Out of Africa: a theory in crisis

[firemonkey]

The sensational discovery of modern humans in the Levant 177-194 thousand years ago should cause a rethink of the currently held Out-of-Africa orthodoxy.

By Out-of-Africa, I mean here the origin of anatomically modern humans, as opposed to the earlier origin of the genus Homo or the later origin of behaviorally fully modern humans.

Two main pieces of evidence supported the conventional OOA theory:

1. The observation that modern Eurasians possess a subset of the genetic variation of modern Africans.
2. The greater antiquity of AMH humans in the African rather than the Eurasian palaeoanthropological record.

Both these observations are in crisis.

http://dienekes.blogspot.co.uk/2018/...in-crisis.html

[firemonkey]

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[lgmayka]

http://dienekes.blogspot.co.uk/2018/...in-crisis.html

Dienekes' initial postulate ("two main pieces of evidence") is incorrect. The primary and still totally unshaken evidence for the OOA theory is the structure and distribution of the Y-DNA and mtDNA haplotrees. As long as both of those haplotrees indicate an African origin, any counter-evidence can be easily dismissed as:
- Extinct offshoots
- Slight autosomal admixture
- Etc.

The most significant recent challenge to conventional OOA theory was the discovery of Y-DNA A00 in some men of Cameroon ancestry. YFull estimates that A00 diverged from A0-T roughly 236,000 years ago. Many experts in this forum suggest adding 10-20% to YFull's estimates, which would yield a range of 260-283 thousand years for the TMRCA of modern human Y-DNA. But Cameroon is still in Africa.

It is actually quite amazing that after all these years of DNA testing, we have not found a single living example of Neanderthal, Denisovan, or other indisputably archaic Y-DNA or mtDNA. Ironically, A00 was initially assumed to be a recent archaic introgression, based on its estimated age of divergence and TMRCA; but the discovery of 300,000-year-old Moroccans with modern faces suggests that A00 might have already been anatomically modern at the time of its divergence.

[Squad]

I was thinking exactly that. The main reason making ''out of africa'' the only valid scenario are uniparental markers. Denying this scenario clearly verges on insanity and I will never understand why people like Dienekes who were involved for many years could even think otherwise, it's actually fascinating how having a personal agenda can make you refute the very reality.

[blackflash16]

This only puts the idea of a single-recent OOA theory in "crisis". Even then, uniparental groups clearly indicate a significantly greater migration involving a single subclade of Y-DNA BT and mtDNA L3'4.

[GailT]

More likely that Dienekes is having some sort of emotional crisis. The conclusion from the paper is that modern humans originated in Africa, and that dispersals out of Africa might have occurred earlier than previously thought:

To date, Misliya-1 appears to represent the earliest fossil evidence of the migration of members of the H. sapiens clade out of Africa. It therefore opens the door to the possibility that H. sapiens dispersal from Africa could have occurred earlier than previously thought (probably before 200 ky ago)

We know from DNA that archaic humans interbred with modern humans outside of Africa, and that archaics contributed a very small amount of DNA to modern humans outside of Africa. The Out of Africa story is complex and not yet fully understood, (Chris Stringer has article in the Edge about that complexity) but autosomal DNA and uniparental DNA show that all living people derive most of their DNA from a recent African origin, around 60,000 years ago.

[TuaMan]

I think some of you are missing the forest for the trees, some of Dienekes obfuscations not withstanding.

The ancestors of all living modern humans evolved over the course the Middle Paleolithic/Middle Stone Age between 150,000 - 300,000 ybp, most likely in Africa. Previously most people naturally assumed this evolutionary process took place in sub-Saharan Africa, more specifically east Africa (namely Ethiopia, Kenya, Tanzania), since that was where the oldest and most stratigraphically consistent track record of Homo fossils had been found, with the Omo Kibish (195,000 ybp) and Herto ( 165,000 ybs) fossils from Ethiopia being being seen as the earliest examples of anatomically modern humans.

Last year's revision of the dating of the Jebel Irhoud remains to 300,000 ybp added a big wrinkle to that picture, since now we have the earliest examples of apparently modern human morphology all the way in Morocco in northwest Africa. And now we have this Misliya finding in Israel, which is nearly contemporaneous the Omo Kibish remains, the oldest known example of AMHs in sub-Saharan Africa.

I think what these findings from both Jebel Irhoud and Misliya suggest for now is that the entire Saharo-Arabian belt from the Atlantic coast of Morocco all the way through the Levant, Mesopotamia and the Arabian peninsula is now in play as a site of modern human evolution during the Middle Stone Age, and that sub-Saharan east Africa is no longer necessarily going to be the locus of human evolution and well-spring of all AMH expansions that it has up till now been seen as.

[vettor]

More likely that Dienekes is having some sort of emotional crisis. The conclusion from the paper is that modern humans originated in Africa, and that dispersals out of Africa might have occurred earlier than previously thought:



We know from DNA that archaic humans interbred with modern humans outside of Africa, and that archaics contributed a very small amount of DNA to modern humans outside of Africa. The Out of Africa story is complex and not yet fully understood, (Chris Stringer has article in the Edge about that complexity) but autosomal DNA and uniparental DNA show that all living people derive most of their DNA from a recent African origin, around 60,000 years ago.

The Out of Africa theory is the evolution of different haplogroups ...............how many haplogroups would there be if we did not leave Africa ?

This evolution was created between south asia and east asia

[firemonkey]

Dienekes Pontikos resurfaces with a post, Out of Africa: a theory in crisis. The title is a bit hyperbolic. But in Dienekes’ defense, he’s been on this wagon for over ten years, and the evidence is moving in his direction, and not against it. I think a little crowing is understandable on this part.

With that being said, I think the biggest rethinking that we’re doing is less about where modern humans arose (Sub-Saharan Africa, North Africa, the Middle East), but how they arose. Some geneticists are quite open to the idea of Eurasian (Neanderthal?) back-migration to Africa several times. Others are positing that a “multiregional” model might actually about within Africa.

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