New Jebel Irhoud Date Causes Rethink of Chinese Dali Skull

Newsweek (Yes, that Newsweek) has a story on the reexamination of the Chinese Dali cranium, in light of the revised dates for the Jebel Irhoud skulls.  Kastalia Medrano writes:

Known as the Dali skull, it was discovered nearly 40 years ago in China’s Shaanxi province. It belonged to a member of the early hominin species Homo erectus. Its facial structure and brain case are intact, despite being dated to around 260,000 years ago. The Dali skull is so old that archaeologists initially didn’t believe it could share features with the modern Homo sapiens.

But Xinzhi Wu of the Chinese Academy of Sciences in Beijing believed that due to the overwhelming physical similarities, Homo erectus must have shared DNA with Homo sapiens. After decades of this idea being dismissed by mainstream academia, Wu and a colleague, Sheela Athreya of Texas A&M University, recently reanalyzed the Dali skull and found it may force us to rewrite our evolutionary history after all. It’s incredibly similar to two separate Homo sapiens skulls previously found in Morocco. “I really wasn’t expecting that,” Athreya told New Scientist.

If we’d found only the Moroccan skulls, and not the Dali skull, it would make sense to keep believing all modern humans evolved in Africa. But the similarities show that early modern humans may not have been genetically isolated from other parts of the world, like what we know today as China.

“I think gene flow could have been multidirectional, so some of the traits seen in Europe or Africa could have originated in Asia,” Athreya told New Scientist.

Okay, now the nuts and bolts.Dali has always been thought to occupy that rarified space between Homo erectus  and early modern Homo sapiens.  It was always thought to be between 200 and 250 kya, and optically-stimulated luminescence dating (a variant of thermoluminescence) places it between 258 and 267 kya.  My analyses of the skull suggested that it was, in no way, shape or form, a modern human but it did not tend to cluster with the Neandertals in terms of head shape.  Athreya and Wu have done an extensive multivariate analysis and conclude (from the article, likely behind a paywall:

When just the facial skeleton is considered, Dali aligns with Middle Paleolithic H. sapiens and is clearly more derived than African or Eurasian Middle Pleistocene Homo. When just the neurocranium is considered, Dali is most similar to African and Eastern Eurasian but not Western European Middle Pleistocene Homo. When both sets of variables are considered together, Dali exhibits a unique morphology that is most closely aligned with the earliest H. sapiens from North Africa and the Levant.

These results add perspective to our previous view of as Dali a “transitional” form between Chinese H. erectus and H. sapiens. Athough no taxonomic allocation is appropriate at this time for Dali, it appears to represent a population that played a more central role in the origin of Chinese H. sapiens. Dali's affinities can be understood in the context of Wu's Continuity with Hybridization scenario and a braided-stream network model of gene flow. Specifically, we propose that Pleistocene populations in China were shaped by periods of isolated evolutionary change within local lineages at certain times, and gene flow between local lineages or between Eastern and Western Eurasia, and Africa at other times, resulting in contributions being made in different capacities to different regions at different times.

In combination with the Xuchang remains, the reanalysis of this skull suggests that, indeed, there is a long and complex interrelationship between different hominin groups that dates back some 400 thousand years. From the paper:

In the braided-stream network model, evolutionary change in China was the result of a shifting network of gene flow among distinct regional Chinese populations, as well as between Chinese and Western Eurasian populations. These were not isolated evolutionary lineages; gene flow both within China and between Eastern Eurasia, Western Eurasia and Africa was intermittent and could explain the similarities in aspects of the neurocranium found here between Dali and Western Eurasian Middle Pleistocene humans. Gene flow would best be described as a braided stream network with periods of isolated evolutionary change within a local lineage at times, and periods of gene flow between local lineages or paleo-demes at other times, resulting in contributions being made in different capacities to different regions at different times.

It is pretty clear that our simplistic models of Recent African Replacement and Multiregional Evolution need to be reworked. It is becoming more apparent that what we are looking at either a polytypic species with a huge geographical range or a syngamion of related species that intermixed regularly. The Xuchang skulls were, apparently, not unique.

BioLogos, Ken Ham and David Menton—A Response, Part V

This is part five of the response to David Menton's post on the Answers in Genesis page, on human origins.  It is also a few days late.  We are now to the section that he calls “Making Apes Out of Men.”

Point 10.  He writes:

In an effort to fill the gap between apes and men, certain fossil men have been declared to be “apelike” and thus, ancestral to at least “modern” man. You might say this latter effort seeks to make a “monkey” out of man! Human fossils that are claimed to be “apemen” are generally classified under the genus Homo (meaning “man”). These include Homo erectus, Homo heidelbergensis, and Homo neanderthalensis.

The best-known human fossils are of Cro-Magnon man (whose marvelous paintings are found on the walls of caves in France) and Neanderthal man. Both are clearly human and have long been classified as Homo sapiens. In recent years, however, Neanderthal man has been downgraded to a different species—Homo neanderthalensis. The story of how Neanderthal man was demoted to an apeman provides much insight into the methods of evolutionists.

Neanderthal man was first discovered in 1856 by workmen digging in a limestone cave in the Neander valley near Dusseldorf, Germany. The fossil bones were examined by an anatomist (Professor Schaafhausen) who concluded that they were human.
At first, not much attention was given to these finds, but with the publication of Darwin’s Origin of Species in 1859, the search began for the imagined “apelike ancestors” of man. Darwinians argued that Neanderthal man was an apelike creature, while many critical of Darwin (like the great anatomist Rudolph Virchow) argued that Neanderthals were human in every respect, though some appeared to be suffering from rickets or arthritis. 

Here he gets things exactly backwards. Homo erectus, Homo heidelbergensis and Homo neanderthalensis are not classified by any palaeoanthropologists as “ape men.”  Such a statement is ridiculous on its face.  The reason that those fossil species are in the genus Homo is because they are advanced enough to be placed there.  They are classified as “hominids” or “hominins.”

He uses the phrase “Cro Magnon man” as if it pertains to all of modern humans.  He reinforces this by remarking on the cave paintings, even though those don't show up until the Upper Palaeolithic, at Chauvet Cave.  He then writes that both Neandertals and modern humans are classified as Homo sapiens, but that in recent years, Neandertals have been “downgraded.”

Really?  As Dave Frayer¹ put it:

The “Neanderthals are inferior” attitude traces back to their earliest descriptions in the mid-1800s when the first Neanderthal was labeled as “freak” or an “idiot” or “incapable of moral and religious conception.” For many, the discoveries after 1865 confirmed these labels. Even the majority of human paleontologists supported this view.

That is 160 years ago.  How is that "recently?"  Menton is also wrong that Neandertals were first discovered in the Neander Valley.  That is just where the type-specimen were found. Second, he is wrong about what those who discovered it thought it was.  From my BioLogos post on Neandertals:

Known far and wide for its limestone, the Neandertal or Neander “Valley” attracted the attention of local industrial groups in the early 1700s and considerable mining was carried out in this area through the middle 1800s. It was during the mining of one such area in 1856, Feldhofer Cave, that workers discovered a set of bones, which they initially thought belonged to a bear. To the local biology teacher, Johann Fulrott, who had been called in to identify them, they looked remarkably human—but not exactly. Something was not quite right. Intrigued by their form, and knowing that they represented something out of the ordinary, he took them to the city of Bonn and showed them to university anatomist Hermann Schaffhausen. After a joint investigation of the skeletal remains, in 1857 Fulrott and Schaffhausen announced to the world that they represented a new form of human predating modern Homo sapiens and with an as yet undetermined relationship with them.

What they did not know at the time was that the remains from the Feldhofer Cave very closely resembled those that had been removed from the Belgian site of Engis and the Forbes Quarry site in Gibraltar several decades earlier. It was not until 1864 that these remains as a group began to be referred to as “Neandertal Man.”  (King, 1864).

The La Chapelle-aux-Saints Neandertal was discovered by A. and J. Bouyssonie, and L. Bardon, in 1908.  As Menton notes, in 1911 Marcelin Boule, the French anthropologist, wrote an extensive monograph on it.  Boule was handicapped by an almost overwhelming inability to conceive of these remains as being ancestral to modern humans in any way. Consequently, the publication that emanated from his investigation was rife with errors that it is difficult, in hindsight, to justify or excuse.

The La Chapelle Neandertal was also an old man. This could be seen from the number of missing teeth and resorption of bone around those that had fallen out. Also present was considerable osteoarthritis, especially in the vertebrae. The arthritis may have made it hard to walk. Boule took this characteristic in the La Chapelle specimen and made it seems as though the Neandertal’s natural gait was slouching and primitive. Boule also focused on the sloping forehead and the huge eyes and nose, arguing that these were primitive. He contended that these features strongly suggested a placement in the evolutionary line little above the great apes, with little to no intelligence that would have linked this race to modern humans (Boule, 1911-1913)².

He notes that the “great anatomist” Virchow thought that Neandertals were modern human.  Of this, Drell³ writes:

The Neanderthal find was made only three years before Darwin published The Origins of Species and thus the discovery of the Neander Valley was seen to verify his theories.6 An ardent debate evolved, centred around Fuhlrott and Hermann Schaaffhausen, who both proposed that the bones were those of an archaic human form. This was in direct opposition to one of Germany’s leading scientists of the era, Rudolf Virchow, a distinguished pathologist who rigorously rejected the hypothesis. In his view, the bones were those of a recently deceased pathological human. Virchow’s viewpoint had a great impact on the following decades of research, not least because of his prominence in Germany. His persistent dismissal of all discovered hominid fossils is thought to have impeded progress for the rest of the century (see Stringer and Gamble 1993; Trinkaus and Shipman 1993).

Point 11. In his discourse, Menton attempts to portray Neandertals as misunderstood modern humans and that they had completely modern morphology.  This simply is not so.  As Fred Smith, a palaeoanthropologist who has studied Neandertals for decades noted, while there are traits in modern Europeans that are reminiscent of Neandertals here and there, there is no single person alive who bears the entire suite of Neandertal traits.  Harvati⁴ writes this:

Neanderthals are characterized by a multitude of distinctive cranial, mandibular, dental, and postcranial anatomical features (Fig. 2), many of which are unique to them. Neanderthals also show several “primitive” features, i.e., features shared with the common ancestor of both Neanderthals and modern humans

Here is a graphic example of how modern humans and Neandertals differed.  The skull on the left is a cast of the La Chapelle Neandertal, while the skull on the right is cast of a modern human from the site of Predmosti, dated to around 27, 000 years B.P.

There are several things to note about this image.  The entire face of the Neandertal is larger than the modern human skull.  Further, the middle of the face is prognathic, or pulled out.  There is a large brow ridge present on the Neandertal that is missing on the modern human.  The Neandertal's teeth are much larger, especially the front ones.  The Neandertal forehead is also more sloped than the modern human one.  Behind the face, the skull of Neandertals is very long and low, while modern humans possess a much more rounded skull.  It was these features that gave rise to the idea that Neandertals were a separate species from modern humans.  They may yet be, although in recent years, it has been found that at some point in their evolutionary history, they interbred with modern humans to some extent.

In our own analyses⁵ of Neandertal crania, using as a comparison a modern human sample of over 2500 known modern human individuals from 23 different populations, we found that they never fell within the range of the modern sample.  In fact, every bivariate plot that I produced contained a nice grouping of Neandertals, away from modern humans.  Using this statistical morphological definition of modern human, Neandertals cannot be classified as modern. 

Point  11.  Menton writes:

In addition to anatomical evidence, there is a growing body of cultural evidence for the fully human status of Neanderthals. They buried their dead and had elaborate funeral customs that included arranging the body and covering it with flowers. They made a variety of stone tools and worked with skins and leather. A wood flute was recently discovered among Neanderthal remains. There is even evidence that suggests that Neanderthals engaged in medical care. Some Neanderthal specimens show evidence of survival to old age despite numerous wounds, broken bones, blindness, and disease. This suggests that these individuals were cared for and nurtured by others who showed human compassion.

Still, efforts continue to be made to somehow dehumanize Neanderthal man. Many evolutionists now even insist that Neanderthal man is not even directly related to modern man because of some differences in a small fragment of DNA! There is, in fact, nothing about Neanderthals that is in any way inferior to modern man. One of the world’s foremost authorities on Neanderthal man, Erik Trinkaus, concludes: “Detailed comparisons of Neandertal skeletal remains with those of modern humans have shown that there is nothing in Neandertal anatomy that conclusively indicates locomotor, manipulative, intellectual, or linguistic abilities inferior to those of modern humans.”

Here, Menton correctly hits on an area that is very controversial in modern palaeoanthropological studies: whether Neandertals were a separate species from anatomically modern Homo sapiens.  He is correct that Neandertals did practice cultural behaviors that we would associate with modern humans, even if they were not on the level of what one finds in the Upper Palaeolithic.  It is, indeed, quite possible that had Neandertals not been subject to the crushing cold and harsh environment of the Wurm glaciation, they might have achieved considerably more than they did.  We will never know.  Regarding the origins of modern humans, there are competing views. 

On one side of this debate are those who support the multiregional evolution model in which modern humans arose throughout the Old World through a complex interaction of migration, drift and selection between populations.  On the other side are those that argue that modern humans are a completely different species that migrated out of North Africa, "replacing" the archaic humans that they encountered.  It is clear that neither of these extremes is correct.  The earliest modern humans are, indeed, found in Africa and there is evidence that modern humans and archaic humans did, in fact, interbreed to some extent.

This is a debate that has raged for decades and shows no signs of slowing down.  However, while there is considerable debate between different researchers, as noted above, there are clear anatomical differences between Neandertals and modern humans.

Point 12. Menton's statement that Neandertals and modern humans are only differentiated, genetically, by “a small fragment of DNA” is false.  The best palaeogenomic evidence for the relationship between modern humans and Neandertals is contained here. Dennis Venema writes:

Somewhere between 500,000 and 300,000 years ago, the ancestors of the Neanderthals (Homo neanderthalensis) left Africa and migrated into the Middle East region, and from there on to Europe and parts of Asia. (Recall that human ancestors, at this point, are all still in Africa, and will stay put until around 50,000 years ago). Neanderthals persisted in the Middle East and Europe until ~30,000 years ago, meaning there was a time where the humans leaving Africa about 50,000 years ago could have interbred with them before they went extinct. This remained an open question until techniques improved to recover and sequence ancient DNA. It is now possible to obtain and sequence DNA from Neanderthal remains, and the complete genome sequence of Neanderthals was published in early 2010. The results were fascinating: DNA sequence comparisons between the two species indicates that modern, non-African humans have about 1-4% Neanderthal DNA in their genomes. This variation, however, is not present in sub-Saharan Africans, since they are descended from humans that did not leave Africa and and thereby, because of geographical separation, never had the opportunity to interbreed with Neanderthals. We also know that the group that left Africa went through a reduction in population size to about 1200 individuals (a genetic bottleneck), whereas those that stayed behind maintained a larger population size (about 6000) over the same period.

I had some additional comments on this as they related directly to the fossil evidence in a different post in the same series here.  Menton may be correct that there is nothing inferior about Neandertals relative to modern man, but that is not the same thing as saying that there is nothing different.  The two clearly were, even if the significance of the the scope and breadth of the differences is under debate.  While earlier authors did not have access to the statistical and genetic tools that we currently do, their eyeball impressions of Neandertals clearly led them to think that they were not modern human.  This is not a case of modern authors projecting primitiveness on them.  They were seen that way out of the box.

Next, the conclusion.  

¹Frayer, D. W. (2013). Who You Calling a Neanderthal? The New York Times,  May 2, 2013. Retrieved from http://www.nytimes.com/2013/05/03/opinion/global/Who-Are-You-Calling-a-Neanderthal.html?_r=0

²Boule, M. (1913). L'homme fossile de La Chapelle-aux-Saints: Masson.

³Drell, J. R. R. (2000). Neanderthals: A History of Interpretation. Oxford Journal of Archaeology, 19(1), 1-24

⁴Harvati, K. (2007). Neanderthals and Their Contemporaries. In W. Henke & I. Tattersall (Eds.), Handbook of paleoanthropology (pp. 1717-1748): Springer Berlin Heidelberg.

⁵Kidder, J. H., Jantz, R. L., & Smith, F. H. (1992). Defining modern humans: a multivariate approach. In F. H. Smith & G. Bräuer (Eds.), Continuity or replacement (pp. 157-177). Rotterdam: A.A. Balkema.

PhysOrg: Research Team Discovers "Immune Gene" in Neanderthals

Neandertals once again appear to be playing a central role in modern human origins and continued viability.  From PhysOrg:

A research group at Bonn University, Germany, and international collaborators discovered a novel receptor, which allows the immune system of modern humans to recognize dangerous invaders, and subsequently elicits an immune response. The blueprint for this advantageous structure was in addition identified in the genome of Neanderthals, hinting at its origin. The receptor provided these early humans with immunity against local diseases. The presence of this receptor in Europeans but its absence in early men suggests that it was inherited from Neanderthals. The results have been published in advance online in the Journal of Biological Chemistry. The printed edition is expected in a following issue.

Whether or not it predates Neandertals will never be known but the fact that it has time-depth back that far suggests that this receptor evolved separately from the incipient modern humans and that the interbreeding between the two was sufficient enough for it to take hold in some populations of modern humans. The report also notes that this receptor is very rare in Sub-Saharan Africans but is present in at least two-thirds of Europeans. 

I think we are just scratching the surface in terms of determining how much interbreeding went on between Neandertals and modern humans.  It is clear, judging from each new study, that the species lines are becoming more and more blurred. 

Study: Neandertal Speech and Language Abilities Like Modern Humans

Science Daily has a story on Neandertal speech.  Work by Dan Didiu and Stephen Levinson suggests that Neandertals and modern humans share a common ancestry with regard to the use of language.  Science Daily writes:

Dediu and Levinson review all these strands of literature and argue that essentially modern language and speech are an ancient feature of our lineage dating back at least to the most recent ancestor we shared with the Neandertals and the Denisovans (another form of humanity known mostly from their genome). Their interpretation of the intrinsically ambiguous and scant evidence goes against the scenario usually assumed by most language scientists, namely that of a sudden and recent emergence of modernity, presumably due to a single -- or very few -- genetic mutations. This pushes back the origins of modern language by a factor of 10 from the often-cited 50 or so thousand years, to around a million years ago -- somewhere between the origins of our genus, Homo, some 1.8 million years ago, and the emergence of Homo heidelbergensis. This reassessment of the evidence goes against a saltationist scenario where a single catastrophic mutation in a single individual would suddenly give rise to language, and suggests that a gradual accumulation of biological and cultural innovations is much more plausible..

I am still a bit “iffy” on the whole “common ancestor of modern humans and Neandertals” thing since some are trying to argue for a common ancestor based on the material from the Gran Dolina, in Spain, and it sure as all get out looks like modern humans originated in Northeast Africa at, or near, Herto. I have a tendency to think that there was a good deal of panmixia throughout Europe and north Africa.  Otherwise, we are required to believe that there was a species split at H. antecessor into what became modern humans (how'd they get to north Africa?) on one side and Neandertals on the other and that, some 700 to 720 thousand years later, emerging moderns and Neandertals encountered one another and interbred.  That is overly simplistic, I am sure but it seems far-fetched.  It seems easier to argue that the H. antecessor material represents an archaic Homo sapiens population that was the precursor (or something like it was) to later archaics, such as Petralona and Atapuerca, out of which Neandertals came.  Then the Neandertals interbred with the north-moving moderns and somewhere in there, the Denisova population split off.  The panmixia in Europe, western Asia and Russia explains why moderns have both Neandertal and Denisovan genes, along with the modern genes that originated in North Africa.  Subsequent swamping of the archaic genome led to the demise of both the Neandertals and Denisovans.   

Neandertal/Modern Human Hybridization in North Africa?

That is the focus of a new paper in PLoS ONE by Sanchez and colleagues.  Using 780 thousand single nucleotide polymorphisms of 125 individuals from populations in North Africa, they write:

We found that North African populations have a significant excess of derived alleles shared with Neandertals, when compared to sub-Saharan Africans. This excess is similar to that found in non-African humans, a fact that can be interpreted as a sign of Neandertal admixture. Furthermore, the Neandertal's genetic signal is higher in populations with a local, pre-Neolithic North African ancestry. Therefore, the detected ancient admixture is not due to recent Near Eastern or European migrations. Sub-Saharan populations are the only ones not affected by the admixture event with Neandertals.

Well, raise my rent! When we analyzed the modern human remains in the Near East using canonical variates analysis, we found that they showed more of a similarity with North African archaics than they did Neandertals and that this supported a model of a general northern migration of North Africans into the Levant between 100 and 200 thousand years ago. I will be interested to see the reaction to this from the morphologists.

Ironically, the bulk of the evidence supporting the admixture of modern humans and Neandertals has always been based on the fossil record, while the genetic evidence has traditionally been used to argue for a recent African origin. It is interesting to see all of the genetic studies that have turned the tables. There is not a specific level of admixture at which point you can say "hey, these are the same species," but the studies continue to come out suggesting that admixture was taking place wherever these two groups intermingled and that there do not seem to have been biological imperatives to mate.  They simply decided to do so.  Remember the sage words of J. Lawrence Angel: "When two groups of people meet, they may fight but they willl always mate."

Alan Thorne Has Died

Alan Thorne, one of the principle architects of the multiregional evolution model of modern human origins has died. ABC News reports:

Dr Thorne is best known for his research on the Mungo Lake skeletons found in western New South Wales, and his theories on the regional development of early humans.

The research on 'Mungo man' dated the skeleton to 40,000 years ago.

ANU research colleague Colin Groves says the death of Alan Thorne is a big loss for Australian archaeology.

This is a very sad loss and a big one for the palaeoanthropological community.

“Out-of-Africa Replacement Model”: Piling On

On the heels of the recent DNA arguments supporting hybridization between early modern Homo sapiens and archaic Homo sapiens in Africa comes fossil skeletal evidence.  As the Telegraph reports:

A study on human remains found in the Iwo Eleru cave in Nigeria, West Africa, shows that Stone Age humans in the area shared characteristics with much older human relatives. Palaeontologists leading the study believe their findings provide evidence that modern humans and older subspecies of human might have coexisted and even crossbred in Africa. The findings add weight to theories that ancient species of human lived alongside the anatomically modern humans after they first appeared in Africa 200,000 years ago.

Quoted in the article is Chris Stringer, one of the progenitors of the Out-of-Africa replacement model of modern human origins which was based on mitochondrial DNA studies done in the late 1980s.The article continues:

Professor Stringer said: "The majority view was that once modern humans emerged in Africa 150,000 years ago, it was kind of the end of the story and modern humans took over. "I think the reality is that the ancestral forms didn't just disappear but hung around alongside those that had evolved into modern humans. "Somewhere lurking in bits of Africa were these more archaic people and we are starting to get a picture of that."

I suspect that it is going to get very hard to pin down exactly where Homo sapiens starts. It is becoming more and more clear that anatomically modern Homo sapiens and archaic Homo sapiens went for the occasional “roll in the hay.” If so, as I pointed out earlier, there simply was no “speciation event.” This goes more to supporting the multiregional evolution model, as it applies to Africa, in which there was selection for more modern genes. This model may also apply to Europe, with the mixing of modern humans and archaic humans there. I suspect that this will spur reexamination of the early modern material from there, such as Mladeč, where the material dates from the Early Würm/Late Würm interglacial period.

New Chinese Hominid Fossil Supports Multiregional Evolution?

China National News has a story about a hominid find in Guangxi that suggests that there was not replacement of archaic humans by modern humans in this area. The author writes:

The mandible has a protruding chin like that of Homo sapiens, but the thickness of the jaw is indicative of more primitive hominins, suggesting that the fossil could derive from interbreeding.

If confirmed, the finding would lend support to the "multiregional hypothesis", which says that modern humans descend from Homo sapiens coming out of Africa who then interbred with more primitive humans on other continents.

In contrast, the prevailing "out of Africa" hypothesis holds that modern humans are the direct descendants of people who spread out of Africa to other continents around 100,000 years ago.

"This paper acts to reject the theory that modern humans are of uniquely African origin and supports the notion that emerging African populations mixed with natives they encountered," said Milford Wolpoff, a proponent of the multiregional hypothesis at the University of Michigan.

Most Chinese Palaeoanthropologists, pointing to the unique features of remains like Dali and Maba have long believed that there is a continuous line from Homo erectus to the later remains and going to the material found in the Upper Cave at Zhoukoudian, which is dated at around 30 ky BP. This should prove interesting.

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