Out of Africa's end?

By Razib Khan | September 17, 2011 12:54 pm

The BBC has a news report up gathering reactions to a new PLoS ONE paper, The Later Stone Age Calvaria from Iwo Eleru, Nigeria: Morphology and Chronology. This paper reports on remains found in Nigeria which date to ~13,000 years B.P. that exhibit a very archaic morphology. In other words, they may not be anatomically modern humans. A few years ago this would have been laughed out of the room, but science moves. Here is Chris Stringer in the BBC piece:

“[The skull] has got a much more primitive appearance, even though it is only 13,000 years old,” said Chris Stringer, from London’s Natural History Museum, who was part of the team of researchers.

“This suggests that human evolution in Africa was more complex… the transition to modern humans was not a straight transition and then a cut off.”

Prof Stringer thinks that ancient humans did not die away once they had given rise to modern humans.

They may have continued to live alongside their descendants in Africa, perhaps exchanging genes with them, until more recently than had been thought.


In the broad outlines most people still seem to hold that within the last ~100,000 years there was a major demographic pulse which swept out of Africa and populated the rest of the world. Something special did happen. Oceania and the New World were settled by the descendants of anatomically modern humans, whom we can trace back to Africa. The key modifications to the old model seem to be two-fold:

1) The possibility of admixture with other lineages on the way out

2) The sublocalization of the “Out of Africa” scenario, and further admixture with lineages within Africa

There have long been debates about an East or South Africa ur-heimat for the first anatomically modern humans. Others are now even positing a North African origin! To a great extent I wonder if a West or Central African origin is forgone in part due to the paucity of fossil remains entailed by the unfavorable conditions for preservation.

However the details shake out the story seems to be getting more, not less, complicated. This makes for less pithy one liners for the media, but also more work for scientists. Figuring out stuff can be fun!

  • unknown

    Correct me if I’m wrong, but the recent study regarding archaic admixture in Africa did not report back evidence of “archaic” admixture among modern West Africans and the like, but among the Mbuti and Khoisan.

    There are other alternatives of course, it would be incrediably niave of us if we were to disregard the fact that the most “basel” of Africans are the same groups listed above to possess arachaic “admixture” from a group that split some 700,000 years ago (around 300,000 before the Neanderthal-AMH split) and was only assimilated some 35,000 years ago.

    This study does contridict Dienekes theories though… not only is the admixture not enough to explain why Eurasians possess a slightly higher affinity to Neanderthals, most Africans lack any indications of such “arachic” intrussion. It’s much more likely that African hunter-gathers being basel simply have a more closer affinity to the root of the humanoid “familia”, in comparison to other humans, than the ancestors of Eurasians having a closer to affinity to Neanderthals than their African brethren do with the latter.

  • http://sciencepolice2010.com ж

    Interesting; does this sort of discovery mean it’s OK to talk about Kow Swamp now?

  • http://www.buildinghistory.org/distantpast/ Jean M

    Others are now even positing a North African origin!

    If you have me in mind, not so. There is evidence that a Homo sapiens lineage with archaic traits in North Africa moved out of Africa early by the northern route. The general feeling was that they just died out – a dead end. On the basis of Y-DNA and mtDNA we all seemed to be descended from the wave taking the southern route, though inter-breeding between the two lineages seems at least as likely as interbreeding with even more archaic hominids, and more likely to produce viable offspring.

    However, the revising of the Y-DNA tree to show a deep split in A, with just a handful of men carrying a rare A branch, suggests that the rare branch could have emerged in North Africa among the Aterians.

  • Sandgroper

    #2 – Go on, then.

  • http://www.lunarstudio.com Renderings

    The “Out of Africa” theory has come about due to the oldest hominid remains being found there. A major problem with this theory has to due with climate. Areas such as Olduvai Gorge in Tanzania have been historically dry and arid – perfect conditions for preserving the fossil record.

    Areas such as Southeast Asia are historically humid and wet – perfect for conditions of rapid disintegration where the fossil record isn’t preserved.

    So just because one can find the oldest hominid remains in desert-like conditions, doesn’t necessarily mean that this is the region human ancestry comes from. It’s an assumption which keeps on being perpetuated, perhaps incorrectly.

  • http://entitledtoanopinion.wordpress.com TGGP

    Renderings, I thought the theory came about because that’s where most living apes (including our closest relatives, chimpanzees) and it has the most genetic diversity.

  • Justin Giancola

    TGGP, I thought it was because your mom is from there? ;p

    joke friends, it was too tempting and I am weak for stupid.

  • Konkvistador

    Why are archaic remains in Nigeria such a big deal, hasn’t Out of Africa been shifting more to Out of East Africa for some time?

  • S.J. Esposito

    This is very interesting and adds to the growing list of reasons why it’s an exciting time in biological anthropology and human evolution.

  • http://sciencepolice2010.com ж

    @Sandgroper #4:
    I was hoping someone else would step in and clarify it for me! Actually, I see there’s now quite a lot on the net about the Kow Swamp finds (now reburied in accordance…) and if forced talk about them myself I’d summarise them as from SE Australia (not coastal), seemed rather archaic yet are apparently definitely not H. erectus as some had suggested, and are now thought to have been twice as old – 20kish or more – than originally suspected. One or more were quite obviously ‘bound’ in youth, which accentuated the slope of the forehead. Suggested to me that later arrivals in Australia had had more opportunity to mix with people they met in S.E. Asia than the oldest more modern looking Australian fossils. Might have been a Denisovan influence of course, but although 20k old DNA might not have survived in a hot climate anyway, it seems doubtful DNA from Kow Swamp would now be allowed. But since Europe, Asia, and now Africa all seem to have archaic associations, there’s nothing to be concerned about over Australia having them… though I’m not really the person to ask :-) .

    On the African finds, Hawks seems about to express an alternative slant to the authors’.

  • http://www.buildinghistory.org/distantpast/ Jean M

    Renderings, I thought the theory came about because that’s where most living apes (including our closest relatives, chimpanzees) and it has the most genetic diversity.

    That and the fact that we have a clear trail in Y-DNA and mtDNA back to DNA Adam and DNA Eve in Africa. Haplogroup A is at the root of the Y-DNA tree and it is mainly found in Africa. Haplogroup L is at the root of the mtDNA tree and it is mainly found in Africa. From there we can follow the trail of people leaving Africa in the new mutations that cropped up along the way across the globe.

    “Out of Africa” is not in a state of crash and burn, folks. :)

  • Sandgroper

    #9 – Yes, I think the consensus is Kow Swamp was head deformation from binding, not anything associated with ‘archaic’ humans.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    Correct me if I’m wrong, but the recent study regarding archaic admixture in Africa did not report back evidence of “archaic” admixture among modern West Africans and the like, but among the Mbuti and Khoisan.

    there was some in the yoruba. small. only the mandenka lacked it at all.

    If you have me in mind, not so.

    no, i didn’t have you in mind.

  • http://washparkprophet.blogspot.com ohwilleke

    The notion that a relict population or two of archaic hominins survived into the post-LGM era, particularly given the evidence of Homo Florensis, doesn’t itself seem all that outlandish.

    Iwo Eleru, Nigeria wouldn’t have been my first guess for a location of such a relict population, however. It isn’t hidden away deep in a mountain valley or so deep into a tropical rainforest that it might have been ill suited to modern humans. Today, it is prime African real estate for low tech modern humans – generally warm, not too dry, not too wet and reasonably flat.

    The timing of 13,000 years ago would predate the probable date of the expansion of Y-DNA E1b1a and mtDNA L2 into West Africa that defines that region genetically today, possibly leaving less population pressure from modern humans than there is today (quite possibly also spreading Niger-Congo languages and Sahel agricultural methods), and we don’t know so much about the paleoclimate of the area, so it could have been less friendly to modern human hunter-gatherer populations than it is today. But, IIRC, there is evidence of bone harpoon fishing in West Africa from 75,000 years ago (a tell tale tool of modern humans relative to archaic human tools, Neanderthals and Homo Erectus apparently lacked bone tools and didn’t fish).

    Genetic evidence of Pygmy DNA from commuities to the South of Iwo Eleuru would suggest 13,000 years ago is about the time of the split of Eastern and Western Pygmies into separate populations, possibly due to the decline of the tropical forests from a previous more lush level, and Pygmies do show more archaic admixture than the West Africans of today.

    Still, while not to be dismissed out of hand, since this does call for a rather big rethink of the regions prehistory and evolutionary track, it probably does deserve greater than usual scrutiny of dating and authenticity.

  • pconroy

    @OhWilleke,

    I postulated a few years ago that Neanderthals lived on fish, based on:
    1. A few skulls having “diver’s ear” – a bony projection, resulting from diving into icy water repeatedly
    2. The C14/C16 composition of some skeletons, which indicated either they ate mostly mammoth or fish
    3. The long arms, large lung capacity, short legs and large flat feet – an ideal build for swimming

    If I’m correct, they dove in the water and caught fish by hand, no fish hooks needed.

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This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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