The M78 Y chromosome has a North East African, not East African origin.

Tracing Past Human Male Movements in Northern/Eastern Africa and Western Eurasia: New Clues from Y-Chromosomal Haplogroups E-M78 and J-M12

The geographic and quantitative analyses of haplogroup and microsatellite diversity is strongly suggestive of a northeastern African origin of E-M78, with a corridor for bidirectional migrations between northeastern and eastern Africa (at least 2 episodes between 23.9–17.3 ky and 18.0–5.9 ky ago), trans-Mediterranean migrations directly from northern Africa to Europe (mainly in the last 13.0 ky), and flow from northeastern Africa to western Asia between 20.0 and 6.8 ky ago. Asingle clade within E-M78 (E-V13) highlights a range expansion in the Bronze Age of southeastern Europe, which is also detected by haplogroup J-M12. Phylogeography pattern of molecular radiation and coalescence estimates for both haplogroups are similar and reveal that the genetic landscape of this region is, to a large extent, the consequence of a recent population growth in situ rather than the result of a mere flow of western Asian migrants in the early Neolithic. Our results not only provide a refinement of previous evolutionary hypotheses but also well-defined time frames for past human movements both in northern/eastern Africa and western Eurasia.

 
One of the more interesting comments from this is the relocation of M78’s origin from East Africa to North East Africa.

In conclusion, the peripheral geographic distribution of the most derived subhaplogroups with respect to northeastern Africa, as well as the results of quantitative analysis of UEP and microsatellite diversity are strongly suggestive of a northeastern rather than an eastern African origin of E-M78. Northeastern Africa thus seems to be the place from where E-M78 chromosomes started to disperse to other African regions and outside Africa.

And..

In turn, the presence of E-M78 chromosomes in eastern Africa can be only explained through a back migration of chromosomes that had acquired the M78 mutation in northeastern Africa.

Personally, I’m going to put the origin down in the Wadi Kubbanyi area (Southern Egypt, just north of Aswan), for various reasons. This would see an initial northward expansion of the M78 marker match the spread of the Halfan microlithic stone tool culture into the Levant, where it became the Kebaran. This expansion seems to be due to the ability to subsist on a grain based diet (a first about 24,000 years ago), so an expansion into the Sudan and Ethiopia would seem to be logically, as these grains also grow there. I propose that the spread of the e-M78 clades marks the spread of a biological ability and cultural tendency to eat a grain based diet. Also, Wadi Kubbaniya is bang in the middle of the M78 hot spot on the first distribution map. The dates don’t match again though…

This would mean the father of the M78 mutation was probably a part of the southerly Mechtoid populations, where the Eurasian back migration of about 40,000 years ago and indigenous Sub Saharan African populations met. This paper is well worth a read if you are interested in east Africa.

I still have dating issues with the Y chromosomes. Old bones need to be tested to get see if they can pick up the more recent E3b1 clades in Europe and North Africa before their ‘births’