View Full Version : Mesolithic U5b2c1 in Northwestern Spain

08-19-2012, 09:31 PM
A very interesting paper was published in June that includes the full mtDNA genome for 7000 year old late Mesolothic sample in Spain, U5b2c1. There is some discussion of the paper at Dienekes blog (http://dienekes.blogspot.com/2012/06/mesolithic-iberians-la-brana-arintero.html).

The sample appears to be U5b2c1 with no additional mutations reported in Table S2. We have 5 FMS test results in the U5 project for U5b2c1 and 1 partial result from Hernstadt. One person in the project has ancestry in Spain and also has no extra mutations, i.e., this person is an exact match to the Mesolithic La Brana sample. Two U5b2c1 people have ancestry in Ireland, and one has ancestry in Germany. They have between 1 to 5 extra mutations for an average of 2.17 and age estimate of 5700 years (compared to Berhar's estimate of 4200 years). Both estimates are younger than the remains dated to 7,000 years old. However, the age estimates are based on a small sample size and have large uncertainty. The FMS test result is very useful for an independent estimate of the age of U5b2c1, and it confirms a very old date for this group and also confirms that it was present in Europe during the late Mesolithic.

For comparison with other U5b2c in the FTDNA U5 project, we have one U5b2c* with ancestry in Ireland, we have two U5b2c2 with ancestry in Ireland and and 1 in Scotland. We also have 5 people in "U5b2c2 Group A" (defined by 16249C) with ancestry in: Scotland, Sweden, Ireland, North Ireland and England. This "Group A" also appears to be quite old with an average of 2.2 extra mutations in addition to the mutation at 16249.

Behar et al. estimate U5b2c to be about 13,000 years old, so there is a very long history of U5b2c in Europe before the people in La Braņa 7000 years ago. The simplest story would be an Iberian ice age refuge followed by a very early expansion through Spain to England and Ireland. But that migration could have happened very long ago, perhaps with the first people to repopulate England and Ireland after the glacial maximum. The very old age estimates for U5b2c and its present distribution in Ireland, the UK, Sweden and Germany could leave open the possibility of other migration routes for early U5b2c to arrive in England and Ireland. It could even be possible that the U5b2c1 La Brana mtDNA arrived in Spain from Ireland or the UK. Not that I think this is likely, but I do think we need to consider the possibility of very complex migrations over a period of many thousands of years.

Kudos to the authors for doing the extra work on the full sequence - it would be great if other researchers would revisit their previously published HVR test results of ancient remains.

J Man
08-22-2012, 02:02 PM
^Yes this certainly is a very important study. The fact that they actually did a FMS on the La Brana remains is very important. Hopefully they will be doing this with more ancient samples in the not so distant future.

Now it is very interesting to see U5b2c present in Iberia during the late Mesolithic in the form of the U5b2c1 subclade. As you say Gail it appears obvious now that U5b2c is very ancient in Europe. Well in reality we know that all of haplogroup U5 is. It is now looking like haplogroup U and it's subcaldes U5, U4 and U2 were probably the haplogroups that made up the majority of maternal lineages of the Upper Paleolithic and Mesolithic European populations. More ancient DNA testing will help to resolve this even further.

08-23-2012, 02:27 AM
As you say Gail it appears obvious now that U5b2c is very ancient in Europe. Well in reality we know that all of haplogroup U5 is.

Another interesting question is whether some U5 was originally present not in Europe but in the Levant or the Near East and expanded into Europe with the first farmers. U5a2a is estimated by Behar to be about 13,000 years old and 95% of U5a2a are in U5a2a1 that is dated to about 6000 years ago. There is also very large diversity in U5a2a1 indicating that it was in a population that was rapidly expanding 6000 years ago. My guess is that U5a2a1's origin was in Neolithic farming communities, perhaps in the Balkans or maybe even in the Levant. There are only two U5a2a* FMS test results in GenBank and the U5 project, and one of them, JQ705530, has a back mutation at 16270. For these two U5a2a* lines, each represented by a single sample in GenBank, it seems to me more likely that their origin was in Mesolithic hunter gatherers.

There is an ancient U5 sample Hohlenstein-Stadel 5830a (http://www.buildinghistory.org/distantpast/ancientdna.shtml) dated to 8700 ybp in Germany that appears to be U5a2a. Although it only has HVR1 and a few coding region SNPs the HVR1 signature it very distinctive for U5a2a. The Hohlenstein-Stadel 5830a results do not show the 16270 and 16526 mutations expected for U5a2a, but perhaps it also has the back mutation at 16270 and is in the same subclade as JQ705530. If that is true, it would indicate a Mesolithic hunter-gatherer origin for the very rare U5a2a* and leave open the possibility of a Neolithic farmer origin for U5a2a1. It would be very useful to test the coding region for Hohlenstein-Stadel 5830a to confirm if it is U5a2a1 or U5a2a*. If it turns out to be U5a2a1, we have to extend back our age estimate for U5a2a1 and also find an alternate explanation for rapid population growth in a hunter-gatherer U5a2a1 more than 6,0000 years ago.

Also, many thanks to Jean for maintaining the ancient DNA webpage, it is a huge resource for the community!

J Man
08-23-2012, 01:26 PM
^Yes that is an interesting question Gail. You mention U5a1a1 and U5a2a1 both together at the top in reference to it coming into Europe with early farmers but I think that the ''U5a2a1'' may be a typo and you really mean only ''U5a1a1'' correct? Personally I am leaning to U5a1a1 probably being part of the original Mesolithic populations of the Balkans who were absorbed into Neolithic farming communities early on and then spread into the rest of Europe. I think it will be unlikely that scientists will find any U5 in early Neolithic sites of the Levant but time will surely tell for sure.

What are your thoughts on U5b though? We know that both U5b1 and U5b2 were present in Europe during the Mesolithic. I think they both have an Upper Paleolithic/Mesolithic origin in Europe.

08-23-2012, 07:32 PM
You mention U5a1a1 and U5a2a1 both together at the top in reference to it coming into Europe with early farmers but I think that the ''U5a2a1'' may be a typo and you really mean only ''U5a1a1'' correct?

Yes, that was a typo, it should be U5a2a1. I corrected it, and thanks for catching it! However, U5a1a1 and U5a1b also seem to have a lot of diversity perhaps indicating their population began to grow at an early date. So an origin in the Balkans could be consistent with an earlier adoption of farming, and these U5a1a1, U5a1b and U5a2a1 farmers could have then expanded into northern Europe and replaced some of the more scarce U5 subclades. U5b seems to mostly lack the large diversity at an early date, so perhaps they were more likely to have been among Mesolithic western and northern Europe populations that adopted farming later. But we really need FMS test results for the ancient mtDNA to see if there is continuity from the Mesolithic to the present.