In a nutshell, it seems to me that the 50kya OoAfrica model is wrong, falsified by (i) the dating of Neandertal adixture (which precedes it and could only have happened outside of Africa), (ii) the dating of human mtDNA and NRY trees in numerous papers that show a split that precedes 50kya. This in itself proves that the Upper Paleolithic (which is attested in the post-50kya period and rapidly spreads across Eurasia in a genetic Big Bang of expansion leading to the full disappearance of Neandertals by ~40kya) must have local Eurasian origins rather than being an import from Africa.
If UP is not linked to the Out-of-Africa event, then two questions arise: (i) how did the UP arise in Eurasia, and (ii) when did the Out-of-Africa event take place? The increasing adoption of a "slow mutation rate", the discovery of a potential ~100kya layer of ancestry separating Europeans from East Asians, and, on the archaeology side, the proliferation of evidence against the "coastal migration route" all hint in OoAfrica taking place much earlier than the UP revolution in answer to question (ii). Indeed, one of the few stumbling blocks of a much earlier Out-of-Africa (the date of L3~70kya) may actually be falling, if it turns out that African L3 is nested within Eurasian M+N and not vice versa. The new preprint by Rose snf Marks helps answer question (i) by proposing an archaeological scenario that derives the UP of the Levant from the MP of Arabia.
From the paper:
In sum, the tool assemblages of the early Emiran include a combination of both classic UP tool types and MP Levallois points; it cannot be accurately characterized as fully UP, rather, an amalgamation of MP and UP forms. Viewed solely within a Levantine context, the technological and typological patterning of the early Emiran might suggest it derived from local innovation without significant external demographic input.
...
So, with no clear cut antecedents in the Levant, do the three Emiran technological traits that have no deep Levantine ancestry (i.e., bidirectional core preparation, the use of cresting, and the presence of lateral modification on Levallois points), have demonstrable origins elsewhere? Conversely, do those deeply rooted Levantine characteristics of the Emiran (i.e., elongated Levallois point production and UP tool manufacture) have comparable analogues in adjacent areas?
...
Given these technological and typological considerations, we find no direct relationship between any northeast African MIS 5 industry and the early Emiran. The African data do suggest that the Emiran preferential bidirectional Levallois point production strategy ultimately arose in northeast Africa during late MIS 6. This reduction strategy became increasingly widespread during MIS 5, where it spread as far south as the Ethiopian Rift and east into the Arabian Peninsula. This wide distribution suggests extensive cultural contact, either direct or indirect, along the Nile Valley and across the Red Sea during the Last Interglacial, when climatic conditions were optimal.
...
By MIS 5.3 (~ 100 ka), perhaps, even as early as the Last Interglacial, the African Nubian Complex was widespread in Arabia, from the Yemeni Hadramawt to the eastern edge of the Nejd Plateau in southern Oman. Additional manifestations of this technocomplex have been found in the Rub' al Khali, central Saudi Arabia, and the Al Jawf basin of northern Saudi Arabia, less than 300 km southeast of ‘Ain Difla. Given the Nilotic origin of the Nubian Complex, its presence in Arabia may be firmly understood as a huntergatherer range expansion out of northeast Africa.
...
The techno-typological patterns we have observed point to an origin of the Emiran that was neither wholly rooted in the Levant nor the result of a complete demographic replacement from groups expanding out of Africa; rather, the Emiran combines elements of the Nubian Levallois system with typological elements from the southern Levantine Mousterian. This scenario envisions a zone stretching across the interface of northwestern Arabia and the southern Levant, where the territories of Levantine and Arabian huntergatherer populations overlapped during MIS 5. Bilateral exchange over time resulted in the incorporation of an Afro-Arabian core reduction strategy with a Levantine toolmaking tradition that extends back to the Early Mousterian.
...
African Nubian Complex toolmakers, at least, were modern humans. AMH specimens have been documented in North Africa from 150 ka onward (Smith et al., 2007; Hublin and McPherron, 2012), while no other species has yet been found there. An AMH child burial was excavated from an extraction pit associated with Activity Phase III at Taramsa Hill 1 (Vermeersch et al., 1998; Van Peer et al., 2010), with a terminus post quem of ca. 70 ka. Given the technological similarity of the Classic Dhofar Nubian and the Late Nubian Complex of the Middle Nile Valley in Egypt, as well as the fact that there is no evidence for prior MP human occupation in southern Oman, it is reasonable to associate the distribution of Nubian Complex sites with a population of AMHs spread across northeast Africa and the Arabian Peninsula. The presence of Nubian Levallois technology in southern Arabia and the Horn of Africa (Clark, 1954; Kurashina, 1978; Clark, 1988; Beyin, 2013), as well as northern Arabia and in the Red Sea hills of Egypt, suggests that early human groups traveled to and from Africa via both the Arabian and Levantine Corridors.It is unfortunate that Arabia is so poor (to wholly deficient?) in ancient human remains from this critical period. Nonetheless, it makes sense that if modern humans were present in Northeast Africa in association with Nubian Complex tools, they would be the ones who carried them to Arabia. The presence of AMH in the Levant (associated with Mousterian tools) was often dismissed until recently as the Out-of-Africa that failed, partly because the Shkul/Qafzeh hominins were the only pre-UP modern humans in Eurasia (making their extinction plausible) and partly because of the widespread view that Out-of-Africa happened ~70-50kya (which by definition would imply that the Mount Carmel hominins weren't the Out-of-Africa.
However, if AMH were also present in Arabia during the MP it is much more difficult to argue for extinction of Eurasian modern humans and later replacement by a "late" Out-of-Africa event: this would imply that both the Levantine and Arabian humans would disappear. Moreover, the genetics no longer requires a late Out-of-Africa event and the UP is no longer plausibly concurrent with the OoAfrica event. In short, a quite simple explanation is that one group of AMH (from Arabia) mixed with another group of AMH (from the Levant) and the UP arose in this population. The latter group (from the Levant) lived in proximity to Neandertals and thus the evidence for Neandertal admixture in non-Africans is easily explained (no need to invoke unattested Neandertals admixing with "coastal route" migrating humans).
"Out of Arabia" and the Middle-Upper Palaeolithic transition in the southern Levant
Jeffrey I. Rose, Anthony E. Marks
Beginning some 50 thousand years ago, a technological transition spread across the Near East and into Eurasia, in the most general terms characterized by a shift from preferential, prepared core reduction systems to the serial production of elongated points via opposed platform cores. The earliest known occurrence of such a technological shift is the Emiran Industry, whose earliest manifestations are found in the southern Levant. The cultural and demographic source(s) of this industry, however, remain unresolved. Looking to archaeogenetic research, the emerging picture indicates a major dispersal of our species out of Africa between 100 and 50 thousand years ago. Ancient DNA evidence points to low levels of admixture between Neanderthal and these pioneering modern human populations, which some suggest occurred in the Near East between 60 and 40 thousand years ago. These propositions underscore the significance of the Emiran and beg a reassessment of its origins. In this paper, we ask whether the Emiran was a local development, a cultural/demographic replacement, or the fusion of indigenous and exogenous lithic traditions. Our analysis considers the techno-typological features of the early Emiran in relation to late Middle Palaeolithic and contemporaneous assemblages from adjacent territories in Northeast Africa and the Arabian Peninsula, in order to identify overlapping cultural features and potential antecedents. Parsimonious with the archaeogenetic scenario of admixture, the Emiran seems to represent a fusion of local southern Levantine Mousterian typological elements with the Afro-Arabian Nubian Levallois reduction strategy. We conclude that the Emiran is primarily rooted in the Early Nubian Complex of the Nile Valley, which spread into the Arabian Peninsula during the Last Interglacial and developed at the interface of these two contextual areas between 100 and 50 thousand years ago.
Link
25 comments:
Most Africans do not have great genetic diversity (I.E Bantu) . However, because Toba did not effect Africa directly, certain Archaic groups survived as haplogroups, and africans do generally lack flood legands . Before Toba, I think all different kinds of what would now be called A,B, CT* and others would be found in Eurasia, and also Neanderthals, giving Eurasian 400,000 years of Diversity while only giving africa 200,000 years, (70KYa).
The bible and probably other ancient books, say humans came from the near east, and than a great flood killed everyone this might be a remembrance of Toba.
Indeed, one of the few stumbling blocks of a much earlier Out-of-Africa (the date of L3~70kya) may actually be falling, if it turns out that African L3 is nested within Eurasian M+N and not vice versa.
I think you misinterpreted the Rieux tree in Figure 1. Event 8 represents the colonization of Japan by mtDNA haplogroup M7a 32 kya. The 2 African tips to the right of event 8 are most likely the M1a1 and M1a5 African samples. Rieux et al did not label the branches in their tree, and their tree has about 81 tips, while they have 320 samples in their data base, so not all samples are represented in the tips. They have 17 L3 samples, including L3a. L3b, L3c, L3d, L3e, L3f, L3h, L3i, L3k and L3x. The caption of Figure 1 states that only 59 of 320 contemporary samples were used in this tree, and it appears most of L3 subclade tips were excluded - they only show 2 L3 tips close to the left side of the tree. L3 is probably represented by the major branch point some distance above event 3. The Eurasian M and N branches, and the two L3 tips all descend from this branch. This interpretation would be conistent with the current Phylotree.
"In short, a quite simple explanation is that one group of AMH (from Arabia) mixed with another group of AMH (from the Levant) and the UP arose in this population. The latter group (from the Levant) lived in proximity to Neandertals and thus the evidence for Neandertal admixture in non-Africans is easily explained (no need to invoke unattested Neandertals admixing with "coastal route" migrating humans)."
The allele frequency maps at Pypop certainly point this way. The famous HLA-B*73:01, and the HLA-C*15:05 with which it is most often associated, both peak in the Levant.
http://www.pypop.org/popdata/2008/maps/B-7301.gif
http://www.pypop.org/popdata/2008/maps/Cw-1505.gif
And HLA-C*12:02, another allele often found with B73, spread from there across Asia.
http://www.pypop.org/popdata/2008/maps/Cw-1202.gif
' the fact that there is no evidence for prior MP human occupation in southern Oman, it is reasonable to associate the distribution of Nubian Complex sites with a population of AMHs spread across northeast Africa and the Arabian Peninsula.'
maybe evidence for prior MP human occupation lies on the bottom of the Persian Gulf
' The presence of Nubian Levallois technology in southern Arabia and the Horn of Africa (Clark, 1954; Kurashina, 1978; Clark, 1988; Beyin, 2013), as well as northern Arabia and in the Red Sea hills of Egypt, suggests that early human groups traveled to and from Africa via both the Arabian and Levantine Corridors.'
so there is no proof for this ; a one way ticket from Africa to the Persian Gulf area suffieces to explain the presence of the technology in both areas
I think there are very few (Richard Klein?) who still argue for a late OOA dispersal, more or less co-incident with the MP/MSA-UP/LSA transition. Most of us accept the exit must have been with MSA/MP technology.
I made these comments to Jeff and they may be of interest here: There are recent research results which still suggest a later origin for the OOA populations of today, and the Neanderthal interbreeding. One is the soon-to-be-published Ust-Ishim femur data, which seem to pin down the Nea interbreeding found in living humans to a period between 50-60ka. And despite the debate on mutation rates, which is still an open question for the nuclear data, the mtDNA date for the first OOA populations seems to be where it was, at less than 72 ka (see recent papers by Rieux et al. and Fu et al., which use fossil mtDNA to help calibrate)...
The split of African L3 and Eurasian M+N circa ~70 thousand years ago does not necessarily coincide with the Out of Africa event. It could very well be that the common ancestor lived in Eurasia, and the African L3 represents a back-migration. We're certainly not going to find out by counting basal lineages within African and Arabian modern populations, as any old Arabians were wiped out by tens of thousands of years of desertification followed by population replacement.
The picture is much clearer for Y-chromosomes where African E is definitely nested within Eurasian variation CT = ((D, E), (C, F)). While one can imagine scenaria where CT arises in Africa and Eurasians end up having more surivivng male lineages and Africans only E, that doesn't make much sense to me, as one would expect a greater loss of lineages by drift in the smaller (Eurasian) than the larger (African) population.
Autosomal split dates in excess of 100kya between Africans and non-Africans need to be reconciled with much younger splits in mtDNA and Y-chromosomes. Back-migration into Africa would resolve this issue.
The best argument for a late OOA dispersal is the rough contemporaneity of the MP/UP and MSA/LSA transitions, as it is hard to imagine that people in Africa and Eurasia made this "quantum leap" at roughly the same time without some population movement between them.
If, however, the UP had local origins in Eurasia, the argument is turned on its head, and instead of seeking an African origin for the UP, one must seek Eurasian origins for the LSA. But the MP/UP-MSA/LSA transition wasn't some biological or genetic advantage (*) but rather a set of behaviors and technologies that appear in the post-50kya period and then spread far and wide. In Eurasia, this spread was also accompanied by the spread of modern humans beyond their Levantine-Arabian beachhead. But, in Africa, where modern humans originated, the spread was simply one of migration of a limited number of Eurasians who then admixed into the greater African population.
This could all be wrong, but I think is what happened. At least it explains the rough contemporaneity of the LSA/UP appearance:
(i) A model that derives Eurasians from Africans ~100kya but with no more gene flow fails because of the L3/E evidence.
(ii) A model that derives Eurasians from Africans ~70kya but with no more gene flow fails because it cannot well explain the contemporaneity of the LSA/UP emergence (it would require modern humans in Africa and Eurasia to make a crucial transition post-50kya in sync, spooky action at a distance).
I think the back-migration model "saves the phenomena". By proposing a pre-100kya OoA it harmonizes with the archaeology (Nubian Complex, Mount Carmel, Jebel Faya?) and the old autosomal split times. By proposing an Out-of-Arabia migration north it explains the maybe 70-50kya evidence for Neandertal admixture and perhaps the MP-UP transition as imagined by Rose and Marks. And, finally, by imagining a late back-migration into Africa it explains the shallow time depth of L3, the nesting of E within Eurasian Y-chromosomal variation, and the roughly synchronous appearance of the UP/LSA.
(*) The fact that the capacity for modern human behavior exists fully in all modern humans, including Bushmen and Pygmies with split times as old as maybe 200kya proves, I think, that modern human behavior did not arise as a biological change, but that modern humans already had the capacity (the hardware, so to speak) for the new behavior. So, the 50kya transition was a cultural, not a biological revolution.
The split of African L3 and Eurasian M+N circa ~70 thousand years ago does not necessarily coincide with the Out of Africa event.
Autosomal split dates in excess of 100kya between Africans and non-Africans need to be reconciled with much younger splits in mtDNA and Y-chromosomes.
mtDNA and Y-DNA are very crude and imperfect tracers for ancient population migrations because most of the ancient diversity in uniparental DNA has been lost. This is apparent even in the Mesolithic/Paleolithic ancient mtDNA samples which mostly represent extinct mtDNA lineages (of the 4 samples dated to 30-40 kya, B, U2*, U8c and U5, only U5 survives). I expect the extinction rate was even greater 50-70 kya, and there might have been quite a bit of diversity in mtDNA and y-DNA at that time that is lost.
So the only thing that we can conclude from mtDNA is that there was a significant OoA event ca 50-70 kya that replaced any earlier mtDNA diversity in the Levant or Eurasia. This does not preclude the possibility of earlier OoA migrations and mixing of the more recent OoA population with remnants of earlier migrations. We have to rely instead on autosomal DNA (and hopefully more ancient remains) to determine how much these earlier OoA migrations contribute to the present day diversity.
My recollection is that the split time for Bushmen and Pygmies is more like 70kya, around the time of the UP. What is the case for a 200kya date? Y-DNA A00?
@Dienekes
"I think the back-migration model "saves the phenomena".
This "back-migration" is the only ancient migration between Africa and Eurasia. There's no evidence for a 100K YBP migration. Genetic variation in Africa that looks more ancient than L3/CDEF was absorbed from local archaics. This scenario fits all the evidence.
"The fact that the capacity for modern human behavior exists fully in all modern humans, including Bushmen and Pygmies with split times as old as maybe 200kya proves, I think, that modern human behavior did not arise as a biological change, but that modern humans already had the capacity (the hardware, so to speak) for the new behavior. So, the 50kya transition was a cultural, not a biological revolution."
So, humans were biological for 150K and cultural for 50K and Eurasians made Africans cultural through a back migration? Bushmen didn't have a language until Eurasians gave them one? This is nonsense. What would make sense is if Bushmen, Pygmies and some other African populations became fully biologically and culturally human back in Eurasia but they admixed biologically with local archaics in Africa. This would be consistent with higher cultural and linguistic diversity outside of Africa.
I think that old studies looked at genetic diversity of modern humans and though humans came out of Africa. If the Papuans had Neanderthal haplogroups and people had no ancient dna trhis diversity nonsense would lead people to belong humans come from oceania.
Eurasia used to have more diversity than africa, neanderthals denisovans, but it has had many more natural disasters.
Look at
http://en.wikipedia.org/wiki/List_of_natural_disasters_by_death_toll
None of these were in africa.
Even at a mile a day, humans could walk around the world in 100 years. Climate, ecology, and sources of food have been what limited human movement not distance. Two large zones seem to be of particular importance in the movement of human beings out of Africa. One is the very large desert area that stretches across Northern Africa and Arabia. The other is the large plateau created by the collision of India with the rest of Asia that stretches across Anatolia, Iran, Afghanistan, and Tibet. Much of the evolution of modern Europeans, Asians, and Indians seems to have happened among early humans that lived throughout large parts of this plateau area. Israel, the Caucuses, and the Altai are all really border areas of this large Central Asian geography. Its very likely that both Neanderthals and Denisovans also inhabited large parts of this geography. Clearly humans did have to get through the desert to get to the plateau. Perhaps they did spend enough time in the desert to adapt genetically to its ecology. But, that process does not seem very likely. Nor does it seem likely that there is much potential for objectively deciding the question unless it becomes possible to sequence the genes of old bones well enough to understand the phenotypic implications of specific variations.
"The other is the large plateau created by the collision of India with the rest of Asia that stretches across Anatolia, Iran, Afghanistan, and Tibet. Much of the evolution of modern Europeans, Asians, and Indians seems to have happened among early humans that lived throughout large parts of this plateau area".
Absolutely.
"Clearly humans did have to get through the desert to get to the plateau. Perhaps they did spend enough time in the desert to adapt genetically to its ecology".
I think it most likely they moved through that 'desert' when it wasn't one. In other words during a time of increased rainfall through the region. This paper tends to support such a scenario.
"While one can imagine scenaria where CT arises in Africa and Eurasians end up having more surivivng male lineages and Africans only E, that doesn't make much sense to me, as one would expect a greater loss of lineages by drift in the smaller (Eurasian) than the larger (African) population".
It actually makes quite a bit of sense to me. We perhaps have a population spread through northeast Africa and into the Levant/Arabia containing a single male haplogroup: CT. Over that region the four 'sons' become regionally defined even though the haplogroup apparently splits in two first (CF and DE). E comes to dominate in Africa, F in the Anatolian region of the plateau and D and E somewhat further east and north on the plateau. From Dienekes' original post:
"In short, a quite simple explanation is that one group of AMH (from Arabia) mixed with another group of AMH (from the Levant) and the UP arose in this population".
Technological hybrid vigour?
@David Jacobson
"perhaps they did spend enough time in the desert to adapt genetically to its ecology."
Keep in mind that, intermittently from ~125,000 - 75,000, the Saharo-Arabian arid belt was significantly greener and more hospitable. It wasn't about humans adapting to this niche, it was about this niche becoming episodically habitable. It was an engine driving population movements.
"Nor does it seem likely that there is much potential for objectively deciding the question unless it becomes possible to sequence the genes of old bones well enough to understand the phenotypic implications of specific variations."
On the contrary, this is precisely what the lithic data address. Stones don't tell us necessarily what the toolmaker looked like, but they tell us what language (metaphorically speaking) they spoke. Lithic technology is culturally transmitted behavior. If we pay attention to the reduction sequences across different areas, we can map out areas with continuous populations - most notably the Nubian Complex stretching from the Nile Valley to Arabia - versus areas with clearly different culture groups such as the northern Levant, Gulf basin, and Taurus-Zagros mountains.
@ChrisS "One is the soon-to-be-published Ust-Ishim femur data, which seem to pin down the Nea interbreeding found in living humans to a period between 50-60ka. And despite the debate on mutation rates, which is still an open question for the nuclear data, the mtDNA date for the first OOA populations seems to be where it was, at less than 72 ka "
The dates you mention here seem to fit well with the archaeological scenario we have proposed in the paper. Late Levantine Mousterian assemblages (e.g., Ain Difla, Tor Faraj, Tor Sahiba) on the eastern side of the Rift Valley are not strictly Mousterian, but exhibit a combination of Nubian and Levantine Mousterian characteristics. I imagine a zone of overlapping hunter-gatherer ranges in northern Arabia/southern Levant from 100 ka to 50 ka. That blip of increased precipitation in parts of Arabia around 55 - 50 ka (Parton et al. 2013) may have facilitated range expansions.
As I said in our email exchange, a date of 72 ka BP is precisely at the onset of MIS 4 and may indicate the time at which African and Arabian Nubian Complex populations were cut off from one another. You had mentioned one hesitation for you is that the original OofAfr population should have a greater diversity of input from other parts of Africa. If we assume Van Peer is correct in his assessment of Sai Island archaeological sequence, then we have a developed Lupemban population (originating in sub-Saharan Africa during MIS 6) transitioning into the Nubian Complex in North Africa. Might this be the source of that greater diversity?
Finally, you voiced hesitation about the Taramsa child being intrusive into Activity Phase III. No argument here, particularly since we're looking at the fill of a flint extraction pit. But even if we suppose it is from Activity Phase IV or V, these are both assemblages that are technologically derived from the Nubian Complex. Moreover, we have AMH's in North Africa from 150 ka BP onward, and no other candidates in North Africa. Who else could be making the Nubian Complex? On that note, what's your current thinking on the taxonomy of Jebel Irhoud?
@Dienekes
I don't think we can equate Upper Palaeolithic (Eurasian and North African) with Late Stone Age (sub-Saharan African). These two techno-complexes, in the most general sense, are quite different from one another and arise from a different technological base. As we have argued in our paper, the UP in North Africa, Arabia, and the southern Levant developed out of the Nubian Complex. On the other hand, the earliest LSA, as manifested at sites like Enkapune Ya Muto, is a completely different suite of technologies.
That is not to say I disagree about a back migration. In Rose and Usik 2009, we argue that the Hargeisan in the Horn of Africa may be the archaeological fingerprint of a back migration (the "In through the Out Door" scenario). Indeed, Demond Clark interpreted this anomalous group of assemblages as potentially something intrusive. Unfortunately, it's going to be a long time before anyone goes back to Somalia to address this question.
@mousterian
I understand that it's difficult and/or impossible to show an archaeological connection between UP and LSA in either direction.
On the other hand, contemporaneity of emergence is difficult to accept without at least some population movement. It is not perhaps the stone tools that were moving but rather some other "key ingredient" of this transformation, like social organization, an advanced expressive language, a set of competencies in art and fashioning things. The earliest manifestation of this set of advantages in the region of the Levant is associated with one set of tools rooted in the Arabian MP as you suggest, but if its bearers expanded throughout Eurasia (and even back to Africa), they would adapt to local conditions (e.g., using bamboo in East Asia).
@ChrisS
"Most of us accept the exit must have been with MSA/MP technology."
I'm happy to hear most of you accept a much earlier exit. What MP cultures in Europe, East Asia or the Sahul show evidence for a Mid-Pleistocene origin in Africa? What skulls in Europe, east Asia or the Sahul show evidence for a mid-Pleistocene origin from an African source? For the "back-migration" the answer is easy - e.g., the Hofmeyr skull in South Africa at 36K shows UP affinities. Do you have a skull outside of Africa in mind that shows distinctly African affinities?
In the absence of ancient DNA from any MSA sites in Africa or from AMH it's impossible to say whether we are dealing with our ancestors or with an independent late hominin branch that never left Africa but was absorbed by the incoming Eurasians at 50-40,000 YBP.
"That is not to say I disagree about a back migration."
You shouldn't. It's the only migration between Africa and Eurasia that can be illustrated by genetic, anatomical, archaeological, linguistic and cultural evidence.
"one hesitation for you is that the original OofAfr population should have a greater diversity of input from other parts of Africa".
Certainly doesn't apply if the OoA population had been confined to Africans east of the Nile.
"Late Levantine Mousterian assemblages (e.g., Ain Difla, Tor Faraj, Tor Sahiba) on the eastern side of the Rift Valley are not strictly Mousterian, but exhibit a combination of Nubian and Levantine Mousterian characteristics".
Interesting. Does that mean the Nubian/Emiran technology basically didn't cross the Nile? Or was not able to? I have long believed the first modern humans to leave Africa didn't have boats, at least not very efficient ones. The major rivers, including the Ganges and Indus, would have been barriers to human expansion, not routes for it. Within Africa the Congo and Niger Rivers would also have been barriers. To me it has become apparent that humans first crossed major rivers somewhere in the headwaters, not the mouths. The invention of boats enabled a major secondary (or tertiary, or more) huge expansion.
But without boats how would the Nubian/Emiran have crossed the Red Sea? Perhaps at a time sea level was so low the Bab al Mandeb was dry land? Anyway this crossing seems to post-date the northern connection between Africa and the Levant/northern Arabian Peninsula connection. By how much?
"In Rose and Usik 2009, we argue that the Hargeisan in the Horn of Africa may be the archaeological fingerprint of a back migration (the 'In through the Out Door' scenario)".
Perhaps after boats had been invented somewhere.
Dienekes - "Autosomal split dates in excess of 100kya between Africans and non-Africans need to be reconciled with much younger splits in mtDNA and Y-chromosomes. Back-migration into Africa would resolve this issue"
Yes
And perhaps more - the nature of haploid markers themselves . Much more prone to drift , thus the apparent "young age" assumed for AMHs from Y-DNA could be a veneer of recent expansive gene flow overlying much older , more complex history
Of course this would apply not only to the question of AMHs, but to other more regional topics, eg the problem of near -fixation of R1b in Western Europe and the Gordian Knot explanations it invites
I agree with the general idea - a sequence of "Out of x" events
(in my view starting with an "Out of the Tropics" event and including back flow everywhere except back into the tropics because of losing resistance to tropical diseases)
but
"the proliferation of evidence against the "coastal migration route"
given the rise and fall of sea level over the various ice ages and us being currently at a peak then 99% of any evidence that exists for ancient coastal migration is going to be under the sea.
For example
http://www.bbc.co.uk/news/science-environment-26025763
"Scientists have discovered the earliest evidence of human footprints outside of Africa, on the Norfolk Coast in the East of England.
The footprints are more than 800,000 years old and were found on the shores of Happisburgh."
so I don't think a lack of evidence from the current coast line means a lot.
#
Also
"leading to the full disappearance of Neandertals by ~40kya"
I think 1/2 neanderthal, 1/4 neanderthal, 1/8 neanderthal etc populations are likely to have survived until much more recent times - but in the most hard to reach places.
People in Eurasia didn't become 2-4% Neanderthal on average over night. Some of their ancestors must have been 50/50 once and some of them living in regions most suited to them - up mountains for example - may have stayed that way for a long time.
"the apparent 'young age' assumed for AMHs from Y-DNA could be a veneer of recent expansive gene flow overlying much older , more complex history"
Almost certainly the case. In fact we can imagine, to some extent, that as haploid DNA moves through a-DNA populations it alters them only to a limited extent. As haploid DNA moves it mixes with the pre-existing population, the haploid DNA being carried by technological or cultural expansions. Obviously those expansions carry their own a-DNA for at least the beginning of the expansion but the a-DNA they carry changes the further from the source the expansion reaches. Ultimately the technology and even culture outrun even the haploid expansion. We see a similar situation in language expansion where languages often travel way beyond any genetic expansion.
"given the rise and fall of sea level over the various ice ages and us being currently at a peak then 99% of any evidence that exists for ancient coastal migration is going to be under the sea".
I don't know how far you've ever tried to walk along a coastline. Of course it is possible to walk long distances along sandy beaches but most of the coast in the world is either huge cliffs or extensive mangrove swamps, impossible to traverse. In many cases it is not even possible to move in the same direction until moving far inland, a situation that could hardly be called 'coastal'. The 'great southern coastal migration theory' has never made even the slightest sense to me.
"I think 1/2 neanderthal, 1/4 neanderthal, 1/8 neanderthal etc populations are likely to have survived until much more recent times - but in the most hard to reach places".
The '2-4% Neanderthal' equates to something between 1/16 and 1/64, say 1/32. The last proportion is equivalent to having a single Neanderthal great great grandparent. So yes, 'People in Eurasia didn't become 2-4% Neanderthal on average over night'.
@ChrisS AND @Mousterian
Haven't heard any response from either of you. Does it mean that you acknowledge that there's no archaeological/paleontological evidence for a worldwide expansion of an African population at 100K, while all the evidence supports an entry into Sub-Saharan African from Eurasia at 50K?
I know there's no evidence for the former. It'd be good to hear from you if you think I'm mistaken and, if so, why.
Anybody know the specific Neanderthal percentage for Ust-Ishim? I just see "slightly higher" than people today.
@GermanD
I can't speak for the paleontological evidence because I am no expert and, in my opinion, the sample sizes do not allow for any sweeping statements about population distribution during this period. As for the archaeological evidence, I think my position is fairly clear from our draft paper here. In simple terms: there is an expansion of Nubian Complex toolmakers from NE Africa into the Arabian Peninsula during the Last Interglacial. There is then a subsequent expansion out of Arabia sometime between 60 - 50 ka BP. The evidence for this is manifested in core reduction strategies, in which we see a spread of bidirectional point production that is considered the hallmark of the Initial Upper Palaeolithic throughout Eurasia.
@Grey
It is important to keep in mind the bathymetry of the South Arabian coastline. There is virtually no continental shelf between the Bab al Mandeb in SW Yemen and Duqm in central Oman. The modern coastline is more or less the same as it was throughout the Late Pleistocene. The evidence simply isn't there. That is not to say coastal environments did not play a significant role in the post-Arabian expansion across South Asia, just that early modern humans did not exploit marine environments during their tenure in southern Arabia.
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