Haplogroup W occurs primarily in South Asia, the Near East, Central Asia, and Europe, with an average of only 1% of the population being of this group. Due to this low percentage, higher concentrations reported in some studies are only due to the small sample size rather than a result of an actual higher concentration of W's. That said, as indicated on the map, there are clearly peak concentrations of W's (5% to 10% of the population) in Pakistan, Kurdistan and Northwest Iran, and Finland. However these general figures disguise important differences between the subgroups.
The first migration of modern humans out of Africa began 55,000 to 87,000 years ago. Among these were ancestors of the the M and N haplogroups, descended from the African L3. These first Eurasian descendents of genetic Eve are believed to have expanded along the Indian Ocean coastline (in this period there was dry land across what are now the mouths of the Red Sea and Persian Gulf). After a quick initial expansion along the coast, all the way to Australia, there was a slower conquest of the interior of Asia.
In 2004 the birthdate of Wilma, the first member of the W haplogroup, was estimated at between 49,000 and 26,800 years ago. By 2009 this had been reduced to 29,700 to 13,000 years ago. HVR coalescence dates for the W subgroups point to the low end of that range - around 15,000 years ago.
Coalescence ages for W and its subgroups using coding region, HVR1, or HVR1+2 data as available. "Consensus" ages, taking into account the various alternatives and the necessary amount of change for subgroups to develop, are indicated by the vertical boxes.
The earlier theory, based on the believed antiquity of W and the peak concentrations and subgroups of W's in Pakistan and western Anatolia, conjectured that between 40,700 and 23,300 years ago, the W's, U7, and R2 haplogroups were distributed in a band across southwest Asia. With the onset of the last glacial maximum, the area became extremely arid and the mountains blocked by glaciers. The W-U7-R2 people were broken into two groups, separated by an arid desert that stretched from the Indian Ocean up to the glacier-bound Asian mountains. These tribes managed to survive in these two areas of 'glacial refuge'. A similar refuge had been proposed in Spain for the ancestors of the H and V haplogroups that dominate in Western Europe.
After the glaciers receded and the deserts retreated 14,000 years ago, the way was then clear for the expansion of modern humans from their ice age prisons. Wilma's descendants entered Europe through the Balkans, spreading in several directions.
However with the current date estimates, the discovery of significant concentrations of W's in central Asia, and the detailed geographical distribution of the subgroups, an alternate hypothesis seems more likely. It now seems most likely that Wilma was born around 16,000 years ago in Central Asia. Even if this occurred in an Indian subcontinent 'glacial refuge', the main event was that her descedents were part of the post-glacial expansion into the steppes. The W1, W3, W4, and W6 subgroups all originated there. They later migrated into India and Europe with the expansion of pastoralism and agriculture.
Another indication of the Central Asian origin for haplogroup W is the fact that only a single example of the 'sister' N2 haplogroup has ever been found. This was a member of the less than one thousand surviving Kets, a Siberian tribe living along the Yenisey River that is believed to be the last remnant of the original inhabitants of south central Siberia and the linguistic ancestors of the Athabaskan peoples of North America.
W1 emerged next, around 13,000 years ago with the coding-region 07864 mutation. The W1c was the first W1 subgroup, appearing around 10,000 years ago, developed in the steppe horse culture, and expanded with it from Uzbekistan and Turkmenistan, into India and Europe. Notably, but not exclusively, it is found today among Polish Roma and Ashkenazi Jews. W1e was next, at around the same time, but seems to have entered Europe later, gestating in Anatolia and then entering Europe via Neolithic agriculturalists up the Danube valley. The W1a and W1b subgroups appeared only around 2,000 years ago among the Finno-Ugaritic tribes that expanded from Siberia into Finland, the Baltic, and Scandinavia. So far W1e has been found only in Iraq; and W1f only in Austria and the Czech Republic. The trail that led there is not yet knowable.
W3 appeared around 11,000 years ago in the steppes, and spread with the horse culture into Europe and India. A succession of subgroups (W3a, W3a1, W3a1a) are dfined by a series of coding-region mutations. W3 and W3a descendents migrated to both India and Europe, while W3a and W3a1a are only found in Europe.
W4 is defined by the striking HVR2 motif 143-194-196. It appeared in the central Asian steppes around 12,000 years ago. Descendants migrated to Central India and Europe. The road to Europe follows the spread of neolithic agriculture, from Anatolia, up the Danube to Central Europe.
W5 is the youngest major group, and a uniquely European group, originating only 5500 years ago. Its distribution corresponds to the expansion of Celtic, and then Germanic tribes into Europe.
W6 is identified by the 16192 16223 16292 16325 16519 motif, and 20% of W's are of this subgroup. It originated in Central Asia around 11,000 years ago. Its modern distribution corresponds to the expansion of Indo-European pastoralists, which took place beginning 3700 BC.
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