Haplogroup X (mtDNA)

In, Haplogroup X is a which can be used to define genetic. The genetic sequences of haplogroup X diverged originally from, and subsequently further diverged about 20,000 to 30,000 years ago to give two sub-groups, X1 and X2. Overall haplogroup X accounts for about 2% of the population of, the and. Sub-group X1 is much less numerous, and restricted to North and, and also the Near East. Sub-group X2 appears to have undergone extensive population expansion and dispersal around or soon after the, about 21,000 years ago. It is more strongly present in the Near East, the, and ; and somewhat less strongly present in the rest of Europe. Particular concentrations appear in (8%), the  (in ) (7%) and amongst the Israeli  (26%); the latter are presumably due to a.

North and South America
Haplogroup X is also one of the five haplogroups found in the. Although it occurs only at a frequency of about 3% for the total current indigenous population of the Americas, it is a major haplogroup in northeastern North America, where among the peoples it comprises up to 25% of mtDNA types. It is also present in lesser percentages to the west and south of this area -- in North America among the (15%), the  (11%–13%), the  (7%), and the  (5%), and in South America among the  people (12%) in eight villages in  in northwestern.

Unlike the four main Native American haplogroups (,, , and ), X is not at all strongly associated with. The sole occurrence of X in Asia discovered so far is in in South  (Derenko et al, 2001), and detailed examination (Reidla et al, 2003) has shown that the Altaian sequences are all almost identical, suggesting that they arrived in the area probably from the  more recently than.

This absence of haplogroup X2 in Asia is one of the major factors causing the current rethinking of the. However, the haplogroup X2a  is as different from any of the  X2b-f lineages as they are from each other, indicating an early origin "likely at the very beginning of their expansion and spread from the Near East".

The posits that haplogroup X reached North America with a wave of European migration about 20,000 BC by the s, a stone-age culture in south-western  and in, by boat around the southern edge of the.