Monday, June 29, 2015

Y-DNA E Better Understood

A new study of the phylogeny of Y-DNA E (via Bernard's blog) shows more regionally defined structure of different subclades of the Y-DNA haplogroup than had previously been discerned, particularly in Eastern and Southern Africa.

It also provides a wealth of data on the time depth of various Y-DNA E subclades, although given the wide disparities that exist in establishing mutation rate dates, this is more useful in terms of establishing relative ages than absolute one.

The study puts the split of Y-DNA D and Y-DNA E at 69,000 to 69,800 years ago.

Y-DNA E-M81, which is the predominant Berber clade (also found in moderate frequencies in Iberia, in Turkey and in Bedouins, and at low frequencies in Italy), breaks off from the clade that includes my own Y-DNA E-V13 (which is found in high frequencies in the Balkans and moderate frequencies in much of the rest of Europe and Turkey and among the Druze) between 24,100 and 25,000 years ago, around the time of the Last Glacial Maximum.

E-M81 probably arrives in Europe via the Strait of Gibraltar, in the Mesolithic or early Neolithic era, with an additional significant influx to Moorish Spain in the last 1,300 years.

E-V13 probably arrives in Europe via the Levant and disperses from there to the rest of Europe at roughly the same time or perhaps a bit later, around the Mesolithic or Neolithic era (mutation rate dating puts the origin of this clade at about 8,100 years ago).  Ancient DNA from clade E-M78 (which is a parent of E-V13) is found in Iberia ca. 7,000 years ago and Y-DNA clades that are part of the E-M78 clade are present in Iberia in similar frequencies to E-M81.  The spread of E-V13 to the Balkans and its expansion there must have happened sometime in pre-history, because no known historical migrations prior to first wave Neolithic migrations could account for its strong presence in the Balkans.

While a number of individuals have argued for an Eurasian origin for Y-DNA E, based on the fact that its sister clade Y-DNA D is predominantly found in Asia, an examination of the phylogeny of Y-DNA E together with the geographic distribution of its currently known branches argues strongly for an African origin for Y-DNA E, rather than a Eurasian one, as do other factors such as the presence of individuals with Y-DNA DE not further distinguished between D or E in both Tibet and Africa.

Many relatively basal branches of Y-DNA E are found almost entirely in Africa and the African diaspora (e.g. African-Americans and Afro-Caribbean populations), while only a couple of relatively young branches of Y-DNA E are found (mostly at moderate frequencies) in parts of Europe and the Near East adjacent to Africa. See, e.g., page 4 of the supplementary materials for the new study. Those branches of Y-DNA E found outside Africa, moreover, are related to each other only via branches of Y-DNA E found only in Africa.

As Wikipedia notes:
E1a and E-M75 are found almost exclusively in Africa. By looking at the major subclade frequencies, five broad regions of Africa can be defined: East, Central, North, Southern and West. The division can be distinguished by the prevalence of E-V38 in East, Central, Southern and West Africa, E-M78 in East Africa and E-M81 in North Africa. E-V38 is the most prevalent subclade of E in Africa. It is observed at high frequencies in all African regions except the northernmost and easternmost portions of the continent. E-M243 (especially its subclades M78 and M81) is found at high frequencies in North East Africa and North Africa and is the only subclade that is found in Europe and Asia at significant frequencies. E-M243 is common among Afro-Asiatic speakers in the Near East and North Africa as well as among some Nilo-Saharan and Niger–Congo speakers in North East Africa and Sudan. E-M243 is far less common in West, Central, and Southern Africa[.]
It is also unlikely that Y-DNA had origins in Northwest, West, Central or Southern Africa. E-V38, which is most common in these regions, according to the new study, mostly expanded and diversified in the last 15,300 years, making it the youngest major branch of Y-DNA E. Y-DNA E diversity also tends to decline from East to West across North Africa. Instead, East Africa is the likely place of origin of Y-DNA E.

Ethio Helix has some solid analysis of the new data, although his page is hard to read in some browsers.  In particularly, he notes that the study localizes the older part of one of the main branches of Y-DNA E in Northern Ethiopia and Sudan.

2 comments:

Ethio Helix said...

"although his page is hard to read in some browsers"

I have fixed the chart rendering issues (at least for IE 11), the problem was that my click to sort Javascript code was reading some of the functions array return values in a single line, which was ok for firefox and other browsers but apparently not for I.e, should be good now.

Thanks for mentioning this issue.

andrew said...

Thanks for fixing that. You have an excellent blog.