Ancient DNA from Hunter-Gatherer and Farmer Groups from Northern Spain Supports a Random Dispersion Model for the Neolithic Expansion into Europe

Hervella et al. 2012

Samples : 

Haplogroups :

Haplogroup H is the major one, showing a frequency of 45% in the ancient samples analysed. This figure is similar to that observed in some present-day European populations including the North of the Iberian Peninsula

Two of the Palolithic hunter-gatherer from Cantabria belong to mtDNA H .

The three groups of hunter-gatherers considered in this analysis (from Scandinavia, Central Europe and the Cantabrian fringe on the Iberian Peninsula) did not show statistically significant differences between one another, but they are significantly different from any population compared, because to the high frequency of haplotypes within the haplogroup U (50%–80%) .

Abstract

Background/Principal Findings

The phenomenon of Neolithisation refers to the transition of prehistoric populations from a hunter-gatherer to an agro-pastoralist lifestyle. Traditionally, the spread of an agro-pastoralist economy into Europe has been framed within a dichotomy based either on an acculturation phenomenon or on a demic diffusion. However, the nature and speed of this transition is a matter of continuing scientific debate in archaeology, anthropology, and human population genetics. In the present study, we have analyzed the mitochondrial DNA diversity in hunter-gatherers and first farmers from Northern Spain, in relation to the debate surrounding the phenomenon of Neolithisation in Europe.

Methodology/Significance

Analysis of mitochondrial DNA was carried out on 54 individuals from Upper Paleolithic and Early Neolithic, which were recovered from nine archaeological sites from Northern Spain (Basque Country, Navarre and Cantabria). In addition, to take all necessary precautions to avoid contamination, different authentication criteria were applied in this study, including: DNA quantification, cloning, duplication (51% of the samples) and replication of the results (43% of the samples) by two independent laboratories. Statistical and multivariate analyses of the mitochondrial variability suggest that the genetic influence of Neolithisation did not spread uniformly throughout Europe, producing heterogeneous genetic consequences in different geographical regions, rejecting the traditional models that explain the Neolithisation in Europe.

Conclusion

The differences detected in the mitochondrial DNA lineages of Neolithic groups studied so far (including these ones of this study) suggest different genetic impact of Neolithic in Central Europe, Mediterranean Europe and the Cantabrian fringe. The genetic data obtained in this study provide support for a random dispersion model for Neolithic farmers. This random dispersion had a different impact on the various geographic regions, and thus contradicts the more simplistic total acculturation and replacement models proposed so far to explain Neolithisation.

mtDNA L in Europe and Spain

Here is a compilation from many different studies, for the frequencies of the maternal Sub-Saharan haplogroup mtDNA L,  for countries from all around  Europe. At the bottom, there is a compilation for the total of Spain. We'll see that spanish percentages are similar to other countries and/or regions of Europe. 

For some obscure reasons, on the Wikipedia articles  "mtDNA L in Europe", and  "African admixture in Europe" there is only  Iberia and Italy as european countries having mtDNA L, we will see here that this is not the case, there is in all corners of the continent. And I advise you if you dare to edit those articles,  you'll probably get blocked.


Slovaks              n = 2/207    0.97%      Malyarchuk et al.2006

Czechs              n = 1/279     0.36%      Malyarchuk et al., 2008

German-Danish  n = 1/161     0.62%      Richards et al. 1996
Germany            n = 1/335     0.30%      Achilli et al 2007
Germany            n = 4/333    1.20%      Pliss et al. 2005

Albania             n =  1/42      2.38%     Belledi et al. 2000
Bosnia             n=1/144        0.70%    Achilli et al 2007
Bulgaria           n=1/141        0.71%    Achilli et al 2007
Balkans          n= 1/556        0.18%    Regueiro et al. 2012 + King et al. 2011


Poland              n = 1/542     0.20%      Achilli et al 2007
Poland              n = 1/436     0.22%      Malyarchuk et al., 2002
Poles                n = 1/849     0.12%      Malyarchuk et al., 2008


British               n=1/100      1.00%      Piercy et al. 1993
England            n = 2/335     0.60%      Achilli et al 2007
England            n  = 1/142    0.70%     Helgason et al., 2001
Great Britain     n = 1/114     0.90 %     García et al. 2011
Scotland           n = 1/891     0.10 %     García et al. 2011


Finnish             n = 1/50       2.00%     Sajantila et al. 1995
Finland            n = 1/121     0.83%     Achilli et al 2007
Finns               n = 3/580     0.52%     Pliss et al. 2005


Norway          n = 1/74       1.40%     Passarino et al 2002
Norwegians    n = 2/397     0.50%      Pliss et al. 2005


Russia            n =  2/683     0.29%     Malyarchuk et al. 2008


France            n = 1/332      0.30%    Achilli et al 2007
France            n = 5/692      0.72%     Richards et al. 2007
France            n =  3/433     0.69%     García et al. 2011
France            n = 2/320      0.63%     Pliss et al. 2005
France                                 1.40%     Gónzalez et al. 2003


Switzerland      n=1/228        0.44%    Achilli et al 2007


Crete, Greece  n= 2/202       0.99%    Achilli et al 2007


Italy                n = 8/411      1.94%     Plaza et al. 2003,  Romano et al. 2003

NW Italy         n = 100        2.00%    Brisighelli et al. 2012

Sardinian         n = 2/69       2.90%     Di Rienzo and Wilson 1991
Sardinia          n =2/370       0.54%    Achilli et al 2007

Sicily               n= 1/106       0.94%     Cali et al. 2001
Sicily               n = 2/105      1.90%     Achilli et al 2007
Sicily              n = 3/465       0.65%    Plaza et al. 2003,  Romano et al. 2003
South Italy     n = 2/313        0.64%    Boattini et al. 2013 + Stefania Sarno et al. 2014

Tuscany          n= 6/322        1.86%    Achilli et al 2007
Marche (Italy) n=8/813         0.98%    Achilli et al 2007
Latium(Italy)    n=4/138        2.90%    Achilli et al 2007
Murlo (Italy)    n = 1/86       1.16%     Achilli et al 2007
Volterra (Italy) n =  3/114     2.63%    Achilli et al 2007
Casentino (Italy) n =  2/122  1.64%   Achilli et al 2007
Campania        n = 3/313      0.32%   Achilli et al 2007



Spain Total   n = 51 / 4.329     1.18%    From here :

Spain   n = 15/813   1.84%       Achilli et al 2007
Spain,  n =  0/686    0.00%       Rhouda 2006
Spain   n =  0/233    0.00%,      Lopez-Parra 2009
Spain   n =  1/251    0.40%       Plaza et al. 2003
Spain   n =  9/312    2.90%       Álvarez et al. 2007
Spain   n =  1/108    0.90%       Casas et al. 2006 *
Spain   n =  2/226    0.88%       Maca-Meyer et al. 2003
Spain   n = 15/742   2.02%      García et al. 2011
Spain (Basques)  n = 0/462      García et al. 2011
Spain, Zamora Province**  n =10/214    4.67%      Álvarez  et al. 2010
Spain, n = 8/496     1.61%       Pereira et al. 2005

Note that in the García et al. 2011 there is overlapping with other studies, that's why the total shown here  is not the same as the total you might get from the study.

- * Note that Casas et al. 2006 only considered L1-L2 sequences to be of sub-Saharan origin.
-** This study inlcudes only a sample from a small town of the province of Zamora, thus it is not very representative of the population of Spain, I prefer wider regions, anyways I have included them.
- Note about the subclade L3, some scholars don't consider it as Sub-Saharan (Maca-Meyer 2003 et al.) in her words :
""L3 is more related to Eurasian haplogroups than to the most divergent African clusters L1 and L2". L3 is the haplogroup from which all modern humans outside of Africa derive"

Sub-Saharan haplogroup mtDNA L in Spain and Europe

In the study of Rhouda et al. (2006) in a sample of 686 spaniards, not a single individual with haplogroup mtDNA L was found. In the rest of Western Europe, the recent study of García et al. 2011 finds L up to Northern Germany and Denmark . We observe the following percentages  :

Hérault (Languedoc) 2.4 %
Rhône (Lyonnais) 4.4 %
Vendée and Vienne (Poitou) 0.8 %
Calvados and Seine-Maritime (Normandy) 1.8 %
Somme (Picardie) 1.3 %
France Miscellanea 0.6 %
Scotland 0.1 %
England 0.7 %
Great Britain 0.9 %
North-Germany and Denmark 0.7 %

North-African mtDNA in Spain...and Europe

The minor presence of the typical north-african mtDNA haplgroup U6  in Spain, even if at low levels, was tought to be higher than anywherelse in Europe. Interestingly we will see that this is not the case. The truth is that U6 is found everywhere in Europe, but it has been found at higher frequencies in France. Obviously these studies make sure the testees are natives, having the 4 grandparents from the same area, and their surnames native. We see now the studies :

In this study of Dubut et al. 2004 there is a total of 4.5% of U6 in Finistère (Brittany, France) and 1.4% in Périgord-Limousin.

In this very recent study of García et al. 2011 we find these frequencies for France :

• U6a1/a2/a3 Perigord-Limousin (Limousin) 1.4 %
                     Finistère (Brittany) 0.7 %
• U6a  France Miscellanea 0.6 %

Spain : 

Andalusians n=3/158    1.9%   Plaza 2003.

Asturias   n=1/89     1.1%    Garcia 2011.

Aragón     n=0/119    0.0%    Garcia 2011.

Catalonia-Aragón  n=2/164  1.2%  Garcia 2011.
Catalonia n=3/80    3.9%      Garcia 2011.
Catalonia n=78     0.0 %    Plaza 2003.

Central Spain   n=1/50  2.0%   Plaza 2003.

Basques    n=45  ??   0.6%    Maca-Meyer 2003.
Basques    n=0/377    0.0%    Garcia 2011.
Basques    n=1/85     1.2%    Garcia 2011.
Basques    n=173      0.0%    Plaza 2003.

Galicia      ??       2.3%    Maca-Meyer 2003.
Galicia    n=3/185    1.5%    Garcia 2011.
Galicia    n=2/103      1.9%    Plaza 2003.

Cantabria  n=1/105    1.0%    García 2011.
Potes      n=0/72     0.0%    Maca-Meyer 2003.

Lebaniegos n=0/72   0.0%      Maca-Meyer 2003.
Pasiegos   n=0/82   0.0%      Maca-Meyer 2003.

Valencia   n=0/30     0.0 %     Plaza 2003.

% M1 and U6a1a = 2/214 = 0.93%   Álvarez 2010


TOtal SPain = 18/2.022 = 0.89%

Genetic continuity since pre-Roman times

In this study of Sampietro et al. 2005 have retrieved mitochondrial DNA (mtDNA) from a few of the scarce skeletal remains that have been preserved. 
Phylogeographic analyses show that the haplogroup composition of the ancient Iberians was very similar to that found in modern Iberian Peninsula populations, suggesting a long-term genetic continuity since pre-Roman times.

Here is the whole summary :

Summary
The Iberians developed a surprisingly sophisticated culture in the Mediterranean coast of the Iberian Peninsula from the 6th century BC until their conquest by the Romans in the 2nd century BC. They spoke and wrote a non-Indo-European language that still cannot be understood; their origins and relationships with other non-Indo-European peoples, like the Etruscans, are unclear, since their funerary practices were based on the cremation of bodies, and therefore anthropology has been unable to approach the study of this people. We have retrieved mitochondrial DNA (mtDNA) from a few of the scarce skeletal remains that have been preserved, some of them belonging to ritualistically executed individuals. The most stringent authentication criteria proposed for ancient DNA, such as independent replication, amino-acid analysis, quantitation of template molecules, multiple extractions and cloning of PCR products, have been followed to obtain reliable sequences from the mtDNA hypervariable region 1 (HVR1), as well as some haplogroup diagnostic SNPs. Phylogeographic analyses show that the haplogroup composition of the ancient Iberians was very similar to that found in modern Iberian Peninsula populations, suggesting a long-term genetic continuity since pre-Roman times. Nonetheless, there is less genetic diversity in the ancient Iberians than is found among modern populations, a fact that could reflect the small population size at the origin of the population sampled, and the heterogenic tribal structure of the Iberian society. Moreover, the Iberians were not especially closely related to the Etruscans, which points to considerable genetic heterogeneity in Pre-RomanWestern Europe.