Tag Archives: m78

The M78, an Afro-Asiatic Y chromsome

Anyone who reads through the genetic studies of North and east Africa will notice that admixture between Eurasian and indigenous Africa groups is routinely mentioned, measuring the amount of gene flow between the two groups. E3b1 has recently been redefined as North African by Cruciani, so the older papers describing it as sub Saharan are incorrect, and a new term for it should be found.

Given its North African place of origin, M78 can no longer be attributed to a sub Saharan origin, particularly in light of the fact that it is rarely seen in sub Saharan populations without its maternal Eurasian partner M1. North Africa, circa 20,000 year ago, just prior to M78’s birth had just seen a wave of Eurasian settlers (R1b Y DNA, mtDNA types M, U, J/T, H and V) that had about 10,000 years prior wiped out the previous inhabitants as effectively as the Europeans had wiped out the Neanderthals. Who inhabited North Africa prior to this is something of a mystery, as they didn’t leave any mt or Y DNA signature in the modern population. The few very ancient remains from this area are very archaic in appearance, to the point of being misclassified as Neanderthal on occasion.

So it would seem M78 is a son of both African and Eurasian ancestry. It is particularly closely associated with the Eurasian M1 mt DNA in upper Egypt and Ethiopia, suggesting that M1 accompanied it into its journey south east, and back into Asia; something made more likely by the observation that M1 entered Africa via the North much earlier than it appeared in the South.

So this would make attempting to place M78 into Caucasian North African Y chromosome groups or typically sub Saharan groups both inaccurate and misleading. M78 is inherently a ‘mixed’ child, with ancestry from both sides. The same should probably be applied to the M1 mt DNA type in Africa. It appears to be inextricably linked with a large amount of African ancestry, and calling it ‘Eurasian’ doesn’t really reflect the ancestry of its carriers.

M78 also appears to be very closely associated with the spread of Afro-Asiatic languages; probably marking their arrival into the Levant and East Africa in ancient times.

In the light of this I would suggest that the description of Ethiopians as 40%  Eurasian and 60% sub Saharan is a poor description of their ancestry, and assigning the term ‘Afro-Asiatic’  to their M78 Y chromosomes and M1 mt DNA would be more appropriate.

This would make Upper Egyptians 28.8% paternally Afro-Asiatic, and maternally 17.6%  (23.2% average)Afro-Asiatic. Ethiopians would be about 38% paternally Afro-Asiatic, and maternally 17% Afro-Asiatic (27.5% average), with Somalis tracing 77.6% of their Y chromosomes to Afro-Asiatic ancestors, and 11% to Afro-Asiatic mothers (44.3% average). The difference between the Somali and Ethiopians would seem to be that Ethiopia has been more influenced by input from the Arabian area since the Neolithic. The addition of Arabian Y chromosomes has probably impacted significantly on the frequency of M78 in Ethiopia, explaining its lower frequency there than in Somalia. This won’t make much impact on the overall amount of Eurasian ancestry in Ethiopia (since I suspect the U mt DNA in Ethiopia also dates to the Afro Asiatic era). But it might suggest that Somali Eurasian ancestry is higher than thought if E3b1 is partly Asiatic in ancestry.

This would probably explain why the Somalis are the sub Saharan population with the most similarities to the Badarian Egyptian samples. They have more Afro-Asiatic ancestry, about 44%, having not experienced the Neolithic Arabic population expansion to the same degree, and with less Bantu contribution. A few of the older sources have described some of the Badari crania (and modern Upper Egyptians too) as being similar to some Somalian skulls. Which would hardly be surprising as Somalis retain a large signature from the expansion from Egypt, plus a significant amount of mostly east African DNA (about 43%, mostly maternal) and a little Arabian ancestry (overall about 13%). Although, whether this would mean Somalis look a bit like very ancient upper Egyptians or vice versa is a POV issue.