Genetic history of Europe


Genetic history of Europe

European populations have a complicated demographic and genetic history, including many layers of successive migrations between different time periods, from the first appearance of "Homo sapiens" in the Upper Paleolithic to contemporary immigration.

Relation to other populations

Initially, a study by Luigi Luca Cavalli-Sforza of the Stanford University School of Medicine, using 120 blood polymorphisms, provided information on genetic relatedness of the various continental populations. [http://www.pnas.org/cgi/content/full/94/15/7719 Genes, peoples, and languages - Cavalli-Sforza 94 (15): 7719 - Proceedings of the National Academy of Sciences ] ] Genetic distance is a measure used to quantify the genetic differences between two populations. It is based on the principle that two populations that share similar frequencies of a trait are more closely related than populations that have more divergent frequencies of a trait. In its simplest form it is the difference in frequencies of a particular trait between two populations. For example the frequency of RH negative individuals is 50.4% among Basques, 41.2% in France and 41.1% in England. Thus the genetic difference between the Basques and French is 9.2% and the genetic difference between the French and the English is 0.1% for the RH negative trait. Averaged over several traits this can give the overall genetic relatedness of various populationsGenes, Peoples, and Languages By L. L. (Luigi Luca) Cavalli-Sforza ISBN 0520228731] .

According to the study all non-African populations are more closely related to each other than to Africans consistent with the hypothesis that all non-Africans are descended from a single African population. Europeans are most closely related to the people of the Near East, Middle-East and the Indian Subcontinent. Europeans are least related to Africans, however of all the non-African populations, Europeans are most closely related to Africans. As the genetic distance from Africa to Europe (16.6) is shorter than the genetic distance from Africa to East Asia (20.6) and even much shorter than the Genetic distance from Africa to Australia. Cavalli-Sforza proposes that the simplest explanation for this short genetic distance is that substantial gene exchange has taken place between the nearby continents. Cavalli-Sforza also proposes that both Asian and African populations contributed to the settlement of Europe which began 40 000 years ago. The overall contributions from Asia and Africa were estimated to be around two-thirds and one-third, respectively. Europe has a genetic variation in general of about a third of that of other continents. [ [http://www.nytimes.com/books/00/08/20/reviews/000820.20ridleyt.html First Chapter: 'Genes, Peoples, and Languages'] ]

According to Guglielmino et al. (1990),

Principal coordinate analysis shows that Lapps/Sami are almost exactly intermediate between people located geographically near the Ural mountains and speaking Uralic languages, and central and northern Europeans. Hungarians and Finns are definitely closer to Europeans. An analysis of genetic admixture between Uralic and European ancestors shows that Lapps/Sami are slightly more than 50% European, Hungarians are 87% European, and Finns are 90% European. There is basic agreement between these conclusions and historical data on Hungary. Less is known about Finns and very little about Lapps/Sami. [Uralic genes in Europe by Guglielmino CR, Piazza A, Menozzi P, Cavalli-Sforza LL [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=2221031&query_hl=8] ]

European population substructure

In 2006, an autosomal analysis comparing samples from various European populations concluded that “there is a consistent and reproducible distinction between ‘northern’ and ‘southern’ European population groups”. Most individual participants with southern European ancestry (Italian, Greek, Armenian, Portuguese, and Spanish) have >85% membership in the ‘southern’ population; and most northern, western, eastern, and central Europeans have >90% in the ‘northern’ population group. Ashkenazi Jewish as well as Sephardic Jewish origin also showed >85% membership in the ‘southern’ population, consistent with a later Mediterranean origin of these ethnic groups." [http://genetics.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pgen.0020143] It should be noted that many of the participants in this study were actually American citizens who self identified with different European ethnicities and not Europeans.

Somewhat contradicting these findings, a similar 2007 study using samples exclusively from Europe found that the most important genetic differentiation in Europe occurs on a line from the north to the south-east (northern Europe to the Balkans), with another east-west axis of differentiation across Europe. Its findings were consistent with earlier mtDNA and Y-chromosonal based results supporting the theory that modern Iberians (Spanish and Portuguese) hold the most ancient European genetic ancestry, as well as separating Basques and Sami from other European populations. It confirmed that the English and Irish cluster with other Northern and Eastern Europeans such as Germans and Poles while some Basque and Italian individuals also clustered with Northern Europeans. Despite these stratifications it noted the unusually high degree of European homogeneity: "there is low apparent diversity in Europe with the entire continent-wide samples only marginally more dispersed than single population samples elsewhere in the world." [ Measuring European Population Stratification using Microarray Genotype Data [http://vetinari.sitesled.com/euroaims.pdf] ]

In fact, according to another European wide study, the main components in the European genomes appear to derive from ancestors whose features were similar to those of modern Basques and Near Easterners, with average values greater than 35% for both these parental populations, regardless of whether or not molecular information is taken into account. The lowest degree of both Basque and Near Eastern admixture is found in Finland, whereas the highest values are, respectively, 70% ("Basque") in Spain and more than 60% ("Near Eastern") in the Balkans. [http://mbe.oxfordjournals.org/cgi/content/full/21/7/1361/T03] [http://mbe.oxfordjournals.org/cgi/content/full/21/7/1361]

In 2008 a company called "DNA Tribes Europa" has used 13 DNA markers to differentiate genetic related groups in Europe. It offeres a specialized analysis for people of European descent, including a detailed comparison to genetic sub-regions of Europe. These genetic sub-regions include both geographical territories and endogamous trans-national communities, who have retained unique genetic characteristics. The determined regions i.e. populations are the next: Ashkenazi, Balkan, Basque, Celtic, Finno-Ugrian, Germanic, Greek, Italian, Norse, Polish, Portuguese, Russian and Spanish. [ [http://www.dnatribes.com/dnatribes-europa.html DNA Tribes Personal Genetic Analysis ] ] Individuals within each Europe sub-region obtain a spectrum of regional genetic affinities. Because of close genetic relationships within Europe, individuals in a subregion can inherit genetic material that is most common in other sub-regions. Individuals from sub-regions with a history of ethnic endogamy or geographic isolation (such as the Ashkenazi, Basque, or Celtic sub-regions) exhibit higher frequencies of primarily ingroup genetic affiliation. Individuals from centrally located sub-regions, such as the Balkan or Germanic regions, exhibit more variety in genetic affiliations and lower frequencies of primarily in-group genetic affiliation. [ [http://dnatribes.com/sample-results/dnatribes-global-survey-regional-affinities.pdf "DNA Tribes Europa". A new genetic map of living humans in interconnected world regions] - E. Valaitis and L. Martin, p. 13.]

In 2008 two international research teams have compiled a genetic maps of Europe, revealing little genetic diversity between the various nationalities. But the differences are enough to tell which country an individual comes from. The researchers found that the genetic map closely resembled the pattern of three major human migrations mainly from the south. Southern Europeans revealed more genetic diversity, mirroring the migration waves of early humans about 35,000 years ago, post-ice age expansion 20,000 years ago and the population movements driven by farming methods emanating from the Middle East about 10,000 years ago. [http://www.gnxp.com/blog/2008/08/genetic-map-of-europe-again.php] [http://scienceblogs.com/gnxp/2008/08/the_genetic_map_of_europe.php] [http://www.nature.com/nature/journal/vaop/ncurrent/abs/nature07331.html]

Western Europe substructure

It is thought that ancient Iberia served as a refuge for palaeolithic humans during the last major glaciation when environments further north were too cold and dry for continuous habitation. When the climate warmed into the present interglacial, populations would have rapidly spread north along the west European coast. Genetically, in terms of Y-chromosomes and Mt-DNA, inhabitants of Britain and Ireland are closely related to the Basques, [http://www.scs.uiuc.edu/~mcdonald/WorldHaplogroupsMaps.pdf McDonald, World Haplogroups Maps] ] [http://www.nytimes.com/2007/03/06/science/06brits.html] reflecting their common origin in this refugial area. Basques, along with Irish, show the highest frequency of the Y-chromosome DNA haplogroup R1b in Western Europe; some 95% of native Basque men have this haplogroup. The rest is mainly I and a minimal presence of E3b. The Y-chromosome and MtDNA relationship between Basques and people of Ireland and Wales is of equal ratios than to neighbouring areas of Spain, where similar ethnically "Spanish" people now live in close proximity to the Basques, although this genetic relationship is also very strong among Basques and other Spaniards. In fact, as Stephen Oppenheimer has stated in The Origins of the British (2006), although Basques have been more isolated than other Iberians, they are a population representative of south western Europe. As to the genetic relationship among Basques, Iberians and Britons, he also states (pages 375 and 378):

By far the majority of male gene types in the British Isles derive from Iberia (modern Spain and Portugal), ranging from a low of 59% in Fakenham, Norfolk to highs of 96% in Llangefni, north Wales and 93% Castlerea, Ireland. On average only 30% of gene types in England derive from north-west Europe. Even without dating the earlier waves of north-west European immigration, this invalidates the Anglo-Saxon wipeout theory...

...75-95% of British and Irish (genetic) matches derive from Iberia...Ireland, coastal Wales, and central and west-coast Scotland are almost entirely made up from Iberian founders, while the rest of the non-English parts of Britain and Ireland have similarly high rates. England has rather lower rates of Iberian types with marked heterogeneity, but no English sample has less than 58% of Iberian samples...

Brian Sykes, in his book based on genetics Blood of the Isles (2006) comes to similar conclusions. Some quotations from the book follow. (Note that Sykes uses the terms "Celts" and "Picts" to designate the pre-Roman inhabitants of the Isles rather than as linguistic terms.)

Cquote
[T] he presence of large numbers of Jasmine’s Oceanic clan ... says to me that there was a very large-scale movement along the Atlantic seaboard north from Iberia, beginning as far back as the early Neolithic and perhaps even before that. The number of exact and close matches between the maternal clans of western and northern Iberia and the western half of the Isles is very impressive, much more so than the much poorer matches with continental Europe. [Harvnb|Sykes|2006|p=280]

Cquote
The genetic evidence shows that a large proportion of Irish Celts, on both the male and female side, did arrive from Iberia at or about the same time as farming reached the Isles. (...)

The connection to Spain is also there in the myth of Brutus.... This too may be the faint echo of the same origin myth as the Milesian Irish and the connection to Iberia is almost as strong in the British regions as it is in Ireland. (...)

They [the Picts] are from the same mixture of Iberian and European Mesolithic ancestry that forms the Pictish/Celtic substructure of the Isles. [Harvnb|Sykes|2006|pp=281-282]

Cquote
Here again, the strongest signal is a Celtic one, in the form of the clan of Oisin, which dominates the scene all over the Isles. The predominance in every part of the Isles of the Atlantic chromosome (the most frequent in the Oisin clan), with its strong affinities to Iberia, along with other matches and the evidence from the maternal side convinces me that it is from this direction that we must look for the origin of Oisin and the great majority of our Y-chromosomes. The sea routes of the Atlantic fringe conveyed both men and women to the Isles. [Harvnb|Sykes|2006|p=283-284]
Oppenheimer states that most Western Europeans are equally of Iberian origins.

Haplogroups

Human Y-chromosome DNA haplogroups

There are three major Y-chromosome DNA haplogroups which largely account for most of Europe's present-day populationDNA Heritage [http://www.dnaheritage.com/masterclass2.asp] ] [Semino et al (2000), [http://hpgl.stanford.edu/publications/Science_2000_v290_p1155.pdf The Genetic Legacy of Paleolithic Homo sapiens sapiens in Extant Europeans] , Science Vol 290. Note: Haplogroup names are different in this article. For ex: Haplogroup I is referred as M170] .
* Haplogroup R1b is common on the western Atlantic coast of Europe, from the Iberian Peninsula (comprising Spain and Portugal) to Ireland, Wales, England and Scotland, and Jutland.
* Haplogroup I is common across Germany, the Netherlands, Austria, and up into Scandinavia, as well as a very high amount in the western Balkans.
* Haplogroup R1a is common in Eastern Europe (and is also common in Central Asia and the Indian subcontinent).

Most common of all haplogroups among western Europeans is R1b. [World haplogroup maps [http://www.scs.uiuc.edu/~mcdonald/WorldHaplogroupsMaps.pdf] ] [Y-chromosome DNA Haplogroups [http://www.genetree.com/ancestral/paternalAncestryInfo.php] ] The exact following values of Hg R1b are: Basques: 88.1%; Irish: 81.5%; Welsh: 89.0%; Scots: 77.1%; Non-Basque Spaniards: 68.0 (Catalans: 79.2; Andalusians: 65.5); Portuguese(South): 56.0%; Portuguese (North): 62.0%; British: 68.8; English (Central): 61.9% Belgians: 63.0; French: 52.2; Danes: 41.7%, Norwegian: 25.9; Swedish: 20.0; German: 47.9; Italian (Calabria): 32.4; Italian (Sardinia): 22.1%; Italian (North-central): 62.0; Slovenian: 21%; Croatian (mainland): 15.7%; Czech & Slovak: 35.6%; Polish: 16.4%; Bulgarian: 17.0%; Serbian: 10.6%; Greek: 22.8%; Cypriot: 9.0%; Albanian: 17.6%; Romanian: 18.0%; Hungarian: 13.3%. [Oxford Journals [http://mbe.oxfordjournals.org/cgi/content/full/22/10/1964/TBL1] ]

Among European populations, diversity is highest in Eastern Europe, despite lower frequencies. Diversity analysis indicates that all European variants of R1b shared an existence in Central Asia (Kazakhstan) before migrating to Russia and then splitting into two major migrations, moving primarily along rivers and coastlines. [ [http://www.worldfamilies.net/Tools/r1b_ydna_in_europe Variations of R1b Ydna in Europe: Distribution and Origins] ] .

Each haplogroup also have subclades. [Y-DNA Haplogroup Tree 2006 [http://www.isogg.org/tree/ISOGG_YDNATreeTrunk.html] ] R1a and R1b are subclades of Haplogroup R (Y-DNA) [Y-DNA Haplogroup R and its Subclades [http://www.isogg.org/tree/ISOGG_HapgrpR.html] ] Two main subgroups of Haplogroup I (Y-DNA) are I-M253/I-M307/I-P30/I-P40 which according to the International Society of Genetic Genealogy, "has highest frequency in Scandinavia, Iceland, and northwest Europe." The other is I-S31 which according to the International Society of Genetic Genealogy, "includes I-P37.2, which is the most common form in the Balkans and Sardinia, and I-S23/I-S30/I-S32/I-S33, which reaches its highest frequency along the northwest coast of continental Europe." [Y-DNA Haplogroup I and its Subclades [http://www.isogg.org/tree/ISOGG_HapgrpI.html] ]

There is an ongoing debate regarding Neolithic Europe, with evidence both for and against a demic diffusion from the Near East: G Barbujani1 and L Chikhi (2006) state, "Genetic studies have failed to settle the controversy so far, because they have been interpreted in different ways... A rather heated debate followed, and is still continuing." [cite web|url=http://www.nature.com/hdy/journal/v97/n2/full/6800852a.html|title=Population genetics: DNAs from the European Neolithic [http://mbe.oxfordjournals.org/cgi/content/full/21/7/1361/T03] [http://mbe.oxfordjournals.org/cgi/content/full/21/7/1361#F04] ] . However, a recent paper by Cruciani discounts the old hypothesis that there was a significant inflow of genes from Anatolia to Europe, by way of the Balkans, during the neolithic. With specific regard to "Haplogroup E3b", Cruciani concluded that it was actually introduced from Western Asia during the Palaeolithic. It then spread throughout Europe much later (circa 5.3 kYa) via an "in situ" population expansion originating from "witihin" the Balkans, corresponding to the onset of the Balkan Bronze Age [Cruciani et al. (2007) [http://dirkschweitzer.net/E3b-papers/MolecularBiologyandEvolution-07-24-6-1300.pdf Tracing Past Human Male Movements in Northern/Eastern Africa and Western Eurasia: New Clues from Y-Chromosomal Haplogroups E-M78 and J-M12] , "Molecular Biology and Evolution", 24:1300-1311.]

Also, around 4,500 years ago, Haplogroup N3 began moving across from west of the Ural mountains, and seems to follow closely the spread of the Finno-Ugric languages. It is also present at high frequencies in northern Russians, reflecting the absorption of Finno-Ugric tribes. [ [http://www.ajhg.org/AJHG/fulltext/S0002-9297(07)00025-0 Oleg Balanovsky. Two Sources of the Russian Patrilineal Heritage in Their Eurasian Context] ]

Human mitochondrial DNA haplogroups

About mitochondrial DNA haplogroups (mtDNA), according to University of Oulu Library (Finland):

Classical polymorphic markers (i.e. blood groups, protein electromorphs and HLA antigenes) have suggested that Europe is a genetically homogeneous continent with a few outliers such as the Saami, Sardinians, Icelanders and Basques (Cavalli-Sforza et al. 1993, Piazza 1993). The analysis of mtDNA sequences has also shown a high degree of homogeneity among European populations, and the genetic distances have been found to be much smaller than between populations on other continents, especially Africa (Comas et al. 1997).

The mtDNA haplogroups [World mtDNA haplogroup map [http://scs.uiuc.edu/~mcdonald/worldmtdnamap.pdf] ] of Europeans are surveyed by using a combination of data from RFLP analysis of the coding region and sequencing of the hypervariable segment I. About 99% of European mtDNAs fall into one of ten haplogroups: H, I, J, K, M, T, U, V, W or X (Torroni et al. 1996a). Each of these is defined by certain relatively ancient and stable polymorphic sites located in the coding region (Torroni et al. 1996a)... Haplogroup H, which is defined by the absence of a AluI site at bp 7025, is the most prevalent, comprising half of all Europeans (Torroni et al. 1996a, Richards et al. 1998)... Six of the European haplogroups (H, I, J, K, T and W) are essentially confined to European populations (Torroni et al. 1994, 1996a), and probably originated after the ancestral Caucasoids became genetically separated from the ancestors of the modern Africans and Asians. [ Mitochondrial DNA sequence variation in human populations, Oulu University Library (Finland) [http://herkules.oulu.fi/isbn9514255674/html/x367.html] ]

mtDNA Haplogroup N1a while presently rare (0.18%-0.3%) occurred in as many as 25% of Neolithic Europeans and has subsequently been absorbed into the current populations [Haak, Wolfgang, et al. "Ancient DNA from the First European Farmers in 7500-Year-Old Neolithic Sites" Science, vol. 310, pg. 1016 (2005)] [Balter, Michael "Ancient DNA Yields Clues to the Puzzle of European Origins" Science, vol. 310, pg. 964 (2005)] .

Paleolithic migrations

The prehistory of the European peoples can be traced by the examination of archaeological sites, linguistic studies, and by the examination of the DNA of the people who live in Europe now, or from recovered ancient DNA. Much of this research is ongoing, with discoveries still being continually made, and theories rise and fall.

Modern humans (Cro Magnon) began to colonize Europe in the Paleolithic about 40,000 years ago, as evidenced by the spread of the Aurignacian culture. Modern humans may have arrived along two major routes either side of the Black Sea. By about 25,000 years ago the prior inhabitants (our cousin species "H. neanderthalensis") were either killed off or absorbed into the population and ultimately became extinct. [Richard G. Klein (March 2003). "Paleoanthropology: Whither the Neanderthals?". Science 299 (5612): 1525-1527. DOI:10.1126/science.1082025.] About 22,000 years ago the last Ice Age (often referred to as the Last Glacial Maximum or LGM) began, rendering much of Europe uninhabitable. Humans may only have occupied certain regions of Europe at this time, these are often called refuges (or refugia) and were located along the northern Mediterranean and Black Sea coasts, as well as in the Balkans. As the glaciers receded from about 16,000 years ago, the populations that had occupied the refuges are thought to have begun to spread and colonise northern Europe. [Antonio Torroni "et al." "A Signal, from human mtDNA, of Postgalcian Recolonization in Europe, " Am. J. Human Gen.69:844-852 (2001)] [Ornella Semin "et al." "The Genetic Legacy of Paleolithic Homo Sapiens Sapiens in Extant Europeans: A Y Chromosome Perspective" Science 290:1155-1159, 2000.]

After a less severe cold event around 12000-10000 years ago there was an increasing use of microliths and reliance on the coast and sea. Styles of tool making varied from location to location, suggesting that the population of Europe was settling down. Martin Richards showed that about 11% of modern mtDNA types arrived from the Middle East during the Mesolithic [ Tracing European founder lineages in the Near Eastern mtochondrial gene pool, Am. J. of Human Genetics, 67, 1251 ] . These show a significant decline from SE to NW Europe. However Stephen Oppenheimer says that there was further gene flow from Iberia to NW Europe [ The Origins of the British ] . In northern Europe the gene flow was largely from SE Europe and Asia. The population of Europe were hunter-gatherers until the advent of agriculture about eight millennia ago.

Neolithic migrations

The duration of the Neolithic varied from place to place, starting with the introduction of farming and ending with the introduction of bronze implements. In SE Europe it was approximately 7000-3000 BC while in NW Europe it was 4500-1700 BC. Besides the introduction of new plants and animals, the Neolithic also saw the beginning of the use of pottery. The latter allows the tracing of the movement of ideas and possibly people across Europe. The period possibly also saw the spread of Indo-European languages across Europe. One hypothesis is that they spread with farming while another is they came later from the Pontic steppes by expansion of the Kurgan people.

Some academics [ such as Bellwood and Renfrew ] theorise that farming was introduced by people who migrated from the Near East, and that these farmers introduced the Indo-European languages to Europe. This theory is typically associated with the Anatolian hypothesis of Indo-European origins, though it has also been argued that widespread migration is not necessary to support the theory. [Nicholas Wade, "Before the Dawn", ch. 10. ISBN 1594200793 ]

The largest admixture to the European paleolithic/mesolithic stock was due to the neolithic revolution of the 7th to 5th millennia BC. [Cavalli-Sforza, Luigi Luca, Paolo Menozzi, and Alberto Piazza. (1994). "The History and Geography of Human Genes." Princeton University Press. ISBN 0-691-08750-4.] Three main mtDNA gene groups have been identified as contributing Neolithic entrants into Europe: J, T1 and U3 (in that order of importance) [ Oppenheimer ] . With others they amount to around 20% of the gene pool [ Richards] . There is little published information on male immigration during the Neolithic but Oppenheimer suggests that haplotypes J and Eb3 migrated along the coast of Europe at this time. Gene flow from SE to NW Europe seems to have continued.

Bronze to Iron Age migrations

The Bronze Age saw the development of long distance trading networks, particularly along the Atlantic Coast and in the Danube valley. There was migration from Norway to Orkney and Shetland in this period (and to a lesser extent to mainland Scotland and Ireland). There was also migration from Germany to eastern England. Oppenheimer could find no genetic evidence for any Iron Age migration to Britain.

Other theories about the origins of the Indo-European language centre around a hypothetical Proto-Indo-European people, who are traced, in the Kurgan hypothesis, to somewhere north of the Black Sea at about 4500 BCE. They domesticated the horse, and are considered to have spread their culture and genes across Europe. It has been difficult to identify what these "Kurgan" genes might be, though the Y haplogroup R1a is a proposed marker which would indicate that the physical expansion halted in Germany and only the Kurgan culture and language went further. Another approach – the Anatolian hypothesis – suggests an origin in Anatolia with a later expansion from eastern Europe.

To what extent Indo-European migrations replaced the indigenous Mesolithic peoples is debated, but a consensus has been reached that technology and language transfer played a more important role in this process than actual gene-flow. [See Bryan Sykes, "The Seven Daughters of Eve", 1st American ed. (New York: Norton, 2001) for an entertaining account of how this consensus was reached. For historical reasons, in the 1980s mtDNA researchers believed that the Indo-European expansion was overwhelmingly a spread of technology and language, not of genes, while the those who studied Y-chromosome lineages believed the opposite. Gradually the mtDNA guys (Sykes) admitted more physical migration into their scenarios, while the Y folks (Peter Underhill) accepted more technology-copying. Eventually, both groups independently reached a 20% Neolithic - 80% Paleolithic ratio of genetic contribution to today's European population. The mtDNA vs. Y discrepancy is explained by noting that in such conquest-based migrations, a common pattern is invading foreign males producing offspring with indigenous females, though significant numbers of females of the spreading culture would also arrive with post-conquest settlers. However, where migrations are essentially economic (as most migrations appear to be) the scenario of male family members preceding females into new territory looking for opportunities is equally probable.]

During the Iron Age, Celts are recorded as having moved into northern Italy, Eastern Europe and Anatolia.

Medieval to Early Modern admixture

There is some admixture of Sub-Saharan African DNA, due to the Early Modern African slave tradeIt shows a decreasing cline from the southwest to the northeast, which corresponds with the areas most involved in slave trade. Not every population has been studied yet, but enough have so that a picture is starting to emerge. The amount of black admixture in Europe today ranges from a few percent in Iberia to almost nil around the Baltic. [ [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16201138&dopt=Abstract Pereira et al. 2005] (view the specific data [http://dienekes.blogspot.com/2005/06/origin-of-african-mtdna-in-iberia.html here] )]

According to a summary study by [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16201138&dopt=Abstract Pereira et al. 2005] , sub-Saharan mtDNA L haplogroups were found at rates of 3.83% in Iberians (Portuguese and Spanish), 2.86% in Sardinians, 2.38% in Albanians, 1% in the British/Irish (indigenous whites only), 0.94% in Sicilians, 0.62% in a German-Danish sample.

Sub-Saharan African Y-chromosomes are much less common in Europe, for the reasons discussed above. The small presence of the Haplogroups E(xE3b) (i.e. clades of E other than E3b) and Haplogroup A in Europe is almost exclusively attributable to the slave trade, as these haplogroups are characteristic of western, central and southern Africans and are barely observed elsewhere. [Sanchez et al. (2005). "High frequencies of Y chromosome lineages characterized by E3b1, DYS19-11, DYS392-12 in Somali males". European Journal of Human Genetics; 13:856–866] Haplotype A has been detected in Portugal (3%), France (2.5% in a very small sample), Germany (2%), Sardinia (1.6%), Austria (0.78%), Italy (0.45%), Spain (0.42%) and Greece (0.27%). By contrast, North Africans have about 5% paternal sub-Saharan admixture. [ [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?holding=npg&cmd=Retrieve&db=PubMed&list_uids=15042509&dopt=Abstract Cruciani et al. 2004] , [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15280900&query_hl=13&itool=pubmed_docsum Flores et al. 2004] , [http://www3.interscience.wiley.com/cgi-bin/abstract/112139846/ABSTRACT Brion et al. 2005] , [http://dx.doi.org/10.1016/j.forsciint.2005.06.002 Brion et al. 2004] , [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11078479&dopt=Abstract Rosser et al. 2000] , [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15069642 Semino et al. 2004] , and [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12927125&dopt=Abstract DiGiacomo et al. 2003] Bosch et al. 2001 [http://www2.smumn.edu/facpages/~poshea/uasal/DNAWWW/pdfs/Africa-Iberia.pdf High-Resolution Analysis of Human Y-Chromosome Variation Shows a Sharp Discontinuity and Limited Gene Flow between Northwestern Africa and the Iberian Peninsula] ]

North and Northeast African influences

There are a number of genetic markers which are characteristic of Horn African and North African populations which are to be found in European populations signifying ancient and modern population movements across the Mediterranean. These markers are to be found particularly in Mediterranean Europe but some are also prevalent, at low levels, throughout the continent. The spread of the Megaliths and its Cultures seem to have been carried, or kept maritime connections with, the Mediterranean and Northern Africans.

Y-chromosome DNA

The general parent Y-chromosome Haplogroup E1b1b (formerly known as E3b), originating either in the Horn of Africa [Semino et al. (2004), [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1181965 Origin, Diffusion, and Differentiation of Y-Chromosome Haplogroups E and J: Inferences on the Neolithization of Europe and Later Migratory Events in the Mediterranean Area] , "American Journal of Human Genetics", 74: 1023–1034.] or the Near East [http://www.isogg.org/tree/ISOGG_HapgrpE08.html Y-DNA Haplogroup E and its Subclades - 2008] ] , is by far the most common clade in North and Northeast Africa, and is also common throughout the majority of Europe, particularly in the Mediterranean and South Eastern Europe. E1b1b reaches its highest concentration in Greece and the Balkan region, but also enjoys a significant presence in other regions such as Hungary, Italy, Iberia and Austria. [http://www.geocities.com/littlednaproject/Y-MAP.gif] ..

Outside of North and Northeast Africa, E1b1b's two most prevalent clades are E1b1b1a (E-M78, formerly E3b1a) and E1b1b1b (E-M81, formerly E3b1b).

E1b1b1a is the most common subclade of E1b1b and is present throughout Europe. It was originally thought to have been a marker of Neolithic migrations (perhaps coinciding with the introduction of Agriculture into Europe) from Anatolia to Europe, via the Balkans, where it enjoys the highest frequency. However, Cruciani's latest sudy suggests that it actually arrived into the Balkans from Western Asia during the Palaeolithic, and then spread throughout Europe much later (circa 5300 years ago) due to a population expansion originiating from "within" the Balkans.

A study from Semino (published 2004) showed that Y-chromosome haplotype E1b1b1b (E-M81), is specific to North African populations and almost absent in Europe except the Iberia (Spain and Portugal) and Sicily. [ [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1181965#RF18 Origin, Diffusion, and Differentiation of Y-Chromosome Haplogroups E and J: Inferences on the Neolithization of Europe and Later Migratory Events in the Mediterranean Area ] ] Another 2004 study showed that E1b1b1b is found present, albeit at low levels throughout Southern Europe (ranging from 1.5% in Northern Italians, 2.2% in Central Italians, 1.6% in southern Spaniards, 3.5% in the French, 4% in the Northern Portuguese, 12.2% in the southern Portuguese and 41.2% in the genetic isolate of the Pasiegos from Cantabria) [ [http://www.familytreedna.com/pdf/hape3b.pdf Cruciani "et al, 2004", Phylogeography of the Y-Chromosome Haplogroup E3b] ] . The findings of this latter study contradict a more thorough analysis Y-chromosome analysis of the Iberian peninsula according to which haplogroup E1b1b1b surpasses frequencies of 10% in Southern Spain. The study points only to a very limited influence from northern Africa and the Middle East both in historic and prehistoric times. [ [http://hpgl.stanford.edu/publications/EJHG_2004_v12_p855.pdf Reduced Genetic Structure for Iberian Peninsula: implications for population demography. (2004)] ] The absence of microsatellite variation suggests a very recent arrival from North Africa consistent with historical exchanges across the Mediterranean during the period of Islamic expansion, namely of Berber populations.* Semino et al. (2004) [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1181965 Origin, Diffusion, and Differentiation of Y-Chromosome Haplogroups E and J: Inferences on the Neolithization of Europe and Later Migratory Events in the Mediterranean Area] ] . A study restricted to Portugal, concerning Y-chromosome lineages, revealed that "The mtDNA and Y data indicate that the Berber presence in that region dates prior to the Moorish expansion in 711 AD... Our data indicate that male Berbers, unlike sub-Saharan immigrants, constituted a long-lasting and continuous community in the country". [ [http://www.blackwell-synergy.com/action/showFullText?submitFullText=Full+Text+HTML&doi=10.1111%2Fj.1529-8817.2005.00161.x Y-chromosome Lineages from Portugal, Madeira and Açores Record Elements of Sephardim and Berber Ancestry] ]

Haplotype V(p49/TaqI), a characteristic North African haplotype, may be also found in the Iberian peninsula, and a decreasing North-South cline of frequency clearly establishes a gene flow from North Africa towards Iberia which is also consistent with Moorish presence in the peninsula. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11758696&query_hl=3&itool=pubmed_docsum] . This North-South cline of frequency of halpotype V is to be observed throughout the Mediterranean region, ranging from frequencies of close to 50% in southern Portugal to around 10% in southern France. Similarly, the highest frequency in Italy is to be found in the southern island of Sicily (28%). [http://findarticles.com/p/articles/mi_qa3659/is_200606/ai_n17175647/print] [ [http://mbe.oxfordjournals.org/cgi/content/abstract/msm049v1 Tracing Past Human Male Movements in Northern/Eastern Africa and Western Eurasia: New Clues from Y-chromosomal Haplogroups E-M78 and J-M12] ]

A wide ranging study (published 2007) using 6,501 unrelated Y-chromosome samples from 81 populations found that: “Considering both these E-M78 sub-haplogroups (E-V12, E-V22, E-V65) and the E-M81 haplogroup, the contribution of northern African lineages to the entire male gene pool of Iberia (barring Pasiegos), continental Italy and Sicily can be estimated as 5.6%, 3.6%, and 6.6%, respectively.” [Fluvio Cruciani, Et al. ,"Tracing Past Human Male Movements in Northern/Eastern Africa and Eurasia: New Clues from Y-Chromosomal Haplogroups E-M78 and J-M12", Molecular Biology and Evolution, Volume 24, Number 6: June 2007, Oxford University Press, Pp. 1307]

Mitochondrial DNA

Genetic studies on Iberian populations also show that North African mitochondrial DNA sequences (haplogroup U6) and sub-Saharan sequences (Haplogroup L), although present at only low levels, are still at much higher levels than those generally observed elsewhere in Europe. ["Haplogroup U6 is present at frequencies ranging from 0 to 7% in the various Iberian populations, with an average of 1.8%. Given that the frequency of U6 in NW Africa is 10%, the mtDNA contribution of NW Africa to Iberia can be estimated at 18%. This is larger than the contribution estimated with Y-chromosomal lineages (7%) (Bosch et al. 2001)." [http://www.blackwell-synergy.com/links/doi/10.1046/j.1469-1809.2003.00039.x/abs Joining the Pillars of Hercules: mtDNA Sequences Show Multidirectional Gene Flow in the Western Mediterranean (2003)] ] ["Although the absolute value of observed U6 frequency in Iberia is low, it reveals a considerable North African female contribution, if we keep in mind that haplogroup U6 is not very common in North Africa itself and virtually absent in the rest of Europe. Indeed, because the range of variation in western North Africa is 4-28%, the estimated minimum input is 8.54%" [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&uid=16201138&cmd=showdetailview&indexed=google African female heritage in Iberia: a reassessment of mtDNA lineage distribution in present times (2005)] ] ["Our results clearly reinforce, extend, and clarify the preliminary clues of an "important mtDNA contribution from northwest Africa into the Iberian Peninsula" (Côrte-Real et al., 1996; Rando et al., 1998; Flores et al., 2000a; Rocha et al., 1999)(...) Our own data allow us to make minimal estimates of the maternal African pre-Neolithic, Neolithic, and/or recent slave trade input into Iberia. For the former, we consider only the mean value of the U6 frequency in northern African populations, excluding Saharans, Tuareg, and Mauritanians (16%), as the pre-Neolithic frequency in that area, and the present frequency in the whole Iberian Peninsula (2.3%) as the result of the northwest African gene flow at that time. The value obtained (14%) could be as high as 35% using the data of Corte-Real et al. (1996), or 27% with our north Portugal sample." [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&uid=12627534&cmd=showdetailview&indexed=google Mitochondrial DNA affinities at the Atlantic fringe of Europe (2003)] ] Haplotype U6 have also been detected in Sicily at very low levels. It happens also to be a characteristic genetic marker of the Saami populations of Northern Scandinavia. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16201138&query_hl=7&itool=pubmed_docsum] It is difficult to ascertain that U6's presence is the consequence of Islam's expansion into Europe during the Middle Ages, particularly because it is more frequent in the north of the Iberian Peninsula rather than in the south. In smaller numbers it is also attested too in the British Islands, again in its northern and western borders. It may be a trace of a prehistoric neolithic/megalithic expansion along the Atlantic coasts from North Africa, perhaps in conjunction with seaborne trade. One subclade of U6 is particularly common among Canarian Spaniards as a result of native Guanche (proto-Berber) ancestry.

Footnotes

ee also

*Caucasoid
*European ethnic groups
*Human genetic variation
*Population genetics
*Archaeogenetics of the Near East
*White people

External links

* [https://www5.nationalgeographic.com/genographic/atlas.html Atlas of the Human Journey]
* [http://www.scs.uiuc.edu/~mcdonald/WorldHaplogroupsMaps.pdf World Haplogroups Maps]
* [http://www.dnaheritage.com/masterclass2.asp Origins of Europeans]
* [http://hpgl.stanford.edu/publications/Science_2002_v299_2381-2385.pdf Genetic Structure of Human Populations] .
* [http://www.shirleyassociation.com/NewShirleySite/DNA/haplotype_R1b.html Haplotype R1b]
* [http://freepages.genealogy.rootsweb.com/~gallgaedhil/haplo_r1b_amh_13_29.htm Haplogroup R1b]
* [https://www3.nationalgeographic.com/genographic/atlas.html?card=my050 Haplogroup R1b]


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