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.
The PCA and CVA results are quite instructive:
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.
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
20 comments:
Would you consider LH18 (at MSU, at Britannica) something else than H. sapiens? I ask because it falls within modern human time range, it is generally considered H. sapiens (AMH, I could find no instance saying otherwise) and it is similar in many aspects to the Iwo Eleru skulls.
BTW the description mentions a mandible but I see no jaw anywhere. Also it mentions two calvaria and yet only one is displayed (from 4 different angles).
This link describes the site:
http://www.jstor.org/pss/2798263
"The site of Iwo Eleru is a large rock shelter in the rain forest zone of the Western Stae of Nigeria".
It is hardly surprising the humans were late in entering the tropical rainforest, in spite of what many people continue to claim about 'our' adaptability.
Would you consider LH18 (at MSU, at Britannica) something else than H. sapiens? I ask because it falls within modern human time range, it is generally considered H. sapiens (AMH, I could find no instance saying otherwise) and it is similar in many aspects to the Iwo Eleru skulls.
That is not true.
"The specimen has not been monographed, but those who have mentioned it subsequently in passing have mostly regarded LH 18 as "archaic," only a minority emphasizing its resemblances to modern humans"
Source: The Human Fossil Record: Craniodental morphology of genus Homo (Africa and Asia) Jeffrey H. Schwartz,Ian Tattersall,Ralph L. Holloway
This seems to agree with the PCA/CVA analysis that places LH18 as either intermediate or archaic, but certainly not within the range of modern humanity.
Given that LH 18 (from northern Tanzania) is approximately the same age as Skhul/Qafzeh from the Levant, the naive Out-of-Africa theory would have a hard time to explain how the alleged source of modern humans (eastern Africa) is more archaic than the alleged destination (West Asia) at around the same time.
OK, what about Zhoukoudian Upper Cave 101 (UC1 in the graph)? Which are also in the same range in the PC1 which according to authors seems to capture the AMH vs. archaics variation (the PC2 would be Africa vs. Asia).
Zhoukoudian is (also) generally considered an AMH and is dated to very recent dates of 33-10 Ka ago but it also has a low forehead and an archaic skull. In fact one of the first times I was faced with the UC collection I first thought "are these Homo sapiens?" but someone pointed to the chin, which is typically considered an unmistakable trait of anatomical modernity.
That's another reason to ask about the mandible of the Nigerian remains because it can help clarify the matter.
Check out Table S2.
UC actually has a negative Mahalanobis distance to EAM (the Levantine Shkul/Qafzeh)and is clearly within fully modern sapiens range (7.48 with IB). Upper Cave are clearly modern humans.
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.
Thanks for the notice.
I'll change the title of my post.
"the naivete of the passing Out of Africa orthodoxy that bundled all Africans into an amorphous category of "our ancestors in Africa"."
This is a straw man characterization of Out of Africa orthodoxy. The core of the Out of Africa orthodoxy is that (1) the proto-Eurasians are a subset of Africans (2) all modern humans have common origins diverging from the single emergence of the same species, and (3) there were modern humans in African before they were anywhere else. The only element of that orthodoxy that is disturbed by recent findings is that many modern humans have a small percentage of archaic hominin admixture that doesn't completely overlap and have asingle species source. But, we are talking a pretty small percentage for everyone but Melanesians who have the double dose of Denisovian and Neanderthal DNA, and the Neanderthal admixture tends to confirm the notion of there being at most one or two main Eurasian Out of Africa population from which all Eurasians are dervived, as do the Y-DNA and mtDNA lineage structures.
I'd also suggest that a discrepency between Out of Africa 60kya (in line with almost all traces and verifiable modern human archaeology in Eurasia) and Out of Africa 100kya (in line with an iffy single location in China and a number of skulls in the Levant), is not a tremendous blow to Out of Africa, in part because orthodox Out of Africa theory has never reached a consensus on what happened to the Levantine AMHs when they disappeared for 15,000-25,000 years with a West Asian or South Asian or East African refugia that would have retained that proto-Eurasian population in tact competing with an extinction scenario. There also isn't Out of Africa consensus on whether or not the Levatine AMHs had any populations that stayed behind in Africa. Honestly, the 60,000 v. 100,000 is more a resolution of disputes within orthodox Out of Africa, rather than contrary to it.
The core of the Out of Africa orthodoxy is that (1) the proto-Eurasians are a subset of Africans (2) all modern humans have common origins diverging from the single emergence of the same species, and (3) there were modern humans in African before they were anywhere else.
1) This can also be viewed as Africans being a superset of Eurasians, which could have also come about if Africans are the union of a Eurasian-like population and archaic Africans.
2) This seems likely, due to the obvious homogeneity of modern humans relative to other fossil humans and the two published archaic genomes. But, that really does not establish Out of Africa, only recent common descent.
3) Possibly. I would like to see a quantitative characterization of Omo I, as I mention in my other post, because the priority case seems to depend entirely on this find.
Moreover, the African record does not match expectations of the naive Out of Africa story. Were are all the modern humans in Africa after Omo I and before Hofmeyr?
It seems to me that there has been a rush to tie Omo I to the story of our origins. Sure Omo I is definitely modern-leaning in its appearance, but there is no evidence of modern behavior, and apparently whatever population it was part of co-existed with more archaic humans even in east Africa (Herto/LH18) long after. So, I see no reason, at present, to suppose that the expansion that established the relative homogeneity of our species in the Upper Paleolithic had anything to do with it.
In short, I don't know where H. sapiens in the strict sense (like living humans) originated. Perhaps in a green Sahara, perhaps in the Persian Gulf oasis, perhaps in some yet to be identified locality of Africa or Eurasia.
Dienekes writes: “In short, I don't know where H. sapiens in the strict sense (like living humans) originated. Perhaps in a green Sahara, perhaps in the Persian Gulf oasis, perhaps in some yet to be identified locality of Africa or Eurasia”.
And you all did wonder when I said that hg E went to Africa from Asia (and why not from Europe?), that African Languages were too close to the Eurasian ones for being at least 60000 years old, that R1b1/V88+ reached Africa from Italy (or Spain) by sea?
That the core of human languages was Asia and not Africa had been said by Alfredo Trombetti a century ago (Elementi di glottologia, 1923).
You still have to be able to explain the deep y-DNA and mt-DNA lineages in Africa. It would be strange if these came from archaic humans, when we don't have this happening in Eurasia. Of course, one possibility is step-wise interbreeding of numerous different populations, such that at one point sufficient modernity introgressed into archaic forms that they became equally valid partners. This may not have been possible in Eurasia due to the declining climate and small population sizes.
The "green savanna" certainly sounds like a good location if one prefers to stay within Africa. But I thought the fossil evidence there looks rather archaic, as well? Perhaps I remember wrong.
At any rate, I agree this whole thing is a mess and one big conundrum. AMHs came to Europe pretty much ready and well-equipped, as modern painters, carvers, and builders of musical instruments - seemingly out of nowhere. On the flip side, even the Russian sites of ~ the time of entry still show a mix with partially archaic stone tools, only.
We need more research in the entirety of West Asia - including Afghanistan, Pakistan, etc.
You still have to be able to explain the deep y-DNA and mt-DNA lineages in Africa. It would be strange if these came from archaic humans, when we don't have this happening in Eurasia.
On the contrary, I see no reason to think that mtDNA Eve, for example, who lived 200 thousand years ago was a "modern human" either anatomically or behaviorally. There were no behaviorally modern humans at that time, and AMH must have been a minority with archaic features persisting in Africa down to the Holocene.
It may very well be that the most basal Y-chromosome and mtDNA lineages were part of the H. sapiens gene pool, but I see no overwhelming reason to think this.
"I see no reason to think that mtDNA Eve, for example, who lived 200 thousand years ago was a "modern human" either anatomically or behaviorally."
Dienekes,
Of course not.
But those lineages are African-only. What I tried to stress is that if BMHs came from the outside or from just a small part of Africa, then they must have mixed with the older lineages in a way that did not happen in Eurasia (i.e., preserving the older male and female lineages).
But those lineages are African-only. What I tried to stress is that if BMHs came from the outside or from just a small part of Africa, then they must have mixed with the older lineages in a way that did not happen in Eurasia (i.e., preserving the older male and female lineages).
That is not very surprising. Until the invention of agriculture, population densities of humans were substantially higher in Africa than in the northern regions. Neandertals for example, had bigger brains, a predominantly meat diet, and had to eat 3x as many colories as we do today. In Africa, on the other hand, archaic groups would have been well-adapted (they lived there from time immemorial), they would have ample sources of plant and animal food (greater ecological variety than in the periglacial regions), they would live in bigger groups (because of higher population densities), and would have smaller brains (less need for calories) compared to AMH.
This explains their late survival, as well as the possibility that some of their mtDNA and Y-chromosomes may not have gone extinct due to drift (because of larger population size).
@Eurologist
"At any rate, I agree this whole thing is a mess and one big conundrum."
Eurologist, this is simply because people, for 200 years, have been relying on all those random paleoanthropological and archaeological finds to form rigid opinions about Pleistocene realities. We are culturally pre-wired to think about the past in terms of what was randomly left behind, not in terms of what was passed down to the next generation. These finds change all the time, everywhere. Only genetics, linguistics, kinship studies and other field working with more or less exhaustive/complete databases of modern human variation can supply testable hypotheses. It's been always clear that modern human linguistic variation (and fully developed language is the key attribute of behavioral modernity) peaks way outside of Africa (and Europe). This should've been a good starting point for a search for modern human origins. Instead, everything gets vetted through partial, imperfect, ever-changing and whimsical Pleistocene archaeological and paleonthological "record." No surprise, it's such a mess!
@ German Dziebel
It seems to me that a different item from those you've mentioned, "genetics", would be a better starting point for a search for modern human origins, rather than linguistics. I'm sure it's not that hard to explain away whatever linguistic pattern that could be interpreted to indicate some "way out of Africa" origin of modern humans migrating back into Africa, but it's quite hard to explain away the genetics of out-of-Africa as the "far opposite".
Given that LH 18 (from northern Tanzania) is approximately the same age as Skhul/Qafzeh from the Levant, the naive Out-of-Africa theory would have a hard time to explain how the alleged source of modern humans (eastern Africa) is more archaic than the alleged destination (West Asia) at around the same time.
Aren't also modern Australians more archaic/robust than earlier Australians?
Do this sort of thing mean other thing than that the genetic basis for "archaic" and "modern" traits fall on some degree of continuum, present in all these "late archaic" and "early moderns"?
And that, being genetic and not some sort of mystical tendency towards "progress", it would fluctuate in frequency somewhat over time and place, not bearing necessarily a strong phylogenetic tie to archaic or modern lineages?
I also imagine that much more complication can be brought to the discussion if we question how these traits can be homologies or homoplasies.
Bah, my view is that "we" (not really me, I'm not a scientist) are trying to reconstruct a story in too much fine details when we don't have nearly enough information. It would be interesting to see an article dealing with the unknown variables of all this sort of stuff and how some hypothetical (but plausible) values for such variables could alter dramatically how the puzzle is assembled. The only thing sure is that whatever happened is something between a broader but not totally broader (i.e. multirregional continuity) "out of Africa" and a narrower but not absolutely strict "out of Africa". South Africa, East Africa, Northweast Africa, Middle East, Asia, whatever. Just a bunch of apes and ape-men aping around and mating like rabbits. Enough of the subject for me for the rest of the year.
"... naivete of the passing Out of Africa orthodoxy that bundled all Africans into an amorphous category of "our ancestors in Africa""
Is that really something "orthodox"? I think I (barely) recall of only one instance of a proposed "multiregional evolution within Africa", and even then I think it was just something being carelessly being put as a possibility, not the core of the article/research.
What I recall reading most of the time are suggestions of some hypothetical more restricted site of modern humans within Africa, followed by replacement (not to exclude some hybridization or assimilation) not only out of Africa, but also within (which may even be sort of "back into" if such "site" of origin is supposed to be the horn of Africa or the Middle East), based on genetic diversity and/or fossil remains.
Paleoanthropological investigations of
Middle Stone Age sites at Pinnacle Point,
Mossel Bay (South Africa): Archaeology and
hominid remains from the 2000 Field Season .Kills the ,theirs no On the contrary, I see no reason to think that mtDNA Eve, for example, who lived 200 thousand years ago was a "modern human" either anatomically or behaviorally. There were no behaviorally modern humans at that time, and AMH must have been a minority with archaic features persisting in Africa down to the Holocene.
On the contrary, I see no reason to think that mtDNA Eve, for example, who lived 200 thousand years ago was a "modern human" either anatomically or behaviorally. There were no behaviorally modern humans at that time, and AMH must have been a minority with archaic features persisting in Africa down to the Holocene.interesting statements take a look at Paleoanthropological investigations of
Middle Stone Age sites at Pinnacle Point,
Mossel Bay (South Africa): Archaeology and
hominid remains from the 2000 Field Season
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