversity in Europe or Arabs would be indigenous.
Or perhaps I should say - 'that's what many people *want* to believe'.
However such wishful thinking makes no sense, and is close to being the exact opposite of what is true.
quote:I tend to think that certain extreme features actually do come from Arabs.
^ then you contradict your own disclaimer.
the study states: "We show that distance from sub-Saharan Africa is the *sole determinant* of human within-population phenotypic diversity."
^ you protest out of one side of your mouth that everyone knows this, and out of the other - you actually deny this - but based on no data.
Which proves, as I stated: 'that's what many people *want* to believe', even when study after study states the opposite.
I don't know. I'm not doubting you, but based on this study there doesn't seem to be anyway to say whether certain features are "indigenous" or not. It simply says that africa has alot more diversity than other continents. So when I said "everyone knows this" i mean everyone knows that Africans are extremely diverse, but that doesn't mean that some differences come from interactions from back migration.
Posts: 72 | Registered: Aug 2008
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quote:Posted by boofer: It simply says that africa has alot more diversity than other continents.
Boofer,
It seems you're not understanding what you're reading. Africa is the continent with the widest indigenous phenotypic diversity. The farther humans get from Africa, the more those populations(non-Africans) tend to actually look like one another(little diversity). Meaning all features around the world can be found indigenous to Africa, except the pale skin.
quote: Taking a set of measurements across all the skulls the team showed that not only was variation **highest** amongst the sample from south eastern Africa but that it did **decrease** at the same rate as the genetic data the further the skull was away from Africa.
Do tell how a small pond with limited variation in features, compared to Africa, the cradle, with a phenotypic ocean of features, will contribute to the African variation??
quote: Jean Hiernaux "The People of Africa" 1975
p.53, 54
"In sub-Saharan Africa, many anthropological characters show a wide range of population means or frequencies. In some of them, the **whole world range** is covered in the sub-continent.
Here live the shortest and the tallest human populations, the one with the highest and the one with the lowest nose, the one with the thickest and the one with the thinnest lips in the world. In this area, the range of the **average nose widths** covers **92 percent** of the world range:
**only a narrow range of extremely low means are absent from the African record.** Means for head diameters cover about 80 per cent of the world range; 60 per cent is the corresponding value for a variable once cherished by physical anthropologists, the cephalic index, or ratio of the head width to head length expressed as a percentage....."
Btw, did you even bother reading explorers post??
quote:Originally posted by The Explorer: Boofer,
1)The study was not intended to negate "back-migration". Whether potential back-migration has modified some Africans from a physiological standpoint, is trivial to and has no bearing on what the study is relaying -- greatest autochthonous diversity in Africa, especially sub-Saharan Africa, vs. elsewhere.
2)Likewise, it can be said that the regions you speak of, as original points of the said back-migration, have also been impacted by gene flow from mainland Africa.
3)Though the general idea of greatest diversity in Africa had been already known by some of us well-read and learnt ones, the pattern observed in this study, about the "progressive loss of diversity" in correlation to "progressive increase of distance" away from sub-Saharan Africa is necessarily new information. It ties into loss of diversity attained in bottlenecks that generally mark migration events. "Progressive loss of diversity" obviously speaks to additional bottlenecks linked to further dispersals of OOA migrants. Plus, Rasol makes a good point about persisting ignorance and/or wishful thinking on the matter of African diversity, especially in sub-Saharan Africa.
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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quote:Originally posted by Boofer: [QUOTE]Originally posted by rasol: [qb] So when I said "everyone knows this" i mean everyone knows that Africans are extremely diverse, but that doesn't mean that some differences come from interactions from back migration.
Ha! Ha! Ha! Ha! This is funny you guys take Boofer seriously. He probably gets off by sitting at his keyboard making sh1t up to get you guys all excited.
What kind of BS statement is the above. Hey YH!! bump the CULPRIT thread. That is more stimulating.
Posts: 12143 | From: When you have eliminated the impossible, whatever remains, however improbable | Registered: Jun 2007
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quote: Posted by boofer: It simply says that africa has alot more diversity than other continents.
^ nope. that's not all it says. your mannner of not -hearing- what the study is saying is a classic example of denial.
Let me make this clear.
The study is suggesting is that Africa is the source of much of physical diversity, and Asia, Arabs, Europeans have lesser diversity derived from that source.
"We show that distance from sub-Saharan Africa is the sole determinant of human within-population phenotypic diversity".
^ Can you explain the meaning of -sole determinant-?
Posts: 15202 | Registered: Jun 2004
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posted
I'm gonna be frank with everybody. It's not really that I don't understand what's being said. What makes it difficult is my own racial conceptions. It's stubborness, I admit. I have an idea of a "mixed" person (of 1 Afro and 1 Euro parentage) in my head. The image is not unlike some ethiopians I've seen. I have an idea also of arabs and of white people. The image is not unlike many north africans I have seen.
Another problem, when distinguishing phenotypes and ancestries is North Africa. Northern Africa seems to have a great influence from East Africa as well as Eurasia, based on mtdna.
Now based on that, it is hard for me to believe any talk that North Africans are entirely "indigenous", and it also makes it apparent why there is often a distinction between Subsaharan and North African. I also know that Y dna shows a much, much smaller Eurasian influence, but that just shows that there is influence from both.
Posts: 72 | Registered: Aug 2008
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quote:Originally posted by The Explorer: [QB] Boofer,
1)The study was not intended to negate "back-migration". Whether potential back-migration has modified some Africans from a physiological standpoint, is trivial to and has no bearing on what the study is relaying -- greatest autochthonous diversity in Africa, especially sub-Saharan Africa, vs. elsewhere.
Rasol seemed to treat it like it DID negate back migration. My comment was sort of directed at that.
quote:Many people seem to think the diversity in Africa comes from admixture from Arabs and Europeans.
And diversity in Europe or Arabs would be indigenous.
Or perhaps I should say - 'that's what many people *want* to believe'.
However such wishful thinking makes no sense, and is close to being the exact opposite of what is true.
In a nutshell, I was basically saying that, though diversity (in physical appearance)is greatest in africa and increasingly less based on the distance from africa, it does not necessarily mean that a fragment of diversity doesn't come from populations who migrated back to africa. Features I'm specifically talking about are skin color and hair texture.
quote:2)Likewise, it can be said that the regions you speak of, as original points of the said back-migration, have also been impacted by gene flow from mainland Africa.
Understood, as it would make total sense for adjacent countries to have african migrants post OOA.
Posts: 72 | Registered: Aug 2008
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posted
Boofer, you are case in point why posting this study was/is necessary, and why rasol's point is warranted.
Quite simply, cranio-metric diversity is *naturally greatest* in Africa than anywhere else, whereby -- ad nauseam now -- within-population phenotypic diversity tends to decrease as one moves *away* from sub-Saharan Africa; and so, you cannot use extra-African immigration to explain away autochthonous intra-African diversity.
Not to leave out that hair thickness or skin color has no bearing on *cranio-metric* indices.
And if you understand said *bidirectional* gene flow as you proclaim you do, then why do you treat the non-African counterparts as *primary* types, while treating the supposed African counterparts as the recipients of phenotypic modification from gene flow? And for the last time, this has no bearing whatsoever on the premise of the study at hand. Your harping on this, goes to make a case in point for what rasol was telling you, which to borrow, would make it so that you...
seem to think the diversity in Africa comes from admixture from Arabs and Europeans.
And diversity in Europe or Arabs would be indigenous.
...and that that's what you *want* to believe'!
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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------------------------------------ I'm gonna be frank with everybody. It's not really that I don't understand what's being said. What makes it difficult is my own racial conceptions. It's stubborness, I admit. I have an idea of a "mixed" person (of 1 Afro and 1 Euro parentage) in my head. The image is not unlike some ethiopians I've seen. I have an idea also of arabs and of white people. The image is not unlike many north africans I have seen.
Another problem, when distinguishing phenotypes and ancestries is North Africa. Northern Africa seems to have a great influence from East Africa as well as Eurasia, based on mtdna.
Now based on that, it is hard for me to believe any talk that North Africans are entirely "indigenous", and it also makes it apparent why there is often a distinction between Subsaharan and North African. I also know that Y dna shows a much, much smaller Eurasian influence, but that just shows that there is influence from both. ------------------------------------
Then in your own words you are simply a know-nothing numbskull spouting off his fantasy/delusions even when you have evidence that proves your fantasy/delusions are false.
Racially deluded fantasies with regards to typologies, phenotypes, culture, history are your security blanket that gets you through your sorry life.
That is the reason why you take such an unscholarly, anti-intellectual dogma in your views. Unfortunately your trashing up this forum with you're imbecillic lunacy.
Since you're a self admitted dunce who can't learn at even a basic level, it is suggested that no one give this clown anymore attention other than to administer a beatdown.
Posts: 3085 | Registered: Jan 2008
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quote:Originally posted by Boofer: I'm gonna be frank with everybody. It's not really that I don't understand what's being said. What makes it difficult is my own racial conceptions. It's stubborness, I admit. I have an idea of a "mixed" person (of 1 Afro and 1 Euro parentage) in my head. The image is not unlike some ethiopians I've seen. I have an idea also of arabs and of white people. The image is not unlike many north africans I have seen.
Another problem, when distinguishing phenotypes and ancestries is North Africa. Northern Africa seems to have a great influence from East Africa as well as Eurasia, based on mtdna.
Now based on that, it is hard for me to believe any talk that North Africans are entirely "indigenous", and it also makes it apparent why there is often a distinction between Subsaharan and North African. I also know that Y dna shows a much, much smaller Eurasian influence, but that just shows that there is influence from both.
Boofer, what is being said has nothing to do with skin color. The point being made is about ALL human features combined: skull shape, size, thickness, skeletal features and so on. And it is not about Northern Africa it is about ALL of Africa and specifically places South of the Sahara like CENTRAL and EAST Africa. The GREATEST amount of diversity is found among the populations in this region and it is NOT simply those in East Africa, it is a reference to a BROAD RANGE of people from across Central Africa.
The problem here is that African features have been STEREOTYPED for so long as simply being of ONE TYPE and not DIVERSE both within and across various African ethnic groups. Therefore, this oversimplification causes some people to see certain features as being African and others NON African, without actually KNOWING the diversity of features found around the continent. Congo by itself has hundreds of features among its population and similar things can be said about every other part of Africa. But because some people are operating under stereotypical views of Africa, detailed analysis and documentation of such wide ranging features have not been documented for Africans. Therefore, the stereotypical view of Africans as a single monolithic type are allowed to continue in the publich consciousness.
And it is not about Northern Africa it is about ALL of Africa and specifically places South of the Sahara like CENTRAL and EAST Africa. The GREATEST amount of diversity is found among the populations in this region and it is NOT simply those in East Africa, it is a reference to a BROAD RANGE of people from across Central Africa....
The above seems to be fraught with contradictions; was samples from across the continent studied, or was it just east Africa and central Africa? Do you have a citation from the source?
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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posted
While awaiting for the answer or its lack thereof, in the meantime, from another study from pretty much the same authors [albeit sans Lia Betti] but from 2007, it says...
The effect of ancient population bottlenecks on human phenotypic variation
Andrea Manica1, William Amos1, François Balloux2 & Tsunehiko Hanihara3
Abstract
The origin and patterns of dispersal of anatomically modern humans are the focus of considerable debate1, 2, 3. Global genetic analyses have argued for one single origin, placed somewhere in Africa4, 5, 6, 7. This scenario implies a rapid expansion, with a series of bottlenecks of small amplitude, which would have led to the observed smooth loss of genetic diversity with increasing distance from Africa. Analyses of cranial data, on the other hand, have given mixed results8, 9, 10, 11, 12, and have been argued to support multiple origins of modern humans2, 9, 12. Using a large data set of skull measurements and an analytical framework equivalent to that used for genetic data, we show that the loss in genetic diversity has been mirrored by a loss in phenotypic variability. We find evidence for an African origin, placed somewhere in the central/southern part of the continent, which harbours the highest intra-population diversity in phenotypic measurements. We failed to find evidence for a second origin, and we confirm these results on a large genetic data set. Distance from Africa accounts for an average 19–25% of heritable variation in craniometric measurements—a remarkably strong effect for phenotypic measurements known to be under selection.
-------------------- The Complete Picture of the Past tells Us what Not to Repeat Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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And it is not about Northern Africa it is about ALL of Africa and specifically places South of the Sahara like CENTRAL and EAST Africa. The GREATEST amount of diversity is found among the populations in this region and it is NOT simply those in East Africa, it is a reference to a BROAD RANGE of people from across Central Africa....
The above seems to be fraught with contradictions; was samples from across the continent studied, or was it just east Africa and central Africa? Do you have a citation from the source?
Contradictions of what? How can a sample of Africans across Africa be a contradiction of a report about African diversity?
quote: Using a large data set of skull measurements and an analytical framework equivalent to that used for genetic data, we show that the loss in genetic diversity has been mirrored by a loss in phenotypic variability. We find evidence for an African origin, placed somewhere in the central/southern part of the continent,
Contradict variation in features across Africa?
Are you claiming that they only used data from central and southern Africa when speaking of diversity ACROSS the continent AND the planet?
Posts: 8889 | Registered: May 2005
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posted
Doug, I suspect you can read. My question addresses your post, not what I just cited. Now, do you have an answer for the questions therein, or do you not?
What you're citing above, is from an actual paper from the authors in question. Are *you* claiming that you haven't yet read that paper, judging by the character of your question in response to the piece?
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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A mistake that you and others always seem to make is that something genotypically and phenotypically remarkable happen to humans once they cross over to other areas from the African continent.
But that's not the way how nature operates. For example: the genetic distance between West Africans and, say, the San and Twa would be greater that the genetic distance between West Africans and some non-African groups.
And recall that in terms of genetic distance Africans in general are closer to Europeans than are the former to Melanesians.
In other words, once you accept the OOA hypothesis then you would have to admit that traits that you would consider the result of back migration to Africa could have developed right there in the vast and varied environment of Africa.
If not you would have to explain how was possible for the African phenotype to have been transformed phenotypically into those of Europe and Asia-- unless there were intermediary[in a relative sense]stages that could easily have occurred in Africa proper.Posts: 5492 | Registered: Nov 2004
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But that's not the way how nature operates. For example: the genetic distance between West Africans and, say, the San and Twa would be greater that the genetic distance between West Africans and some non-African groups.
Please elaborate.
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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Off the top of my head think of the fact that haplogroup A[not the variants of E] is found among the San of Southern Africa and that the Twa of the Congo, on account of their relatively dimunitive size must have been lived in isolation for several thousands of years.
As you might note greater or lesser relative size are usually markers for genetic isolation.
Posts: 5492 | Registered: Nov 2004
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quote:Originally posted by The Explorer: Doug, I suspect you can read. My question addresses your post, not what I just cited. Now, do you have an answer for the questions therein, or do you not?
What you're citing above, is from an actual paper from the authors in question. Are *you* claiming that you haven't yet read that paper, judging by the character of your question in response to the piece?
Read your own question. It doesn't make sense.
Across Africa means across Africa. So what is the issue?
Posts: 8889 | Registered: May 2005
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posted
You don't have to beat around the bush; if you are reading-challenged, simply say so. I'll dumb it down for you, and see if that works...
You said:
And it is not about Northern Africa it is about ALL of Africa and specifically places South of the Sahara like CENTRAL and EAST Africa.
"It is about all of Africa" seems to contradict "specifically places like Central and East Africa"
You added:
it is NOT simply those in East Africa, it is a reference to a BROAD RANGE of people from across Central Africa
...which gives me the impression that you think that these two regions were the focus of the study in question, if not the places that were *actually* tested sans the rest of the continent. You mentioned Central and East Africa twice in that comment, with no mention to any other part of the continent. Hence, these questions:
was samples from across the continent studied, or was it just east Africa and central Africa? Do you have a citation from the source?
Which remain unanswered, as you *pretend* that I'm arguing against the very point of the thread, "greater diversity in Africa vs. that elsewhere", as a smokescreen to stall delivering the answers to those simple questions.
The last abstract I cited was to assist in adding some clarity to the head abstract of the thread. It doesn't absolve you from the questions above, nor was it intended to contradict the head abstract -- i.e. "greatest diversity in Africa", as you *pretend* I'm questioning.
-------------------- The Complete Picture of the Past tells Us what Not to Repeat Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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Off the top of my head think of the fact that haplogroup A[not the variants of E] is found among the San of Southern Africa and that the Twa of the Congo, on account of their relatively dimunitive size must have been lived in isolation for several thousands of years.
As you might note greater or lesser relative size are usually markers for genetic isolation.
I fail to see how haplogroup A being in San, and the size of the Twa, is indicative of greater genetic distance between these groups vs. west Africans than between west Africans vs. some non-Africans. You do realize that haplogroup A occurs in west Africa, albeit in relatively lower frequencies than say in eastern Africa or southern Africa, don't you?
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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quote:Originally posted by The Explorer: You don't have to beat around the bush; if you are reading-challenged, simply say so. I'll dumb it down for you, and see if that works...
You said:
And it is not about Northern Africa it is about ALL of Africa and specifically places South of the Sahara like CENTRAL and EAST Africa.
"It is about all of Africa" seems to contradict "specifically places like Central and East Africa"
You added:
it is NOT simply those in East Africa, it is a reference to a BROAD RANGE of people from across Central Africa
...which gives me the impression that you think that these two regions were the focus of the study in question, if not the places that were *actually* tested sans the rest of the continent. You mentioned Central and East Africa twice in that comment, with no mention to any other part of the continent. Hence, these questions:
was samples from across the continent studied, or was it just east Africa and central Africa? Do you have a citation from the source?
Which remain unanswered, as you *pretend* that I'm arguing against the very point of the thread, "greater diversity in Africa vs. that elsewhere", as a smokescreen to stall delivering the answers to those simple questions.
The last abstract I cited was to assist in adding some clarity to the head abstract of the thread. It doesn't absolve you from the questions above, nor was it intended to contradict the head abstract -- i.e. "greatest diversity in Africa", as you *pretend* I'm questioning.
I think you lack reading comprehension. The fact that you highlighted a perfectly valid and well formed English sentence and are unable to comprehend what is being said proves that.
ALL of Africa includes Central and East Africa does it not?
Therefore, you can study ALL of Africa and also focus on specific parts at the same time can you not? It isn't like I said study ALL of Africa and focus on South America, which is a contradiction.
Seems to me you are wasting time and space on the thread with nonsense.
The study used data FROM ACROSS THE GLOBE but found specific patterns of diversity in Central and Southern Africa. Is that a contradiction?
You can't call out the fact that Africans are MORE diverse than NON Africans without studying and capturing data for BOTH now can you? And does that not ALSO mean that you must also capture data from ALL Africans?
ALL humans are diverse, so ALL humans were studied, but the VARIATION in Central And Southern Africa is the MOST DIVERSE. Which follows from Sub Saharan Africa has the MOST feature diversity in human populations. No contradiction there at all.
Anything else you are confused about?
Posts: 8889 | Registered: May 2005
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posted
Doug, you know as a matter of fact, yes; one thing baffles me: the limitlessness of your stupidity.
Let's test who "lack of reading" makes a better fit...
You were supposedly attempting to correct someone else's short-sightedness by emphasizing "north Africa" even though the study deals with "all of Africa", only to replace it with your own:
If the study was focusing on "central and east Africa" as you say, how was that done so, vs. the rest of Africa?
Yes, your "finding specific patterns of diversity in central and southern Africa" would be a contradiction to your earlier "*specifically* central and eastern Africa" in two respects:
1)it doesn't say that the study is "specifically" about "central and southern Africa".
2)"central and southern Africa" is not the same as "central and east Africa".
And third, you read the abstract wrong; it makes reference to "central/southern Africa". "/" sign is not "and" in English grammar.
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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quote:Rasol seemed to treat it like it DID negate back migration. My comment was sort of directed at that.
^ this is an example of a strawmen used to destract from an 'unpleasant' truth.
the study states that Africa is the *sole determinent* of diversity.
you try to run from this by introducing 'back migration' which by definition of what this study is saying -> is utterly irrelevant.
However you prove precisely why this factual study is necessary - to refute the bias, wishful thinking, and strawman arguments, such as proferred by you.
Posts: 15202 | Registered: Jun 2004
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