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View Full Version : Demographics, Caution, and the Orthodoxy: The Posth Study on Euro mtDNA



moore2moore
07-02-16, 23:32
If someone had posted here that mtDNA Haplogroup M had been present in Europe, they would have likely experienced the Internet Age equivalent of being shouted down.

Why? Challenging the orthodoxy is never fun, for the person posting the new idea -- or for the people being challenged. However, the latter form a majority, so they often band together to make people who challenge the orthodoxy seem crazy, wacky, or that they don't understand science.

However, no one has a monopoly on fact, and good scientists approach their work with a bit of humility. :heart: They only accept the orthodoxy if it has been proven, for years, beyond a reasonable doubt. Within the field of Physics, for example, there has been no real orthodoxy, on many subjects, for decades. This scientific skepticism is the mark of a mature field and mature scientists.

A few months ago, I posted a series of monographs here on how an understanding of demographics is necessary to truly understand aDNA. The principles I posted were:

1. Many, old haplogroups existed in Europe at one point in time, even, of course, Neandertal haplogroups.

2. The fact that those HGs are not found in the modern world can give very false impressions of the mechanisms for HG spread.

3. These false impressions include thinking that a HG originated somewhere where it did not.

4. Or that there was a mass slaughter / genocide / conquering event that occurred, when no such event did.

5. The more likely explanation is always boring demography: certain groups simply started with a significantly smaller population size.

6. Furthermore, there is about a 12.5% chance with each generation that a male has no male offspring, or a woman has no female offspring.

7. Couple a small initial population size with this randomness, and you can explain much of the current distribution of haplogroups.

In other words, many current HG distributions are simply explained by who came later in time and who came with greater numbers. :good_job: Not the highly dramatic "genocide / mate selection" theories that dominate the orthodoxy on this board.

Now comes an exhaustive study of Ancient DNA by Posth et al. Hundreds of samples of ancient mtDNA.

Lo and behold, the authors find that Haplogroup M existed in Europe for quite some time. But its initial population size was tiny. (Perhaps these were the female equivalent of the Y DNA HG C men).

Their tiny initial numbers, combined with the randomness of being there for many generations, and each generation giving a ~12% chance that you would not have an offspring of the same gender (needed to give the appearance you survived) -- have made it so Ancient DNA scientists for 20 years now -- and the Orthodoxy -- never even considered that Haplogroup M would be found in Europe.

This rewrote the entire tale of the peopling of the world. The authors emphasize the same caution and the same model that I did (and got laughed at for).

The take away? Be respectful of "weird" people. Be respectful of different ideas. Think things through; model them in your head. Appearances are not always accurate.

You can read my explanation of the model here.

(http://snplogic.blogspot.com/2015/12/the-spread-of-haplogroups-in-europe.html)I reviewed the various theories here. (http://snplogic.blogspot.com/2015/12/a-review-of-all-theories-on-why-r1b-is.html)
(http://snplogic.blogspot.com/2015/12/the-spread-of-haplogroups-in-europe.html)
You can read the landmark study here. (http://www.cell.com/current-biology/fulltext/S0960-9822%2816%2900087-7)

Tomenable
08-02-16, 14:17
In other words, many current HG distributions are simply explained by who came later

The case of Hungarians seems to be dramatically different.

Linguistic ancestors of Hungarians (who gave them their Uralic language) came later, conquering areas previously inhabited by Indo-European groups.

However, studies such as Tömöry 2007, Csányi 2008 and Szécsényi-Nagy 2015 seem to indicate that there is surprisingly little genetic continuity between original Hungarians and modern Hungarians, though maybe this is due to unrepresentative conquest era or modern samples:

Tömöry 2007 (apparently lack of mtDNA continuity: "high-status individuals, presumably conquering Hungarians, show a more heterogeneous haplogroup distribution, with mtDNA haplogroups - N1a, X - which are present at very low frequencies in modern worldwide populations and are absent in recent Hungarian-speaking populations. Our findings demonstrate that significant genetic differences exist between 27 ancient Magyars and 177 modern Hungarian-speakers, and no genetic continuity is seen"):

http://www.ncbi.nlm.nih.gov/pubmed/17632797

http://doktori.bibl.u-szeged.hu/1088/3/T%C3%B6m%C3%B6ry_t%C3%A9zisek-angol.pdf

Csányi 2008 (Y-DNA) - it indicates that among Magyars haplogroup N1c was common, but it is almost absent from modern Hungary (two 10th century elite status Hungarians had Y hg N1c and mtDNA Tat C, but in a modern sample of 197 Hungarian-speakers just 1 had Tat C):

http://onlinelibrary.wiley.com/doi/10.1111/j.1469-1809.2008.00440.x/abstract

http://www.ancestraljourneys.org/medievaldna.shtml

http://s14.postimg.org/ks60eodup/Samples.png

2015 study (mtDNA: see Table 8. on page 137 - it shows total lack of continuity of informative mtDNA haplotypes between a sample of 25 conquest era original Hungarians and a sample of 284 modern Hungarians; even continuity with Cumanians is greater):

http://ubm.opus.hbz-nrw.de/volltexte/2015/4075/pdf/doc.pdf

Also such a study on Cumanians: http://www.ncbi.nlm.nih.gov/pubmed/16596944

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Possible explanations is that Magyars (original Hungarian-speakers) imposed their language on much more numerous locals. It is also possible that the original Magyar stock eventually got extinct, maybe due to being overrepresented compared to local subject stock among warriors and thus suffering high casualties in wars such as against the HRE, against Mongols, or against Turks. For example, after the battle of Lechfeld in 955, most of retreating Magyars were ambushed and slaughtered by local peasants (according to Bachrach's "Warfare in Tenth-Century Germany"):

According to Bachrach, the battle itself was inconclusive (they were halted, not defeated), only the withdrawal was disastrous:

http://www.jstor.org/stable/10.7722/j.ctt1x7355


https://www.youtube.com/watch?v=vJbwSOI3wX8

Magyars fought so far and wide in Europe (map), that probably they decimated themselves while trying to conquer Europe:

https://upload.wikimedia.org/wikipedia/commons/9/99/Kalandozasok.jpg

berun
09-02-16, 08:54
The case with magiars is precisely related to demographics. If there were some 1500000 locals in pannonia and it came some 100000 magiar tribals around the year 900... bare mathematics will tell that after a millenia you can get as much one from a hundred for magiar y or mt dna (and that supposing that all tribal dna was previously unrelated to the local)

laetoli
02-03-16, 12:55
6. Furthermore, there is about a 12.5% chance with each generation that a male has no male offspring, or a woman has no female offspring.

7. Couple a small initial population size with this randomness, and you can explain much of the current distribution of haplogroups.

What you say must be true if all variation is neutral with regard to selection but is it possible that there is no such thing as a neutral mutation? Could there also be degrees of selective pressure acting with relation to diversity within a population? mtDNA with its short length and crucial role within the cell may not have behaved quite so randomly. It might be the case that the M mtDNA haplogroup was differentially outcompeted by N in pleistocene Europe or by events like disease epidemics that contributed to its demise. How can we know? A lot more ancient DNA (and not just human DNA) might resolve the issue.

Best wishes

MOESAN
03-03-16, 20:42
The case with magiars is precisely related to demographics. If there were some 1500000 locals in pannonia and it came some 100000 magiar tribals around the year 900... bare mathematics will tell that after a millenia you can get as much one from a hundred for magiar y or mt dna (and that supposing that all tribal dna was previously unrelated to the local)

there are maths and maths.
upon 100000 men, I'm not sure (if they had a majority of the same HaploG) it will stay NONE of these haplo's at last (selection kept apart). Above all for elite Haplo's. And hazard is not a straightaway thing. Some men have NO son, some others of the same haplo's can have a lot.
And a socially stratified population is not perfectly submitted to genuine hazard. THeir genes are not all of them in the same panel, I think.

MOESAN
03-03-16, 20:45
I agree with Laetoli for mtDNA which has a proved metabolic role in life and so can be submitted to natural pressure and selection. For YDNA I remain confused concerning selection.