Friday, October 9, 2015

Ancient Ethiopian Genome has some interesting things to share

Well, it seems we no longer have to utilize modern Africans as a reference for a completely "African" population (from a genetic point of view) with essentially no "Eurasian" input as we now have an ancient genome from Southwest Ethiopia that's about 4,500 years old and he has interesting things to share about modern Africans.

"Characterizing genetic diversity in Africa is a crucial step for most analyses reconstructing the evolutionary history of anatomically modern humans. However, historic migrations from Eurasia into Africa have affected many contemporary populations, confounding inferences. Here, we present a 12.5x coverage ancient genome of an Ethiopian male (‘Mota’) who lived approximately 4,500 years ago. We use this genome to demonstrate that the Eurasian backflow into Africa came from a population closely related to Early Neolithic farmers, who had colonized Europe 4,000 years earlier. The extent of this backflow was much greater than previously reported, reaching all the way to Central, West and Southern Africa, affecting even populations such as Yoruba and Mbuti, previously thought to be relatively unadmixed, who harbor 6-7% Eurasian ancestry."

They're not joking about that last emboldened part either. Yorubas and various African populations thought to completely lack "Eurasian" / Out-of-Africa ancestry are in fact anything between 5 to 10% Eurasian (seemingly West Eurasian) based on comparing them to Mota (the name for this ancient individual being based on the the "Mota cave" which he was found in) and ancient Eurasians like Early European Farmers whom I talk about here.

Basically every population from Mbuti pygmies to Yorubas to Kenyan Bantus now demonstrates non-negligible non-African / Euraisan / Out-of-Africa ancestry. It seems that yet again, we were misguided to use modern samples to try and fully understand Human history.

The reason we now have these estimates is because Mota seems to utterly lack any signs of Eurasian ancestry; signs that Yorubas among other groups have shown in the past like Yorubas showing non-zero Neanderthal ancestry levels [2] whilst Mota unlike various modern Africans utterly lacks any signs of Neanderthal ancestry.

This really shakes up and complicates African genetics and slightly back-ups statements I've made in other areas of the internet somewhat based on what geneticists like David Reich have said; even populations like Yorubas thought to be mostly "pure" due to ADMIXTURE analyses like the following one from an old study- :

- are not in fact "pure" but clearly somewhat complex mixtures like many Eurasian and other African populations like Horn Africans, various Southeast AfricansCentral Asians, Europeans and so on. [note] We will of course need more ancient genomes from Africa in the future to add to and further comprehend what these results show as well as even back them up but for now; that's what we have.

But for now that's all I'll be saying about this paper until I've gotten around to reading it more thoroughly than my current skimming of it.

I also highly recommend going through the study yourself or at least it's currently available supplementary information.

Reference list:


1. Mota belong to Y-DNA E1b1 & mtDNA L3x2a

2. Seems to be a lot of news on this study in the mass media...

3. A fruitful discussion about this study is ensuing here.

4. One interesting thing to note is that when Mota & the Druze are used to asses how "Eurasian" all of these populations are; the West Eurasian ancestry in Horn Africans increases but then decreases (something that doesn't happen to other populations like Yorubas and Mbutis) when Mota & Early European Farmers (LBK) are used...

The Druze have a small amount of "African" ancestry, if I recall correctly at about ~3% or some such (some of this may in light of this recent find carry Eurasian ancestry?) so perhaps this causes the sudden lowering in Horn Africans in respect to when LBKs are used or perhaps it's the greater European Hunter-Gatherer-related ancestry in LBKs? It's an interesting thing to note, I suppose.


  1. Weren't there previous (pre-Mota) migration(s) into the Horn from the Middle East, as I recall--- perhaps 20kya?

    1. The 20 kya estimate is incorrect and based on the authors of a paper from last year thinking that a mixed (West Eurasian + "Nilo-Saharan-related") component ("Ethio-Somali") was fully "Eurasian", I explained this here:

      Also, as a friend explained on ABF below- :

      -one shouldn't make too much of Mota (a sample from ancient Southwest Ethiopia) in respect to the substantial West Eurasian ancestry present in Horn Africans like Somalis or Habeshas; this does not at all prove our West Eurasian ancestry is only 3,000 years old unless some sort of huge population replacement occurred all across West Asia just over the last 3,000 years, which is more than unlikely...

  2. DNA stores biological information. The DNA backbone is resistant to cleavage, and both strands of the double-stranded structure store the same biological information. Biological information is replicated as the two strands are separated. For above situation, I have another hypothesis: the sudden lowering in Horn Africans was caused by gene mutation.