Showing posts with label Out-of-Africa. Show all posts
Showing posts with label Out-of-Africa. Show all posts

Wednesday, July 23, 2014

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.

Tuesday, March 26, 2013

More Trouble for the Complete "Out-of-Africa" Model

Science Daily is reporting on research done on migration patterns involving early anatomically modern humans.  They write:
The team, led by Johannes Krause from Tübingen University, was able to reconstruct more than ten mitochondrial genomes (mtDNAs) from modern humans from Eurasia that span 40,000 years of prehistory. The samples include some of the oldest modern human fossils from Europe such as the triple burial from Dolni Vestonice in the Czech Republic, as well as the oldest modern human skeletons found in Germany from the site of Oberkassel close to Bonn.

The researchers show that pre-ice age hunter-gatherers from Europe carry mtDNA that is related to that seen in post-ice age modern humans such as the Oberkassel fossils. This suggests that there was population continuity throughout the last major glaciation event in Europe around 20,000 years ago. Two of the Dolni Vestonice hunter-gatherers also carry identical mtDNAs, suggesting a close maternal relationship among these individuals who were buried together.
It was also suggested that the split between non-Africans and Africans was much later in time, between 62 and 95 ky BP. This would mean that the window of hybridization would be much larger than originally thought and that archaic and modern hybridization was a good deal more common until a later time than thought.  The first moderns that we have are from the site of Bouri, in the Afar Triangle, and date to around 160 ky BP.  Maddeningly, what we are lacking is good material between that time and around 100 ky BP, when the Near Eastern Skhul and Qafzeh material are found.  A friend of mine and I argued that the archaic traits in those skulls represent African archaic traits and not hybridization with Neandertals.  This would seem to support that.  They suggest that there are discrepancies between these results and previous ones but, critically, that these results tend to support both the palaeoanthropological and archaeological evidence.    Here is the citation:

Fu et al., A Revised Timescale for Human Evolution Based on Ancient Mitochondrial Genomes,
Current Biology (2013), http://dx.doi.org/10.1016/j.cub.2013.02.044

Friday, February 17, 2012

Language Origin Not in Africa?

Science Daily is reporting a story that follows up on a story from last year in which it was posited that Africa was the birthplace of language. They write:
In the beginning was the word -- yes, but where exactly? Last year, Quentin Atkinson, a cultural anthropologist at Auckland University in New Zealand, proposed that the cradle of language could be localized in the southwest of Africa. The report, which appeared in Science, was seized upon by the media and caused something of a sensation. Now however, LMU linguist Michael Cysouw has published a commentary in Science which argues that this neat “Out-of-Africa” hypothesis for the origin of language is not adequately supported by the data presented. The search for the site of origin of language remains very much alive.
Cysouw argues that the methods that Atkinson used, borrowed from population genetics, are not directly applicable to linguistics research. He argues that language origins can only be traced back around 1o,ooo years.

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Sunday, January 22, 2012

Chris Stringer on Modern Human Origins

Chris Stringer was one of the original progenitors of the Out of Africa model of modern human origins, which posited that anatomically modern Homo sapiens arose in sub-Saharan Africa as a speciation event1 and then replaced the archaic humans that they came into contact in other areas of the Old World. Needless to say, this perspective has been rocked by a number of astonishing studies that have come out in the last few years, including but not limited to these reports:
These have cast considerable doubt on the integrity of anatomically modern humans as a separate species but suggest, instead that despite the timing of some of these trysts, Homo sapiens was a much more polytypic species then met the eye.

Now the grand don of the replacement model is undergoing a re-think. The Edge provides us with a wonderful trek through the history of the origins of modern humans debate and the current evidence for it. He hasn't given up the ship yet, though. He notes:
In my view the Neanderthals were closely related and probably potentially able to interbreed with modern humans, but until recently I considered that while there could have been interbreeding forty or fifty thousand years ago, it was on such a small scale that all trace of it vanished in the intervening years. But it now seems from Neanderthal genome studies that that was not so. We do have a bit of Neanderthal in us, you and I—it's a small amount, but certainly not negligible..

Does that mean Neanderthals are a different species or does it mean we should include them in Homo sapiens? Well, they are still only a small part of our makeup now, reflecting something like a 2.5% input of their DNA. Physically, however, they went extinct about 30,000 years ago. They had distinct behavior and they evolved under different conditions from us, so I still think it's useful to keep them as a separate species, even if we remember that that doesn't necessarily preclude interbreeding.
The percentage of Neandertal genes ranges from a low of 2% to a high of 9%, depending on who you read. The problem here is that, while we currently only have the small percentages, what can be said of the early modern Europeans, or of the people in Europe even as late as the Neolithic? It is almost certain that they would have had much higher percentages.

Further, do these genes explain the traits that Dave Frayer has been seeing for years in the earliest modern humans, such as the extended hemi-buns of the central European sample from Předmosti or archaic characteristics of the Mladeč crania?

The talk is quite long but worth every minute to get the full understanding of how vexing the search for the origins of modern humans has been. As Glenn Reynolds would say: Read the Whole Thing.

1Stringer, C. B., & Andrews, P. (1988). Genetic and Fossil Evidence for the Origin of Modern Humans. Science, 239(4845), 1263-1268.
http://www.jstor.org/stable/1700885

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Thursday, September 22, 2011

“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.