October 03, 2008

Climate history of the Sahara


Related press release
Reconstructing the climate of the past is an important tool for scientists to better understand and predict future climate changes that are the result of the present-day global warming. Although there is still little known about the Earth's tropical and subtropical regions, these regions are thought to play an important role in both the evolution of prehistoric man and global climate changes. New North African climate reconstructions reveal three 'green Sahara' episodes during which the present-day Sahara Desert was almost completely covered with extensive grasslands, lakes and ponds over the course of the last 120.000 years. The findings of Dr. Rik Tjallingii, Prof. Dr. Martin Claussen and their colleagues will be published in the October issue of Nature Geoscience.

...

The scientists were able to reconstruct the vegetation cover of the last 120.000 years by studying changes in the ratio of wind and river-transported particles found in the core. "We found three distinct periods with almost only river-transported particles and hardly any wind dust particles, which is remarkable because today the Sahara Desert is the world's largest dust-bowl," says Rik Tjallingii.
Nature Geoscience doi:10.1038/ngeo289

Coherent high- and low-latitude control of the northwest African hydrological balance

Rik Tjallingii et al.

Abstract

The evolution of the northwest African hydrological balance throughout the Pleistocene epoch influenced the migration of prehistoric humans1. The hydrological balance is also thought to be important to global teleconnection mechanisms during Dansgaard–Oeschger and Heinrich events2. However, most high-resolution African climate records do not span the millennial-scale climate changes of the last glacial–interglacial cycle1, 3, 4, 5, or lack an accurate chronology6. Here, we use grain-size analyses of siliciclastic marine sediments from off the coast of Mauritania to reconstruct changes in northwest African humidity over the past 120,000 years. We compare this reconstruction to simulations of palaeo-humidity from a coupled atmosphere–ocean–vegetation model. These records are in good agreement, and indicate the reoccurrence of precession-forced humid periods during the last interglacial period similar to the Holocene African Humid Period. We suggest that millennial-scale arid events are associated with a reduction of the North Atlantic meridional overturning circulation and that millennial-scale humid events are linked to a regional increase of winter rainfall over the coastal regions of northwest Africa.

Link

33 comments:

eurologist said...

If anyone was doubtful and still needed a convincing graph that shows the impossibility of a Northern route out of Africa for AMHs, and the same impossibility of a Levant/Iraq route to Europe, here it is.

McG said...

I don't follow your logic. Re: a northern route out of Africa? The story I would weave would start in Egypt and wend west as the climate started improving 10 - 15K BP. There would have then been a period of settling population growth. As the aridness returned; there would have been a population shift to the West and North, since the climate to the North was also improving? The presence of "stonehenge" like constructions in the Egyptian western desert are very similar to other constructions found throughout western europe?(note they predate stonehenge).

Maju said...

Me neither: there are AMH remains dated (old techs, should probably benefit from a refinement) c. 130,000 BP and related modern datations of H. sapiens artifacts in North Africa (Aterian) of c. 90,000 BP. These are reasonably coincident with the two old periods of "Green Sahara" 110-100,000 BP and 90-80,000 BP.

Furthermore, we can easily extrapolate that similar conditions would have existed in the deserts of Arabia (an extension of the Sahara mostly) allowing/restricting human use of such areas.

And, if you don't like the timings or whatever you can always consider that the Nile would be reasonably good for a living, and that could also be the case of the coastal areas of the Red Sea for people used to fishing and seafood gathering.

IMO, there is a reasonable possibility that an initial OOA migration happened in those windows, followed after 80,000 BP by a restriction due to increased aridity, the consequences of Toba eruption (c.74,000 BP) and Neanderthal expansion. This would have seen H. sapiens in Eurasia restricted to South Asia mostly (if not totally), showing the current Eurasian genetic distribution that appears largely centered in South Asia.

IMO it's at least as likely as the "rapid coastal migration" model after Toba.

eurologist said...

We are talking about 65ky to 50ky ago, based on archaeological and genetic evidence of AMHs spreading out of Africa via the coastal Indian Ocean area to Australia.

The time you mention is relevant to the harvesting of grains, and the advent of agriculture, 30,000 to 40,000 later than the populating of Asia and Europe by anatomically and, apparently, culturally modern humans.

I tried to draw attention to the large gap of a hospitable environment in the Sahara, and by proxy, in the Levant and Iraq, between about 75,000 and 15,000 years ago. Such inhospitable conditions necessitated early modern humans to follow a milder, resources-richer route along the coast, rather than following the Nile and Levant, or the two-stream area of Iraq. Once established, these people were predestined to accomplish this coastal path all the way to Australia.

On the other hand, population growth in resources-rich nowadays southern Pakistan and India drove modern humans northward along the river deltas and valleys that were rich in grazing animals. They followed these valleys and adapted to the shorter years and dryer climate by learning how to extend their already existent building structures to those circumstances, and making them more transportable.

Finally, they had to adapt all of their daily live and technology to the seasonal migration of animals in the fertile yet cool valleys, and their perennial disappearance, by developing long-term food storage (smoking and drying) and transportation technologies.

The complete tool-set of this is what is seen once these people spread out of northern Pakistan/Afghanistan into the Caucasus, and from there into two separate paths, Northern Turkey to Southern Europe in conflict with the present an climate-knowledgeable Neanderthals on one hand, and the Northern route via big game hunting to Ukraine and the Northern European plains, arriving 5,000 years later in a yet more complete technological package.

eurologist said...

Maju,

Of course we know that the earliest modern humans both were capable of doing just that, and had an opportunity to do so in the wetter climate periods. Yet, by all archeological accounts, they were not successful at establishing a permanent presence, nor an extended migration. Perhaps there was an early admixture with Neanderthals in the Levant 100,000 years ago.

However, no trace of any of this has been found to date in the genetic nor archeological record.

Things that have been found point to 60,000 years ago or less, and a coastal route, and AMHs entering the Levant (again) and Europe much later - in agreement with the climate finds.

McG said...

I have no strong opinion on the early, 50K - 75K migration out of Africa. My comment was directed toward the westward flow of mankind 10 - 15K years ago. We have refuges in the Caucasus, Balkans and Iberia. Were they peopled by the same HG's? As the Ice Age ended, the climate started improving and food became more available in western europe. I think it is plausible to imagine one early migration: 10 to 15K BP and then a second one at about 5K to 7K BP as the climate deteriorated across northern africa. Its not clear to me that the same HG's populated the different refugia?? Clearly Iberia was the domain of R1b and subsequently the Isles and northern western europe. As you go eastward, the HG mix changes fairly rapidly: I, J , G all become more populous. I think after 3 to 4K BP, people were moving in both directions?

ren said...

Maju:
Along desert rivers, there is water but no sufficient food (no relatively large game or large shellfish populations can be supported by a river, nor did the ancients have nets to catch enough fish like modern Egyptians).
Along desert coastlines, there is no water.

eurologist: A brilliant summation/harmonizing of all the data. What is your opinion of Central Asia in relation to this expansion?

Maju said...

We are talking about 65ky to 50ky ago, based on archaeological and genetic evidence of AMHs spreading out of Africa via the coastal Indian Ocean area to Australia.

The archaological evidence is less clear than you seem to think: we do not just have the evidence of H. sapeins in Palestine and North Africa before such dates but we also can see in the Indian archelogical record two things:

1. Evidence of stone blades earlier than anywhere else (dated c. 103,000 BP)

2. Cultural and therefore human continuity before and after the Toba ash layer (Jawalpuram)

The genetic "evidence" is all based in conservative (i.e. super-safe) interpretations of the fossil record (both of AMHs and of chimpanzees) and the controversial MC hypothesis. For me it is not conclusive yet.

Therefore I am strongly considering that an earlier OOA, followed by a major bottleneck c. 80-70,000 BP (and temporary loss of West Asia and North Africa to Neanderthals) is very likely. I cannot be 100% sure but I think it is a very serious posibility.

It would not contradict the coastal route model totally. Though it's clear from the archaeological data that in South Asia they spread not just along the coast but also along the main riverine routes (and inland travel/habitat may also have been the case in SE Asia and in the backflow to West/Central Asia at least to an extent) - what really argues against a purely coastal process. Oversimplifying can be most dangerous.

Yet, by all archeological accounts, they were not successful at establishing a permanent presence, nor an extended migration.

Not all archeological accounts. The archaelogy of South Asia is most important and has been largely ignored except by a few. It does seem to point to an earlier presence of H. sapiens in the area than Toba and the "conservative" account.

There are maybe other indications (old finds with unclear dates, ok: I won't say it's hard evidence) in the East that could also point to this earlier dispersal. Instead we have no direct archaeological data of the coastal route via Arabia and the genetic data supporting this route is as thin as for the mainland route through the Fertile Crescent.

terryt said...

I'm with Maju here. "we have no direct archaeological data of the coastal route via Arabia and the genetic data supporting this route is as thin as for the mainland route through the Fertile Crescent". In fact there are many arguments against a coastal route. I've already covered them elsewhere so if you insist I'll direct you to them.

It seems human expansions are generally associated with overpopulation in some region. The out of Africa expansion was probably no exception (as Dienekes covered in the previous post) therefore it is more likely to have occurred during the wetter Sahara phase 80,000 years ago, or even earlier.

This date in fact fits the mtDNA evidence anyway, but perhaps not the Y-chromosome. But there is no reason at all why the two must coincide.

eurologist said...

As to the coastal route:
- sea levels clearly have created a problem, but I am confident much will be discovered via underwater explorations in upcoming decades
- only the coastal route can explain the rapid expansion to Australia

As to earlier dates out of Africa:
- while I see no problem in principle with a date 10,000 or 20,000 earlier, the fact remains that we have overwhelming archeological evidence (in terms of out-of-Africa skeletal finds) after about 45,000 year before present, but zero (with the exception of Qafzeh) for the 50,000+ years prior.

In all of the above, I am a firm adherer to Occam's razor.

As a side note, clearly, south-east Asia would have been populated both quickly along the coast, and more slowly up the river valleys (requiring development of new technologies, and adaption to different environments). A second route, 10,000 to 20,000 years later, was north of the Himalayas eastward - originally starting with the same general group of people who ended up populating much of Europe. Note that, if starting from a sufficient population size, this does not mean that even a few thousand years later, the same Y and MT chromosomes would have survived/ dominated. People from the two routes (Asian coastal and northern) evidently met and mixed at a fairly northern Pacific coast location. IMO, only much later, with the advent of rice farming, did other northern tribes move south and spread into and mixed with southeast Asia.

ren said...

The Himalayas is "impossible" to cross. A "Central Asian" route is more logical, but I think the only convincing archaeological evidence of AMH there (at this early time period) is the possible origins of the Aurignacian at the Altai, possibly the northernmost possible reach for the capabilities of AMH at that time and location. From there it expanded southwards and then NW-wards into Europe.

terryt said...

"clearly, south-east Asia would have been populated ... quickly along the coast". And where did the required technology develop, do you think? The Hadramawt and Makran coast may be resource rich for residents but it's hardly a four lane highway, even at times of much lower sea level.

"but zero (with the exception of Qafzeh) for the 50,000+ years prior". Now that's an exaggeration!

Maju said...

@Eurologist: I don't see such a big deal with people slightly modifying their behaviour to adapt to non coastal enviroments. Surely people never stopped hunting on land and rivers also offer plenty of aquatic food and can for the most part benefit of the travel tech (boat) used at the coast as well.

It's not like they had to adapt to colder climates, what must have been some sort of real barrier.

The inland routes through South Asia have some reasonable archaeological confirmation for both the Middle and Upper Paleoltic (the age divide in India is somewhat arbitrarily traced c. 30,000 BP). Maybe pure coastal boaters were faster but all had to pass through the Ganges Delta (or alternatively follow the inland rute through the Brahmaputra river) to go to the East (SE Asia, Australia, etc.). There was no transoceanic travel at the time, that's clear.

Things that have been found point to 60,000 years ago or less, and a coastal route...

There is more: there is a very old African-related South Asian MP, that has the earliest blade tools on Earth ( c. 103,000 BP) and that shows continuity before and after the Toba ash layer (see Petraglia et al, 2007). There is also quite low high-level genetic diversity in West Eurasia, what appears pretty much inconsistent with a nearly synchronous colonization with the Asian East and Sahul that the 60-50,000 years chronology suggests.

I'd say that humans were in South Asia c. 100,000 BP, that, after the Toba bottleneck, they expanded rapidly from South Asia to the East. And that they needed more time to overcome Neanderthal hegemony (and desertic barriers) in the West.

@Ren: Altaian proto-Aurigancian, no matter how old it may be, cannot explain the colonization of East Asia and Sahul. It would be in the frame of the colonization of West Eurasia only, though it may also help to pinpoint where did the few haplogroups shared between West Eurasia and Sibero-Americans (Y-DNA P, mtDNA X) might have coalesced and branched out. It certainly does suggest, if the old TL dates could be confirmed, that inland routes were being transited c. 50,000 BP and that some peoples had adapted well not just to inland economy but also to very cold climates.

ren said...

Where did I say it was responsible for the colonization of East Asia and Sahul?
As for Q and X in "Sibero-America", it looks to be rather a post-ice age thing more and more now.

eurologist said...

ren:

The Himalayas is "impossible" to cross.

Yes, it seems quite clear that there is a continuity of occupation from Neanderthal to modern humans in Pakistan, Afghanistan, and the surrounding regions to the north and north of the Himalayas. It seems that life was very sustainable there. The paleoclimate, geography, and sufficient possible population size make this a straightforward passage region for further populating extreme western Asia and Europe to the west, and northeast Asia to the east.


terryt:

If you know of any AMH skeletal findings outside of Africa and Qafzeh, before about 45,000 years ago, please let me know.


maju:

As to rivers: again, they are clearly major migration paths for people, no one debates that. The problem with the Asian geography is that rivers predominantly lead to south-north travel, and largely end up in dead ends, when you consider the largest scales. That's why I am saying it is much faster to go along the coast. There are of course a few exceptions, the most important of them the Indus river valley, which IMO is crucial for the populating of Europe and Northern Asia.

My problem with a very early migration (say, before ~80,000 years ago) to and populating of India is that there is little evidence of early AMHs in the surrounding areas. If they were as advanced as people 40,000 to 60,000 years ago, why were they unable to populate neighboring areas, that clearly show traditional mesolithic signatures associated with earlier humans until about 50,000 years ago? Why would it take them 40,000 years or longer to get to Australia or any other place along the Asian coast?

Sure, the problem of facing and replacing Neanderthals or other earlier humans is not just a European one, it applies as well to Asia. Yet, it seems that after about 50,000 years ago, things happen very quickly. Replacement is swift, and migration takes only about 5,000 to 10,000 years to get to many if not most places in Asia and Europe. Again, the easiest explanation is that it started then.

I understand the Toba bottleneck, but if there were AMHs in India at the time, wouldn't the have been more easily replaced by freshly arriving people out of Africa, who where farther away, and thus less affected? I am currently neutral on which people should be associated with the Toba ash layer finds, but it seems that whoever they where, they had little impact for at least about 25,000 years. That is just very strange.

It does remind one though of the African analog, in that at major advances happen very late and quickly, considering that AMHs were around for at least 150,000 to 200,000 years. It seems very much like not all things were in place until perhaps 50,000 to 60,000 years ago or so.

ren said...

I repeat, "The Himalayas is/are impossible to cross," even for modern man...

As for archaeological evidence of an initial AMH peopling from Central Asia eastwards, there is nothing reliable. The same can be said for peopling westwards from Central Asia. Rather as you said, Europe was populated from the SE. There are two very good reasons for the limit. One that's obvious is the extreme cold that was always a frontier.

Maju said...

As to rivers: again, they are clearly major migration paths for people, no one debates that. The problem with the Asian geography is that rivers predominantly lead to south-north travel, and largely end up in dead ends, when you consider the largest scales.

Most relevant paper: "The southern dispersal hypothesis and the South Asian archaeological record:Examination of dispersal routes through GIS analysis", by Julie S. Field et al. Journal of Anthropological Archaelogy, 2007. Published online at sciencedirect.com (behind paywall - I can send you a copy if you wish anyhow).

There it's made pretty clear that the Narmada-Son and another semi-interior route via the Deccan are equal in orographic difficulty to the coastal route.

As mentioned before both these routes are pretty much coincident with know archaeological data for Indian MP and UP, so the GIS simulation seems to be making much sense.

My problem with a very early migration (say, before ~80,000 years ago) to and populating of India is that there is little evidence of early AMHs in the surrounding areas.

There is little evidence of nearly anything. Furthermore, there is no direct evidence of H. sapiens in South Asia until c. 36,000 BP. Would we use only that info, we would conclude that the colonization of South Asia happened after the one of Europe, Australia and Altai, among other places. Luckily we have other data to work with as stone assamblages, extended genetic info, etc.

Still there are controversial findings east of South Asia (Australia, Southern China) that, if confirmed, would point to an older OOA migration. It's not enough but absence of evidence is not evidence of absence in any case.

We do have the tool assamblages and these seem to suggest, quite strongly IMO, that there is a strong possibility of H. sapiens being in India some 100,000 years ago (and surviving Toba). We won't be sure until we find at least one well dated remain of our species but considering the scarcity of such remains even for later periods in the area, it seems that we can take a seat if we are going to wait for that uncotrovertible evidence.

Sure, the problem of facing and replacing Neanderthals or other earlier humans is not just a European one, it applies as well to Asia.

Maybe you over value H. erectus. I don't think these early people (at least for the skulls I've seen for Asia) had the brains to compete with us the same Neanderthals did. Additionally, Toba superexplosion may have helped to wipe out any resistence (except maybe for isolated pockets like H. floresiensis).

I understand the Toba bottleneck, but if there were AMHs in India at the time, wouldn't the have been more easily replaced by freshly arriving people out of Africa, who where farther away, and thus less affected?

Would there have been two migratory waves, maybe. Really, I don't see why a small group of newly arrived people would have any adantage over groups of already estabilished people anyhow: the locals should have all the advantages as soon as the situation improves, they are closer, they know the place, they don't have to cross the deserts of Arabia anymore. If H. sapiens succeeded in the colonization of Eurasia it was surely because there was little real competition and that means no other H. sapiens (Neanderthals may have been a trouble for a while though but only in the West). But, anyhow, it seems that the route from Africa got closed at some point because we see what appears the result of a single migratory event.

We do not have any particular archeological indication of change in South Asia c. 60,000 BP. We have continuity since before Toba (and maybe as early as 100,000+ years ago: Patpara blade implements) until c. 45,000 BP, when the UP appears more defined.

We know that Europe was colonized by H. sapiens c. 41-40,000 BP (excepting some parts of the Balcans that may be older) because we have the fortune of having penty of well studied archaeological data pointing out to that date very clearly, not because genetics or any speculative model hypothesis tells us that. If we want to know when the same process happened in South Asia, that appears to be the core region of Eurasian colonization, we must look at South Asian archaeology. And this does not seem to suggest any moment after Toba, unless it is already the UP c. 45,000 BP (what doesn't fit at all with what we know for the rest of Eurasia and Sahul, nor with our knowledge re. the African craddle either).

For me South Asian archaeology, with all its open questions, does seem to suggest an older colonization in the MP, stuff like the Jawalpuram, with their apparent technological connections to Africa may be missing link. But there may be more to find out.

eurologist said...

ren,

I think no one doubts that the Himalayas are impossible to cross. However, quite early, modern humans appeared north of the Himalayas all the way to the Pacific coast. IMO the only reasonable way to get there and adapt to the surroundings is via modern-day Afghanistan, Uzbekistan/ Tajikistan, Kyrgyzstan, northwest China, and Mongolia. You don't cross the Himalayas, you go around them, through valleys that in sufficiently moist times had huge herds of grazing animals and plenty of rivers and lakes.

The timing seems also right, with the same adaptations and tool set required to conquer Northern Europe, in the other direction.

Genetic evidence also has established a clear chasm between northern and southeast Asians that supports two distinct routes.

eurologist said...

maju,

Thanks for your long response, I do enjoy reading your insights. I can access papers fine, so also thanks for the link.

That paper seems like a nice attempt, but I am sure better work will follow. I think there are some serious weighting issues in this early analysis, and the assumption of origin from the Levant just seems weird, considering climate and resources.

At any rate, on the largest scales, this paper has little impact on the populating of Asia outside of India. Yet clearly, India was a huge pool that would have supported one of the largest populations during early times of Asian migrations.

Since I am more interested in the western Asian origin of Europeans, I was more thinking about Neanderthals and other Heidelbergensis off-springs in current-day Pakistan and areas north and only slightly east. Those clearly presented more of an obstacle than some remnant erectus populations.

As to the timing, if you postulate a single migration (which seems to conform to genetic analysis), but place it at 100,000 years ago, then you start getting into a number of very difficult questions, as I tried to explain before. Why did people live for 50,000 years in a very limited region of India, before being able to move anyplace else? Not even westward into the (at times sufficiently wet) Pakistan-equivalent Thar desert/large-game savanna, or up the Indus river? Is there genetic evidence for a 50,000 year isolation in India?

Again, for Africa, we know that not all AMHs were created equal. There seem to have been huge local differences in behavior and culture during the 120,000 to 50,000 year time span, or so. If there were AMHs in India by 80,000 years ago, with tools a bit different from Neanderthals, for me that is is not enough to believe that these people were in any way cognitively or culturally different from Neanderthals, or related to us. Moreover, the stone tools themselves, in a large subcontinent like India, may very well have developed asynchronously and independently with Africa or Europe.

ren said...

eurologist, there is not much evidence, if at all, for your theory on Central Asia as some sort of Eurasian cradle (it's a myth created by the likes of Spencer Wells), except that Aurignacian may have developed in adaptive, selective response to harsher climates, but it expands/is pushed southwards. Rather AMH (or most of them) reached the extremes of Siberia by following the Asian coast.

As for the division of NE Asians and SE Asians, that's been debunked for a long time now. SE Asians are mainly a Neolithic stock from "NE Asia". The original SE Asians are remnants, such as "negrito" populations that resemble Africans.

eurologist said...

ren,

I respectfully disagree based on what I explained in much detail before and overwhelming evidence, but I will no longer respond to your unexplained one-liners.

ren said...

Well, your "much detail" is not much to go by if you don't cite evidence. It's just your opinion.

My "one-liner's" comes from reading a lot of published journals. Maju can vouch for that.

Maju said...

Or via Burma, Vietnam or surroundings. There's no impassable barrier anymore once you reach to SE Asia.

Maju said...

That paper seems like a nice attempt, but I am sure better work will follow. I think there are some serious weighting issues in this early analysis, and the assumption of origin from the Levant just seems weird, considering climate and resources.

Yah, placing the source north of Iran doesn't seem to make much sense. But I count only from Hormuz on, what I think it is the intention anyhow.

At any rate, on the largest scales, this paper has little impact on the populating of Asia outside of India.

South Asia is a must-go-through if you are heading to Australia and do not want to take a very difficult alterntaive path through Siberia. All routes converge at Bengal though.

Since I am more interested in the western Asian origin of Europeans, I was more thinking about Neanderthals and other Heidelbergensis off-springs in current-day Pakistan and areas north and only slightly east. Those clearly presented more of an obstacle than some remnant erectus populations.

AFAIK, the presence of Neanderthals in West and Central Asia is a post-Toba epysode. H. sapiens pre-dates them in West Asia in any case.

As to the timing, if you postulate a single migration (which seems to conform to genetic analysis), but place it at 100,000 years ago, then you start getting into a number of very difficult questions, as I tried to explain before. Why did people live for 50,000 years in a very limited region of India, before being able to move anyplace else?

They were west of India (Skuhl, North Africa) and IMO they may have begun the penetration in the East too. In any case South Asia is a huge territory, almost the size of Europe that should have provided shelter and food for many people for many generations. But I do think that the expansion into Eastern Eurasia (Sahul included) began before that in the West. When exactly? Not sure.

...for me that is is not enough to believe that these people were in any way cognitively or culturally different from Neanderthals, or related to us.

H. Sapiens in Eastern Eurasia used mostly non-UP techs even well into the UP chronology. You can't judge based on European standards, as things obviously were pretty different elsewhere (and nobody dares to claim that Europeans with blade tools and expressive mural art colonized the World). Stone tools give us only some info on how the old people lived. Most of the materials they used (ropes, baskets, clothes, wooden and bamboo artifacts...) were perishable and left virtually no remains. Not everybody made tools the same way and it's been argued quite reasonably that Aurignacian tech was not significatively superior to Mousterian, for instance (the difference must have been in something else, something not so obvious).

H. sapiens used Mousterian assamblages and other techs that can hardly be considered UP techs even well into the UP. This says little or nothing re. their actual abilities much less re. their humanity. Because if you are going to look for really "modern" differential behaviour, you must wait at least till the Neolithic or better to Civilization. But that's not what makes us humans, is it?

ren said...

Maju, East Eurasia did have UP technology, just not the Neanderthal-Mousterian derived type in the West. Why should they without mixing with Neanders?
In fact, at the terminal Pleistocene, UP technology in East Eurasia was more advanced than in western Eurasia.

Maju said...

Ren: I did not mean they did not have UP (stone blade) tech at all, only that it was not as homogenous as in West Eurasia (but similar to the diversity found in South Asia instead).

Moore and Brumm, "Stone artifacts and hominins in island Southeast Asia: New insights from Flores, eastern Indonesia (JHE, 2006), state that much of the UP of SE Asia and Sahul is flake-based tech and argue that this apparently posed no problem for the peoples using such technology instead of typically UP blade or other core-based artifacts.

I consider therefore that "typical UP" is not any signature of modern human behaviour but just one among many possibilities. I also think that the greatest technological diversity found in SE Eurasia, Sahul and South Asia, with many flake-based tech sites, suggests that this "school" was present in South Asia since the very origins of colonization by H. sapiens and possibly before.

It does pose a problem where there is no direct evidence of H. sapiens presence (skeletal remains mainly) but it does seem clear anyhow that lack of blade tech is not evidence of lack of H. sapiens but rather of an alternative technological school charactristic of he SE Eurasian area (broadly speaking).

terryt said...

Ren wrote: "As for the division of NE Asians and SE Asians, that's been debunked for a long time now".

I'm not aware of that. Last I heard research confirmed it. The difference is explained by the genetic survival of people "such as 'negrito' populations" (who don't really resemble Africans all that much, except for having dark skin) amoung the later "Neolithic stock from 'NE Asia'". But SE Asians are by no means "mainly" this last. Varying amounts, sort of less as you move south to Timor and New Guinea.

Eurologist wrote: "if you postulate a single migration (which seems to conform to genetic analysis)". But genetic analysis also fits a protracted one, say from 100,000 to 50,000. It's really only the Y-chromosome data that tells against it, but there's no reason at all to assume surving Y-chromosome haplogroups outside Africa must have come out with the first emmigrants.

This interpretation of the evidence easily fits your "IMO the only reasonable way to get there and adapt to the surroundings is via modern-day Afghanistan, Uzbekistan/ Tajikistan, Kyrgyzstan, northwest China, and Mongolia". I accept that totally. And I suspect the very first people into Australia came via this route.

ren said...

I'm assuming, in the conext, eurologist was refering to the old Cavalli-Sforza dichotomy, which has been debunked.

But whatever, I hope to say nothing more in this thread...

ren said...

The claim that NE Asians+Native Americans cluster closer to Europeans and Middle Easterners than to SE Asians having been debunked, I mean.

terryt said...

Eurologist asked, "If you know of any AMH skeletal findings outside of Africa and Qafzeh, before about 45,000 years ago, please let me know".

As far as I can find Skhul and Tabun, as well as Qafzeh, all seem to be dated earlier than 45,000 years. I'd be interested in your comments regarding them. I admit there is argument over whether they are fully 'modern' but the fact this argument is possible suggests some sort of hybridism is involved.

Maju said...

On the issue of core/blade and flake technologies, there is today an interesting post by A. Steenhuyse and his blog. He comments extensively on a new paper that strongly suggests (again) that blade tech is not anymodern behaviour defining trend, nor is small flake tech either probably.

eurologist said...

As far as I can find Skhul and Tabun, as well as Qafzeh, all seem to be dated earlier than 45,000 years.

terryt,

...when I mentioned Qafzeh, of course I was thinking of independent caves that are not within walking distance!

As anyone here, I just keep hoping for more fossil finds. Until then, much is guess-work with weak associations between stone tools, culture, and people.

At any rate, it seems to me that if AMHs were able to spread during the moist times, they would have done so quickly (within a few thousand years) from the Levant over Iraq, Iran, Afghanistan, Pakistan, and the-then Thar savanna, into India and beyound. And northward above the Himalayas.

However, from what I can tell, most of that region shows no change in stone tools and/or Neanderthal/Heidelbergensis-type bones and fragments until at least 50,000 years ago. So the region that should have been affected first, and most prominently, doesn't show any impact, not for 50,000 years or so.

That either means "they" didn't make it, or they were not all that different from Neanderthals, anatomically, intellectually, and culturally, after all.

Maju said...

And northward above the Himalayas.


As Ren daid very well, the Himalayas are impassable even today, except maybe for the most risk-taking mountaineers. Besides behind the Himalayas it is a vast cold arid region that is equally or more unhospitable. From South Asia there are two realistic exit routes: eastward to SE Asia and beyond (East Asia and Sahul) and westward to West/Central Asia and beyond (Europe and North Africa, maybe parts of Siberia too).

However, from what I can tell, most of that region shows no change in stone tools and/or Neanderthal/Heidelbergensis-type bones and fragments until at least 50,000 years ago. So the region that should have been affected first, and most prominently, doesn't show any impact, not for 50,000 years or so.

Neanderthals are also not apparent until some 60,000 years ago. I have no knowledge of any H. heidelbergensis in Eurasia anyhow, btw.

My impresion is that, after the moist periods, H. sapiens vanished or became very scarce in the area. Then Neanderthals took over, maybe supressing or admixing with the remnant local sapiens. Then West Asia was recolonized from South Asia.

This is valid for both the post-Toba coastal migration or the earlier OOA hypothesis. Both models fit well with a long absence or rarity of H. sapiens in West Asia, replaced by H. neanderthalensis eventually. The real question is: who were the "Indians" (early Eurasians) who colonized West Asia c. 50,000 BP? In which period did they arrive to India?

1.- c. 100,000 BP (what would amke them likely relatives of the Skuhl people)

2.- c. 50-45,000 BP (what would make them a more recent arrival almost directly from Afrca)

I understand that the evidence is not yet sufficiently conclusive but that there are many indications pointing to an origin that is quite older than Toba. Hence option 1, at least as a serious possibility.