Genetic History of Europe - European Population Sub-structure

European Population Sub-structure

Geneticists agree that Europe is the most genetically homogeneous of all the continents. However, some patterns are discernible. Cavalli-Sforza’s principal component analyses revealed five major clinal patterns throughout Europe, and similar patterns have continued to be found in more recent studies.

1. A cline of genes with highest frequencies in the Middle East, spreading to lowest levels northwest. Cavalli-Sforza originally described this as faithfully reflecting the spread of agriculture in Neolithic times. This has been the general tendency in interpretation of all genes with this pattern.
2. A cline of genes with highest frequencies amongst Finnish and Saami in the extreme north east, and spreading to lowest frequencies in the south west.
3. A cline of genes with highest frequencies in the area of the lower Don and Volga rivers in southern Russia, and spreading to lowest frequencies in Iberia, Southern Italy, Greece and the areas inhabited by Saami speakers in the extreme north of Scandinavia. Cavalli-Sforza associated this with the spread of Indo-European languages, which he links in turn to a "secondary expansion" after the spread of agriculture, associated with animal grazing.
4. A cline of genes with highest frequencies in the Balkans and Southern Italy, spreading to lowest levels in Britain and the Basque country. Cavalli-Sforza associates this with "the Greek expansion, which reached its peak in historical times around 1000 and 500 BC but which certainly began earlier"
5. A cline of genes with highest frequencies in the Basque country, and lower levels beyond the area of Iberia and Southern France. In perhaps the most well-known conclusion from Cavalli-Sforza this weakest of the 5 patterns was described as isolated remnants of the pre-Neolithic population of Europe, "who at least partially withstood the expansion of the cultivators". It corresponds roughly to the geographical spread of rhesus negative blood types. In particular, the conclusion that the Basques are a genetic isolate has become widely discussed, but also a controversial conclusion.

He also created a phylogenetic tree to analyse the internal relationships amongst Europeans. He found four major 'outliers'- Basques, Lapps, Finns and Icelanders; a result he attributed to their relative isolation (note: with the exception of the Icelanders, the rest of the groups speak non-Indo-European languages). Greeks and Yugoslavs represented a second group of less extreme outliers. The remaining populations clustered into several groups : "Celtic", "Germanic", "south-western Europeans", "Scandinavians" and "eastern Europeans".