Distribution maps of autosomal admixtures in Europe, the Middle East and North Africa
Last update September 2011
The following maps were created based on the K=12 admixtures from the Dodecad Project. The 'West European' admixture from Dodecad was renamed 'Northwest European' on Eupedia, as it fits better the overall distribution of this admixture. The African admixture was computed by adding up the Northwest African, East African, Neo African and Paleo African components, which were too minor in Europe on their own.
Please be aware that the maps are very approximate due to the scantity of regional data available, and the complete lack of data for some countries at present (including the Czech Republic, Slovakia, Bosnia-Herzegovina, Serbia, Albania and Macedonia).
|Comparing maps of autosomal DNA with Y-DNA haplogroups|
It is tempting to make analogies between the distribution of autosomal admixtures and that of Y-DNA haplogroups. While both of them represent the migrations of certain populations and may roughly correspond to the same source populations, it is essential to understand that any correspondance has its limits for a number of reasons.
Whereas Y-chromosomal lineages can be organised in a neat genealogical tree ('phylogenetic tree' is the technical word), it is much harder for autosomes due to the fact that they get mixed up ('recombined') at every generation with other autosomes. To trace back the origins of a population, the idea is to check which modern populations share the same unique mutations spread out on all 22 pairs of non-sex chromosomes. That's why they are referred to as "admixtures". The names for each admixture are arbitrary and do not necessarily refer to the source population who spread those genes, but usually the geographic region where it is most common today. For example, the Southwest Asian admixture got its name because this set of mutations is most common in the Arabian peninsula nowadays. But Arabic people descend from nomadic herders who lived around the Zagros and Taurus mountains, around northern Mesopotamia, during the Neolithic period. This is also the case of Y-haplogroup J1, with which the Southwest Asian admixture best correlates. In other words, the so-called Southwest Asian admixture found in a European individual may never have come from Southwest Asia (Arabic peninsula) at all, but rather from Anatolia.
Any admixture can be broken down into a number of more specific admixtures, splitting populations that may otherwise have looked closely related. The Northwest European admixture almost certainly comprises DNA markers from two completely different source populations. That is why it is found at high frequencies among the Finns, the Irish and the Iberians, three populations that do not share a lot in common history or phenotypes. It is also found at lower but still substantial frequencies in the Chuvash people (22%) from the Volga region, and the Adygey people (16%) from the North Caucasus, and the Uyghur people (10%) from Northwest China. In all likelihood, the Northwest European component is composed of markers belonging to the Paleolithic population of northern and western Europe (haplogroup I), as well as an Indo-European element (haplogroup R1b) that originated in the Black Sea region.
The way Y chromosomes and autosomes are transmitted is very different. Y chromosomes are strictly inherited from fathers to sons and never recombine, while autosomes are inherited at 50% through each parent. This will inevitably affect their respective geographic distribution since it is known that in most European societies through the ages male children (usually the eldest sons) were the ones who inherited the land, house, farm or even castle from their parents, and therefore stayed from generation to generation at the same place. Women, on the contrary, were married off to men from neighbouring tribes, villages or towns. They were sometimes sent quite far away, especially in royal and noble families that frequently used daughters to seal alliances with other families, or just sought a suitor of a similar social level which they could not find close to home (or at least not without risking inbreeding). This is still common practice among the high aristocracy nowadays. This explains why maternal lineages (mtDNA) and autosomal DNA is much more evenly spread out geographically than paternal lineages (Y-DNA).
Y chromosomes sometimes disappear for evolutionary reasons. Mutations in one lineage can have a negative incidence on male fertility, causing men to have more female offspring (who do not pass on Y-DNA), have less children (contraction of the Y-DNA lineage), or in extreme cases even become sterile (extinction of the Y-DNA lineage).
Y chromosomes may suffer dramatic decline in frequency due to wars, in the event men from a tribe or ethnic group are killed in large numbers by their opponents, and their women taken by the winners. Since autosomes are also passed on by women, autosomes would survive such a scenario even if all male lineages went extinct (which was probably very rare, but once in history is enough to affect a region permanently).
Northwest European admixture
Distribution of the Northwest European admixture in Europe, the Middle East and North Africa
East European admixture
Distribution of the East European admixture in Europe, the Middle East and North Africa
Distribution of the Mediterranean admixture in Europe, the Middle East and North Africa
West Asian admixture
Distribution of the West Asian admixture in Europe, the Middle East and North Africa
Southwest Asian admixture
Distribution of the Southwest Asian admixture in Europe, the Middle East and North Africa
Distribution of the African admixture in Europe, the Middle East and North Africa