Tuesday, May 17, 2016

mtDNA R0 is Native to Arabia

A new paper makes a very solid case that mtDNA R0, which is the sister clade to mtDNA HV (which is the dominant West Eurasian and North African Berber mtDNA clade) has a source in Arabia.  It has maximum diversity there in addition to most clades being most common there.  R0 is mostly found in Arabia and to a lesser extent West Asia, but mtDNA R0a1 is found at low frequencies across Europe as well and it as well as mtDNA R0a2'3 dispersed in the Mesolithic a.k.a. Epipaleolithic a.ka. 17kya to 13kya or so.

The full story is more complicated but generally fits a Mesolithic dispersal from Arabia which would have served as a refuge during the Last Glacial Maximum ca. 20kya.

The subclade mtDNA R0a2b2 is strongly associated by location, proximity, and age with the Ethio-Semitic migration from Arabia to East Africa, while R0a2b1 which strongly overlaps with it geographically, could be part of the same migration but might be from an earlier wave of Arabian to East African migration as the clade is two and a half times older than R0a2b2 along with a couple of other rare mtDNA R0 clade of the same age.

A rare clade mtDNA R0a6 is found mostly in Pakistan, mostly in the Kalash, but single individuals with this clade have also been noted in Iran, Palestine and Italy.


terryt said...

I have always presumed R0 originated in SW Asia, at least. However that doesn't mean in the least the R as a whole originated there.

Krefter said...

Now we have ancient DNA from Europe to test the theories made by these type of papers. Essentially every theory was proven wrong. So, I wouldn't take the theories made by this paper pertaining mtDNA R0 very seriously. It's usually impossible to detect ancient origins by looking at modern DNA.

andrew said...

I wouldn't say that "essentially every theory was proven wrong" is at all a fair assessment of the effect of ancient DNA. Indeed, I'd be inclined to say that the theories proven wrong have been in the minority.

terryt said...

The only thing I think the theories have been wrong in is the actual DNA found seems more ancient than expected. I think it's the 'molecular clock' that has the problems. And I also think it is almost certain that the paper is correct regarding the origin of R0.

Krefter said...


That was a little harash. Most popular theories based on modern DNA in academics about European genetics have been proven wrong,, but not all.

I've read lots of old mtDNA papers and have noticed they often make big claims with small data, because in my opinion they want to get published. We should cherish the data they make public but take their theories with a grain of salt. When it comes to Europe most theories about mtDNA based on modern mtDNA were wrong or they weren't able to learn anything valuable about mtDNA origins. I don't think this paper on Arabian R0 is any differnt.

We like to think we can learn a lot from modern DNA but we can't. 1,000 fully sequenced mtDNA samples from 10 differnt populations can't tell us much about the history/origins of those population's mtDNA. We can create theories from those 10,000 fully sequenced mtDNAs and we'll be able to expand our mtDNA tree, but we won't learn where haplogroup ___ was in 10,000 BC.

terryt said...

Krefter, I slightly disagree. Before a particular haplotype is able to expand it would generally have to come to dominate a core area. That core area would preserve the greatest variation because just a subset of the haplotype would lead an expansion in any direction. Therefore conditions for its survival long-term would have to be reasonably good. What ancient DNA has told us is that haplotypes have often become extinct at the margin of their expansion.

As for the surprises ancient DNA has given me: the first was the presence of mt-DNA B in Tianyuan at 40,000 years ago. I was surprised it had reached so far north at such an early age. Then the surprise of Ust'-Ishim Y-DNA being K2a* so far west at 45 kya. The mt-DNA being pre-B was less of a surprise given Tianyuan of course. And K2a* made it even further west at Oase but this time it had picked up a basal N. No surprise with the last, but K2a* had moved a huge distance only to become extinct as the climate cooled.

Another surprise revealed by ancient DNA is the huge distances haplotypes were capable of moving so long ago. I've already pointed out mt-DNA B and Y-DNA K2a* but Y-DNA C1b* at Kostenki 37 kya has also moved a huge distance through South Asia from SE Asia. Only to also become extinct in the west. Y-DNA C1a at Goyet 35 kya is no surprise at all, apart from the mt-DNA M which was not really unexpected with data that has recently come out. C1a has held on in the west.

Was anyone really surprised that 25 kya MA-1 had Y-DNA R*? I don't really think so. Consequently I find the idea that R0 originated, and expanded from, SW Asia completely unsurprising and fitting all the evidence as we have it so far.