Saturday, July 29, 2017

The evidence says one thing, they say another

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While searching for new mtDNA data on google today I came across gold mine: Olivieri 2013 et al. This study sequenced  many mitogenomes belonging to mHGs W and N1a1b, two widespread and poorly understood lineages.

Though I do appreciate the amazing work the people who took part in this study did, the conclusion they made about N1a1b is complete bonkers. Their conclusion isn't bonkers because they aren't aware of other data which disproves their conclusions, it's bonkers because their own data dis agrees with their conclusions.

The conclusion/assumption they came up with is that haplogroups N1a1b  took part in repopulating Europe after the Ice age('Last Glacial Maximum') about 15,000-12,000 years ago. But if they looked at the their own age estimates for mHG N1a1b clades they would have seen this isn't very probable.

A large majority of European N1a1b is I1a1, I3a, and I2. Look at the age estimates Olivieri 2013 got for those clades.

I1a1; 4,900yp
I2; 6,800yp
I3a: 7,400yp

The LGM ended 12,000yp, long before any of these clades are estimated to have began. How did Olivieri 2013 not see this? Ancient mtDNA shows I1a1, I2, and I3a likely spread into Europe from the Russian Steppe about 4,000-5,000 years ago. The oldest example of I3a is in Poltvaka. Plus Andronovo, Bell Beaker, and Unetice had a really high frequency of these mHGs.

I use Soares 2009's age estimator to get estimates for mtDNA haplogroups and it gets similar age estimates for these N1a1b clades as Olivieri 2013 did.

Soares 2009's estimator gives similar age estimates for all the major European mtDNA haplogroups. So what this mans is a large majority of European mtDNA belongs to mHGs that, according to Soares 2009's age estimator, arose less than 10,000 years ago. That's consistent with what ancient mtDNA shows; European mtDNA mostly derives from two migrations that occurred between 5,000yp and 10,000yp and originated from relatively small regions with *relatively* low mtDNA diversity.

This isn't an isolated incident, Olivieri 2013 is just one example of a host of mtDNA studies which make the same naive assumption about European origins. They all assume the current European gene pool derives from southern refugiums that repopulated Europe after the Ice age roughly 15,000 years ago.  Oh yeah and they also think modern day Basque are basically fossils from Ice age Europe.

No matter what the data actually indicates, they come to the same ole conclusions in their studies. Well, now that ancient DNA has thoroughly disproven these assumptions, hopefully mtDNA studies about the peopling of Europe will begin to explore more possibilities.

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They aren't horrible people for making these assumptions. It's human nature we all make assumptions like this. 5-10 years ago, it appeared the evidence suggested the European gene pool formed during the LGM. That's what all the smartest experts though. I also tend to make assumptions based on what the most popular current theories are. I'm sure many current theories will be proven wrong in the future. 

I can understand why a geneticists in 2013 would think modern European origins can be explained mostly by LGM migrations but geneticists who think this in 2017 have no excuse. Commercial DNA testing companies like 23andme and FTDNA still preach these old disproven theories as fact to their customers. There's no excuse for this, data that disproves these theories has been around for several years now. 

5 comments:

  1. .....good catch! This is why I follow your Bolg.

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  2. I have emailed FTDNA several times about their out-dated information regarding MtDNA H6.

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  3. From FTDNA regarding MtDNA H6 " H6 is one of the oldest branches of haplogroup H. Its age is estimated at around 26,000 years. It is one of the most frequent branches of H found among Arabian lineages, and is the most frequent branch among those found in Central Asia. It likely originated in the Middle East or Central Asia. H6 is also found at very low frequencies in Europe"

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  4. Apparently H6 is older than her mother MtDNA H....

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  5. At least they don't say H6 expanded after the Ice age.

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