HAPLOGROUP X DESCRIPTION
(The) mtDNA and ... part of the Y chromosome are widely used in archaeogenetic studies that aim to reveal the human past. (Renfrew 2000, Cavalli-Sforza and Feldman 2003) ...these two loci allow an unambiguous determination of the ... relationships between individual lineages. However, the ... histories of the lineages ... do not fully reflect the complex dynamics of ancient populations; thus, the data must be interpreted carefully. ... mtDNA haplogroups has been found to be congruent with geography. There are haplogroups specific to African, Asian, European/West Eurasian, and Native American populations. (Torroni et al. 1993)
Haplogroup X is an exception to this pattern of limited geographical distribution. It is found, generally at low frequencies, in both West Eurasians and some northern groups of Native Americans, ... but,... it is absent in modern north Siberian and East Asian populations, ... which are genetically and geographically closest to those of Native Americans....
... Haplogroup X mtDNAs from Europe and the Near East are found to yield similar coalescence times: 17,000- 30,000 years before present (YBP) and 13,700-26,600 YBP, respectively (Richards et al. 2000) ... For Native Americans, the relatively old presence of haplogroup X is confirmed by the analysis of ancient human remains. (Stone and Stoneking 1999; Malhi and Smith 2002) Moreover, Native American haplogroup X mtDNAs form a clade distinct from that of West Eurasians and with coalescence time estimates varying widely.......(Brown et al. 1998).
