 There have been a number of studies about the mitochondrial DNA haplogroups (mtDNA) in Europe.In contrast to Y DNA haplogroups, mtDNA haplogroups did not show as much geographical patterning, but were more evenly ubiquitous.Apart from the outlying Saami, all Europeans are characterised by the predominance of haplogroups H, U and T. The lack of observable geographic structuring of mtDNA may be due to socio-cultural factors, namely the phenomena of polygyny and patrilocality.