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Economy?, nuclear war?, class struggle?, ethnic tensions?
Nope. Mere and simple imminent ecological disaster caused, probably, by global warming.
Timeline? A century or two ahead?, several decades?, an undefined future?
Nope. By October this year.
While the USA and China are succumbing to brutal massive floods, Australia is facing the worst of the worst drought ever. It's been nicknamed the Big Dry and it's been going on for many years now, since 2003, sending many farmers into bankrupticy and becoming one of the factors behind increased food prices worldwide (as Australia used to be one of the main food exporters of the World).
Drought affected croplands
Now an expert panel has warned that the most important river system of Australia, the Murray-Darling basin, the Australian breadbasket, will be beyond the point of recovery unless it gets enough water by October. In practical terms it means that the whole ecology of the single most important agricultural and economical region of Australia will take at least a decade to recover or will not recover at all in any foreseable future.
The Murray-Darling basin
The reaction of the government? Wait until November. Incredible but true. The report has been leaked to the press anyhow sparkling great concern and political scandal in the island-continent.
20 comments:
One thing is for sure: Australia's climate has fluctuated wildly since humans first got there about 50,000 years ago.
One of my brothers and two nephews are dairy farming in the Murray/Darling basin (northern Victoria). And I lived in Oz for four years in the early 80s (including the 82/83 drought).
One of the first things I realised was that statistics are meaningless. Although the region I lived in averages 900 mm of rain a year it is not seasonal. You can't rely on it to fall at particular times of the year. I read an article recently expanding on the idea. Alice Springs is a sizable settlement in the middle of Oz and averages 200 mm a year but it can all fall at once at almost any time of year in a torrential downpour. In the 80s the big news was that it rained in Alice and for most children under 6 years old it was the first time they'd ever seen rain.
And yet the Australian government is still calling for increased immigration.
I can't know for sure but if experts say that the situation is dire and will cause irreversible (or hardly reversible, depending on the cases) damage in the basin, then I would listen to them.
Alice Springs is a totally different ecosystem, AFAIK, as it's in the middle of the desert. It's an oasis - like Riyad. But in any case Australia is probably one of the most vulnerable areas of the planet to climatic change because of it's dominant arid climate and the important agropecuarian pressure on the soil.
And yet the Australian government is still calling for increased immigration.
It's a different thing: imigration is "good" from the viewpoint of Capitalism: cheap labor that nag less that the rest and don't vote nor have rights in many years. There are many other countries with larger populatations than what they can support locally: all Europe, Japan, Saudi Arabia are the first that come to my mind. The real problem is when you are overpopulated and too poor to buy your bread or rice elsewhere, like with Egypt, Philipines, etc.
Also, the problem is not direct human pressure on he basin anyhow but very longlasting drought caused surely all around the globe by vehicles, industries and heating mostly.
It's a global problem that requires global and radical solutions.
The problem in Australia is a shortage of water for the major cities, so it is a bigger problem than it is for such countries as Europe and Japan, although I suppose Saudi arabia is in a similar siuation. It's possible to import food easier than it is to import water. And I agree "the situation is dire and will cause irreversible (or hardly reversible, depending on the cases) damage in the basin".
But it's dire because everyone always seems to believe climate doesn't change. In the case of Oz it has changed considerably, even in the two hundred years people of European origin have been living there.
Another thing: "the problem is not direct human pressure on the basin". The problem is more than just partly a direct result of human pressure on the water resources in the basin itself. Irrigation especially has diminished the flow in the Murray River although it has ceased flowing altogether many times in the past.
Ok. I don't really know how important is direct human presure and water usage on the situation of the basin but the impression from the article is that that it is not the main cause of the problem, climate change is instead.
As for urban water usage, I can't tell for sure but I'm under the impression (from a documentary on Perth) that wasteful uses such as gardening are important. In most of the world anyhow, agricultural and industrial uses make up about most of the water usage cake. Just from memory.
While most of the energy is spent in warming inefficient buildings (it may be as much as 50%), which is domestic cosume (even if fuelled by awful urbanistic policies), most of the water is normally spent in irrigation agriculture and very little in domestic consume. Of course this may be different in places with little agriculture and loads of misplaced gardening (i.e. lawns in the desert and things like that).
In any case it's quite obvious that something has to change if we want to live with some sustainability. Some people believe that what economists call "growth" is in itself untenable (mere consume and speculation for the most part, always extracting from the resource of Earth) and that negative growth is necessary. This obviously demands a radical change in the economic paradigm.
Of course I actually agree with you. Just providing a wider view of the problem seeing that I have a brother and nephews directly involved. By the way, congrats on the football. I like to see Spain do well.
Not on the subject, but another by the way. You mentioned Eurocentric perspectives of human evolution. I live virtually opposite you. Well, opposite Ceuta actually, on the other side of the world. This does provide an interesting perspective. For example Australia provides the first evidence for modern human presence after they left Africa; New Zealand the last. Understanding the reason for this provides fascinating evidence for our evolution.
I've nearly finished Spencer Wells' book "The Journey of Man". Most of it is very good but it's the book where he first proposed the 'southern route'. As you could guess I have criticism of this aspect.
He writes, "the line of sandy highway circumnavigating the continents". I suppose we can excuse him. He grew up in Lubbock Texas, not noted for its coastal environmnets. The coast is far from being a single simple environment.
He accepts dates for the first appearance of the Upper Paleolithic through the region are problematic, but immediately ignores the implications. The earliest anywhere near India is in the south, Sri Lanka: 31,000 years. Thailand: 37,000 years. Eastern New Guinea: 40,000 years. Even he concedes the dates imply migration west rather than east but leaves it at that.
He suggests rising sea level has covered the evidence for the southern route yet he uses as supporting evidence the shell middens on the East African coast. So how come these weren't covered at the same time?
He gets the mtDNA evidence for Australia wrong too, as do most Eurocentric anthropologists. While mtDNA haplogroup M is common in New Guinea it is far from common in Australia itself. There it is mostly hap N and descendant lines S and P. The preponderance of hap M in New Guinea suggests to me a likely more recent migration into that island and Melanesia, but excluding Australia, rather than resulting from bottlenecks, drift and founder effect.
By the way, congrats on the football. I like to see Spain do well.
Honestly, I don't care. In fact I rather prefer that Spain loses - I'm Basque and Spain and France are the enemy, you know.
Australia provides the first evidence for modern human presence after they left Africa; New Zealand the last. Understanding the reason for this provides fascinating evidence for our evolution.
I don't have very clear that Australia actually provides the oldest human remains out of Africa. The accepted Lake Mungo datations are not older than 30,000 BP, what is much more recent than European settlement. There is a thermoluminscence datation in another site of c. 50 KYBP but that's not older than proto-Aurignacian datations in Altai by the same method either (no human remains here yet though).
And of course you have the Skuhl remains, that are dated before 100,000 BP (even if they are old datations they correlate well with the modern ones re. North African Aterian). This can be a cul-de-sac but could also be the real origins of all Eurasians (incl. Oceanians and Americans), provided a deep bottleneck. Their skulls are certainly close in typology to Aurignacian ones.
As mentioned in other occasions, the South Asian late Middle Paleolithic shows continuity and traces of modern behaviour since c. 103,000 BP. The human remains are lacking but in this case lack of evidence is not evidence of lack, certainly.
I've nearly finished Spencer Wells' book "The Journey of Man". Most of it is very good but it's the book where he first proposed the 'southern route'. As you could guess I have criticism of this aspect.
He writes, "the line of sandy highway circumnavigating the continents". I suppose we can excuse him. He grew up in Lubbock Texas, not noted for its coastal environmnets. The coast is far from being a single simple environment.
He accepts dates for the first appearance of the Upper Paleolithic through the region are problematic, but immediately ignores the implications. The earliest anywhere near India is in the south, Sri Lanka: 31,000 years. Thailand: 37,000 years. Eastern New Guinea: 40,000 years. Even he concedes the dates imply migration west rather than east but leaves it at that.
Well, it's a theory and can be challenged. But as said before skeletal remains are in themselves, due to their scarcity, only evidence of the most recent possible date of arrival. The simplification on a coastal-only route is surely an error anyhow. It's been modelled with GIS that South Asia presented three easiest routes, only one of which is purely coastal. The other two are very well documented archaeologically even if we lack of the decisive skeletal remains).
He suggests rising sea level has covered the evidence for the southern route yet he uses as supporting evidence the shell middens on the East African coast. So how come these weren't covered at the same time?
Not sure but obviously the coastal changes due to sea rise are irregular (in some places the continental platform is almost nonexistent and the sea directly borders the mountains) and in some cases tectonic movements have placed ancient beaches at rather high altitudes (what is very handy for archaeologists, certainly).
He gets the mtDNA evidence for Australia wrong too, as do most Eurocentric anthropologists. While mtDNA haplogroup M is common in New Guinea it is far from common in Australia itself. There it is mostly hap N and descendant lines S and P. The preponderance of hap M in New Guinea suggests to me a likely more recent migration into that island and Melanesia, but excluding Australia, rather than resulting from bottlenecks, drift and founder effect.
Does he claim that M is common in Australia? That alone could invalidate all the book.
Whatever the case, I would not make much of these differences. Both M and R have a quite clear South Asian core and that is also probably the case for N, so I'd say the local distribution differentials are mostly due to founder effects.
One thing is clear: to reach Australia, Paleolithic humans must have gone through all the southern Asian arch (from West to SE Asia), either by the coast or by the interior. This is just not subject to dispute, right?
The debate (and most importantly: the research) should be focused then in which of these areas played major coalescing roles (South Asia is the best single candidate so far), as the Eurasian humankind shows a narrow array of related macro-haplogroups (both for mtDNA and Y-DNA) that most likely had a single shared coalescence area.
In theory there could be up to two separate coalescence cores (one for N and another for M) but IMO the farthest I can go within this line of thought is to think of different subareas in South Asia (including arguably its immediate periphery in West and SE Asia).
"to reach Australia, Paleolithic humans must have gone through all the southern Asian arch ... either by the coast or by the interior. This is just not subject to dispute, right?" Correct, but not necessarily only "through all the southern Asian arch", possibly straight south from East Asia, or even ultimately from both directions.
As I understand it there would be few people who would dispute a time of 50,000 years for the arrival of Australians. Many accept even older dates. Increase in fires, extinction of megafauna etc. support older dates. The sites you mention are not associated with Upper Paleolithic, merely Middle Paleolithic. Mind you it's probably not valid to consider the first Australians as belonging to the Upper Paleolithic anyway.
"This can be a cul-de-sac but could also be the real origins of all Eurasians". Now I agree with that totally. The reason it's dismissed by most anthropologists as being the origin of modern humans is that dates for Y-chromosome haplogroups are difficult to reconcile with its dating. However mtDNA easily fits and so it's quite probable that female lines from this group survive today, but male lines emerged from Africa more recently.
"Does he claim that M is common in Australia? That alone could invalidate all the book". Quote from the book: "M is virtually absent from the Middle East, and is not found at all in Europe, but it constitutes 20 per cent or more of the mitochondrial types in India, and close to 100 per cent of those in Australia". Make of that what you will.
"In theory there could be up to two separate coalescence cores". Almost certainly so in my opinion. M almost certainly in India but N could easily be part of the Skuhl population, perhaps then becoming part of the "proto-Aurignacian ... in Altai". Then across Central Asia to East Asia, and then south to ultimately be first mtDNA line into Australia.
The sites you mention are not associated with Upper Paleolithic, merely Middle Paleolithic. Mind you it's probably not valid to consider the first Australians as belonging to the Upper Paleolithic anyway.
Did I say UP? I hope I didn't. H. sapiens certainly participated of the Middle Paleolithic (and in some cases Neanderthal did with UP - or at least transitional forms).
The MP/UP division associated to species change only seems to make sense (and not strictly anyhow) in Europe. Indian Middle Paleolithic has stone blade tools since c. 100,000 BP - and in other contexts blade tools are considered definitory of UP.
"This can be a cul-de-sac but could also be the real origins of all Eurasians". Now I agree with that totally. The reason it's dismissed by most anthropologists as being the origin of modern humans is that dates for Y-chromosome haplogroups are difficult to reconcile with its dating. However mtDNA easily fits and so it's quite probable that female lines from this group survive today, but male lines emerged from Africa more recently.
Agree with the issue of age estimates, that too many people take literally, when they should always be taken as what they are: mere estimates, often conflicting with each other.
But I'm not sure if mtDNA age estimates fit easily with a 100,000 BP (or even as much as 130,000 BP) chronology. And in any case the Eurasian mtDNA tree fits very badly with a West Eurasian urheimat. It fits well with a South Asian one instead and quick expansion from there (starlike phylogenies).
So, if the Skuhl people represent the first Eurasians, they must have gone through a very radical bottleneck and/or merely been expelled from West Asia, or at least the non-marginal areas in it, by Neanderthals, climate or both.
Quote from the book: "M is virtually absent from the Middle East, and is not found at all in Europe, but it constitutes 20 per cent or more of the mitochondrial types in India, and close to 100 per cent of those in Australia"
Wow! A book I won't read. Thanks.
"In theory there could be up to two separate coalescence cores". Almost certainly so in my opinion. M almost certainly in India but N could easily be part of the Skuhl population, perhaps then becoming part of the "proto-Aurignacian ... in Altai". Then across Central Asia to East Asia, and then south to ultimately be first mtDNA line into Australia.
I don't make any sense for the "across Central Asia" part. The oldest presumably Sapiens remains of Central Asia are proto-Aurignacian and this tech (nor anything similar) is not found AFAIK in Eastern Eurasia. I am not very sure about Australian technology but I understand that it does not break this rule.
If there's a separate western origin for the N branch, it must have migrated eastward through South Asia. And certainly if any clade shows a very very clear South Asian phylogeny, it is R.
To me at most it can mean a more NW and SE coalescence areas for N and M within South Asia (including peripheries such as Iran or Burma maybe).
What I may consider is a "lost land" in West Asia that was not just southern Arabia. But this also has a problem: North African genetics.
North African Aterian is key to validating the dates of West Asian oldest sites. And there is very little N(xR) in North Africa, the most significative being X1 (yes: X is surely an old clade with a wide distribution but alone doesn't seem to support an older origin for Western Eurasians. The rest is all R of either European or West Asian origin (and a good deal of Tropical African Ls, allegedly recent): U6, H, V, K, T, J...
And R is clearly of South Asian origin.
So I am more inclined for a much older (before 100,000 BP) coastal route migration into South Asia and from there into the rest of Eurasia (and Sahul and North Africa...).
Of course, it could be that North African Aterian, like Skuhl, was a cul-de-sac, a "lost land" that had to be recolonized later on. But I have serious doubts about that.
The question remains open (at least for me) but I don't think you can sideline South Asia as you seem willing to do. It's clearly central for the most important West Eurasian macro-clades: mtDNA R and Y-DNA F and can be argued the same for the rest of macro-haplogroups.
I think it's possible that Toba explosion and Neanderthal expansion placed the early Eurasian humankind in a difficult situation temporarily, limiting them to few lineages in South Asia. That would be the "moment" when both mtDNA R and Y-DNA K could have arisen among the most succesful/innovative Sapiens, who would lead later expasions to both east and west. But this surely happened in India, not anywhere else.
Maju. I thought I should expand on the situation in the Middle East.
Any account of modern human emergence from Africa concedes they first appeared in the Middle East about 100,000 years ago. However most anthropologists do not accept that these humans were responsible for the spread of modern Y-chromosome and mtDNA haplogroups. The reason for this reluctance is because Neanderthals reappear in the Middle east btween 70,000 and 50,000 years ago. Check out Kebara and Amud caves in Israel and this link:
http://www.athenapub.com/8shea1.htm
The idea of the earlier dispersal of Y and mt haplogroups is dismissed because this could raise serious problems for those who maintain Neanderthals and modern humans were incapable of forming fertile hybrids. It implies the incoming Neanderthals may have absorbed the lines. The population on the Iranian Plateau and in Central Asia could have been a hybrid population.
Because of this it has become the zeitgeist that modern human haplogroups emerged from africa with the second arrival of modern humans in the Middle east, around 40,000 to 50,000 years ago. However as you point out modern humans could well have been in India and Central Asia long before this. They also seem to have reached Australia by then.
The reason for this reluctance is because Neanderthals reappear in the Middle east btween 70,000 and 50,000 years ago.
Not just that: the main reason is that the dispersal center of Eurasian haploid DNA seems to be further east: in South Asia probably. That really seems to "forbid" a direct continuity between the Skuhl people and us, but it's not impossible an "indirect" continuity via South Asia.
The idea of the earlier dispersal of Y and mt haplogroups is dismissed because this could raise serious problems for those who maintain Neanderthals and modern humans were incapable of forming fertile hybrids.
No. I don't think that is the problem. The key is that too many assumptions were made based on the molecular clock hypothesis (DNA age estimates) and on maybe circumstantial evidence like the Toba explosion. These are all just hypothesis and guesses and is not enough. It doesn't really matter if Neanders and Sapiens could make fertile hybrids, because the documented reality is that mostly they remained as much as separate populations as lions and tigers in India, or almost.
It implies the incoming Neanderthals may have absorbed the lines. The population on the Iranian Plateau and in Central Asia could have been a hybrid population.
I don't think it implies anything nor it would matter anyhow. We just have no strong evidence for any hybrid individual, just vague speculations. We do have instead much negative evidence for Neanderthal ancestry of modern humans anywhere: both morphological and genetic.
That is not the problem: the problem is that West Eruasian haploid DNA seems to spawn from South Asia and not the other way around, as would be logical if the old people of Skuhl would have been the acestors of Eurasian humankind or even only West Eurasians. There is a clear discontinuity what suggests that Neanders, those very strong people that could fight a sabertooth tiger barehanded (or so is claimed) and had brains coparable to ours, just kicked our kin out from the Levant and probably all West Asia.
However as you point out modern humans could well have been in India and Central Asia long before this. They also seem to have reached Australia by then.
Well, the arrival to Central Asia, Australia and West Asia (and other places surely) seems to be simultaneous or almost so. The dates for European Aurignacian have been recently revised back (due to improved C14 calibration) to c. 41,000 BP, Bakhokirian is at least as old as 46,000 BP and West Asian human arrival must have been somewhat older. So guess that we can well think of c. 50,000 as the time of expansion out of South Asia in all directions. The particular dates of each site may vary somewhat, of course.
I don't think there is any reason to think that H. sapiens were in Central Asia earlier than elsewhere (except India-subcontinent). I think that the evidence quite strongly supports the coastal spread model, generally speaking:
1. Central Asian transitional MP/UP sites seem related to Western Eurasia, not to East Asia.
2. The southern origin of East Asian haplogroups is gaining more and more empirical support.
3. The route between Central and East Asia in early UP times was quite difficult. Not impossible but much less likely than the southern one, specially for tropics-adapted apes as we are (consider issues such as vit.D generation, plus clothing and shelter).
I see where we part company. We both accept that "West Eruasian haploid DNA seems to spawn from South Asia". We also both accept "that we can well think of c. 50,000 as the time of expansion out of South Asia in all directions". However you seem not to accept that the clades involved in this West Eurasian expansion are confined to mtDNA lines descended from R and Y-chromosome lines descended from K.
The evidence, and common sense, tells us that these lines don't spring up from nowhere. Their ancestors almost certainly also have a long history that includes population movements. There's a lot of time to fill in between whenever the lines first came out of Africa and just 40,000 to 50,000 years ago.
We know that mtDNA line R evolved from N but (if we disregard W, which is almost certainly the product of a relatively recent arrival) there is no N, or any of her sister lines, anywhere near India. Coastal migration?
It seems to me that you are looking for a single moment when we can be defined as human. Sorry. It's been a long, slow process, and there's no need to accept it has run its course. Or even that of the many who accept the label some fail to reach the level of the type specimen.
I see where we part company. We both accept that "West Eruasian haploid DNA seems to spawn from South Asia". We also both accept "that we can well think of c. 50,000 as the time of expansion out of South Asia in all directions". However you seem not to accept that the clades involved in this West Eurasian expansion are confined to mtDNA lines descended from R and Y-chromosome lines descended from K.
Obviously not: if you look at West Asian genetics with minimal attention, you'll see that most Y-DNA is F(xK), i.e. JI and G. There is K too but only two subclades as well: R1 and T (former K2). So claiming West (eur-)Asian Y-DNA is confined to K is absolute nosense. No offense meant but it's obviously not looking at what is there.
MtDNA also is not exclusively R: both N(xR) (X,I,W,N1) and M (M1) are found in West Eurasia as well and, furthermore, all these clades are exclusively or almost exclusively West Eurasian (the main exception being X2 that has one single American subclade).
Furthermore, Cro-Magnon ancient mtDNA has yielded (by the moment) only N* and Danubian Neolithic ancient mtDNA has yielded an unusual ammount of N1a (25% of sample). Excluding N(xR) from Western Eurasia is absolutely arbitrary.
And excluding F(xK) is even more arbitrary. In fact F(xK) is specially distributed in South Asia and West Eurasia, being almost non-existent in the East.
We know that mtDNA line R evolved from N but (if we disregard W, which is almost certainly the product of a relatively recent arrival) there is no N, or any of her sister lines, anywhere near India. Coastal migration?
What about N*? And what about R? Most importantly, there is also N(xR) east of India: in Eastern Asia and Sahul! Agreed that you could argue for other places for the coalescence of N, including SE Asia and Western Asia, but I don't know why that would be that important. I really don't see the Central Asian route neither necessary nor convenient to explain anything, specially as the East Asian clades of N(xR) have mostly a coastal distribution.
To me the different subclades of N represent founder effects of a clade that was not numerically important in MP South Asia but that was important in the groups that migrated outside of it, groups in which R was important too. I think this founder effect is more clear (and therefore more important) in West Eurasia than in the East, what may mean that either the original N and R population(s) were specially concentrated in NW South Asia (or Iran maybe?) and/or that the groups migrating westward were much less numerous than those migrating eastward (so they had less diversity).
It seems to me that you are looking for a single moment when we can be defined as human.
How come? Humankind arose in Africa. We were human long before entering Asia. The formation of humankind as species has nothing to do with its Eurasian spread.
Abracadabra, bottleneck, drift, founder effect. With such magic words anything becomes possible.
Not a serious reply, Terry: I only used the term "founder effect" once in all my comment (no "drift", no "bottleneck"). You are elluding to face the fact that your hypothesis is distant from reality, I think.
Founder effects are certainly important. Imagine that you and your brothers have to migrate to a new land: the resulting population will necesarily have your father's Y-DNA haplopgroup (and yours).
Imagine that a group of five families like the above migrate: even if they have 5 different Y-DNA clades (what is not guaranteed at all), that means that in the mid run, one or two are the only ones likely to remain (drift). MtDNA may be slightly less affected by drift but exactly the same by founder effects: even pernitious mutations could be benefitted from founder effect accidents: check Rh- in Europe, for instance, an obvious founder effect.
It is not "abracadabra" it's understanding.
And personally I hate bottlenecks too because they appear to mean near-extinctions and that's extremely rare (though shit happens, indeed). But what looks like a bottleneck can be just a founder effect, and founder effects are very real and extremely common, in fact they are the only possible scenario for new colonizations.
OK. Let's look at the evidence and assume no bottlenecks, founder effect or drift.
That means there is no reason at all to assume Y-chromosome lines "JI and G" were part of any migration from India. The F clade includes F*, F1, F2, F3, F4, and we could in fact refer to H as F5 (simply another Indian version of F), G as F6 and JI as F7. Ignoring possible founder effect it now looks as though all these lines are just part of a cline of F stretching from the Caucasus and Zagros Mountains through India to Sri Lanka and parts of SE Asia. There's absolutely no need to believe they are all the product of founder effects following a single expansion of F. More likely they are the product of regional diversification of the haplogroup that gave rise to F.
So, the only haplogroups involved in a more recent exansion from India become "R1 and T", memebers of Y-hap K". I'd actually say haplogroup PQR rather than just R1.
Similarly with mtDNA. "N(xR) (X,I,W,N1) and M (M1) are found in West Eurasia". Again there is absolutely no reason to assume these haplgroups emerged from India. After all, Indian haplogroups' ancestors must have passed through some region between Africa and India, so haplogroups X, I, W and N1 are likely to be products of early branches along the route of that movement, as are A, Y and S.
So once more we have the relatively recent movement from India consisting only of haplogroups derived from R. Sure, members of haplogroups outside India may have been picked up and carried along with this movement, but their distribution is not a product of founder effect.
And this interpretation of the evidence is totally consistent with "Cro-Magnon ancient mtDNA has yielded (by the moment) only N* and Danubian Neolithic ancient mtDNA has yielded an unusual ammount of N1a". N's expansion has to be ancient and probably not connected at all to any movement from India.
OK. Let's look at the evidence and assume no bottlenecks, founder effect or drift.
You cannot. It's not abracadabra, it's how things happen. Take a hypothetical simple original small population with two haplos: X and Y. When it spreads it's likely that most groups end up with only X or Y (due to founder effects and drift) or with very unbalanced derivate sets of both (something like 90% X and 10% Y, for instance). What you cannot expect is that all groups randomly end up with exactly 50-50 of both clades because it's just way too likely that each of the migrating expeditions were originally unbalanced, even extermely so (all brothers for instance) and that's founder effect, or it is just normal that, generation after generation, one of the two clades ends up totally displacing the other (drift). It is how things happen, specially when populations are small (large populations have very low drift), not any magic.
There's absolutely no need to believe they are all the product of founder effects following a single expansion of F. More likely they are the product of regional diversification of the haplogroup that gave rise to F.
How did that diversification happen? Only founder effects and drift can explain it.
"Diversification" without a mechanism explaining it is "abracadabra".
And they (F1, F2, etc.) are product of F, not of "of the haplogroup that gave rise to F".
So, the only haplogroups involved in a more recent exansion from India become "R1 and T", memebers of Y-hap K". I'd actually say haplogroup PQR rather than just R1.
I don't see any clear reason for two waves. P was certainly very active and R could well have starred secondary waves, probably from Central Asia, rather than India. But T (K2) looks more like it migrated with IJ and G: it's just the K that migrated with them.
Similarly with mtDNA. "N(xR) (X,I,W,N1) and M (M1) are found in West Eurasia". Again there is absolutely no reason to assume these haplgroups emerged from India.
M1 certainly seems to be an offshot of South Asian M. N(xR) is more questionable, it could have arosen near Hormuz maybe but the difference is a matter of boundaries, not of concept. It could have arisen in Burma as well for what we know.
After all, Indian haplogroups' ancestors must have passed through some region between Africa and India, so haplogroups X, I, W and N1 are likely to be products of early branches along the route of that movement, as are A, Y and S.
And you are the one complaining about thining in terms of bottlenecks? If the Eurasian genome coalesced in West Eurasia we should see much higher diveristiy in this region. We just don't. A more eastern coalescence niche is much more reasonable.
Sure that people had to pass by somewhere else but certainly they never managed to suceed in that intermediate region as they did farther east. If it was southern Arabia, the aridity of the climate can explain even a total (or almost total) extinction of the remnants. If it was the Fertile Crescent, then we seem to need a more elaborate explanation like hordes of violent Neanderthals or something. In any case we don't see any radiation in (from) West Asia. But we see it in (from) South Asia or around the Bay of Bengal.
Ok that N(xR) could be from anywhere in the southern Asian arch but M and R are clearly of South Asian origin (or SE Asian in the case of M maybe - but not West Asian). And, as always, South Asia is the place in the the middle of all, the route that anybody travelling from Western to Eastern Eurasia (or viceversa) had to take almost compulsorily.
So once more we have the relatively recent movement from India consisting only of haplogroups derived from R. Sure, members of haplogroups outside India may have been picked up and carried along with this movement, but their distribution is not a product of founder effect.
And it correlates with what archaeologically documented migration? May I know?!
West Eurasia is almost exclusively R, some of its subclades (haplogroup U specially) are as old as Aurignacian or even older. Ok, that N(xR) may have been more common in the past 8as per some aDNA tests) but that may also be a distortion caused by insufficient or inefficient aDNA sampling. I will not let aDNA interfere with my analysis until it has been confirmed independently several times.
And this interpretation of the evidence is totally consistent with "Cro-Magnon ancient mtDNA has yielded (by the moment) only N* and Danubian Neolithic ancient mtDNA has yielded an unusual ammount of N1a". N's expansion has to be ancient and probably not connected at all to any movement from India.
So how did it arrive at about the same time to Europe, China and Australia? Flying?
And how was it overrid by clades like H, U5 and U8 (K specially)? Is it all "Neolithic"? Then why the core of H diversity is in SW Europe? Why Danubian Neolithics had apparently so much N1a while modern Europeans have almost none?
You don't have a model to explain R radiation after N, specially as you are cimenting that in ancient West Eurasians (from totally different times: Gravettian and Neolithic) being apparently N(xR), or largely so.
I am positive that whatever the fluctuations of apportions of N(xR) and R-derived clades in West Eurasia, they happened all in this part of the world, not outside it. The Indian origins pre-date all that. Neither U, nor R0/HV nor IJ are present in South Asia in significative ammounts (only U2 and U7, the latter shared with West Asia). R as such seems to be original from South Asia but U, R0/HV and IJ radiated in West Eurasia. And U5, HV and R8a did it in Europe (and, IMO, U6 did too). For N(xR) clades N1, X, W and I all radiated in West Eurasia too, but many other N(xR) subclades did not: they radiated in India, SE Asia, East Asia and Sahul. There's absolutely no good reason to think of West Asia as the urheimat of N. It might be but it may perfectly be not.
Of course I accept that bottlenecks, founder effect and drift have been active. That's how evolution works after all. What I have a problem with is your selective use of the concepts.
You said elsewhere: "I can perfectly get very old and reasonable dates of Y-DNA diversification too: 100-120 KY for the diversifications of D, F and C".
So what you are saying is that over the period from 100,000 to 50,000 years ago virtually all haplogroups, both mtDNA and Y-chromosome, diversified in one region. Now, diversification indicates no bottlenecks, founder effect or drift, very unlikely in a population confined to just one region. This population then expanded from that region about 50,000 years ago, at which point you are forced to call on unbelievably massive doses of bottlenecks, founder effect or drift to account for the present distribution. Doesn't make sense.
So what you are saying is that over the period from 100,000 to 50,000 years ago virtually all haplogroups, both mtDNA and Y-chromosome, diversified in one region. Now, diversification indicates no bottlenecks, founder effect or drift, very unlikely in a population confined to just one region.
It's not a parcel! It's a subcontinent... and they were not confined in any material sense. Our conceptual and political borders may not have been theirs. But they seemingly thrived in South Asia and not elsewhere.
Bottelneck is not the same as drift or founder effect. Drift and founder effect are normal and happen all the time. Drift is accented when the population is small, founder effect when there is a colonization. That is normal diversification.
Bottleneck instead implies a dramatic epysode of near-extinction. True that a founder effect can look much of the same (radical restriction of the genetic pool) but it's not the same. Bottlenecks are rare, drift is normal when the population is locally small, founder effect is normal when a new territory is colonized. The local population can be a tribe or clan, the colonization can be of a new valley.
This population then expanded from that region about 50,000 years ago, at which point you are forced to call on unbelievably massive doses of bottlenecks, founder effect or drift to account for the present distribution.
I call for founder effects certainly because each time a new land is colonized a founder effect happens.
I call for drift because it is normal too.
I do not call for bottlenecks. They may have happened or they may just be the apparent result of founder effects: when a population expands, not uniformly but with select groups of pioneer settlers, the result is a narrowing of their genetic pool.
Uniform expansion is what is unbelievable: it's irregular. The people in the middle have not the same expansion chances as those in the edges of the overall territory in this scenario of expansion and colonization. The people in worst hunt territories have not the same expectatives as those controlling the best ones.
It may well happen that the people in the middle controls the best lands and hence becomes regionally dominant with time (normal drift) and meanwhile the people in the edges may control worse lands but find their opportunity outside the urheimat. The latter would become rare in the homeland as time passes but would thrive in the new conquered lands.
The above is a supersimplified hypothetical scenario. I cannot know he exact factors that shaped the actual genetic and demographic processes in South Asia (or elsewhere) but you don't really need anything strange: just the normal processes of drift and founder effect that happen all the time.
Admitted that, since Neolithic allowed for much larger demographic units, drift is rarer and much more limited in its effects. But for all the Paleolithic it was a most important force.
Terry: I have opened a new thread on this issue: http://leherensuge.blogspot.com/2008/07/funadamental-conceps-of-population.html
I think we have already discussed more than enough in this very off-topic thread and therefore it's best to close the discusion here.
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