this may indicate that the Na-Dene migration occurred from the Russian Far East after the initial Paleo-Indian colonization, but prior to modern Inuit, Inupiat and Yupik expansions.[9][10][42]mtDNA[edit]For more details on mtDNA in general, see Mitochondrial DNA.Mitochondrial Eve is defined as the woman who was the matrilineal most recent common ancestor for all living humans. Mitochondrial Eve is estimated to have lived between 140,000 and 200,000 years ago,[43][44] Mitochondrial Eve is the most recent common matrilineal ancestor, not the most recent common ancestor.[45][46]Schematic illustration of maternal (mtDNA) gene-flow in and out of Beringia, from 25,000 years ago to present.When studying human mitochondrial DNA (mtDNA) haplogroups, the results indicated until recently that Indigenous Amerindian haplogroups, including haplogroup X, are part of a single founding east Asian population. It also indicates that the distribution of mtDNA haplogroups and the levels of sequence divergence among linguistically similar groups were the result of multiple preceding migrations from Bering Straits populations.[22][47] All Indigenous Amerindian mtDNA can be traced back to five haplogroups, A, B, C,D and X.[48] More specifically, indigenous Amerindian mtDNA belongs to sub-haplogroups that are unique to the Americas and not found in Asia or Europe: A2, B2, C1, D1, and X2a (with minor groups C4c, D2, D3, and D4h3).[47] This suggests that 95% of Indigenous Amerindian mtDNA is descended from a minimal genetic founding female population, comprising sub-haplogroups A2, B2, C1b, C1c, C1d, and D1.[48] The remaining 5% is composed of the X2a, D2, D3, C4, and D4h3 sub-haplogroups.[47][48]X is one of the five mtDNA haplogroups found in Indigenous Amerindian peoples. Unlike the four main American mtDNA haplogroups (A, B, C and D), X is not at all strongly associated with east Asia.[5] Haplogroup X genetic sequences diverged about 20,000 to 30,000 years ago to give two sub-groups, X1 and X2. X2's subclade X2a occurs only at a frequency of about 3% for the total current indigenous population of the Americas.[5] However, X2a is a major mtDNA subclade in North America; among theAlgonquian peoples, it comprises up to 25% of mtDNA types.[49][50] It is also present in lower percentages to the west and south of this area among the Sioux (15%), the Nuu-chah-nulth (11%13%), the Navajo (7%), and the Yakama (5%).[51] Haplogroup X is more strongly present in the Near East, the Caucasus, and Mediterranean Europe.[51] The predominant theory for sub-haplogroup X2a's appearance in North America is migration along with A, B, C, and D mtDNA groups, from a source in the Altai Mountains of central Asia.[52][53][54][55]Sequencing of the mitochondrial genome from Paleo-Eskimo remains (3,500 years old) are distinct from modern Amerindians, falling within sub-haplogroup D2a1, a group observed among today's Aleutian Islanders, the Aleut and Siberian Yupikpopulations.[56] This suggests that the colonizers of the far north, and subsequently Greenland, originated from later coastal populations.[56] Then a genetic exchange in the northern extremes introduced by the Thule people (proto-Inuit) approximately 8001,000 years ago began.[11][57] These final Pre-Columbian migrants introduced haplogroups A2a and A2b to the existing Paleo-Eskimo populations of Canada and Greenland, culminating in the modern Inuit.[11][57]A 2013 study in Nature reported that DNA found