150,000-year palaeoclimate record from northern Ethiopia supports early, multiple dispersals of modern humans from Africa Henry Lamb C. Richard Bates, Charlotte L. Bryant, Sarah J. Davies, Dei G. Huws, Michael H. Marshall & Helen M. Roberts
quote:Abstract Climatic change is widely acknowledged to have played a role in the dispersal of modern humans out of Africa, but the timing is contentious. Genetic evidence links dispersal to climatic change ~60,000 years ago, despite increasing evidence for earlier modern human presence in Asia. We report a deep seismic and near-continuous core record of the last 150,000 years from Lake Tana, Ethiopia, close to early modern human fossil sites and to postulated dispersal routes. The record shows varied climate towards the end of the penultimate glacial, followed by an abrupt change to relatively stable moist climate during the last interglacial. These conditions could have favoured selection for behavioural versatility, population growth and range expansion, supporting models of early, multiple dispersals of modern humans from Africa.
doi:10.1038/s41598-018-19601-w
Posts: 1781 | From: New York | Registered: Jul 2016
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What's the significance of this? Is it gonna be controversial for some reason?
Posts: 44 | From: West Bumble... | Registered: Apr 2017
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Breathing room for this.... It's just Ironic how procedural these articles appear.
Posts: 1781 | From: New York | Registered: Jul 2016
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So they're effectively obfuscating the validity/invalidity of that claim?
Posts: 44 | From: West Bumble... | Registered: Apr 2017
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This is a bunch of Welsh geologists studying palaeoclimatology of Ethiopia and vaguely tieing it in to origins of modern humans, which was completed before the L3 preprint was even posted.
The L3 preprint (which I haven't read) is three Canarian (and one Saudi) geneticists who have been studying human mitochondrial DNA. Specifically one of them was working on broad patterns of haplogroups M and N and figured that both had primarily expanded from the southeast to the northwest in Eurasia based on TMRCAs of different subclades. His original interpretation was that modern humans had travelled eastward through northern Asia before a population expansion in the tropics. I guess he is now just putting the original movement much further back.
Clearly it is an interdisciplinary Welsh-Canarian conspiracy though.
Finds of very early yet quite modern-looking human fossils from East and Southeast Asia have been piling up over the last few years, leading people to believe that modern human migrations out of Africa prior to the main expansion of people ancestral to living non-Africans ~60-50 thousand years ago were more extensive and successful than previously thought.
Between about 130 and 70 thousand years ago (MIS 5) there were several wet periods that would have allowed humans to cross the Saharan or Arabian deserts out of Africa and generally seem like they'd have been better for that than anything after 70 thousand years ago (MIS 4-3). The hypothesis that the successful expansion of proto-Eurasians was from a population that had left Africa during MIS 5 rather than a fresh Out-of-Africa population in MIS 4 or 3 is certainly not new (Dienekes was arguing this back in 2011). There is nothing unreasonable about considering that this early Out-of-Africa was *the* Out-of-Africa and the later one is spurious. But if so it is probably older than the breakup of mt hg L3 (and Y hg CDEF too), hence requiring a significant back-migration from Eurasia into Africa (unless the TMRCAs are way off).
So the main hypothesis is that the Out-of-Africa migration which gave rise to living non-Africans occurred about 70-50 000 years ago and the earlier dispersal made little to no genetic contribution to people today. The alternative (rarely even mentioned in academic studies) is that the early dispersal was the big event and there was a substantial Back-to-Africa migration later on. There is not, as far as I know, any convincing archaeological trail going in either direction (please point it out if you do know!). Genetic evidence IMO favours the former scenario but does not completely rule out the latter.
Posts: 660 | From: Canada | Registered: Mar 2017
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Since when is climate condition proof of OOA migrations for this time period? It seems the authors are simply jumping to conclusions based on one finding. The only way OOA migrations for that time period can be confirmed is through skeletal remains in Eurasia if not cultural remains. The former is preferable as it is more conclusive since the latter could be attributed to archaic species as is shown in this paper that Swenet cited.
quote:Originally posted by Elmaestro: Breathing room for this.... It's just Ironic how procedural these articles appear.
According to that paper they're simply stating that it's a possiblity that L3 coalesced in Eurasia before back-migrating to Africa but unless they find evidence of ancestral L3'4 in Asia or/and an archaeological site in Asia Pre-Toba in age that is derived from an African one, then it is just wishful thinking. And of course they propose the same Eurasian origins in regards to a paternal counterpart in this case YAP+ (DE). Though the highest frequency of DE* to date yet is found in Africa.
-------------------- Mahirap gisingin ang nagtutulog-tulugan. Posts: 26252 | From: Atlanta, Georgia, USA | Registered: Feb 2005
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I've always wondered about these failed attempts at OOA expansion. If a climatic or other natural disaster hit which impeded further expansion, did these early populations just die off or simply turned around and came back to Africa? If it's the latter then I could see the possibility of 'Eurasian' origins followed by back-migrations, but this begs the question if L3 and/or DE developed in Eurasia i.e. Southwest Asia exactly how "Eurasian" were these populations to begin with it?
Not only is Southwest Asia (the Levant and Arabia) right next to Africa, but geologically and biogeographically they are continuous with Africa with the Arabian plate seperating from the African plate and the Rift Valley system extending all the way to the Jordan Valley. An African population moves there and lives there a little while only to move back to Africa sounds like the Beringian/American back-migrations to Asia.
-------------------- Mahirap gisingin ang nagtutulog-tulugan. Posts: 26252 | From: Atlanta, Georgia, USA | Registered: Feb 2005
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It's weird that no researcher has sampled DNA from these early OOA AMHs yet. All that would have to be done is taking a Eurasian AMH sample that's older than 55ky ago (i.e. aDNA older than M, N, C, F, D and E). They've already done this with even older samples (e.g. Neanderthals) that have good coverage, so there is no technical hurdle preventing us from sequencing their aDNA.
I've been waiting a long time for this to happen, and it's not adding up that it hasn't happened yet. Researchers are accidentally and randomly discovering unforeseen archaics like Denisovans, and unknown arhaics who donated ancestry to Denisovans, but no progress whatsoever on pre-Toba Eurasian AMHs?
Based on chance their aDNA should have already been found. We have more than 20 archaic human aDNA samples (including mtDNAs and autosomal samples), but no pre-Toba AMH aDNA. The picture that is emerging is a picture that supports certain ideas of the establishment (like the idea that there were only archaics in Eurasia prior to a single OOA after which Africans and Eurasians supposedly became isolated), even though this established OOA notion is wrong. Statistically this discrepancy means early OOA AMH aDNA will be published very soon, or... I'm going to have to assume something is not adding up about the premise of random aDNA sampling.
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^ Dude, I've been wondering about the same exact thing! Folks keep postulating earlier pre-Toba OOA but never any genetic data from such existing populations yet we keep getting data about this archaic species and that one and another one over here! LOL It's like these experts better put up the data or shut-up altogether.
-------------------- Mahirap gisingin ang nagtutulog-tulugan. Posts: 26252 | From: Atlanta, Georgia, USA | Registered: Feb 2005
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I have to ask why these writers keep postulating prehistoric back-migrations to Africa on such flimsy evidence. It's almost like they have some secret, or maybe subconscious, agenda, but what on earth could it be?
quote:The early, multiple dispersal model supported here dispenses with the anomalously long time gap between modern human emergence and behavioural, technological advances in southern Africa that could have driven demographic expansion within Africa at ~80–60 ka, with subsequent dispersal into Asia 35.The contrast between favourable interglacial conditions at Tana and contemporaneous mega-droughts at Malawi supports the view that north-eastern rather than southern Africa was the principal region of AMH increase and dispersal.
They're trying to challenge Mellars et al's positions here. @Djehuti. Remember that researcher we discussed days ago?
Since a MIS 5 OOA migration is consistent with Mellars' model, I don't see how Lamb et al 2018 "dispense" with anything. Mellars et al acknowledge the presence of humans in South Asia during MIS 5. The blue bar in the righthand model shows that Mellars puts humans in Eurasia during MIS 5. The model on the left is what Lamb et al 2018 subscribe to: continuation between living Eurasians and the humans that were there since MIS 5:
Another thing: other researchers have already preceded Lamb et al 2018 in pointing out these wet climate episodes. For instance:
All Lamb et al are doing, is confirming these old discoveries also apply locally, in northern Ethiopia. There is no new discovery here that changes anything as far as OOA migrations. Africa's history is filled with periods of climatic amelioration. So what? That's old news. The point of contention is which of these opportunities for OOA migration contributed primarily to living humans. The point of contention isn't whether or not humans migrated out of Africa several times. You can't take a bold position on the former point of contention, when you're merely addressing the latter point of contention (which has already been settled decades ago).
There is nothing here that allows them to pin-point which of these climate-driven expansions contributed to living humans inside of Africa, let alone to living humans outside of Africa. If anything, this paper shows that, when researchers want something to be true, they'll happily lower the bar of evidence and sensationalize their findings. Just like in that L3 backmigration paper (Cabrera et al), where they blatant admit that the Y-DNA specifics don't support them. They tried to reconcile the shaky Y-DNA correlations by saying there must be problems with dating that cause CT and L3 to be misaligned.
quote:In the same way, the exit of the companion men could be dated at the split of branch CDEF-M168 from B-M181 about 86-120 kya [59, 90]. However, given the inaccuracies of the molecular clock, we rather prefer to trust on the fossil and climatic records to establish the out of Africa of early modern humans across the Levant around 125 kya as the most favorable period.
"we rather prefer to trust on the fossil and climatic records". Oh, I'm sure you do. Because the uniparentals damn sure aren't cooperative.
Posts: 8785 | From: Discovery Channel's Mythbusters | Registered: Dec 2009
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quote:Originally posted by Djehuti: ^ Dude, I've been wondering about the same exact thing! Folks keep postulating earlier pre-Toba OOA but never any genetic data from such existing populations yet we keep getting data about this archaic species and that one and another one over here!LOL It's like these experts better put up the data or shut-up altogether.
With all the multiregionalists in China claiming they're descendants from Chinese archaics you would think we'd have some early AMH aDNA from China, by now.
Posts: 8785 | From: Discovery Channel's Mythbusters | Registered: Dec 2009
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quote:Originally posted by Swenet: It's weird that no researcher has sampled DNA from these early OOA AMHs yet. All that would have to be done is taking a Eurasian AMH sample that's older than 55ky ago (i.e. aDNA older than M, N, C, F, D and E). They've already done this with even older samples (e.g. Neanderthals) that have good coverage, so there is no technical hurdle preventing us from sequencing their aDNA.
From what I hear some have been tried, without success so far. DNA is not always going to be preserved. Hopefully it will eventually be managed but it's not like you can just dig up an 80 000 year old tooth from the humid tropics and expect to recover DNA. Denisova Cave is in the mountains in Siberia, the supposed early AMH fossils are from Southern China, Laos, Philippines AFAIK. I'm told modern humans are tropically adapted or something.
The archaic humans we do have DNA from are all from relatively far north. We don't even have Levantine Neanderthal DNA.
Posts: 660 | From: Canada | Registered: Mar 2017
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^ DNA like all organic material is best preserved in dry cold conditions this is why ancient DNA is hard to come by.
quote:Originally posted by Swenet:
quote:Originally posted by Djehuti: ^ Dude, I've been wondering about the same exact thing! Folks keep postulating earlier pre-Toba OOA but never any genetic data from such existing populations yet we keep getting data about this archaic species and that one and another one over here!LOL It's like these experts better put up the data or shut-up altogether.
With all the multiregionalists in China claiming they're descendants from Chinese archaics you would think we'd have some early AMH aDNA from China, by now.
LOL The Chinese, specifically the government, are unsurprisingly worse than the Egyptian government when it comes to propaganda about their heritage. This should come as no surprise considering their facsist form of governing. Are you aware they are even hailing Peking Man (an east Asian variant of H. Erectus) as ancestral to Chinese people?!
The even have a world heritage site dedicated to him!
Well I guess this is better than the traditional national mythology of the Chinese being created by mud from the Yellow River by the goddess Nu-Wa. LOL
quote:Originally posted by Swenet: It's weird that no researcher has sampled DNA from these early OOA AMHs yet. All that would have to be done is taking a Eurasian AMH sample that's older than 55ky ago (i.e. aDNA older than M, N, C, F, D and E). They've already done this with even older samples (e.g. Neanderthals) that have good coverage, so there is no technical hurdle preventing us from sequencing their aDNA.
From what I hear some have been tried, without success so far. DNA is not always going to be preserved. Hopefully it will eventually be managed but it's not like you can just dig up an 80 000 year old tooth from the humid tropics and expect to recover DNA. Denisova Cave is in the mountains in Siberia, the supposed early AMH fossils are from Southern China, Laos, Philippines AFAIK. I'm told modern humans are tropically adapted or something.
The archaic humans we do have DNA from are all from relatively far north. We don't even have Levantine Neanderthal DNA.
Since aDNA extraction is usually not announced beforehand, we don't know to what extent all results are published without censoring or shelving undesired results. There have been aDNA sequencing efforts that were dropped because they were deemed to go against "national interests". Researchers have hinted hinted at aDNA work several times, but these results were never published. To assume these are just incidents, would be to assume that scientists (and the governments that may be employing them) don't have biases. Since aDNA extraction is not announced beforehand, researchers can theoretically sequence aDNA with the intention to publish, and then cop out because the results were not to their liking. If that has happened, and people in the know don't want you to know, you would never know. And we have at least two examples of something similar happening. And in these cases, we only know about it because it was reported in the press.
Also, researchers don't justify their sampling choices. Why were the Natufians sampled in the north? Why was the recent Egyptian aDNA sampled in the north? Why is there no justification why most Egyptian aDNA samples date to the latest periods? Is it a coincidence that the Taforalt and Afalou aDNA samples are very old compared to Egyptian ancient DNA? Why is Egyptian aDNA of a similar age lagging behind? Is it a coincidence that the first old North African aDNA was taken from samples that have a history of being described as European (Afalou and Taforalt)? Could it be that we don't have aDNA of the same age in Egypt, because no Late Palaeolithic/Epipalaeolithic remains there have a history of being described as European? Is it a coincidence that a supposed lack of SSA ancestry is on the forefront of the minds of all authors of North African aDNA papers? Why are they more concerned with a SSA presence, than with finding the indigenous North African component or with finding out when the non-African lineages arrived?
Given this weird obsession with denying SSA influence, how do we know other samples with unexpected results were never shelved? One can apply similar questions to Eurasian samples. There are examples of DNA enthusiasts online, who aren't even sequencing DNA, who are distorting published results. So why would I automatically put it past researchers that they can do the same thing?
quote:Originally posted by Swenet: Lastly, you'll note that the webmaster of that site has rejected some of the African haplogroup assignments and offered his own. There are also suspicious omissions. For instance, TM-11 conveniently doesn't have its L2 assignment listed and its haplogroup assigment box is empty. The other Tres Montes individual with the same hg isn't even listed. Just be mindful of that.
quote:Originally posted by Djehuti: ^ DNA like all organic material is best preserved in dry cold conditions this is why ancient DNA is hard to come by.
quote:Originally posted by Swenet:
quote:Originally posted by Djehuti: ^ Dude, I've been wondering about the same exact thing! Folks keep postulating earlier pre-Toba OOA but never any genetic data from such existing populations yet we keep getting data about this archaic species and that one and another one over here!LOL It's like these experts better put up the data or shut-up altogether.
With all the multiregionalists in China claiming they're descendants from Chinese archaics you would think we'd have some early AMH aDNA from China, by now.
LOL The Chinese, specifically the government, are unsurprisingly worse than the Egyptian government when it comes to propaganda about their heritage. This should come as no surprise considering their facsist form of governing. Are you aware they are even hailing Peking Man (an east Asian variant of H. Erectus) as ancestral to Chinese people?!
The even have a world heritage site dedicated to him!
Well I guess this is better than the traditional national mythology of the Chinese being created by mud from the Yellow River by the goddess Nu-Wa. LOL
People in the anthro blogosphere think politics don't play a role in aDNA extraction. Personally, I don't think published aDNA is a real reflection of ancient DNA. Politics may not apply to pre-Toba AMHs. I'll give aDNA researchers more time to prove the scenario above wrong. It could be that they genuinely haven’t been sampled yet.
But as far as West Eurasian, Egyptian and Maghrebi aDNA samples, I definitely don’t think those are a real reflection of aDNA in those regions. They can prove me wrong by sampling skeletal remains with African features, and showing they’re genetically indistinguishable from other samples that don’t have those features. Of course, that will never happen in any systematic way. What happens instead is a selectiveness in choosing aDNA samples. Hence, the recent Natufian samples from northern Israel, which supposedly lack SSA ancestry. Let’s see aDNA from more southern, Shuqbah Natufians, which were specifically described as having African features. Interestingly, some of the Shuqbah sample went "missing" for some reason, but these remains have been "found" again, recently. Which is an excellent opportunity to put what I just said, to the test.
Posts: 8785 | From: Discovery Channel's Mythbusters | Registered: Dec 2009
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Not to go off-topic but I remember someone making a good point(probably doesn't want his named mentioned) that the Egyptian government probably doesn't want certain samples released because it may damage their tourism industry if the results is something they don't like. I heard this conspiracy many times for it to be just some paranoia. Who knows?
And Southern Natufians? I did not know? I assumed Lazaridis sampled the majority of them? So the ones he sampled weren't the SSA described ones by Brace?
Posts: 1891 | From: NY | Registered: Sep 2014
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^The Natufian sample in Lazaridis et al comes from Raqefet cave, which lies west of the Sea of Galilee, while the Shuqbah cave lies west of the Dead Sea.
On my blog I talked about the Shuqbah Natufians and heterogeneity in the Natufian sample. I will do another blogpost addressing this and my latest thoughts on Natufians. You will be very surprised. The Levant was one big melting pot. It was supposed to come out early Januari this year, but I can't continue work on it right now. But I will publish it in March, probably.
Anyway, this is a whole 'nother subject. As you said, let's not go off-topic.
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Eh, well, bias, political pressure, even conspiracies do exist.
But to suppress a sample because you don't like the unexpected results - that means everyone in the lab colluding in scientific misconduct, and throwing out hard-earned and expensive results that could have got high-profile publications... for what?
yeah, I don't buy it. If they found frigging aliens or something - okay, yeah. But who the fuck cares if Natufians have Sub-Saharan African affinity or whatever? (Yeah, basement-dwelling nazis, no one cares what hurts their feelings.)
Posts: 660 | From: Canada | Registered: Mar 2017
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quote:Originally posted by capra: Eh, well, bias, political pressure, even conspiracies do exist.
But to suppress a sample because you don't like the unexpected results - that means everyone in the lab colluding in scientific misconduct, and throwing out hard-earned and expensive results that could have got high-profile publications... for what?
yeah, I don't buy it. If they found frigging aliens or something - okay, yeah. But who the fuck cares if Natufians have Sub-Saharan African affinity or whatever? (Yeah, basement-dwelling nazis, no one cares what hurts their feelings.)
Eurocentrism does not begin and end with NAZIs. Stop being naive. Are you pretending as if you are not aware of the history of pseudo-scientific racism in academia?
A single glance at the world of genetic-blogging shows just how resistant and even hostile people are to the idea of African genetic input in so-called Eurasia.
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It's like these experts better put up the data or shut-up altogether. 
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Because the uniparentals damn sure aren't cooperative.
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