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View Full Version : Is R1b Paleolithic in Europe? Is the old Out of Iberia LGM refuge theory still good?



TigerMW
05-23-2013, 01:29 PM
This topic can be long and convoluted so I'm starting up a thread just for it here and have copied over some related comments from another thread to get it going.

My original report from National Genographic said that I, an R1b person, had R1b ancestry in Europe for up to 40K years as part of the first modern men in Europe, the Cro-Magnon men of the Aurignacian culture.
http://en.wikipedia.org/wiki/Cro-Magnon
http://en.wikipedia.org/wiki/Aurignacian


.... Using Klyosovs method and his 22 slow markers, of which I have 3, I would estimate my TMRCA as 12K + BP using his set of data. It is clear to me that a major bottleneck occurred and a recent report identifies a major disaster c. 10 to 12K BP. Thus, I am left with the question of how valuable is the modal concept in the face of a disaster when many haplotypes are terminated and only after a long period of time does the population build up begin with new, and later, STR values. It seems to me that the modal value is of little use in estimating SNP origin times when disasters/bottlenecks have occurred.


The bottleneck argument has always struck me as a form of special pleading. When a haplogroup or clade looks younger than you want it to be, just whip out a bottleneck and problem solved! The haplotypes only look younger because almost everybody died, you see.

What gives the bottleneck argument its force is that such things are possible.

The problem with it is that, despite the fact that it can never be proven, the bottleneck is regarded as an argument ender: Oh, well, there was a bottleneck; of course the Cro-Magnons were R1b.

One argument I found compelling involves pointing out the relative variance of y haplogroup I versus R1b in Europe. If one uses the fudge factor with R1b, he has to use it on I, and the result is an age for I that strains credulity, something like 40k ybp or more, if I recall correctly.

Or was the big bottleneck selective, targeting R1b and leaving I alone?

There original R1b is Cro-Magnon theory is old and has been largely killed off by more recent studies. That's just my opinion.

mcg11
05-23-2013, 02:42 PM
mike: I'll continue my discussion here. Until we had the concept of using STR analysis to estimate time; I believe the consensus based on climate, some linguistics, most of the "ologies" that there were three refuges of man c. 10K BC of so; Iberia, Northern Italy and the Balkans?

The only thing really new is STR analysis. I believe that STR temporal analysis is flawed: 1. multisteps 2. hidden mutations. 3. bottlenecks. Each of these issues adds uncertainty to the validity of TMRCA analysis.

I think the academic position is pretty clear: (I quote Busbys August 2011 paper) "we further investigate the young STR-based time to the most recent common ancestor estimates proposed so far for R-M269-related lineages and find evidence for an appreciable effect of microsatellite choice on age estimates. " He goes on to say that any conclusions re: timing of its origin should be viewed with caution.

I think it is fair to conclude that this is a "controversial" issue, and shouldn't be dismissed "out of Hand". In my judgment, nothing has been killed!

So, as I said on another blog, is there some other way, using what we do know about STR's, that we can sort out the approximate times for origins of sub-clades?

I have mentioned Klyosov and Maliclavelli as persons who have questioned some of the assumptions we are currently implicitly using.

Some of this reminds me of academias response to Velikovsky and some of his assertions in the 1950's. There are some books still being issued discussing that controversy. re: that controversy, I find it very interesting that the book by his bedside when Einstein died is purported to be "Worlds in Collision".

One approach may be to collect and analyze all the "odd" haplotypes in the various R -L21 subclades. Is there anything to be learned by evaluating the entries that have a 10 at 632?

TigerMW
05-23-2013, 05:57 PM
... I think the academic position is pretty clear: (I quote Busbys August 2011 paper) "we further investigate the young STR-based time to the most recent common ancestor estimates proposed so far for R-M269-related lineages and find evidence for an appreciable effect of microsatellite choice on age estimates. " He goes on to say that any conclusions re: timing of its origin should be viewed with caution
....

There is not one academic position. There are several. You apparently are citing this study.
"The peopling of Europe and the cautionary tale of Y chromosome lineage R-M269" by Busby, et. al.m 2011.

Do you see anywhere where Busby asserts that the MRCA for the extant R1b people of Europe was in Europe prior to the Neolithic and the advent of farming? I haven't found it yet. All that can find so far is
the existing data and tools are insufficient to make credible estimates for the age of this haplogroup, and conclusions about the timing of its origin and dispersal should be viewed with a large degree of caution.

Sounds more like a note of caution than an affirmative statement of a European Paleolithic existence for R1b. Is there something else Busby is saying that is more affirmative?


I have mentioned Klyosov and Maliclavelli as persons who have questioned some of the assumptions we are currently implicitly using. Are the questions credible? ... but I don't see where Klyosov is writing R1b was Paleolithic in Europe.

"Ancient History of the Arbins, Bearers of Haplogroup R1b, from Central Asia to Europe, 16,000 to 1500 Years before Present" by Klyosov, 2012.
In the abstract, Klyosov seems to making this a key point, when he says

The regions considered are from South Siberia/Central Asia in the east (where R1b haplogroup arose ~16,000 ybp) via the North Kazakhstan, South Ural to the Russian Plain and further west to Europe (the northern route entering Europe around 4500 ybp); from the Russian Plain south to the Caucasus (6000 ybp), Asia Minor (6000 ybp) and the Middle East (6000 - 5500 ybp) to the Balkans in Europe (the southern route, entering Europe around 4500 ybp); along North Africa and the Mediterranean Sea (5500 - 5000 ybp) via Egypt to the Atlantic, north to Iberia (the North African route with arrival to the Pyrenees 4800 ybp).

Klyosov's point of view is clearly that R1b was not in Europe during the Paleolithic. The Paleolithic ended about 10,000 ybp (Wikipedia "It extends from the earliest known use of stone tools ... to the end of the Pleistocene around 10,000 BP"). Klyosov is listing 6000 ybp at the earliest.

DMXX
05-23-2013, 06:17 PM
As Vineviz demonstrated years ago and as the DNA now currently shows, R1b SNP diversity is greater the further east you go towards Europe and relevant parahaplogroups are readily observed in places such as Turkey or Iran. There is simply no room for a paleolithic origin of R1b in its' entirety in Europe. As with R1a1a-M17's hypothesised origins in India, SNP data has conclusively ruled such a possibility out.

Also, can someone shed light on the manner in which Klyosov is obtaining these selective dates and locations for the developments concerning R1b and other haplogroups? If he is using modern population data and back-extrapolating those to map prehistoric movements, well, I don't need to waste characters explaining the pitfalls of this.

alan
05-23-2013, 06:24 PM
R1b clearly did (in its very early days) have an ice age existence but it looks like the wrong refugia was focussed on and it probably wintered it out in the east somewhere. However, without even going into variance, it is clear that the west had very much downstream subclades and the further east you go the more ancestral they get. Also interclade dates removes most concerns about variance. I have also pointed out that haplogroup I as a whole has 4 or 5 times as much variance as western R1b so if P312 was really trapped in the western refugia 20000 years ago then haplogroup I in relative terms would have to be about 80-100,000 years old That if course is impossible given that western Europe did not even recieve modern humans until less than 40000 years ago.

Rather than asking why not the franco-Cantabrian refugia, I would ask why? There was never anything special about R1b in that area other than the fact that it had higher frequency. Is there any other reason to see SW Europe as the origin point of R1b? There really isnt. In fact its a very poor option even if variance is ignored. For a start other than near the French border Iberian R1b is overwhelmingly a derived clade DF27. By definition that cannot be ancestral to non-DF27 R1b. However the real question is why do people even focus on SW Europe? Other than the old chestnut of the Basques as some sort of iceage survival language there is no reason to look at the R1b there any more than anywhere else. So the question is not why not the Franco-Cantabrian refugia theory for R1b but more why do people seem to really want this to be true when they have the whole of Eurasia to chose from? We know frequency is not a reliable indicator of origin. I think this all goes back to the archaeological fact of the Franco-Cantabrian refugia, the Basques being in this general area and simple R1b frequency all creating a 2 and 2 =5 false correlation all these years ago.

Basically even if the variance dating is horribly wrong and R1b is twice as old than we currently think, that would still make western R1b's most likely correlation with the earliest farmers reaching the west, not hunter-gatherers. As far as I am concerned there is absolutely no reason to add three independant facts of a high R1b count (not a very meaningful thing anyway), ice age refugia and the Basques together when they do not appear to be related to each other. What if much more interesting is trying to pinpoint the real refugia in the east which surely was somewhere between eastern Europe, central Asia or SW Asia. I think though we are seriously hampered in pining this down closer. I am of the opinion that it cannot have been close to the routes into the early farming areas of Europe in the period 8000-6000BC as it does not seem to have moved into Europe if ancient DNA is giving the correct impression. I think the fact that the most ancient P297 clade, M73 (c. 6000BC), today is is located in what was an area beyond the farming zone proper is probably a hint as to roughly where P297 (the c. 8000BC ancestor of both M269 and M73) was located at the start of the Neolithic. In other words in or close to the steppes

GailT
05-23-2013, 06:33 PM
I don't think we see evidence of a human population bottleneck at 12,000 to 10,000 BP, although people would have retreated from northern Europe during the Younger Dryas.

And I do think that the theory of Paleothic European R1b is dead. There is no data to support the theory, and there really never was any good data. It was only a very naive phlogeographic analysis that gave rise to the theory, and it was bad science. It's mostly useful now as an object lesson in how NOT to do phylogeographic analysis.

Rathna
05-23-2013, 06:35 PM
As with R1a1a-M17's hypothesised origins in India, SNP data has conclusively ruled such a possibility out.


� � R1* -
� � R1a L62/M513/PF6200, L63/M511/PF6203, L145/M449/PF6175, L146/M420/PF6229
� � � R1a* -
� � � R1a1 L120/M516, L122/M448/PF6237, M459/PF6235,
Page65.2!/SRY1532.2!/SRY10831.2!
� � � � R1a1* -
� � � � R1a1a L168, L449, M17, M198/PF6238, M512/PF6239, M514, M515
� � � � � R1a1a* -
� � � � � R1a1a1 M417, Page7

R1a1a-M17! Where have been found in Asia and India the upstream subclades R1a1 and above all R1a-M420? Asia seems to get the Eastern subclades of R-Z93, largely present in Europe in its most ancient form.

(Rathna/Maliclavelli/Gioiello)

TigerMW
05-23-2013, 06:49 PM
R1b clearly did (in its very early days) have an ice age existence but it looks like the wrong refugia was focussed on and it probably wintered it out in the east somewhere. However, without even going into variance, it is clear that the west had very much downstream subclades and the further east you go the more ancestral they get. Also interclade dates removes most concerns about variance. I have also pointed out that haplogroup I as a whole has 4 or 5 times as much variance as western R1b so if P312 was really trapped in the western refugia 20000 years ago then haplogroup I in relative terms would have to be about 80-100,000 years old That if course is impossible given that western Europe did not even recieve modern humans until less than 40000 years ago.

Karafet placed the R1 TMRCA at 18.5k ybp using what she describes as a "novel" method of counting SNPs. This method does not have STR variance issues.
"New binary polymorphisms reshape and increase resolution of the human Y chromosomal
haplogroup tree by Karafet, et. al., 2008
The et. al. in this case includes Michael Hammer, FTDNA's Chief Scientist. Soon after the paper, at an FTDNA conference, Hammer stated that R1b-M269 spread across Europe 4-8K ybp. This is the chart he used.
https://dl.dropboxusercontent.com/u/17907527/R1b-M269_Migration_Map_by_Hammer_2008.jpg

FTDNA has also presented this chart. The net is European R1b is almost all L11+, which is downstream of M269 and includes both P312 and U106. L11 subclades probably didn't even exist during the Paleolithic.
https://dl.dropboxusercontent.com/u/17907527/R1b-M269_LGM_Iberian_Refugium_questioned_by_FTDNA_2009 .jpg

TigerMW
05-23-2013, 06:55 PM
... Also, can someone shed light on the manner in which Klyosov is obtaining these selective dates and locations for the developments concerning R1b and other haplogroups? If he is using modern population data and back-extrapolating those to map prehistoric movements, well, I don't need to waste characters explaining the pitfalls of this.
My reading of Klyosov's papers are that he is primarily using what he calls "DNA genealogy" methods to extrapolate backwards from modern DNA. He does try to adjust for interclade analysis but I don't think he has a robust math model like Ken Nordtvedt's. That's just my opinion.

Klyosov does try to triangulate with with ancient DNA, archaeology and linguistics, however, I think that is where it gets very speculative, to put it kindly.

As far as his TMRCA estimates for R1b subclades, they seems to line up with other germ-line mutation rate methods, but he does try to extrapolate that to geographies and that is probably going too far. That is problematic if that is the primary rationale.

alan
05-23-2013, 06:55 PM
As Vineviz demonstrated years ago and as the DNA now currently shows, R1b SNP diversity is greater the further east you go towards Europe and relevant parahaplogroups are readily observed in places such as Turkey or Iran. There is simply no room for a paleolithic origin of R1b in its' entirety in Europe. As with R1a1a-M17's hypothesised origins in India, SNP data has conclusively ruled such a possibility out.

Also, can someone shed light on the manner in which Klyosov is obtaining these selective dates and locations for the developments concerning R1b and other haplogroups? If he is using modern population data and back-extrapolating those to map prehistoric movements, well, I don't need to waste characters explaining the pitfalls of this.

Problem is other than ancient DNA (which there is only a very small sample off) that is about all there is and is what most of this hobby is based on.

mcg11
05-23-2013, 07:12 PM
I don't think we see evidence of a human population bottleneck at 12,000 to 10,000 BP, although people would have retreated from northern Europe during the Younger Dryas.

And I do think that the theory of Paleothic European R1b is dead. There is no data to support the theory, and there really never was any good data. It was only a very naive phlogeographic analysis that gave rise to the theory, and it was bad science. It's mostly useful now as an object lesson in how NOT to do phylogeographic analysis.

Cosmic Impact 12,800 Years Ago Caused Mass Extinction: Impact Spherules Tell All. This is an article published just days ago. You can google it to find out more. The claim of mass distinction covers most of the northern hemisphere.

alan
05-23-2013, 07:20 PM
Karafet placed the R1 TMRCA at 18.5k ybp using what she describes as a "novel" method of counting SNPs. This method does not have STR variance issues.
"New binary polymorphisms reshape and increase resolution of the human Y chromosomal
haplogroup tree by Karafet, et. al., 2008
The et. al. in this case includes Michael Hammer, FTDNA's Chief Scientist. Soon after the paper, at an FTDNA conference, Hammer stated that R1b-M269 spread across Europe 4-8K ybp. This is the chart he used.
https://dl.dropboxusercontent.com/u/17907527/R1b-M269_Migration_Map_by_Hammer_2008.jpg

FTDNA has also presented this chart. The net is European R1b is almost all L11+, which is downstream of M269 and includes both P312 and U106. L11 subclades probably didn't even exist during the Paleolithic.
https://dl.dropboxusercontent.com/u/17907527/R1b-M269_LGM_Iberian_Refugium_questioned_by_FTDNA_2009 .jpg

The last glacial maximum which is generally what is seen as driving Euroasians into refugia. Wiki describes this as 'The Last Glacial Maximum (LGM) refers to a period in the Earth's climate history when ice sheets were at their maximum extension, between 26,500 and 19,000–20,000 years ago'. According to a number of dating attempts R1b did not even exist in this timeframe. In fact even R1 is dated to around 18500 years ago and that would also put into question if R1 was in existence during the LGM. I tend to be more confident of the dating of the major haplogroups than the more recent clades. It may well be that for the duration of the LGM our ancestors were in the R-M207 stage. http://en.wikipedia.org/wiki/Haplogroup_R_(Y-DNA)

TigerMW
05-23-2013, 07:38 PM
The Myres paper is a major and recent paper on R1b. For background, Wikipedia has the "The Holocene is a geological epoch which began at the end of the Pleistocene (around 12,000 to 11,500 14C years ago) and continues to the present." The Holocene starts as the Paleolithic ends.

"A major Y-chromosome haplogroup R1b Holocene era founder effect in Central and Western Europe" by Myres, et. al., 2010.

the phylogeographic argument for their origin outside Europe, likely somewhere in West Asia, arises from the geographic distribution of the primary splits in the R1 phylogeny: at least three basic R-M207-derived haplogroups – R1a-M420*, R1b-M343* and R2 – occur mostly outside Europe.
...
Major R1b Founder Effect in West Europe
R1b-M412 appears to be the most common Y-chromosome haplogroup in Western Europe (>70%), while being virtually absent in the Near East, the Caucasus and West Asia (Figure 1f). Recent founder effects could explain why the M412-L11 assemblage of chromosomes is abundant and restricted to Western parts of Europe.

Another major paper that proposes R1b came into Europe after the Paleolithic is Balaresque's.

"A Predominantly Neolithic Origin for European Paternal Lineages" by Balaresque, et. al., 2010.

Haplogroup R1b1b2 (R-M269) is the commonest European Y-chromosomal lineage, increasing in frequency from east to west, and carried by 110 million European men. Previous studies suggested a Paleolithic origin, but here we show that the geographical distribution of its microsatellite diversity is best explained by spread from a single source in the Near East via Anatolia during the Neolithic.

To Alan's point about maintaining a relative difference in aging between haplogroups R1b and I:

Indeed, hg I is the only major lineage for which a Paleolithic origin is generally accepted.

I think all of these academic papers have their faults, but we have recent academic studies that support what FTDNA has said. The phylogenetic trail, diversity and ancient DNA is lining up so far with a late arrival of R1b-M269 to Europe.

mcg11
05-23-2013, 08:10 PM
I wonder if the cosmic event in the younger dryas was the driving force to the refugia? The fact that man survived at all in Western Europe surprises me.

TigerMW
05-23-2013, 09:32 PM
R1b clearly did (in its very early days) have an ice age existence but it looks like the wrong refugia was focussed on and it probably wintered it out in the east somewhere. However, without even going into variance, it is clear that the west had very much downstream subclades and the further east you go the more ancestral they get. Also interclade dates removes most concerns about variance. I have also pointed out that haplogroup I as a whole has 4 or 5 times as much variance as western R1b so if P312 was really trapped in the western refugia 20000 years ago then haplogroup I in relative terms would have to be about 80-100,000 years old That if course is impossible given that western Europe did not even recieve modern humans until less than 40000 years ago.

Rather than asking why not the franco-Cantabrian refugia, I would ask why?

I dug up this 2011 study as well. This pretty well kills the Out of Iberia concept for R1b. Sjodin ran multiple simulations using a different program/method, SPLATCHE2 and both evolutionary (EMR) and germ-line (GMR) mutation rates. They did this is to double check Balaresque's work which used BATWING and germ-line rates.

"Wave-of-Advance Models of the Diffusion of the Y Chromosome Haplogroup R1b1b2 in Europe" by Sjodin, Francois, 2011.

Here we examine the date of expansion and the geographic origin of hg R1b1b2 considering two current estimates of mutation rates in a total of fourteen realistic wave-of advance models. We report that a range expansion dating to the Paleolithic is unlikely to explain the observed geographical distribution of microsatellite diversity, and that whether the data is informative with respect to the spread of agriculture in Europe depends on the mutation rate assumption in a critical way.
...
We found that wave-of-advance models can reproduce the geographical distribution of the microsatellite diversity of hg R1b1b2 very accurately
...
In the Zhivotovsky method, the ages of haplogroups in populations are estimated using an evolutionary effective mutation rate of Y-STR of 6.9661024 per generation. In preliminary runs, we also investigated expansions corresponding to the initial colonization of Europe by modern humans around 40,000 years ago (1,500 generations ago) but we did not retain these models due to their poor fit to the observed data.

They can't make a cultural diffusion model Out of Iberia work no matter what mutation rates they used.

TigerMW
05-23-2013, 09:56 PM
Wow, I didn't realize out much support there is in scientific papers against the R1b Paleolithic Out of Iberia hypothesis. Here is another recent paper. What's important with Wei's paper is that they did not use STR variance methods, but other more stable mutations and expansive coverage of the Y chromosome.

"A calibrated human Y-chromosomal phylogeny based on resequencing" by Wei, et. al., 2012.

we identified 6,662 high-confidence variants including SNPs, MNPs and indels. We constructed phylogenetic trees using these variants
...
the lineages found outside Africa dated to 57-74 thousand years, both as expected. In addition, we dated a striking Paleolithic male lineage expansion to 41-52 thousand years ago
...
The third internal node was that of R1b, a well-documented expansion in Europe, but with a much-debated time depth. Here, we estimate a time of 4.3-13 KYA, the most uncertain of the dates. Despite the range of estimates, all these dates favor a Neolithic (Balaresque et al. 2010) more than a Paleolithic (Semino et al. 2000) or Mesolithic expansion of this lineage.

P.S... for you Geno 2.0 guys, our favorite CTS, Chris Tyler-Smith, was co-author on the Wei paper.

alan
05-23-2013, 10:22 PM
If we accept the normal dating then really R1b and R1a did not have an existence during the LGM and even R1 is too young. I suppose R folks ancestors were really still in the R* phase during the LGM.

This map gives some idea of the environmental options at the LGM

http://en.wikipedia.org/wiki/File:Last_glacial_vegetation_map.png

It should be noted though that the idea of refugia is too simplistic. In the west of Europe there was a retreat into the relatively hospitable areas of the south and south-west. However, in eastern Europe many hunters had adapted to the rough conditions but high hunting potential of the steppe tundra. According to this review of a book on the subject of humans in the LGM eastern Europe thrived while much of central and western Europe was evacuated and retreated SW.

razyn
05-23-2013, 10:36 PM
Very little attention has ever been paid to the posts (mainly on WorldFamilies, occasionally on Molgen) of Dr. S. Johannes VanVliet (aka Spanjool), a geneticist in Amsterdam who actually knows what he's talking about, but is somewhat uncomfortable posting in English. He was working on a separate dating method, based on pairwise mismatches, and using some software packages none of these other guys (Klyosov, Nordtvedt, Jost, etc.) have tried. Anyway, his TMRCA dates are in line with the other younger ones -- and not with the ones that think Cro-Magnon guys in Spain 40 K ybp, or anybody else in Western Europe before the Copper age, were R1b.

alan
05-23-2013, 11:21 PM
Its also worth noting that its not enough to just stretch the date of R1b to touch the end of pre-farming era is the west and no more (say 9000 years ago). No new culture had entered the Franco-Cantabrian area since the LGM so whoever was expanding from Iberia with the Magdalenian culture after the LGM had probably been bottled up there since at least 20000BC when the last impulse into the west from central Europe, the Badegoulian, seen as ancestral to the Magdalenian, appeared in France. So 20000BC is the minimum age that a hunter-gather Franco-Cantabrian lineage could have arrived. That is the age of the suspected arrival of the ancestral culture to Magdalenian in the west. The latter culture is the only 'out of Iberia/Franco-Cantabria' hunter-movement. So, to correlate R1b to this would imply it is 22000 years old in the Franco-Cantabrian area at the minimum. That is 5 times the estimated date of P312. Again if R1b was 22000 years old in the west then haplogroup I having 5 times the variance would make it nearly 90000 years old which is more than twice the age of modern humans in Europe and impossible. Interestingly though 22000 years old is pretty close to what has been suggested for haplogroup I. It all fits rather well with the model that haplogroup I is the main European remnant of the Palaeolithic hunters of Europe. So I think the R1b franco-cantabrian idea is dead.

rms2
05-23-2013, 11:38 PM
If a "cosmic impact" causing mass extinction in the northern hemisphere around 12.8k years ago is the reason why R1b (meaning of course the derivatives of L11) in Western Europe looks relatively young, then shouldn't R1b in Western Europe look around 12.8k years old or something in that ballpark, and not 4k -5k years old? And wouldn't the devastation have affected y haplogroup I (and all the others), as well?

I mean, if you kill all but a few R1b lines off 12.8k years ago and start over, then the surviving lines should appear to be about 12.8k years old, unless one wants to argue for more than one bottleneck. But if one argues for later bottlenecks, then the latest one is the only one that really matters, since it must be the one that is producing the illusion of relative youth.

A 12.8k year old bottleneck is irrelevant if it is really a later bottleneck, say about 5k years ago, that is causing the problem.

razyn
05-23-2013, 11:44 PM
But if one argues for later bottlenecks, then the latest one is the only one that really matters, since it must be the one that is producing the illusion of relative youth.

Really the more elegant solution is to believe the massive evidence, that it's not an illusion.

rms2
05-23-2013, 11:52 PM
Really the more elegant solution is to believe the massive evidence, that it's not an illusion.

I'm for that. My point is that the alleged "cosmic impact" of 12.8k years ago is a non sequitur.

And bottlenecks, absent some compelling evidence, amount to special pleading.

alan
05-23-2013, 11:56 PM
If a "cosmic impact" causing mass extinction in the northern hemisphere around 12.8k years ago is the reason why R1b (meaning of course the derivatives of L11) in Western Europe looks relatively young, then shouldn't R1b in Western Europe look around 12.8k years old or something in that ballpark, and not 4k -5k years old? And wouldn't the devastation have affected y haplogroup I (and all the others), as well?

I mean, if you kill all but a few R1b lines off 12.8k years ago and start over, then the surviving lines should appear to be about 12.8k years old, unless one wants to argue for more than one bottleneck. But if one argues for later bottlenecks, then the latest one is the only one that really matters, since it must be the one that is producing the illusion of relative youth.

A 12.8k year old bottleneck is irrelevant if it is really a later bottleneck, say about 5k years ago, that is causing the problem.

That is a very good point. Also why would it only affect L11? Why wouldnt European haplogroup I also be truncated to that sort of date? I think most of the arguements for the old Franco-Cantabrian ice age regugia idea can be put in the 'very special pleading' file.

Another point I would make without even leaving R1b is that if an R1b clade like L11 normally dated to 4500 years ago is multiplied up five fold to make it correlate with the hunters of the Franco-Cantabrian refugia then what does that mean for the earliest branching of R1b or R1 normally dated to something like 18000 years ago. They would become something like 100,000 years old if the same fudge factor was applied and their age was multiplied by five which is impossible.

R.Rocca
05-24-2013, 12:40 AM
Unless R1b was extremely hidden (and unsuccessful) in the SW most corner of Iberia for a long time, I don't see how the Paleolithic Out-of-Iberia can still be taken seriously. While ancient DNA sampling is small, it is enough to at least make the probability very low.

GailT
05-24-2013, 02:42 AM
Cosmic Impact 12,800 Years Ago Caused Mass Extinction: Impact Spherules Tell All. This is an article published just days ago. You can google it to find out more. The claim of mass distinction covers most of the northern hemisphere.

I've seen the paper but I'm not convinced that this was the cause of the megafauna extinction, and there is no evidence of a significant human bottleneck at this time. An alternate theory is that the Younger Dryas was caused by the collapse of the North American ice sheets. I'm curious to see if the scientific community accepts the cosmic impact as a better explanation. The answer will probably depends on how accurately they estimated the size of the 12,000 ybp impact.

mcg11
05-24-2013, 11:01 AM
I've seen the paper but I'm not convinced that this was the cause of the megafauna extinction, and there is no evidence of a significant human bottleneck at this time. An alternate theory is that the Younger Dryas was caused by the collapse of the North American ice sheets. I'm curious to see if the scientific community accepts the cosmic impact as a better explanation. The answer will probably depends on how accurately they estimated the size of the 12,000 ybp impact.

re: humans, the paper says only that there was an impact on the "human cultural condition", whatever that means. Instant winter could have been fatal to many large fauna; the frozen in ice Siberian mammoth may be an example? Personally, I don't think the ice sheets (Agassiz lake) collapsed until much later, c. 6000 BC or so. At a minimum, human impact would have been some number of casualties and mass migration south.

GailT
05-24-2013, 01:28 PM
The impact theory is not new and has been criticized - see quote from a 2011 paper (http://www.sciencedirect.com/science/article/pii/S0012825211000262) below. Perhaps this new paper addresses the earlier criticisms that the data were not reproducible, I don't know, but it will be interesting to see how the critics respond to the new paper. Regardless of the cause of the Younger Dryas, we know that it affected human populations in northern Europe and Asia, but there does not seem to be a bottleneck in European mtDNA at the Younger Dryas. There is a clear sign of a bottleneck in typical European mtDNA haplogroups at the LGM, but diversity in mtDNA begins to increase at the end of the LGM and continues to increase through the Younger Dryas.



In summary, none of the original YD impact signatures have been subsequently corroborated by independent tests. Of the 12 original lines of evidence, seven have so far proven to be non-reproducible. The remaining signatures instead seem to represent either (1) non-catastrophic mechanisms, and/or (2) terrestrial rather than extraterrestrial or impact-related sources. In all of these cases, sparse but ubiquitous materials seem to have been misreported and misinterpreted as singular peaks at the onset of the YD. Throughout the arc of this hypothesis, recognized and expected impact markers were not found, leading to proposed YD impactors and impact processes that were novel, self-contradictory, rapidly changing, and sometimes defying the laws of physics. The YD impact hypothesis provides a cautionary tale for researchers, the scientific community, the press, and the broader public.