Chris Stringer video on BBC on Iwo Eleru skulls

Skull points to a more complex human evolution in Africa

"[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.

The researchers say their findings also underscore a real lack of knowledge of human evolution in the region.

My previous blog post on the published article here.

A thing that has troubled me in reading a few recent palaeoanthropological comparative analyses is the fact that the Omo I, the "modern" of the ~195ka Omo skulls, as well as Herto do not seem to be included. Is this a case of anthropologists guarding their data, a problem that seems to have particularly plagued paleoanthropology? This is not an idle question: how would these ~200ka and ~150ka finds, widely touted as our ancestors fare when placed in the same analysis as the skulls of Harvati et al. (2011) or Mounier et al. (2011)?

Omo II, the most "archaic" of the Omo skulls was included in Mounier et al. (2011) and seemed to be related to Skhul 5 and Jebel Irhoud 1, which would probably place it in the intermediate (archaic/modern) category. How about Omo I?

I don't know, and I'd like to see some hard numbers on exactly how modern it is compared to extant humanity. It has often been repeated, for example, that the Skhul/Qafzeh hominins from the Levant represent an early Out-of-Africa movement, but they appear, at least in the latest Harvati et al. analysis to be well within the range of modern human variation, and certainly more so than all the included African samples of similar, or even younger age.

This seems counterintuitive: if, as the current orthodox theory holds, modern humans -in the strict sense of being like living people- originated in Africa ~200ka and spread to the rest of the world ~60ka, why are the Mt. Carmel hominins apparently more modern than their African counterparts of similar age? Remember, that it has been hypothesized that Skhul/Qafzeh represent a population that may be mixing with Eurasian Neandertals, which would make them less like modern people, not more.

Moreover, if modern humans did originate in Africa ~200ka, then why did they admix with archaic Africans only ~35ka (per Hammer et al. 2011) and had not replaced archaic Africans even ~13ka? Apparently, the current narrative proposes, they replaced all archaic hominins in Eurasia in practically a few thousands of years, but they could not achieve the same in nearly 0.2My in Africa? Or, they admixed with archaic Eurasians before they admixed with their next-door neighbors, the archaic Africans? Something does not seem right.

How would Omo I and Herto fare if they had been included? Ancestral H. s. sapiens, where art thou? Let's find out.

16-12 ka humans with archaic features from Iwo Eleru, Nigeria

This is a nice physical anthropological complement to the recent Hammer et al. paper on archaic admixture in Africans. It is also added to a growing list of late survivals in the African palaeoanthropological record with apparent archaic features.

As I have mentioned before, people have been too quick to generalize about "modern humans in Africa" from the early anatomically modern humans of eastern Africa, forgetting that our focus on them has been an artifact of the good geological conditions for preservation in that area, and the resulting overwhelming scientific interest in the region.

But, eastern Africa is the periphery of Sub-Saharan Africa, and we are lucky to have new finds described from West Africa and elsewhere, as in this paper.

I bet that a few years from now, we will look with amazement at the naivete of the passing Out of Africa orthodoxy that bundled all Africans into an amorphous category of "our ancestors in Africa". It is also becoming clearer that increased African genetic variation is, at least in part, due to the continent being home to multiple deeply divergent populations that persisted, in various admixtures down to the present.

The PCA and CVA results are quite instructive:

Symbols: Grey diamonds. Modern humans; Black up triangles: Upper Paleolithic modern humans; Purple up triangles: Late Pleistocene African and Near Eastern hominins; Red stars: H. neanderthalensis; Red squares: H. heidelbergensis (s.l.); Black squares: H. erectus (s.l.). Ellipses indicate 95% confidence ellipses for Neanderthals (red) and modern humans (gray).

From the paper:

Modern human populations were characterized by more positive scores on PC 1, and there was only minimal overlap among their 95% confidence ellipses and that of the Neanderthals. The Middle-Late Pleistocene African specimens (LH 18, Singa, Djebel Irhoud 1 and 2) and the early modern human specimens from Qafzeh and Skhul fell in the intermediate zone between Neanderthals / H. heidelbergensis on one hand and modern humans on the other. Qafzeh 9 was the exception, falling on the positive end of PC 1 and close to Upper Paleolithic European specimens. The latter sample, which included some of the earliest modern human specimens in Europe (Mladec 1 and 5, Oase 2, Muierii 1, Cioclovina), clustered within the modern human range of variation, and not in the zone of overlap with the archaic specimens.

Note a few things:

• the similarity of Qafzeh 9 with Upper Paleolithic Europeans; geneticists had better stop inferring that the Skhul/Qafzeh hominids were the "first Out-of-Africa that failed"
• the similarity of Qafzeh 6 with Upper Cave 1 from Zhoukoudian.

If you have Qz9 and Qz6, i.e., more than 100,000 year old West Asian skulls clustering with Upper Paleolithic Europeans and East Asians, it is becoming increasingly difficult to maintain the naive Out-of-Africa orthodoxy that a recent Out-of-Africa push as late as 60,000 years is responsible for the peopling of Eurasia.

This is especially the case when Qafzeh 9 may be the earliest unambiguously modern human with no "ifs and buts", with Skhul and Qz6 following close behind.

In the conclusion of their paper, the authors mention another skull with archaic features, from Congo:

Thus our restudy of the Iwo Eleru cranium confirms previously noted archaic cranial shape aspects, and the U-series age estimates on its skeleton support the previously proposed terminal Pleistocene date for this burial. Our findings also support suggestions of deep population substructure in Africa and a complex evolutionary process for the origin of modern humans [16], [17], [7], [18], [19], [20], [21]. Perhaps most importantly, our analysis highlights the dearth of hominin finds from West Africa, and underscores our real lack of knowledge of human evolution in that region, as well as others. As also indicated by restudy of the Ishango (Congo) fossils [22], Later Stone Age fossils from at least two regions of Africa retain significant archaic aspects in their skeletons. We hope that the next stage of this research will extend studies to the Iwo Eleru mandible and postcrania, and to comparative materials such as those from Ishango.

According to paper co-author Chris Stringer:

Hi Dienekes, Unfortunately PLoS introduced a typo in the summary regarding the date, which should have read ~11.7–16.3 ka. Everyone please bear in mind the analysis only covered the superior cranial vault, as there was no face - I discuss the results further in my new book The Origin of Our Species.

UPDATE: Chris Stringer video and more thoughts

PLoS ONE 6(9): e24024. doi:10.1371/journal.pone.0024024

The Later Stone Age Calvaria from Iwo Eleru, Nigeria: Morphology and Chronology

Katerina Harvati et al.

Background
In recent years the Later Stone Age has been redated to a much deeper time depth than previously thought. At the same time, human remains from this time period are scarce in Africa, and even rarer in West Africa. The Iwo Eleru burial is one of the few human skeletal remains associated with Later Stone Age artifacts in that region with a proposed Pleistocene date. We undertook a morphometric reanalysis of this cranium in order to better assess its affinities. We also conducted Uranium-series dating to re-evaluate its chronology.

Methodology/Principal Findings
A 3-D geometric morphometric analysis of cranial landmarks and semilandmarks was conducted using a large comparative fossil and modern human sample. The measurements were collected in the form of three dimensional coordinates and processed using Generalized Procrustes Analysis. Principal components, canonical variates, Mahalanobis D2 and Procrustes distance analyses were performed. The results were further visualized by comparing specimen and mean configurations. Results point to a morphological similarity with late archaic African specimens dating to the Late Pleistocene. A long bone cortical fragment was made available for U-series analysis in order to re-date the specimen. The results (~11.7–6.3 ka) support a terminal Pleistocene chronology for the Iwo Eleru burial as was also suggested by the original radiocarbon dating results and by stratigraphic evidence.

Conclusions/Significance
Our findings are in accordance with suggestions of deep population substructure in Africa and a complex evolutionary process for the origin of modern humans. They further highlight the dearth of hominin finds from West Africa, and underscore our real lack of knowledge of human evolution in that region.

Link