Monday, November 19, 2012

So What's the Deal with the Neanderthal, Their Demise? - 4

This a carry-over topic from a previous installment: So What's the Deal with the Neanderthal, Their Demise? - 3

To recap:

Were contemporary modern humans, you know—the species that lives on to this day, responsible? Or did everything else that was working fine for the Neanderthals' survival, prior to the arrival of the so-called anatomically modern humans, came to a halt for some reason or another?

Introduction: 

The discovery of  Neanderthal remains [see the entry: How are the Media and Schools catching up with Scientific Progress? Pt.4] has naturally raised the curiosity of people, because they seem so close to us humans, and so, many inquiring minds want to know what happened to these extinct human cousins. Preexisting evidence so far only presents sketchy explanations of not only exactly how they (Neanderthals) reached their extinction, but also precisely where and from what ancestral line [although there are guesses as to what that might be] Neanderthals emerged. Notwithstanding significant strides made in the discipline of molecular genetics, as well as new findings in human paleontological record, researchers are still battling out the search for the most solid and parsimonious answers to those main aforementioned fronts.

Where the demise of the Neanderthal is concerned, there have been suspicions of the role of modern humans in this within the scientific community for a while now, although there seemed to be an air of reluctance to want to explore that very possibility. To that end, the more popular narratives which have circulated the web for years, generally looked mostly to abrupt environmental shifts as the prime suspect in the demise of the Neanderthals, purportedly in accompaniment with the insufficient resourcefulness of the Neanderthal; the role of modern humans had generally taken somewhat of a back seat in such narratives.

Discussion: 

Here the discussion will reach its conclusion. In previous segments, the role of weapon technology, and the interplay between that and body build morphology were discussion in detail. Throw into that mix, the role of language, particularly complex language capability. Socially-derived culture ought to not be left out of the equation either. The interactions of these factors could make a difference in how the two human species, namely Neanderthals and modern humans, cope with both their traditional environments and changing environments. A combination or any of these factors could have given modern humans an edge over their Neanderthal counterparts. Coupled with these mechanisms as underlying factors, flexibility could have been the right recipe for coping with changing environments, and it's possible that modern humans eventually managed to get a better handle of this flexibility than Neanderthals, thereby enhancing their ability to respond to challenges posed by erratically-changing environment. The emergence of modern humans in Africa, and their fairly long habitation therein, raises the prospect that the varying and very challenging environment of that continent shaped the evolution of modern humans in both behavior and biology, in the way it occurred.

Almost certainly, the capacity to have a highly complex language, featuring a fairly high capacity for vocabulary, would have given modern humans an edge in facilitating almost sudden shifts in, and the proliferation of technology, if Neanderthals did not have the same speech capability. Saying that Neanderthals and modern humans likely had different language speaking capacities is not the same thing as saying that the Neanderthals were incapable of speech altogether, or that they were mutes. It is simply recognizing the very real possibility that they had different speech capabilities, which could just as well also make a difference in how they responded to new challenges posed by environmental shifts.

"Clash of The Cavemen" tells us:

Narrator:
“The only indisputable proof of language is a written record, and that wouldn't exist, but there is circumstantial evidence that these Cro-Magnons did communicate verbally some 25,000 years earlier. For example, it appears they had an organized trade system.”

Katerina Harvati:
“There is evidence of long-distance transfer of materials, such as raw materials for making special tools, for instance, which happens much more frequently with early modern humans than with previous groups, such as Neanderthals.

Narrator:
Amber dating from this period and traced to the Baltic region has been found in southern Europe, and ancient seashells from the Mediterranean show up in Cro-Magnon dig sites as far north as Ukraine. Coordinating such an organized exchange of resources would likely have required advanced communication skills.”

Katerina Harvati:
“Everybody would argue that they had complete language, modern human communications skills, based on all of these behaviors. I think it just fits with the whole picture of early modern humans as being very culturally sophisticated, having very complex social networks, fully modern culture and behavior.”

All of these things could have converged with one another to some degree or another, through a mixture of happenstance and environmental pressures, to enhance modern human's capacity for survival in changing environment, BUT it is almost certain that such a prospect would not have been possible in the absence of the right brain development to go along with it!!! Just because modern humans appear to be very closely related to the Neanderthals, according to fossil record, and to some extent, genetic analysis, does not mean that they did not still exhibit differences in the way their brains functioned. By volume, these differences may well seem minute, but implications could have been profound. Considering the separate evolutionary paths, followed by substantial length of isolation between the two species, it is not inconceivable that such distinctions could exist; in "Clash of The Cavemen", with regards to the last possible common ancestor, we were told:

Narrator:
“the leading candidate may be Homo Heidelbergensis, aka "Heidelberg man," named for the town in Germany where its first fossil was found a century ago.”
   
T. Holliday:
“Homo Heidelbergensis is every bit as robust as Neanderthals, powerfully built, but a smaller brain, and it is essentially--they're using the same tools that the Neanderthals are using.
   
There's very little difference in the Homo Heidelbergensis technology and the Neanderthal technology.

   
Narrator:
“It’s logical to trace the Neanderthals back to Heidelberg man. After all, his fossil was found in prime Neanderthal territory.

Modern humans, on the other hand, didn't enter Europe until hundreds of thousands of years after the last of the Heidelbergs were gone, so linking our lineage to them isn't so cut-and-dry.”


Narrator:
“But it turns out, Heidelberg man had an African brother who lived during the same time period, somewhere between 200,000 and 600,000 years ago. It is Homo Rhodesiensis, Rhodesian man. The size of their brain, so to speak, is very similar. Their facial morphology is very similar. This has led many people to consider them a single species.”

If Heidelberg man and Rhodesian man are indeed a single species, it is highly likely that some migrated from Africa to Europe and evolved into Neanderthals while others stayed behind and eventually became Homo Sapiens.

It would be hundreds of thousands of years before these two groups of humans meet in ice age Europe.”


But recalling from the last blog entry, studies undertaken to date the emergence of complex language capability of modern humans have pointed a relatively late date for this emergence, i.e. considering how long modern humans are estimated to be around. The potential flaws in Philip Lieberman's research on this were identified in the earlier segment, i.e. given the singular specimens of the Middle Paleolithic and earlier that he based his assessment of human language capability on vs. the larger samples of specimens traced to later dates. Looking past that, the suggestion is that indicators of "fully modern language capability" were came relatively late in human evolution, i.e. from ancestral hominids to early modern humans...

As I have stressed, the anatomy that allows us to produce the full range of human speech would not have been useful without a brain that can reiterate the complex articulatory gestures that underlie speech. The evidence that is briefly reviewed in my paper and in greater detail in Lieberman (2000, 2006b) shows that the neural bases of speech motor control, cognition, and language involve the same structures of the human brain. There are no apparent disjoint neural motor control, syntax, or cognition “modules.” The neural bases of human motor control, cognition, and language are intertwined. Therefore, it is probable that fully human syntactic and cognitive abilities were also present 50,000 years ago. - Lieberman, 2007.

Studies involving the measurement of vocal tract proportions and shape yielded a date of around 50,000 years ago, that can confidently be associated with "fully modern speech anatomy"; recalling:

Fully modern speech anatomy is not evident in the fossil record until the Upper Paleolithic, about 50,000 years ago.

Genetic data, which in this case was assessed through mutations on the FoxP2 locus, yielded a relatively higher end date of no earlier than 100,000 years ago:

The FOXP2 gene provides a means to date the evolution of the human brain and the emergence of fully human speech capabilities. Despite the high degree of similarity, there are important distinctions between the mouse, chimpanzee, and human versions. The mouse and human versions are separated by three mutations, the chimpanzee and human versions by two. Enard et al. (2002), using the techniques of molecular genetics, estimate that the human form appeared fairly recently, sometime in the last 100,000 years—in the time frame (Stringer 1998) associated with the emergence of anatomically modern H. sapiens.

In bridging date suggested by vocal tract shape and proportion with that suggested by such genetic formation as that obtained from FoxP2, and factoring in the role of brain development...

"The evolution of speech was driven by Darwinian natural selection, the opportunistic use of existing structures adapted for another purpose, and mutations on regulatory genes that had far-reaching consequences. Contemporary human speech and cognitive capabilities, including enhanced syntactic and lexical abilities, are species-specific properties of H. sapiens derived from anatomy and neural mechanisms that appear to have co-evolved. The FOXP2 gene is clearly implicated in the formation of neural circuits that regulate human cognitive and motor capacities. Natural selection acting on the mutations that yielded its human form would have enabled rapid, encoded speech, in turn enhancing the selective value of the mutations that shaped the modern human vocal tract. These events, which led to the emergence of fully modern speech, language, and cognition, appear to have occurred sometime in the period between 90,000 and 50,000 BP, the time frame between fossils like Skhul V and fully modern humans who were capable of talking and acting (Klein 1999) as we do."

And...

I am partially in agreement with Tattersall regarding the late appearance of fully human language. The time frames for the evolution of the human form of FOXP2 and that of speech anatomy are consistent with his view that fully human language appeared after the appearance of hominids who resembled us in many respects. However, these archaic hominids did not have vocal tracts that could produce fully human speech. They also may have lacked fully modern human brains capable of freely reiterating speech motor commands, syntactic processes, and cognitive acts. I do not think that language provided the cultural stimulus that triggered human symbolic thought. Language and other symbolic behaviors appear to derive from the evolution of a complex interdependent neural substrateone that was not present until 50,000 or so years ago. - P. Lieberman, 2007.

Can the relatively late appearance of the "fully modern speech anatomy" and "fully human syntactic and cognitive abilities" be correlated with what elements within the research community see as a relatively late inroad of humans into vast territories outside of the African continent? Commentators in "Clash of The Cavemen" churned out some speculations on this seemingly relatively late foothold of modern humans in lands outside of Africa as follows:

T. Holliday:
“Early modern humans appear 190,000 years ago, roughly, in Africa, and they're using the same tools there in Africa 190,000 years ago that they were using 100,000 - 80,000 years ago, and those are the same tools that the Neanderthals are using in Europe at the same time.”

Narrator:
“Within a network of ancient caves in Israel, bones and tools from both sets of humans have been uncovered. Radiocarbon dating tests on the artifacts reveal that the two species may have briefly crossed paths there 90,000 years ago, long before the Cro-Magnons entered Europe.

But in this earlier age, before our species had developed any technological advantage, it seems it was the Neanderthals who prevailed.

If you went down to the deepest levels, you found signs of modern humans having lived in these sites, and then, some thousands of years later, you found evidence of Neanderthals having occupied those same caves.

So what happened? Well, it's hard to know for sure. It may well be that Neanderthals drove them out.

After their close encounter with the Neanderthals in the Middle East, there's no evidence of modern humans leaving Africa for another 45,000 years.

But when they finally did venture out again, they were armed with a new weapon more powerful than any seen before or since, a fully developed human mind.”


Indeed, it appears that from around the time modern humans emerge in archaeological record, humans in Africa and Europe were using similar levels of stone tools. However, as noted in an earlier entry, some time in the African Middle Stone Age, between 80,000 and 50,000 years ago, projectile armature technology figures sharply first in the African record. Thereafter, it starts to appear in other lands outside of the continent, suggesting a spread due to eventual migrations out of Africa. Due to the relative dating of such eventual migrations, curiosity has abound the intellectual state of modern humans in eras prior. As posted above, "Clash of The Cavemen" even goes as far as to speculate that there were armed conflicts between Neanderthals and modern humans, in earlier adventures outside Africa by modern humans, i.e. before the permanent occupation of Europe by the latter.

Such a prospect is highly speculative, as no evidence has been provided for it, for one. It could just as well have been that earlier modern human migrants were not as well equipped to quickly adapt to the challenging changing environment as later migrants would prove to be. There has been estimation within research circles, that early modern humans met with harsh/adverse environmental conditions in the Levant. "Clash of The Cavemen" commentary tells us that "some thousands of years later" from the time of the deepest archaeological layers of modern human occupation in the Levant, Neanderthals leftovers begin to appear in the same sites, which prompted them to suggest that "Neanderthals must have driven them out" and that the "Neanderthal appear to have prevailed" during this would-be first encounter(s). Are we to believe that it took Neanderthals "thousands of years" to drive modern humans out?

Could it not just as well be that, given the alleged relatively late appearance of "fully modern speech anatomy" and "fully modern syntactic and cognitive abilities", and couple that with the suggested appearance of projectile weaponry from 100 kya or 80 kya ago, that early modern humans grappled with unpredictable environmental changes, something which some observers have also factored into the demise of Neanderthals, especially given that their technological capacity was not that dramatically different from preceding hominids and Neanderthals? If Neanderthals succumbed, at least partially, to sudden climatic and ecological changes, it could be that early modern humans similarly succumbed to erratic environmental changes, until such time the aforementioned "fully modern" aspects kicked in.

Another flaw in thinking that dominates in anthropological academia, is this idea that human migrations were necessarily "mass" migrations, as opposed to spurts here and there, involving relatively small groups. It's not inconceivable that migrations started out like that before becoming a relatively common or frequent phenomenon in later periods, possibly due to pressures of changing environment in accommodation with shifts in cognitive capabilities.

If one were to entertain the prospect that earlier modern human occupations outside the African continent were cut relatively short due to close encounters with the likes of Neanderthals, which ended tragically for early modern humans, then how come this same fate did not seemingly apply to early modern humans within Africa itself, before the migrations? Archaic humans would not have been only outside Africa, but also within it!!! How did early modern humans overcome them, given that the understanding is that earlier archaic humans and Neanderthals all did not have stone tools and weaponry much different or superior to those of early modern humans? The aforementioned Rhodesian man itself was estimated to have been around some time after the emergence of modern humans, and the Rhodesian man was no less robust in body build than Neanderthals, as noted above.

Modern humans by many accounts, were comparatively more gracile in body build, but then, they made up for this, with their nimbleness, recalling the tropical body proportions which would have enabled modern humans to spend less energy in running than Neanderthals, and cover much more distance in running. In a close combat situation, that is, prior to the attainment of more advanced weaponry, modern humans would have had the ability to avoid tragic consequences, by taking advantage of their superior running skills. In this context, it should be remembered that the likes of Neanderthals were mostly adept at "close-contact" application of weaponry. P. Lieberman has an interesting perspective on human capacity for running:

Selection for walking, starting from the base apparent in present-day chimpanzees, which can walk for limited periods, was perhaps the starting point for the evolution of human speech, language, and cognition. The evolution of the genus Homo was marked by adaptations for endurance running (Bramble and D. Lieberman 2004), which places still further demands on the basal ganglia sequencing engine. Lacking more data, we can only speculate that a neural substrate permitting voluntary speech motor control was in place in early H. erectus. Further selection for speech production may have resulted in the human form of FOXP2 and the motor, cognitive, and linguistic abilities of contemporary humans. Developmental-neurophysiologic studies comparing the development of walking and speech may move this proposal beyond speculation.

Could there have been an environmental trigger for a shift in change in human language skills and cognitive capacity, which would have been absent within the Neanderthal context? And could this be in any way tied to seemingly late modern human dominance of landmasses outside the African continent? John Shea's (2009) notes, while mostly still speculative in nature, adds another dimension to this matter:

First, potential prey behavior is likely to have influenced early humans’ choice of subsistence aids. Heavy, hand-cast, and slow-moving weapons, such as thrusting spears or throwing sticks, lose kinetic energy rapidly in flight. To be effective, they have to be launched in close proximity to their intended targets. With larger prey such increased proximity would have involved considerable risk of injury. The probability of injury would have been greater still in the cases of large terrestrial African species with whom humans had co-evolved for millions of years. Familiar with hominins and their antics, many of these species (e.g., elephant, hippo, rhino, Cape buffalo) have developed proactive defense strategies that held them in good stead until the invention of high-powered firearms. Faced with such “killer herbivores”, African hominins would have had powerful incentives to develop projectile technology at very early stages in their evolution. Indeed, probably the most remarkable thing about the African record is that clear evidence for projectile technology appears so relatively late. As evidence for early hominin carnivory continues to grow stronger, one might reasonably expect evidence for projectile technology to appear in Middle Pleistocene or even Plio-Pleistocene contexts. Perhaps what we are seeing in the MSA is not the origin of projectile technology so much as a strategic shift towards the use of specialized stone and bone armatures with high archaeological “visibility”.

Reading on...

Second, projectile technology also has to be understood as a niche-broadening technology, rather than just as a means for killing large game. The arrow or dart that can kill a giraffe can with minor adjustments kill a bison, a gazelle, a deer, an ibex, a seal, a rabbit, a bird, or a fish. The modern counterparts of the equatorial African habitats associated with Pleistocene human fossils in Africa feature greater plant and animal species diversity than their temperate Eurasian counterparts (Groombridge and Jenkins, 2002). Thus they also offer greater superior opportunities and more commonly recurring incentives for human economic diversification (pursuing a wider range of species) and intensification (putting more effort into procuring the same species)(Kuhn and Stiner, in press; O'Connell, in press). Incentives for diversification and intensification are likely to have become increasingly common through the Pleistocene, as Northern Hemisphere glacial cycles resulted in repeated and prolonged episodes of aridity and desert growth in northern and southern Africa (Ade Ajayi, et al., 1985; Roberts, 1984). That equatorial hunter-gatherers live at higher population densities than their temperate and arctic counterparts (Binford, 2001) suggests that evolutionary pressure for them to develop novel aids to subsistence may have been higher than in other habitats occupied by Pleistocene hominins. The numerous “bottlenecks" (reductions of breeding populations) inferred from genetic variation among living humans supports a scenario in which African human populations were packed into such equatorial woodland refugia (Ambrose, 1998). Among these populations, there would have been powerful incentives for subsistence diversification, including improvements in pre-existing subsistence technology, perhaps including traps, nets, and plant-harvesting equipment, as well as projectile technology. The amelioration of arid conditions would have provided opportunities for these innovations, and the populations who created them, to expand out of equatorial habitats within Africa and north towards the Levant, Europe and Asia, and further on to Australia and the America.

It seems that Shea is making the case that increased climatic fluctuations but also prolonged ones, along with corresponding distribution of fauna, towards the Upper Paleolithic, may have shaped human behavior (including subsequent expansions outside of the continent) and food acquiring habits, i.e. keeping in mind, the more heavily carnivorous slant of hominid species during the Middle Paleolithic and earlier part of the Upper Paleolithic. Shea does note that these factors would have been accompanied by "contingent evolutionary reasons", thereby acknowledging that ecological pressures alone may not be objectively enough to explain subsequent enhanced survival capacity of modern humans. Dramatic shifts modern human survival strategies from earlier times seem unlikely to have been possible in the absence of changes in cognitive capacity as well. The change in cognitive capabilities could well have come about initially through happenstance via genetic mutations, but were subsequently selected for.

Keeping these things in mind, it may be the case that what we are seeing in archaeological record, i.e. for instance as Shea notes, is not the "origin of projectile technology" but "a strategic shift towards the use of specialized stone and bone armatures with high archaeological “visibility”", which is to say that certain behavioral traits were likely already around for a while, but only became more common and fine-tuned later on, upon shifts in survival strategies, as opposed to abrupt sudden changes in behavior. Even P. Lieberman alluded to this, when he noted as follows, to recap a bit:

Boe et al. (Boe, Maeda, and Heims 1999; Boe et al. 2002) claim that we concluded that Neanderthals were a “speechless species.” However, this was not our conclusion. What we wrote was that Neanderthals represent “an intermediate stage in the evolution of language. This indicates that the evolution of language was gradual, that it was not an abrupt phenomenon. The reason that human linguistic ability appears to be so distinct and unique is that the intermediate stages in its evolution are represented by extinct species” (Lieberman and Crelin 1971, 221). Some form of speech must have been in place in the archaic hominids ancestral to both humans and Neanderthals. There would have been no selective advantage for retention of the mutations that yielded the species-specific human supralaryngeal vocal tract at the cost of increased morbidity from choking unless speech was already present. The question is when.- P. Lieberman, 2007.

Can Shea's assessments be fitted with those put forward by Lieberman and others? The relatively heightened appearance of projectiles during the Middle Stone Age, from ca. 80 kya or so, than in earlier periods in the African record is not inconsistent with the time range Lieberman and co. allow for the appearance of "fully modern speech anatomy" and "fully modern syntactic and cognitive abilities", between ca. 100 kya and 50 kya,  as briefly hinted to earlier passages of this entry. It's been mentioned here time and again, that flexibility was and is a key ingredient in the success of modern humans' survival strategies:

The main impact of projectile weaponry on the course of Late Pleistocene human evolution was that it conferred on Homo sapiens the capacity to become the apex predator of any ecosystem our ancestors chose to inhabit. Throughout much of the world today, most potential rival carnivore species and many former human prey species have either been extirpated by humans or exist at our sufferance. Paired with the capacity to construct a broad ecological niche through the use of nets, traps, fishing gear, and bone-degreasing techniques, projectile technology gave Homo sapiens an evolutionarily unique quality of strategic flexibility. The capacity to fine-tune their subsistence strategies to novel ecological circumstances, would have made it possible for expanding Homo sapiens populations to exploit ecozones within the habitats of rival hominin species that had been temporarily abandoned, due to reduced foraging returns. It was probably this quality of ecological flexibility, rather than projectile weaponry by itself, that made our ancestors uniquely formidable competitors in an evolutionary contest whose “second prize” was extinction.- Shea,.

Neanderthals by contrast, don't appear to have been as flexible, with regards to not only to the range of habitation, but also in food preferences. As briefly mentioned in an earlier entry of this very discussion, "Neanderthals were probably the most carnivorous human species", more so than their predecessors and modern humans, courtesy of John Rennie (2008). He notes that meat made up "85%" Neanderthal diet, and that:

We know this because of a technology called stable isotope analysis, which enables scientists to determine what ancient people were eating by evaluating the levels of carbon and nitrogen in their bone tissue. In order to survive, the Neanderthals need to consume around 5,000 calories per day, twice that of modern adult males.

Another loud group of advocates suggest that instead of Neanderthals undergoing extinction either through failure to cope with erratic environmental changes and/or through violent encounters with recently-arrived modern humans, Neanderthals may have bred with modern humans, who were likely numerically greater in size compared to their Neanderthal counterparts. In other words, numerically dwindling Neanderthals were essentially bred out of existence, through miscegenation with modern humans. Among those who push forward this idea, paleontologist Trenton Holliday, of Tulane University, appears to be a particularly strong advocate. Holliday is even of the mindset that offspring of "viable fertility" were produced through Neanderthal-Cro-Magnon interbreeding. Of course, Holliday produced no specific evidence for this prospect—only raising it as a possibility. He does however, point to the case of the  Lagar Velho child from Portugal as evidence of Neanderthal-modern human interbreeding.

Physical anthropologist Shara Bailey of New York University, for one, counters that proposition, noting that the estimated age of the Lagar Velho child, ca. 24 kya, postdates the demise of Neanderthals by some 6k years. She notes that the dentition of the child is "completely modern". A number of studies had shown time and again that Neanderthal uniparental markers, particularly mtDNA, were radically distinct from recent human examples. Caramelli et al. (2003, 2008) made it a point to authenticate their Cro-Magnon DNA findings, by assuring their readers that the Neanderthal DNA they've examined were markedly distinct from the modern human counterparts, not only concerning the Cro-Magnon specimens, but also those of the researchers themselves. This, it was demonstrated, removed any doubts about contamination of Neanderthal DNA by exogenous modern human DNA or vice versa (also see: Following Trails of the Cro-Magnon - I ). Caramelli et al. note that Neanderthal DNA failed to amplify from using primers arranged to amplify modern human DNA.

DNA analysis of the Vindija Neanderthal specimen was undertaken by geneticist Svante Paabo, of Max Planck Institute, Germany. Again, the verdict of that analysis was Neanderthal mtDNA was noticeably different from modern human counterparts. Paabo worked with some 70 Neanderthal bones, and only 3 of them proved useful for serious DNA analysis. Holliday's critique of examinations done on Neanderthal DNA, is to say sample sizes have been very low—making reference to DNA extraction from some 7 accessible early modern humans and "just" 5 accessible Neanderthals, while at the same time noting that the amount of interbreeding between modern humans and Neanderthals would have been also "very low". Henceforth, sample is to low to detect any possible interbreeding between Neanderthals and their modern human contemporaries.

For all Holliday's reasoning, gene pools of living human populations virtually feature no Neanderthal uniparental lineage, either from the paternal or the maternal side. If Caramelli et al.'s example is anything to go by, even among the likes of earlier modern humans like the Cro-Magnon, finding Neanderthal parentage fell noticeably short. Are we to assume that uniparental lineage, which are normally highly conservative segments of the genome, managed to escape "tainting" by Neanderthal DNA, but somehow segments of the autosomal DNA were not spared from that prospect?...that genetic drift had a reversal of effect, with respect to the uniparental segments of the human genome and the autosomal segments? One possible scenario to imagine, to this end, is random genetic drift favoring only a long line of male-derived offspring ultimately from a modern human male/Neanderthal female conception. What are the odds of the absolute occurrence of such in any given population? Ah, but one research team has come forward to raise that very prospect: the publication by Yotova et al. (2011).

Rather than reliance on the biparentally-inherited autosomal segments of the genome, as other teams have focused on, Yotova et al. (2011) looked towards another biparentally-mediated DNA, the X chromosome! The particular X-DNA locus in question, is dys44, located on band 1 of region 2 of the short arm of the chromosome, Now, the authors here try to make it a point, to convince their readers that their study is as objective as it can be, noting that they are merely recalling their earlier findings of a "rare" haplotype relatively prevalent in their non-African samples, which in retrospect, and in light of findings of the likes of Green et al. (2010), they now suspect to be of Neanderthal origin. In other words, their goal for this recent study, was to confirm their suspicions that what they were dealing with back in the day, was a haplotype of Neanderthal heritage. The authors would like this to be seen as an entirely objective undertaking, but it is not so straight forward as to how that can be, when individuals are going into a study already with a preconceived opinion about what they are studying.

As expected, Yotova et al. (2011) appeared to have been actively looking for sites, which they determined would lend credence to their aforementioned suspicion, while possibly ignoring those which don't so much. The pick of 12 haplotypes was presumably driven by what was only available in the HapMap3 database, which happened to contain information for extended sequences for said haplotypes. Those extended sequences were used apparently to further affirm the relationship between the Neanderthal sequence and the suspected Neanderthal-derived sequence, namely haplotype B006. To this end, the authors tell readers that they rooted for the extended sequences featuring the core haplotypes and flanking sequences on either side, supposedly because the corresponding case of haplotype B006 was suggestive of an association in linkage disequilibrium.

Keep in mind, that all these recent human sequences are being compared to a single Neanderthal sequence. It is presumptive to assume that this single Neanderthal sequence would be sufficient to inform one of the pattern of haplotype and allelic diversity among Neanderthal dys44 sites. Just as there is clear diversity of this X-DNA site among recent humans, there must have been some degree of diversity among the Neanderthals in the same locus. There is no reason to assume that this locus is so stable that some random mutation(s) could not just as well give the wrong impression about a sequence from a single source alone. Moreover,  given that ancient DNA are particularly more prone to it, who is to say that deamination and/or depurination could not have altered nucleotide information? Well of course, the authors cannot definitively rule out such a possibility, because they did not even sequence the Neanderthal sample themselves; rather they relied on third party account. That in itself is not all that significant of an issue, as much as excessive reliance on a single specimen is, so as to draw up broad conclusions not only about recent human ancestry, but also about the actuality of Neanderthal gene pool.

The authors' case for a Neanderthal-derived B006 haplotype in recent humans, is primarily hinged on a single substitution at rs11795471 (polymorphic site #31). Now because haplotype B006 happens to be the sequence that shares the substitution at this site with the Neanderthal sequence, of all the 12 haplotypes cited for the table, it has been the special status of being "Neanderthal-derived". On the backdrop of the 35 polymorphic sites of the 12 selected haplotypes, it does indeed appear that haplotype B006 shares a number of sites with the Neanderthal sequence, aside from two so-called "derived alleles", which includes that aforementioned substitution at rs11795471; but so do other haplotypes share polymorphisms with the Neanderthal sequence at various sites, and on top of that, information on only 20 of the 35 polymorphic sites is available for the Neanderthal sequence! As such, other sites of these 35 polymorphic locations wherein the B006 does exhibit "derived alleles", and there is only a very few of them at that, NO information is available for the corresponding sites on the Neanderthal haplotype.

For instance, the 8-nucleotide duplicate at np 32141804 of  haplotype B006 is not traceable to the Neanderthal sequence, which lacks information for the corresponding location. Such sites, while not necessarily entirely unique to haplotype B006, nonetheless contribute to shaping individualism for haplotype B006, and yet, the Neanderthal sequence barely has the necessary corresponding information for them. Little wonder then, the authors felt compelled to look to other sequences flanking the haplotype, to affirm their preconceived case about haplotype B006's relationship with the Neanderthal sequence. This association with haplotype B006, so says the authors, appears to be one of linkage disequilibrium, as noted in a passing earlier, thereby making the prospect attractive, of more sharing between the Neanderthal sequence and B006. The authors note:

all derived alleles shared with Neandertals occur at high frequencies (0.75 and more) on a background of the extended B006 haplotype (fig. 3 and supplementary table S2, Supplementary Material online) as expected in a segment of recent Neandertal origin.

...but the Neanderthal yet again, lacks any information on the additional 28 flanking polymorphisms on the left end of the haplotype, while several of the "13 derived alleles" of the additional 49 flanking polymorphism on the right are variably shared across haplotype B006 chromosomes, and in some cases, shared with remaining non-B006 chromosomes—at times, at considerable frequencies. Yet as a law of nature, the whole point behind the underlying mechanism of an association in linkage disequilibrium, is to minimize the reshuffling effect of recombination that will alter an association that has proven to be selectively advantageous.

The retention of a certain sequence arrangement featuring so-called "derived Neanderthal alleles" at certain nucleotide positions, even in the face of successive recombination events, suggests that there could very well be some selective advantage about the association, and so, a noticeable breakdown of such an arrangement across extended B006 haplotypes weakens that prospect. It opens the door to the possibility that some of the seemingly "derived Neanderthal alleles" may actually be relics of genetic drift acting on random genetic mutation on a common ancestral background. Indeed, the authors seem to pride themselves with their findings that, of all the 12 dys44 haplotypes cited, haplotype B006 comes closest to following the sequences of the Neanderthal haplotype for all those sites where information is available for that Neanderthal sequence. However, it should be noted that these are generally ancestral sites, save for the two polymorphic sites of rs6631517 and rs11795471.

Polymorphisms in ancestral nucleotide positions are fairly likely to occur in a more or less similar direction; there is just far too many data missing in the Neanderthal sequence for those sites where the B006 haplotype exhibits nucleotide substitutions. For what's worth, the supplementary material provided by the authors also implicates the much-noticed aforementioned rs11795471 substitution in some 8 individuals among the remaining "non-African" chromosomes outside the B006 chromosomes! That nucleotide substitution rendered haplotype B006 relatively "unique" from the remaining standard dys44 haplotypes, in sharing it with the Neanderthal sequence. The subsequent sharing of the same substitution with other non-B006 chromosomes only thus diminishes that special status. These findings are far from unequivocal proof of Neanderthal origin of haplotype B006 or Neanderthal ancestry of living humans.

The authors also present contradicting information. One minute readers are told that some African chromosomes carried haplotype B006, often under the excuse that they were attained through "admixture", and then in the next, readers are told that the haplotype is "absent from Africa".

From this:

“Of 1,420 sub-Saharan chromosomes, only one copy of B006 was observed in Ethiopia, and five in Burkina Faso one among the Rimaibe and four among the Fulani and Tuareg, nomad-pastoralists known for having contacts with northern populations (supplementary table S1, Supplementary Material online). B006 only occurrence at the northern and northeastern outskirts of sub-Saharan Africa is thus likely to be a result of gene flow from a non-African source.”

“Interestingly, some of the HapMap3 haplotypes from the segments proposed by Green et al. 2010 and fulfilling our criteria of Neandertal admixture, also turn out in Maasai, where, however, their occurrence can be due to recent back-to-Africa migration (Sikora et al. 2011).”

The authors come to this:

“The third category, absent from Africa, is represented by B006, which carries two types of derived alleles that are shared with Neandertal DNA.”

Segregating B006 chromosomes from remaining dys44 haplotypes, as it seems—possibly influenced by data laid out in supplementary table, does not make the African incidences go away, i.e. if that was the strategic intentions of the authors, as a means to bolster their preconceived theory of a Neanderthal origin of an X-chromosome haplotype in living humans. The remaining notes seem to be driven by such an application of tabulated (esp. table S2) supplementary material:

Haplotypes, such as B007, B010, and B012 in table 1 are specific to sub-Saharan Africa. They carry common (sites of type 1 and 3) and African-specific polymorphisms (sites 2, 4, and 6). The remaining haplotypes, except B006, are cosmopolitan and are found both inside and outside Africa.

Those sites claimed be "African-specific" appear to be those which remain in their so-called "ancestral" state, in both African and non-African chromosomes, while those claimed to be "common polymorphisms" appear to strongly correlate with those which are in the so-called "derived" state, again in both African and non-African chromosomes.

The authors cite other works (namely, J. Shea, 2008 & Petraglia et al., 2010) which maintain that occupational sites of early "anatomically modern" humans and Neanderthals in the Levant occurred at "non-overlapping times", and hence, suggesting that no contact between those earlier modern human migrants and Neanderthals took place, but they ignore these findings, without so much a rebuttal, and press on with their own theory of the exact opposite, i.e. early "hybridizing" between early modern human migrants and Neanderthals outside of Africa. They note:

Our data indicate that Neandertal admixture occurred very early or prior to their worldwide expansion.

"Prior to their worldwide expansion" would suggest "admixture" took place prior to the most recent OOA migration events which led to contemporary non-African human populations. There are two possibly ways to interpret such a prospect: the Neanderthals entered Africa and interbred with modern humans or modern humans interbred with Neanderthals during early contacts outside mainland Africa, in the Levant. The authors' position parallels another which they cited as follows:

The ubiquity of B006 lineage reflects a worldwide contribution of Neandertal lineages to non-African genomes. It indicates very early Neandertal admixture prior to successful range expansion of the population ancestral to virtually all contemporary non-African populations and confirms earlier contention of very early admixture based on the analysis of Neandertal segments in European, Han, and Papuan genomes (Green et al. 2010). Hodgson et al. 2010 proposed such admixture through early Levantine contacts of modern humans and Neandertals, prior to the most recent out-of-Africa expansion, and suggested that traces of such admixture should be still detectable in sub-Saharan populations of Northeastern Africa.

If the idea is that modern humans interbred with Neanderthals through "Levantine contact" and thereafter some returned back to Africa, hence possibly leaving "traces of such admixture" in "sub-Saharan populations of Northeastern Africa", then there is no archeological or paleontological evidence of such a back-migration. On the other hand, if the ideas is that modern humans interbred with Neanderthals through Levantine contact, from where population ancestral to "virtually all contemporary non-African populations" began to spread, then that is unlikely, according to archeological material that suggests that early modern human occupation disappears out of archeological record for a while and then reappears, coinciding with the often-mentioned recent OOA migration events. Additionally, such a prospect would ignore the implicated southern route taken during the OOA dispersions from the African mainland via an east African corridor, which would have led to such populations in southern parts of the Indian sub-continent, Melanesia and Australia; the often talked about Neanderthal range does not extend to these regions. Yet, Australian aboriginals were implicated in said "admixture" too:

Outside Africa, B006 is found in all habitable continents including Australia, as determined from a remote community of isolated indigenous Australians living in Central Australia (fig. 1).

Not too long ago, some study came out (Green et al. 2010) claiming to have come across some "genetic evidence" of interbreeding between Neanderthals and modern humans in Eurasia, and another coming on its heels, about the supposed "Denisovan" archaic human's interbreeding with modern humans. Needless to say, many anti-OOA proponents have received these revelations with quite some fanfare. The claim that some "1-4%" of non-Africans DNA comes from a supposed Neanderthal ancestry is taken as gospel truth without much critical examination.

Few of these adherents bother to put such findings into context; they don't question whether this percentage is a reference to size with respect to the entire human genome, or just a reflection of the sample size the said authors were working with. Those two prospects would be two very different ideas. Contextualization is warranted, as any considerate person would do, for variation among modern humans only amounts to about .01%, if not even less...much less than 1% or 4%.

In another development, findings (e.g. Manica et al., 2012)  have come out challenging the aforementioned study and others proposing similar theories; accordingly, it was argued that the alleged Neanderthal "1-4%" contribution may actually be residuals of shared common ancestry between modern humans and Neanderthals, as opposed to interbreeding. Here's the twist they give to this idea however; they propose that such shared ancestry likely happened in the backdrop two major population structuring on the African continent prior to the migration event(s) that led to the emergence of the Neanderthal itself.

In this scenario, it is envisioned that an ancestral population with lineage more similar to Neanderthals than the other ancestral substrate-population must have situated itself mostly in the northern parts of the continent, from where it would expand into Europe via the Levant, or both Euirope and the Levant respectively, to give rise to Neanderthals. The other major ancestral substrate population would have mainly been concentrated in the relatively lower climes of the continent, and go onto form the basis of much of the indigenous African populations which seem to be spared this "1-4%" Neanderthal contribution. The authors note:

Then, about 350-300 thousand years ago, the European range and the African range became separated. The European range evolved into Neanderthal, the African range eventually turned into modern humans. However, because the populations within each continent were not freely mixing, the DNA of the modern human population in Africa that were ancestrally closer to Europe would have retained more of the ancestral DNA (specifically, genetic variants) that is also shared with Neanderthals. On this basis, the scientists created a model to determine whether the differences in genetic similarities with Neanderthal among modern human populations, which had been attributed to hybridization, could be down to the proximity of modern humans in northern Africa (who would have later gone on to populate Europe) to Neanderthals.

By examining the different genetic makeup among modern human populations, the scientists' model was able to infer how much genetic similarity there would have been between distinct populations within a continent. The researchers then simulated a large number of populations representing Africa and Eurasia over the last half a million years, and estimated how much similarity would be expected between a random Neanderthal individual and modern humans in Africa and Eurasia.

The scientists concluded that when modern humans expanded out of Africa 60-70K years ago, they would have brought out that additional genetic similarity with them, making Europeans and Asians more similar to Neanderthals than Africans are on average – undermining the theory that hybridization, and not common ancestry, explained these differences.

Now, because the gene pool of all living human populations point to monophyletic heritage from one common paternal ancestor and one common maternal ancestor, who were not necessarily contemporaneous like that elicited by the bible, thus drawing ultimately from a common ancestral modern human gene pool, the only way the above-mentioned scenario can work, is if the newly emerging modern human social unit started spreading and joining the ancestral archaic humans, who would have carried said lineages, thereby attaining elements of their DNA arrangement through genetic exchange. It should be remembered that the ancestral population which would have given rise to Neanderthals must have been some archaic human type, but which would have represented a bottle-necked derivative of the African source population. The Neanderthal gene pool would have thus been partially reflective of the source population and of comparatively modest diversity. In the end then, this scenario would present a theory of hybridization, but of a different kind: rather than hybridization between two different sub-species of humans, it would have been one of ancestral-to-derivative hybridization.

The alternative would be to suggest, that the modern human populations in Africa that were "ancestrally closer to Europe", retained "more of the ancestral DNA that is also shared with Neanderthals" due to environmental pressures and/or selective pressure. That prospect opens up a new conversation.

Others have yet come up with theories of hybridization with another archaic human kind, namely the Denisovans. All these theories of hybridization coming out of the woodwork as of late, follow more or less the same formula,  where the argument revolves around the supposed rare occurrence of some "rare" DNA sequence among sub-Saharan Africans and relatively more prevalence in some non-African gene pool or another. Rarely do these sort of findings offer solid or unequivocal proof of a unique origin for an archaic human DNA that somehow made its way into modern humans, mainly the species' non-African element.

Conclusion:


Summing things up, the demise of Neanderthals need not be a simple one of either unfavorable environmental alteration, for which they were unprepared, or human annihilation. It does seem too coincidental however, that their disappearance from archeological record occurs just about the time modern human occupation in archeological have re-surfaced. Several studies have pointed to the role of physiological constraints of Neanderthal bodies, from body proportions, shape of vocal tract and possibly layout of brain, to mechanisms for regulating body temperature (e.g. excessive body heat production during the prolonged period of hot climate; see: Newcastle University scientists) in interfering with their ability to cope or keep up with the changing environmental landscape. Clearly they lost edge somewhere wherein modern humans gained one; modern humans are here, and they are not. Initially, modern human social development appeared to parallel the levels of Neanderthals, but later on, one starts to see changes in the modern human development in archeological record, suggesting shifts in modern human survival strategies, while those of Neanderthals remained mostly unchanged. From the Neanderthal perspective, it could have been, until the point things started unravel for the worse, why fix what's not broken?! They did after all, have a fairly long run in Europe and the Levant before their eventual demise.

The differences between Neanderthal and modern human survival strategies as indicated by archeological record, seems to be the relative degree of flexibility, whereby burgeoning diversity of tools and range of occupation suggests that modern humans eventually developed a higher degree of flexibility in survival strategies than Neanderthals. What could have brought this about? It doesn't appear from fossil record, that there was any modern human advantage over Neanderthals in brain size, and again, from an archeological standpoint, there doesn't appear to be any particularly marked difference in either technological or cultural sophistry between Neanderthals and early modern humans. So it doesn't appear that modern humans had any predisposed intellectual superiority over Neanderthals from very early on. Something must have happened, to bring about change in the course of development of modern humans, but was elusive to Neanderthals. Could it have been the neural circuitry layout of the brain, for which there is no way to ascertain from fossil record?

It is reasonable to assume that given the observed close physiological and genetic relationships between Neanderthals and modern humans, much more so than that between modern humans and their closest living relatives, that the likelihood that their brains operated in very similar ways, or at least, had a potential to, is fairly high. However, this should not preclude the possibility that there were also differences, however small or miniscule they may have been. Small differences in brain design could have made a considerable difference in say, for instance, how modern humans managed the mechanisms of their vocal tract so as to produce complex language, and the ability to "reiterate" motor commands stored as motor pattern generators within certain neural circuits of the brain, as well as syntactic and cognitive pattern generators necessary for complex language capability. Then marry this with such physiological peculiarities, like the shape and proportion of the vocal tract to facilitate "quantal sounds" necessary for "rapid encoded-human speech"; quote, courtesy of  P. Lieberman, 2008:

The data in McCarty et al. (n.d.) show that the necks of Neanderthals and all other fossils that predate 50,000 years before the present were too short to support a vocal tract in which the tongue had the proportions necessary to produce the full range of human speech. That assessment is based on “hard” skeletal evidence the vertebrae of the neck. Neanderthals and Middle Pleistocene fossil hominids (including Skhul V, which has often been considered anatomically modern) would not have been able to eat if they had had a long SVTv. The laryngeal maneuvers necessary to swallow would have been blocked by the sternum bone.

"Rapid, encoded, speech" with a fairly high vocabulary volume such as human speech in of itself would not have been responsible for eventual technological edge of modern humans over Neanderthals, but would it would have facilitated more effective communication and exchange of ideas between humans of various backgrounds, thereby bringing about innovation and relatively quick proliferation of new technology or survival strategies. In other words, advances in communication and corresponding exchange of ideas, looks to be a key factor in further diversifying survival strategies of modern humans beyond stimulus provided by immediate ecological pressures, and hence, bringing about technological growth and cultural flexibility needed to command a wide range of ecological systems. Neanderthal habitation range, for instance, would have been constrained by the level of Neanderthals' cultural flexibility and ability to to quickly adapt to changing/changed environment.

There are indications that while Neanderthals for the most part appeared to be culturally conservative, throughout the span of their existence, there are also signs that on occasion they may have experimented with taking on new strategies, and hence, not entirely inflexible; courtesy of Clash of The Cavemen:

Narrator:
At present, the archeological record doesn't provide indisputable proof of direct interaction between Neanderthals and Cro-Magnons, but there are a few clues that suggest there might have been not only contact, but even an exchange of ideas between the two groups.

In the 1840s, in the region of Chatelperron, France, a railroad engineer uncovered an assortment of primitive stone tools and bone fragments of long-dead animals. At the time, modern archaeology was in its infancy. The first Neanderthal skull wouldn't be identified for another decade. The significance of these tools wouldn't be fully understood, for over a century. These tools are more sophisticated than those typically made by Neanderthals, having sharper-edged blades, for instance. But they're still too crude to belong to Cro-Magnons.

Similar tools have been found more recently, alongside Neanderthal remains. As such, they are widely interpreted to be the work of enlightened Neanderthals.

As far as stimulus from immediate ecological pressures go, modern humans would have inherently been exposed to relatively more diverse environmental situations than their Neanderthal counterparts, given the larger size of the African continent vs. Europe and/or the Levant, and its wider range of latitudinal climes. So, modern humans in Africa would have been compelled to survive under different environmental situations during the formative years of their evolution as a species.

While there appears to be no physical evidence of change in modern human brain development in fossil or archeological record, fossil record does seem to indicate that the vocal tract proportions associated with "fully modern human speech anatomy" was not always around from the start or dawn of modern humans. Findings, though of known limitations, indicate that this was a development that came relatively late in modern human development, sometime between 100 ky and 50 ky ago. As such, there is no reason to assume that Neanderthals, or earlier hominids for that matter, inherently shared the so-called "fully modern human speech anatomy". Is it then possible that "strategic shifts", as opposed to seemingly abrupt changes, in human survival strategies and technology in prehistory were complementary to this development? The possibility is worth entertaining. It does however, fit in with the seemingly late, more permanent, range of expansion of modern humans, spanning more diverse environments.

In some quarters, there has been talk of Neanderthals pushing back modern human advances in early  periods before the more permanent occupation of Europe and the Levant—as the main occupation sites of Neanderthals—by modern humans. However, no evidence is offered for these potentially violent early encounters between Neanderthals and modern humans. These sort of theories seem to be driven by the urge to explain away what is perceived as a relatively late modern human command of vast areas of the globe. If anything, archeological findings suggest that there was no overlap in time frames of occupation sites of early modern humans and Neanderthals in the Levant, an area where one finds the earliest known fossils of modern humans outside of Africa, suggesting lack of direct contact between the two human types.

The early contact theory also seems to be particularly favorable to those who posit early interbreeding between Neanderthals and modern humans. Indeed, the surge in studies coming out of the woodwork and making a case for interbreeding between Neanderthals and modern humans, seems to be tied to the change in the tide of thinking within the research community, where there is a emerging trend of a new-found respect for Neanderthals which was not there in the yesteryears. This change of attitudes is partly driven by accumulation of new revelations in data, and partly by the peer-pressure to elicit a posture of scientific objectivity.

Whereas the popular line of thought was that of a relatively dimwitted, stocky, generally more apish, brute caricaturization of Neanderthals back in the day, now more elements of academia are coming forward to alter such characterizations and cast these humans more favorably, even to the point of essentially saying that "they are us"! It's true that in the past, there were ample advocates in the 'west', who anointed Neanderthals as the true ancestors of modern Europeans in a bid to reject the OOA proposition of modern humans, but even then they were usually perceived as capably lesser beings then their supposed modern descendents.

Now, with the growing "they are us" following within the research community, peculiarities of Neanderthals are increasingly be portrayed as more of as part of normal variations of modern humans, than as those underlying a separate species (albeit very closely related) in its own right; Jeffrey Laitman (1996) was compelled to note the following about the so-called adherents:

This group, often called "lumpers," is primarily comprised of those who view Neanderthals as falling within the range of variation represented by diverse modern human populations (27). Given their predilection, it becomes a priori impossible for them to view Neanderthals as ever being sufficiently different so as to exhibit highly derived respiratory anatomy or specialized respiratory or vocal behaviors. If they are us, then they cannot be fundamentally different. Observations on the difference between Neanderthals and extant populations are routinely dismissed as being within the range of "human" variation.

It has gotten to a point where the entertaining of a possible modern human contribution in the extinction of Neanderthal, in terms of armed conflict wherein the former may have had an edge due to a some degree of technological gap, is done away with, and instead, a contribution as crude as the spreading of an exotic disease from modern humans onto Neanderthals, is preferred. Such scenario has been liked to the situation visited upon "Native Americans", when they encountered Europeans who brought foreign diseases that said natives did not have immunization in place for. Then again, that scenario could just as well be more about face-saving from the prospect of having distant brutal ancestors who engaged in a genocidal removal of a species not too different from us.

Even in the case of "Native Americans", affliction by exotic disease was not the sole factor in population reduction; armed removal contributed heavily in their marginalization and erosion of their population sizes. The other means, as already discussed, by which modern humans may have prevailed over Neanderthals in survival, without having so much an edge in either physiological aspects or behavioral capacities, is the alleged breeding them out of existence, through interbreeding.

While evidence of Neanderthals violently pushing back advances of early modern humans is wanting, there is reportedly tentative evidence of potentially non-peaceful encounter between Neanderthals and modern humans. In a National Geographic article (2009), we are told:

The Neanderthal, dubbed Shanidar 3, was discovered in an Iraqi cave in 1959. His remains show that he likely died of a clean wound to his left side that nicked one rib but left the others relatively unharmed.

"People have been speculating about this injury for about 50 years," said study leader Steven Churchill of Duke University in North Carolina.

Experts have suggested that the Neanderthal may have fallen on his own spear, been fatally poked by a fellow hunter—or been killed by a projectile weapon, which only modern humans were known to use.


However...

"When we replicated the lower energies involved with projectile weapons, we tended to get the nice clean incisions that we see in Shanidar," Churchill explained.

By contrast, "injuries caused by a thrusting spear usually involved at least two ribs, and there was massive collateral damage."

Also, whatever nicked the Neanderthal's rib entered the body at a 45-degree downward angle, which is consistent with the curved "ballistic trajectory" of a thrown weapon, Churchill said.


It may however, be presumptuous to assume that potential armed conflicts between Neanderthals and modern humans, possibly in competition for the then dwindling animal food sources, alone wiped out Neanderthals. An interplay of different factors may have been in work in the lead up to the eventual demise; this is what seems to be the most popular viewpoint within the research community, although the details of which factors were at play tends to differ between research teams. It seems likely that a slow dwindling of Neanderthals was already underway due to relatively unfavorable ecological changes, when modern humans entered Levant and Europe, to pave way for a more permanent occupation. The arrival of modern humans would have only effected more difficulty in acquiring dwindling food sources due to competition, particularly if modern humans came with foreign survival strategies which proved very effective in acquiring food in a possibly brutal ice-age wintry weather.

To reiterate, the Neanderthals may well have tried to broaden their hunting weaponry by emulating those which they may have noticed modern humans using at the time, hence showing some degree of behavioral flexibility in times of crises, but for the most part, were still fairly conservative; their dietary would not have dramatically changed from heavy meat consumption. Recall that 80% of Neanderthal diet would have been made up meat; by contrast, meat constitutes about 20% of modern human diet today, on average. So, modern humans hunting the same big game in ice-age wintry conditions of Europe, would have seemed like a big deal to the Neanderthals.

Its not inconceivable that this competition for resources would have made the likelihood of occasional hostile close-encounters between the two human types a fairly high one. Plus, modern human presence would have rendered less accessible, what used to be a relatively free reign for Neanderthals to wander about in the landscape, because the Neanderthals would now have to worry about being weary of the newcomers (modern humans) and cautious about how they encounter the latter. That's something additional for the Neanderthals to worry about, besides any traditional dangers associated with hunting large animal. Seemingly discrete obstacles can become loosely connected and build up in a way that will prove to be unbearable to a social unit that is undergoing an ecologically-related crisis and grappling with occupational decline. Modern humans would have had no qualms about eliminating the competition, if it came right down to it, in a bid to have the available resources all to themselves. It happens to this day, and it could have happened that far back. Tattersall (Clash of The Cavemen, 2008) also alludes to this prospect, when he says:

I think it's almost certain that they [Neanderthal and Cro-Magnons/modern humans] must have come in contact. It's very very unlikely there would not have been some kind of direct conflict between the Cro-Magnons and the Neanderthals, if only because we know how nasty we are to each other today.

Exactly what transpired in the lead up to the Neanderthals' demise will likely remain in the realm of a good degree of speculation, as each new revealing data wipes away the mist on the window [to borrow terms of one researcher],  because our peek into prehistory relies on highly fragmentary material, but one thing is hard to pass up: that it is perhaps a little too coincidental that their demise happens shortly after arrival of modern humans in Europe and the Levant. The arrival of modern humans must have played some role in sealing the fate of Neanderthals.

On another and final note: Whatever talking heads (particularly in the 'west') today may say about the African continent, i.e. where the modern humans hailed from, to go onto forever change the landscape of Asia and elsewhere, it has proven itself to be a hub of some noticeably major human social development milestones, ranging from the innovation of complex modern human speech, the art of projectile weaponry that would forever change human survival capacity and is still used to this day (albeit in more sophisticated forms), development of the art of writing, attainment of highly structured social complexes (otherwise known as "civilizations"), conception of a calendar system used in much of the world today, contribution in bringing about the spark that altered the course of the so-called "Dark Age" Europe in the medieval era, to ushering in popular uprisings which would reverberate around the world and inspire movements in other parts of the globe, spanning such phenomenon as the so-called "Arab-Spring" in the Arabian peninsula and the Levant and "Occupy" movements in the U.S., Europe and elsewhere. Naysayers will naturally try to downplay the impacts of these world-changing events, but the continent remains a challenging place and a host to notable social milestones of humanity!

*Content may be altered by additional or new information for updating without notice. Click on the following for the preceding entries of this topic: Part 1, Part 2 & Part 3

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 Neanderthal in the News:

Neanderthal Cloning Project

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References:

Clash of The Cavemen, History Channel, documentary, 2008. Featuring speakers: John Rennie - editor in chief of Scientific American magazine; John Shea - paleoanthropologist, Department of Anthropology, Stony Brook University; Katerina Harvati- paleoanthropologist at Max Planck Institute, Germany; Ian Tattersall - paleontologist at American Museum of Natural History; Shara Bailey - physical anthropologist/dental anthropologist, Associate Professor of Anthropology at New York University; Trenton Holliday - Professor of Anthropology at Tulane University; Svante Paabo - geneticist, Max Planck Institute, Germany; Jeffrey Laitman - anatomist, Departments of Cell Biology and Anatomy, and Ontology, Mount Sinai School of Medicine, New York.

—John Shea, 2009, The Impact Of Projectile Weaponry On Late Pleistocene Hominin Evolution.

—Daniel E. Lieberman, The Evolution of the Human Head, Harvard University Press, Jan 3, 2011.

—American Museum of Natural History, New York, New York, USA for photographs [e.g. Homo Ergaster].

—Arensburg et al, 1990, "A Reappraisal of the Anatomical Basis for Speech in Middle Palaeolithic Hominids," American, Journal of Physical Anthropology 83:137-146, p. 145.

—The Free Library website, Neanderthal Neck bone Sparks Cross Talk, 1993.

—The Telegraph website, Richard Gray - Science Correspondent; Neanderthals could have died out because their bodies overheated, 2008.

—Discover Magazine website, Eliza Strickland, Neanderthal Tools Were a Match for Early Homo Sapiens’, 2008.

—Laitman et al., 1996, What the nose knows: New understandings of Neanderthal upper respiratory tract specializations.

—Philip Lieberman, 2007, The Evolution of Human Speech; Its Anatomical and Neural Bases, Current Anthropology vol. 8.

—Jeffrey H. Schwartz & Ian Tattersall, 2005, The Le Moustier Adolescent: A Description and Interpretation of its Craniodental Morphology.

—Gunz et al., 2011, Virtual reconstruction of the Le Moustier 2 newborn skull - Implications for Neandertal ontogeny.

—National Geographic, Ker Than, July 22, 2009, Human Likely Killed Neanderthal, Weapons Test Shows.

—Yotova et al., 2011, An X-Linked Haplotype of Neandertal Origin Is Present Among All Non-African Populations. Featuring references to Green et al., 2010, A draft sequence of the Neandertal genome. Science.

—Manica et al., August 2012, University of Cambridge, Effect of ancient population structure on the degree of polymorphism shared between modern human populations and ancient hominins, PNAS; courtesy of Phys. org website - New research raises doubts about whether modern humans and Neanderthals interbred.

—Personal notes: January & July 2010, November 2011 and August 2012.

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