tag:blogger.com,1999:blog-7785493.post1640762956690285665..comments2024-01-04T04:11:55.717+02:00Comments on Dienekes’ Anthropology Blog: New evidence for archaic admixture in African hunter gatherers (Lachance et al. 2012)Dienekeshttp://www.blogger.com/profile/02082684850093948970noreply@blogger.comBlogger39125tag:blogger.com,1999:blog-7785493.post-87033322821762345832015-04-06T16:58:32.066+03:002015-04-06T16:58:32.066+03:00The biggest mistake these scientists make are
1. ...The biggest mistake these scientists make are <br />1. Assuming that where there is an anatomically modern human, there is a human ancestor.<br />2. Assuming that we always absorbed archaic genes straight from the source, rather from a "ghost" or "sister" population of humans. <br />The first anatomically modern humans from south china and australia DID NOT involve into us. Maybe the african ones didnt either...or perhaps it only evolved into our female line.<br />There are more lineages of HSS that DIDNT survive than lineages that DID survive. Why does every scientist think that every amh they find had descendents that lived to the present day?Joe Lyonhttps://www.blogger.com/profile/07853388386082915414noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-70682045213702883742013-10-02T04:21:37.938+03:002013-10-02T04:21:37.938+03:00Another thing that may help in pinpointing the ori...Another thing that may help in pinpointing the original area from which most of "modern man" came, might be looking at diseases.<br /><br />Amerindians were almost wiped out by Pox which Europeans introduced. Seeing that Amerindians and Europeans are not so distantly related according to DNA shows that Pox immunity of Europeans must have come from a later stage after the split in Central Asia. This could indicate a purely European origin of Pox. Eg. <br /><br />The sickle cell found in Africa and the middle East is not present outside that areas as far as I know. If all modern humans came from central Africa there must have been some kind of Malaria resistance in all of us or the sickle cell trait must have been more widespread. Eg.<br /><br />If we could look at all diseases and find the ones that most of us have immunity against it might pinpoint an area of origin.....Bear101https://www.blogger.com/profile/02933288257706063120noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-18556847360477627832013-10-02T04:20:27.851+03:002013-10-02T04:20:27.851+03:00Another thing that may help in pinpointing the ori...Another thing that may help in pinpointing the original area from which most of "modern man" came, might be looking at diseases.<br /><br />Amerindians were almost wiped out by Pox which Europeans introduced. Seeing that Amerindians and Europeans are not so distantly related according to DNA shows that Pox immunity of Europeans must have come from a later stage after the split in Central Asia. This could indicate a purely European origin of Pox. Eg. <br /><br />The sickle cell found in Africa and the middle East is not present outside that areas as far as I know. If all modern humans came from central Africa there must have been some kind of Malaria resistance in all of us or the sickle cell trait must have been more widespread. Eg.<br /><br />If we could look at all diseases and find the ones that most of us have immunity against it might pinpoint an area of origin.....Bear101https://www.blogger.com/profile/02933288257706063120noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-25057471431807068352013-10-02T02:47:44.190+03:002013-10-02T02:47:44.190+03:00Another question or two.
If you have 10 brothers...Another question or two. <br /><br />If you have 10 brothers from the same mother and father, would their DNA and Haplogroups be mostly the same ?<br /><br /> And if they are would't it be reasonable that most would inherit the same potential for a specific mutation to happen under certain circumstances ?Bear101https://www.blogger.com/profile/02933288257706063120noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-88240349013250485002013-10-01T08:34:33.941+03:002013-10-01T08:34:33.941+03:00I'm quite new at this subject, but would like ...I'm quite new at this subject, but would like to ask some questions. Is the mutation of Genes from lets say A to B not in a very short time not caused by mixture of two subspecies ? If it is, could the different Haplogroups not count as the amount of times interbreeding took place between subspecies ? For me reading through the discussions, I get the distinct feeling that DNA of Homo Heidelbergensis or Ergaster is needed to clarify a great many maybees.Bear101https://www.blogger.com/profile/02933288257706063120noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-2440027767765199362012-08-01T05:31:24.726+03:002012-08-01T05:31:24.726+03:00"The larger question is this: if strong selec..."The larger question is this: if strong selection for certain MtDNA lineages is taking place, can we trust the ages that the mitochondrial clock gives us for when populations split? I'm not qualified to give an answer to that, but I suspect that the answer is no". <br /><br />We also seem to be in agreement here. I have very strong doubts about the molecular clock, whether for mt-DNA or Y-DNA. However it is very interesting to accept such dates presented literally and then try to draw some conclusions. Dienekes blog on Y-DNA falls into this category. <br /><br />"but it seems to me that everything we're talking about with MtDNA would probably also apply to the Y-chromosome, wouldn't it?" <br /><br />Yes. But with a subtle difference. I've been suggesting for years that mt-DNA represents selection for culture and Y-DNA represents selection for technology. So far I have had little agreement with that idea.terrythttps://www.blogger.com/profile/17327062321100035888noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-12050020454407464392012-07-31T13:48:26.285+03:002012-07-31T13:48:26.285+03:00Terryt, I can see now that we're singing the s...Terryt, I can see now that we're singing the same tune. It's precisely the logical requirement that "carriers of that mt-DNA must have had some advantage" that I was talking about. To me, the scenario where archaic autosomal DNA is retained while MtDNA is mysteriously lost, repeatedly, again and again, requires we invoke selection. But invoking selection in MtDNA lineages is its own can of worms with far reaching implications for the calibration of the mitochondrial clock. We invoke selection at our peril. It is also a bit of mathematical fudgery, if we're honest, like using imaginary "lethals" to make complex Punnet squares fit the phenotypes you see with your eyes. It's a black box cheat-- but it is sometimes also the right answer. The larger question is this: if strong selection for certain MtDNA lineages is taking place, can we trust the ages that the mitochondrial clock gives us for when populations split? I'm not qualified to give an answer to that, but I suspect that the answer is no. Also, it's late here, and I can't sleep, so I'll go ahead and throw this out there, too, and risk undermining everything I've said by going too far (always a risk in science) because I haven't thought about it deeply... but it seems to me that everything we're talking about with MtDNA would probably also apply to the Y-chromosome, wouldn't it? There is a distinct lack of archaic Y's floating around the modern gene pool.T. Kosmatkahttps://www.blogger.com/profile/12248826786957657011noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-56954666454021517892012-07-31T07:05:04.743+03:002012-07-31T07:05:04.743+03:00The relevant John Hawks link is here:
http://joh...The relevant John Hawks link is here: <br /><br />http://johnhawks.net/weblog/reviews/genomics/non-primate/polar-bears-coyne-2012.html<br /><br />This is what he starts with (in capital letters): <br /><br />"DO NOT MAKE EVOLUTIONARY TREES OF ANIMALS AND PLANTS BASED ENTIRELY ON MITOCHONDRIAL DNA (mtDNA): PLEASE USE NUCLEAR DNA WHENEVER YOU CAN. THIS IS BECAUSE mtDNA APPEARS TO MOVE MORE READILY BETWEEN SPECIES THAN DOES NUCLEAR DNA (nDNA), CAUSING A DISCORDANCE BETWEEN EVOLUTIONARY TREES BASED ON MITOCHONDRIAL GENES (‘GENE TREES’) AND THOSE BASED ON POPULATION AND SPECIES HISTORY THAT ARE DISCERNED FROM ANALYSES OF MANY NUCLEAR GENES (‘SPECIES TREES’)".terrythttps://www.blogger.com/profile/17327062321100035888noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-28538242414819215892012-07-31T07:00:38.092+03:002012-07-31T07:00:38.092+03:00"the fact remains that modern humans carry a ..."the fact remains that modern humans carry a significant amount of archaic admixture--regardless of social organisation, tribal acceptance, or whatever else-- and yet no archaic mitochondria". <br /><br />Those mt-DNA haplogroups would have been lost because the 'parent' tribes to which they belonged have become extinct. The archaic admixture present in modern humans is from members of those lost tribes who joined the incoming groups. Remember that once a new haplogroup enters a region and has children with residents half their offsprings' autosomal DNA will be from the 'indigenous' tribe. So there is an immediate mismatch between the offsprings' autosomal DNA and their haplogroup. In the case of non-human hybridisation the survival of haplogroup and autosomal DNA is more balanced. But even in that case you will find John Hawks has a post at his blog claiming introgression and replacement of mt-DNA and Y-DNA is widespread amoung animals and birds. <br /><br />"Yet, every single time, in every population in which mixture has happened, the archaic MtDNA lineage appears to have been lost. That, to me, is still a mystery". <br /><br />The carriers of that mt-DNA must have had some advantage. And I think it unlikely that the advantage lay in the mt-DNA itself. The advantage has to be something non-genetic carried by those women who emerged from Africa.terrythttps://www.blogger.com/profile/17327062321100035888noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-2312383707158435952012-07-30T09:43:33.907+03:002012-07-30T09:43:33.907+03:00TerryT, I may be dim, but it feels like we're ...TerryT, I may be dim, but it feels like we're still talking past each other. I'm not sure what you mean by: "the legacy is not as great as if we were dealing with a simple hybrid situation. People who were not actually direct members of the tribe must have been accepted in as spouses to members. But the incoming 'tribal group' with complex social organisation came to dominate"<br /><br />--That may well be true, but the fact remains that modern humans carry a significant amount of archaic admixture--regardless of social organisation, tribal acceptance, or whatever else-- and yet no archaic mitochondria. I could buy into the chance loss of archaic lineages if it happened just once, or twice, in one or two of the discreet populations where we find specific evidence for admixture. But now we're looking at admixture from Neanderthals, Denisovans, and whatever this archaic lineage in Africa was… and according to this paper, the list will go on. <br /><br />Yet, every single time, in every population in which mixture has happened, the archaic MtDNA lineage appears to have been lost. That, to me, is still a mystery.T. Kosmatkahttps://www.blogger.com/profile/12248826786957657011noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-153578414888222742012-07-30T04:15:19.696+03:002012-07-30T04:15:19.696+03:00'TerryT, I don't follow".
Sorry. ...'TerryT, I don't follow". <br /><br />Sorry. I'll try to explain. <br /><br />"Still, shouldn't these other groups have left behind a MtDNA legacy in modern populations?" <br /><br />If the spread was simply genetic we would expect to find 'ancient' mt-DNA. But if the spread was 'familial', spread by social group or 'tribe', only the direct family would leave either Y-DNA or mt-DNA. I strongly suspect that mt-DNA spread is associated with cultural innovation and Y-DNA with technological. In the first culture is largely spread from mother to daughter and in the second technology is largely spread from father to son. <br /><br />"They certainly left behind a legacy in the autosomes". <br /><br />Yes, but the legacy is not as great as if we were dealing with a simple hybrid situation. People who were not actually direct members of the tribe must have been accepted in as spouses to members. But the incoming 'tribal group' with complex social organisation came to dominate, and even eliminate previous less complexly organised populations. <br /><br />"To me, it's still a mystery that needs solved". <br /><br />I'm certainly prepared to accept any alternative explanation but to me the above seems to explain the end result adequately. <br /><br />"When population replacement takes place today, you see lots of MtDNA evidence for it. What percentage of the Brazilian population carries native American MtDNA?" <br /><br />True, but we are dealing with larger well-organised populations and the process is only a few hundred years old. What will the situation be like in 20,000 or 40,000 years time? Haplogroup lines are eliminated over time in a population of constant size. <br /><br />"There is still hunter/gatherer MtDNA banging around Europe. But nothing from the archaics that modern humans interbred with". <br /><br />Those hunter-gatherer genes are a minority though, and are more recent than are Neanderthal lines. <br /><br />" I strongly suspect that we are getting even the Big Bang idea wrong, because so much of the maths in human genetics has been built around assumptions made when OOA was king. I'm betting several small bangs with gene flow inbetween is a more accurate description of what actually happened". <br /><br />I accept both ideas. My brother says that humans are obsessed with finding single origins or single explanations for everything, but reality is much more complicated.terrythttps://www.blogger.com/profile/17327062321100035888noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-45696306808993118292012-07-30T01:14:04.372+03:002012-07-30T01:14:04.372+03:00This is a fascinating paper. I strongly suspect th...This is a fascinating paper. I strongly suspect that we are getting even the Big Bang idea wrong, because so much of the maths in human genetics has been built around assumptions made when OOA was king. I'm betting several small bangs with gene flow inbetween is a more accurate description of what actually happened.<br /><br />A word of caution re making assumption about "archaics" (time to ditch that word) in East Africa.<br /><br />The Hadza are genrally supposed to be related to the Khoisan for linguistic reasons, and the Sangawe are supposed to be related to the Hadza for geographical and cultural reasons. Given this relationship, there is no evidence to suppose they were even in East Africa 60k-1050k years ago. Their ancestors (on the distinctive line)could have been in South Africa, or at a point intermediate between their and the Khoisan's present territories.<br /><br />They could have been anywhere in Africa, or even outside it (although the last option is least probable).Belenoshttps://www.blogger.com/profile/15576215104931708232noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-25050548626504779912012-07-29T04:23:15.821+03:002012-07-29T04:23:15.821+03:00TerryT, I don't follow. You wrote: "Not...TerryT, I don't follow. You wrote: "Not if the haplogroups' spread was the product of a newly developed social structure, which did pull in a number of humans from other groups. Such certainly takes place today."<br /><br />Still, shouldn't these other groups have left behind a MtDNA legacy in modern populations? They certainly left behind a legacy in the autosomes. To me, it's still a mystery that needs solved. When population replacement takes place today, you see lots of MtDNA evidence for it. What percentage of the Brazilian population carries native American MtDNA? Lots. There is still hunter/gatherer MtDNA banging around Europe. But nothing from the archaics that modern humans interbred with. That MtDNA is missing. As is the MtDNA of ALL the archaics whose autosomal DNA we find in modern genomes.T. Kosmatkahttps://www.blogger.com/profile/12248826786957657011noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-66186919444624706032012-07-29T03:32:02.720+03:002012-07-29T03:32:02.720+03:00"L3 is irrelevant to the origin of modern hum..."L3 is irrelevant to the origin of modern humans, because modern humans existed before it. I will not repeat the arguments for the Asian origin of L3" <br /><br />In spite of what you say I find it very difficult to make a case that L3 originated outside Africa, even though some other L haplogroups are found just beyond Africa. These latter appear to be downstream members of the various African haplogroups, presumably originating and emerging from Africa after M and N had already formed. L3 is very relevant 'to the origin of modern humans' as both the haplogroups widespread outside Africa belong to it. I agree that mt-DNA is far from the only consideration though. <br /><br />"I personally suspect CT may have accompanied mtDNA L3 as it spread out of Africa, with DE either representing a subsequent migration out of Africa, or a migration back into Africa". <br /><br />That is the most likely explanation as I see it, but I agree with Dienekes: <br /><br />"It's more probable that CT originated in Asia, and one of its subclades (DE) back-migrated to Africa where it spawned E". <br /><br />Certainly the most likely scenario. DE is most likely a migration back into Africa. So just one Y-DNA and two mt-DNAs managed to emerge from Africa at that time. Previously many other lineages had obviously left Africa several times since H. erectus evolved though. <br /><br />"We don't see 'bottlenecks' of equivalent intensity associated with humans crossing from one region of Eurasian to another". <br /><br />But that huge bottleneck during the OoA (whatever that was) is perhaps evidence of a very narrow 'gateway'. More evidence against a sea crossing and evidence in favour of a Sinai Peninsula exit? <br /><br />"Then, something drastic takes place, Neandertals are wiped off in Europe, 'Denisovans' in East Asia, and eventually even the archaic humans in Africa die out, some of them absorbed by modern humans coming from Asia who absorb both the pre-existing AMH in Africa" <br /><br />I strongly suspect some 'cultural package', perhaps the development of wider social connections allowing improved survival during adverse conditions. In fact the evidence is mounting that the haplogroups expanded much more widely, and more completely, than many of the other genes. That argues against some sudden 'genetic' improvement as explanation. <br /><br />"Admixture here, admixture there, but no archaic mitochondria anywhere. A mystery, no?" <br /><br />Not if the haplogroups' spread was the product of a newly developed social structure, which did pull in a number of humans from other groups. Such certainly takes place today. <br /><br />"how many different homo species existed at the time of emergence of modern humans?" <br /><br />Personally I would prefer to use the term 'subspecies' as they obviously were capable of producing fertile hybrid offspring. <br /><br />"But we lack studies of premium dna analysis from +30ky modern human from Europe. A new model is needed, but history of admiwture could be different from continent to continent. The future will tell". <br /><br />Yes. I'm sure we would all agree with that. However we have to work with the information we have.terrythttps://www.blogger.com/profile/17327062321100035888noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-46964884694123330922012-07-28T21:03:12.185+03:002012-07-28T21:03:12.185+03:00Proofs of admixture arise from everywhere: Europe ...Proofs of admixture arise from everywhere: Europe (Neanderthal), Asia (Denisova) and Africa (unknown). At this point, Dienekes is right to point the end of Out Of Africa. I'm alos agree to consider Arabia (or around) the most plausible region to the point of origin of modern humans'colonization of the world.<br />But lots of questions don't have answer and lead to other questions: how many different homo species existed at the time of emergence of modern humans? which ones have contributed to our genes? how admixture happened (rape, birthrate,....) and so on.<br />An answer could be with the way modern human dealed with neanderthal, the only well-documented archaic homo. If the level of admixture of ancient modern human of Europe is higher then the present one, and perhaps with specific Y or Mt haplotypes (or absence of), we will have some answers. But we lack studies of premium dna analysis from +30ky modern human from Europe. A new model is needed, but history of admiwture could be different from continent to continent. The future will tell.Folkerhttps://www.blogger.com/profile/16269054619016691149noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-43532967835143553142012-07-28T06:58:07.491+03:002012-07-28T06:58:07.491+03:00Admixture here, admixture there, but no archaic mi...Admixture here, admixture there, but no archaic mitochondria anywhere. A mystery, no?<br /><br />It seems that the archaic lineages have been selectively lost from admixed populations again and again and again.T. Kosmatkahttps://www.blogger.com/profile/12248826786957657011noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-75170476869466789092012-07-27T19:07:09.535+03:002012-07-27T19:07:09.535+03:00@ brwntrd
According to these two recent studies a...@ brwntrd<br /><br />According to these two recent studies addressing archaic admixture in Africa, the genetictsts only detected archaic admixture among Africa's divergent hunter-gatherer populations, i.e. Central African pygmies (Biaka and Mbuti), the South African Khoisan (Khoe and San), and the distantly related Hadze and Sandawe in Tanzania. Traces of this admixture were detected among other African populations with known admixture from these groups, for example the Xhosa of South Africa. West Africans lacked such admixture, most notably the Mandenka of the Senegambian region.Joshua_Gaterahttps://www.blogger.com/profile/06543071588530396013noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-46917828334091649492012-07-27T18:44:42.622+03:002012-07-27T18:44:42.622+03:00When you say 'pre-modern humans mixed with loc...When you say 'pre-modern humans mixed with local archaic forms to make modern humans',<br />what does it mean to be 'pre-modern' ?<br /><br />Coelacanths, for example, can be described as living fossils anatomically but genetically there is little chance that their modern DNA sequences doesn't show up as very different from the old forms. And inversely, the 200 000 years old modern humans from Africa might have been modern anatomically (more or less) but still completely archaic genetically. Therefore could that mean that archaic admixture in genetic terms was indistinguishable from a persistence of archaic sequences present in the so-called 'modern humans' in 200 000 years old Africa?<br />These archaic sequences would have been lost by the time European and Asian O-O-Africa invaders mixed with their own local archaics.<br /><br />Great blog by the way.Calculushttps://www.blogger.com/profile/00968975589327744087noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-20003690079785850352012-07-27T15:04:01.665+03:002012-07-27T15:04:01.665+03:00@German Dziebel,
What part of "Out of Americ...@German Dziebel,<br /><br />What part of "Out of America discussion is not allowed here" don't you understand?<br /><br />You were banned recently, I let you post again anyway, but it seems that old habits die hard.Dienekeshttps://www.blogger.com/profile/02082684850093948970noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-67116011363058876712012-07-27T15:01:59.237+03:002012-07-27T15:01:59.237+03:00@Terry
"I'm sorry German but I think mos...@Terry<br /><br />"I'm sorry German but I think most of us here agree with PConroy here."<br /><br />This makes me think that I'm onto something with out of America.<br /><br />@Tobus<br /><br />"and let's not overlook Australia."<br /><br />A more likely source for modern humans than Sahara, that's for sure.German Dziebelhttps://www.blogger.com/profile/10703679732205862495noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-71484344386480306082012-07-27T14:45:01.892+03:002012-07-27T14:45:01.892+03:00Great. Now apply this same logic to mtDNA L3.
No...<i>Great. Now apply this same logic to mtDNA L3. </i><br /><br />Not sure what you mean by that. There are Eurasian-specific and African-specific clades within L3; the bifurcating structure is unknown.<br /><br />Even if it turns out that L3 in Africa includes two of the descendant clades and Asia only one (which is uncertain, but let's assume it for the sake of argument), then there is a perfectly good explanation why that would be so, without recourse to any Out-of-Africa event: deterioration of living conditions in Arabia post-70ka. <br /><br />And, of course, the biggest argument for the Asian origin of L3 is the fact that there is absolutely no evidence for Out-of-Africa at the time of its emergence, while there are much earlier archaeological links with Africa, and numerous, populous settlements of humans in Arabia at the time of the supposed "extreme bottleneck".<br /><br />The situation is different in CT, because we actually know how it bifurcates and Eurasia has 2 and Africa has 1.Dienekeshttps://www.blogger.com/profile/02082684850093948970noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-38963750148456610032012-07-27T14:22:02.764+03:002012-07-27T14:22:02.764+03:00If CT was African, and Eurasians passed through a ...<i>If CT was African, and Eurasians passed through a dramatic bottleneck, it is very strange (and improbable) that it would be Eurasians (the bottlenecked population) that would end up with two surviving lineages (DE and CF), and Africans that would end up with one (DE).</i><br /><br />Great. Now apply this same logic to mtDNA L3. <br /><br /><i>It's more probable that CT originated in Asia, and one of its subclades (DE) back-migrated to Africa where it spawned E. This was probably the carrier of certain technological and/or cultural-behavioral innovations and was thus able to almost completely outcompete the pre-existing male population.</i><br /><br />It wouldn't be that strange at all. And I'm not opposed to DE back-migrating, it's just not clear that it did.Lankhttps://www.blogger.com/profile/09164328821211694856noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-20878422077202509092012-07-27T13:48:40.815+03:002012-07-27T13:48:40.815+03:00I personally suspect CT may have accompanied mtDNA...<i> I personally suspect CT may have accompanied mtDNA L3 as it spread out of Africa, with DE either representing a subsequent migration out of Africa, or a migration back into Africa.</i><br /><br />If CT was African, and Eurasians passed through a dramatic bottleneck, it is very strange (and improbable) that it would be Eurasians (the bottlenecked population) that would end up with two surviving lineages (DE and CF), and Africans that would end up with one (DE).<br /><br />It's more probable that CT originated in Asia, and one of its subclades (DE) back-migrated to Africa where it spawned E. This was probably the carrier of certain technological and/or cultural-behavioral innovations and was thus able to almost completely outcompete the pre-existing male population.<br /><br /><i>Y-DNA bottlenecks are not anything unusual in human populations, and probably nothing new. They still happen, and probably always have. </i><br /><br />That is not really true. The massive decrease we see Out-of-Africa is not evident really evident for any other human migration (except perhaps the American one, for easy to understand reasons).<br /><br />There are differences in effective size between Eurasians, but these pale in comparison to the difference between Eurasians and Africans. We don't see "bottlenecks" of equivalent intensity associated with humans crossing from one region of Eurasian to another.<br /><br />Also, as I've said, an assumption of a bottleneck makes certain predictions, and one of them is that there will be a loss of diversity in the bottlenecked population; we observe the exact opposite in CT, where Eurasians are more diverse than Africans.<br /><br />The simplest explanation for the observed pattern is that modern humans originated in the Sahara or North Africa. The Sahara would have acted as a barrier to gene flow, which explains why archaic African DNA didn't leave Africa. Humans emanated from this primary homeland to both Asia and deeper into Africa. In neither case did they have the "tech" or behavioral adaptations necessary to replace pre-existing hominins, because for 150k years the earliest AMH co-inhabit the planet with other human types. Then, something drastic takes place, Neandertals are wiped off in Europe, "Denisovans" in East Asia, and eventually even the archaic humans in Africa die out, some of them absorbed by modern humans coming from Asia who absorb both the pre-existing AMH in Africa (the A's and B's), as well as the archaic forms that existed there and which had been incompletely assimilated by early AMHs who lacked the "killer package" that emerged near the UP boundary.Dienekeshttps://www.blogger.com/profile/02082684850093948970noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-54210167425134408322012-07-27T12:31:36.807+03:002012-07-27T12:31:36.807+03:00L3 is irrelevant to the origin of modern humans, b...<i>L3 is irrelevant to the origin of modern humans, because modern humans existed before it. </i><br /><br />That was in reference to the likely possibility of mtDNA L3 Out-of-Africans emanating from East Africa. <br /><br /><i>But, this doesn't square with the fact that within the CT clade, Eurasians possess both main subclades CF and DE, and indeed both subclades of DE (D and E), whereas Africans possess only the E twig.</i><br />Let's break that down a bit, shall we? <br /><br />Y-DNA DE is found in Africa and Tibet. D has a somewhat random distribution across the more easterly parts of Eurasia, and there's no indication it has anything to do with populations resembling modern West Eurasians. <br /><br />E is found in Africa and West Eurasia, with its West Eurasian representatives being overwhelmingly of the Y-DNA E1b1b1 clade, which is of recent African origin. So, E is basically African, D is basically Asian, and DE is found in both regions. The origin of DE is hence ambiguous, and I will not pretend to know where it originated. I personally suspect CT may have accompanied mtDNA L3 as it spread out of Africa, with DE either representing a subsequent migration out of Africa, or a migration back into Africa.<br /><br /><i>On the one hand, we are expected to believe that out of all the huge mtDNA tree only the N/M twigs made it Out of Africa due to the huge bottleneck, but the picture is completely different on the Y chromosome side. </i><br /><br />Y-DNA bottlenecks are not anything unusual in human populations, and probably nothing new. They still happen, and probably always have. <br /><br />As for mtDNA L3, I don't see what your objection is? The closest relatives of L3 did not make it out of Africa, and neither did most of its basal subclades. Looks like a bottleneck to me. Bottlenecks happen everywhere. The patterns of genetic diversity and linkage disequilibrium may or may not be related to this bottleneck.Lankhttps://www.blogger.com/profile/09164328821211694856noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-1759830472892119552012-07-27T11:47:05.397+03:002012-07-27T11:47:05.397+03:00The argument that all of "sub-Saharan Africa&...<i>The argument that all of "sub-Saharan Africa" is irrelevant to modern human origins does not hold any water. I could similarly argue that all of "Western Asia", including Arabia, is out because of Neanderthals found north of Arabia.</i><br /><br />Neandertals were a cold adapted species and have never been found in Arabia or South Asia.<br /><br />We now have evidence of archaic admixture of a deep nature in several places in Africa. Moreover, it does not appear that the two papers (Hammer and Lachance) refer to the same archaic population. <br /><br />If modern human populations lived in Sub-Saharan Africa for a long time (they evolved there), then they would have admixed with the archaic hominins, and would have carried the African archaic DNA into Eurasia. After all, they're supposed to have received Neandertal and Denisova DNA almost immediately after they left Africa, so why wouldn't they have exchanged genes with African archaics with whom they lived together for a much longer period of time?<br /><br />Moreover, if modern humans had been long established in Sub-Saharan Africa, why did it take them so long to replace local hominins (archaic forms persist down to the Holocene)? They would have had ample opportunity to do so, if they began their existence 200,000 years ago. It is not reasonable that they could not replace archaic humans in Africa over 190,000 years, but they did replace Neandertals and Denisovans in 10,000 years.<br /><br /><i> it is also the place with the richest variation of mtDNA L3 lineages.</i><br /><br />L3 is irrelevant to the origin of modern humans, because modern humans existed before it. I will not repeat the arguments for the Asian origin of L3 (http://dienekes.blogspot.com/2011/11/age-of-mtdna-haplogroup-l3-about-70.html).<br /><br />The case is much more solid for DE-YAP which is almost certainly of Asian origin. According to recent Out of Africa theory, Eurasians' incredible reduction in genetic diversity is due to them having undergone a bottleneck of Biblical proportions. But, this doesn't square with the fact that within the CT clade, Eurasians possess both main subclades CF and DE, and indeed both subclades of DE (D and E), whereas Africans possess only the E twig.<br /><br />On the one hand, we are expected to believe that out of all the huge mtDNA tree only the N/M twigs made it Out of Africa due to the huge bottleneck, but the picture is completely different on the Y chromosome side. <br /><br /><i>However, in general, I think we need to start accepting the idea that prior to the Neolithic Revolution, it's highly possible that archaics may have persisted in many parts of the world.</i><br /><br />I don't see what the Neolithic Revolution has to do with it. Archaic forms were replaced in some parts of the world long before it.Dienekeshttps://www.blogger.com/profile/02082684850093948970noreply@blogger.com