This a carry-over topic from a previous installment: So What's the Deal with the Neanderthal, Their Demise? - 2
To recap:
Were contemporary modern humans [the species that lives on to this day] responsible for the Neanderthals' demise? Or did everything that was working fine for the Neanderthals' survival, prior to the arrival of "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 aforementioned fronts.
There have been suspicions within the scientific community about the role of modern humans in the demise of Neanderthals for quite a while now, although there seemed to have been 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 to abrupt environmental shifts as the prime suspect in the demise of the Neanderthals, supposedly 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:
The discussion will pick up from where the previous segment left. In the first segment, the matter of the changing direction of the wind, in terms of how the Neanderthal is perceived in academia, was briefly looked at, and the launch of an examination of whether so-called "anatomically modern" humans had any role in the former's demise. Naturally, one of the first things to look at in pursuit of the answer(s), is the determination of any role of differences in either intellectual capacity and/or culture at the sub-species level in the way the evolutionary paths of the two human species have manifested. It is obviously hard to overlook the fact that the 'anatomically modern' human is the only human species that lives on to this day. It therefore follows that modern humans had the benefit of something that gave their sub-species an evolutionary upper hand.
There is an emerging segment in academia which is getting more vociferous about the prospect of neither the intellectual nor behavioral capacity of the Neanderthal being significantly different or inferior to that of their 'anatomically modern' human contemporaries. If we were to give it the benefit of doubt and put the aspect of intellectual capacity aside, then one will have to explore the role played by culture and/or the impact of ecology. To this end, the discussion in the first segment looked at the possible role of technology. In the Upper Paleolithic context, much evidence of this is in the form of a variety of stone tools found in occupation sites that have been subject to archaeological scrutiny.
In the last segment, the role of the interplay between respective technological peculiarities and body plan was analyzed. Osteological examinations of post-cranial remains have provided clues to a very real possibility that Neanderthals and their 'anatomically modern' counterparts adopted different hunting strategies. Additionally, species-specific morphological patterns of Neanderthals and recent human bodies provide insights into certain behavioral capacities of these two closely related but distinct species of humans; extrapolation of what were the fortes of either species, and what could have been their limitations just from the restrictions and degree of freedom dictated by stature and body build alone. This discussion led to a look at various osteological distinctions between Neanderthals and recent humans at the sub-species level.
It is true that prejudice and bias in academia had, and still do to some extent, clouded objective assessment about the intelligence and behavioral capacity of Neanderthals and how these beings have been visually portrayed. This doesn't, however, mean that acknowledging systematic differences between Neanderthals and recent humans is tantamount to such prejudice against Neanderthals and in favor of recent humans. There are very real anatomical differences between Neanderthals and humans that cannot simply be ignored.
Some of these anatomical differences, whether we, as observers, like it or not, have had some impact on what either human species were able to do or how far they were able to undertake a particular activity. Intelligence itself cannot be ascertained by osteological data alone without outside factors—as determined by tangible evidence—taken into consideration. Neurological capacities can only tentatively be assumed from size or capacity of the neuro-cranium, from the osteological standpoint. Outside of that, evidence of behavioral capacity through art, tool making and possible patterns in prehistoric handling of pre-historic burial sites are much more tangible clues of behavioral complexity or sophistry.
There are sufficient clues to suggest that 'anatomically modern' humans attained an edge of some degree over the Neanderthals at some point; before then, the two human species had identical levels of behavioral sophistry for a considerable amount of time. What could have brought about this shift in technological capacities, which, from the looks of things, seemed to have tilted more favorably towards 'anatomical modern' humans?
Some have talked about the possibility of language having a prominent role. Measuring the neuro-cranium obviously does not discern this, but researchers have turned to another osteological [indirect] clue: the position of the hyoid bone. For instance, by comparing the throat bones of Neanderthals against those of modern humans, anatomist Dr. Jeffrey Laitman, of Mount Sinai School of Medicine, estimated that the location of the larynx likely played a role in the development of spoken language.
Adult modern humans have the larynx down the throat, which enables them to produce a number of important sounds, particularly vowels. In contrast, osteological reconstructions have determined that Neanderthals would have had the larynx at a higher location in the throat than the case was/is for modern humans (Laitman, Clash of The Cavemen). Interestingly, infantile humans are said to have the larynx high up the throat—to facilitate simultaneous swallowing and breathing; a lower larynx allows a smooth transition from breathing to swallowing and vice versa, thus removing the necessity of simultaneous breathing and swallowing. Henceforth, Neanderthals wouldn't have been able to make certain vowel sounds, like for example, the "oo" sound.
The hyoid bone aside, another possible marker of the situation of the larynx, is the shape of the skull base. Neanderthal's skull base was determined by Jean Louis Heim (1989), of the Natural Museum of Natural History, to be angled in such a way that speaks to the placement of the larynx low in the neck, thereby contradicting earlier findings which put forward that earlier hominids feature a comparatively "flattened base" relative to recent humans, and that the Neanderthal shared this trait. Subsequent findings (e.g., Laitman et al. 1992) stick to the general premise of the earlier observations. A comparatively flattened base is said to be indicative of a positioning of the larynx that would be higher than that in an adult modern human.
Things to keep in mind about the aforementioned findings: 1) University of Kansas paleo-anthropologist David Frayer's (1992) case about identical Neanderthal-recent human speech capability relied on two separate lines of evidence from two separate specimens: the skull of the La Chapelle Neanderthal skull for basicranial analysis (Jean Lois Heim, 1989), and the hyoid bone of only one specimen--the incomplete Kebaran specimen, dubbed both as "KMH2" and as the "most complete Neanderthal skeleton", which lacks a skull--save for the remnant of the mandible, for neck analysis.
2) The researchers implicated here, with respect to the speech capabilities of Neanderthals vs. modern humans, arrived at essentially opposite conclusions around the very same specimen, namely, the La Chapelle skull. Laitman's computer reapplication of Heim's measurements for simulation, for instance, reportedly suggested a pattern more similar to an infantile than an adult human. The rationale is that the larynx positioned with respect to the degree to which cranial base flexes (Daniel Lieberman, The Evolution of the Human Head):
“...modern human infants have a flat (extended) cranial base and a high, intra-narial larynx (see Figure 8.7), and that the larynx descends as the cranial base flexes (George, 1978). These correlated changes were argued to be related casually by two factors. First, because the larynx is partially suspended by muscles that originate on the basioccipital, a flexed (lower) basioccipital might position the larynx lower relative to the palate. Second, the basicranial flexion would shorten the anteroposterior distance between the back of the palate and the vertebral column. As the cranial base flexed, this would leave insufficient space for the larynx, requiring it to descend to keep a patent airway. Because Neanderthals had flatter cranial bases, like those of infants, the CLL group [aka Ed Crelin, Philip Lieberman, and Jeffrey Laitman] reasoned that they probably also had high larynxes, which, in combination with longer faces, would lead to SVT(h):SVT(v) ratios other than 1:1 [SVT = supra-laryngeal vocal tract, i.e. airway from the larynx to the lips]. If that was the case, Neanderthals would have had difficulty in articulating a full range of acoustically distinct vowels, especially vowels such as /i/...” - Daniel Lieberman, The Evolution of the Human Head.
Besides reiterating the case about the influence of the basicranial flexure on the relative positioning of the larynx in the neck, as put forward by researchers like Crelin, Lieberman [Philip] and Laitman, Daniel Lieberman raises another interesting matter in this subject, namely, SVT(h) and SVT(v). These two concepts will be revisited in the coming passages. Daniel Lieberman's insights bring a dimension to this subject matter that is different from the aforementioned reliance on basicranial flexure.
It is not certain though, that an inability of producing such sounds like vowels would necessarily have meant that Neanderthals lacked language. However, it does suggest that they would have had considerable difficulty in how far they would have been able to systematize language and allow it to have the capacity to possess a fairly large, complex and flexible vocabulary.
With regards to the hyoid, we are told the following, courtesy of The Free Library webpage:
In their new study, the Mount Sinai investigators took measurements of hyoid shape and size from a variety of mammals, including humans, apes, gibbons, baboons, dogs, sheep, pigs, rabbits, rats, dolphins, and whales.
Considerable variation in hyoid shape appeared, both among species and among individuals in the same species, Reidenberg says. Even within species that exhibit little variation in the neck position of the hyoid, individuals display marked differences in the bone's shape, suggesting that the shape of a single hyoid offers no clues as to where it sat in the neck, she asserts.
Further analysis found marked overlap between human and pig hyoids on four of six measures of shape and size, Reidenberg says. Pig hyoids overlap with the Neandertal specimen on two of those measures, she holds.
The discoverers of the Neandertal hyoid reported that the specimen overlaps with modern human hyoids on five of the same six measures (SN: 7/8/89, p. 24).
Despite the anatomical ties between pig and human hyoids, only humans possess a voice box positioned low in the neck and a vocal tract capable of producing speech sounds, Reidenberg says. Thus, researchers should not assume that the fossil hyoid's shape announces an advanced capacity for speech among Neandertals, she concludes.
On the other hand, ...
Frayer also compared pig and human hyoids. Shape differences are readily apparent and seem to stem from the bone's contrasting functions in pigs and humans, he argues. Reidenberg and Laitman's focus on a few discrete features rather than the whole bone may mask these divergences, in his view.
The Neandertal hyoid is "indistinguishable" from those of modern humans, Frayer contends.
The fossil's shape does not establish where the Neandertal voice box lay, he adds. But Frayer deems Reidenberg and Laitman's data "irrelevant." - Neandertal neck bone sparks cross talk, courtesy of The Free Library .com.
Well, it can be argued that if there are overlaps in the morphology of the "whole bone," which is what Frayer argues should be the focus, i.e., between humans and various other animals, then differences in impact of the hyoid bone's shape and metrics in the positioning of the "voice box" ought to be the result of the "few discrete features". However, Frayer argues that the "overlaps in morphology" in this case, are due to what he sees as "arbitrary" discriminants chosen by researchers, for the sake of trying to find relations between recent human hyoid bone and various other animal hyoid bones; rather, the "overall shape" should be the overriding determinant around which to draw the final conclusion about the relationship between recent human and other animals' respective hyoid bones vs. that between recent human and Neanderthal respective hyoid bones.
Frayer latches onto the idea that shape differences are "readily apparent" between pig and human hyoid bones, but it should be pointed out that no argument has been put forward for a lack of differences between pig and human hyoid bones. What was put forward, rather, is that there were "overlaps" in shape and/or size. Furthermore, this idea does not confront the finding that "considerable" variation in hyoid bone shape was found not only across species, but between individuals of the very same species, thereby rendering highly questionable, the drawing of a fairly broad conclusion based on a single prehistoric hyoid bone!
For all the criticism directed at using variables in studying the significance of hyoid bone shape and size on the location of the larynx, it is noted that the discoverers of the KMH2 remains—aka the Neanderthal specimen whose hyoid bone was found--used the VERY SAME "six measures" of shape and size applied by the Mt. Sinai analysts, so as to claim that the Neanderthal hyoid bone overlapped with recent human counterparts on "five" of those six measures. In other words, Frayer's protest against usage of variables as opposed to the singular factor of "overall shape" or "whole bone" was with respect to the conclusions of the Mt. Sinai team, with which he apparently disagrees, but in an ironic twist, the discoverers of KMH2 used the very same variables as the Mt. Sinai team to draw a conclusion that is more in line with Frayer's own viewpoint.
It is therefore unlikely that Frayer would have rejected the usage of said variables in assessing relationships in shape and size, had the discoverers' conclusion been the only one out there around such variables. Furthermore, conceding that the shape of the hyoid bone "does not establish where the Neanderthal voice box lay" only undermines Frayer's position.
Some have interpreted the conclusions of the so-called CLL group, aka Philip Lieberman, Ed Crelin and Jeffrey Laitman, as supposedly professing "speech inability" of Neanderthals. From around the web, one such interpretation was put forth along with this reference, which was presented as supporting "counter" material against the interpretation attributed to the said group of researchers:
"The discovery of the first fossil hominid hyoid bone from Kebara provides important insights into the vocal tract of Middle Palaeolithic hominids, because a previously unknown portion of the anatomy is available for study and its anatomical relationships can be evaluated.
The bone itself is not notably different, in either size or morphology from that of modern human hyoids. The relations of the hyoid to the mandible and cervical vertebrae probably did not differ from the modern pattern; the Kebara neck appears to be anatomically and proportionally similar to that of living peoples.
These new data strongly suggest that Middle Palaeolithic people shared structural relationships with modern humans in terms of their vocal tracts. They appear to be as 'anatomically capable' of speech as modern humans when hyoid positioning and supralaryngeal space are the critera considered.
The hyoid bone from Kebara is a 'singular' discovery, yet the evidence for marked similarities of this bone to those of living peoples cannot be easily dismissed; this research has demonstrated that it is a component in a suite of morphological relationships that collectively display a modern human configuration." ~ B. Arensburg et al, "A Reappraisal of the Anatomical Basis for Speech in Middle Palaeolithic Hominids," American, Journal of Physical Anthropology 83:137-146, p. 145.
Apparently in an effort to set the record straight and dispel such interpretations of his and colleagues' position, Laitman et al. notes:
“The general picture of the Neanderthal upper respiratory tract that has emerged over the last few decades by those attempting to reconstruct it has been of a region which differed somewhat from that in living humans. Both our own (15, 16, 24) and other studies (17, 18, 25) have emphasized that some Neanderthals (such as the "Classic" western European specimens) would have exhibited a larynx slightly higher in the neck than that of modern humans, with these Neanderthals having a more limited oropharyngeal segment with a greater portion of the tongue occupying the oral cavity. When one factors in their large external nose and sizable paranasal sinuses, the overall Neanderthal anatomy suggests a group that relied more heavily upon the nasal rather than the oral route for respiration then do living humans. These specializations were very possibly due to respiratory-related adaptations to their environment. A by-product of this respiratory-driven anatomical configuration would be that Neanderthals could not have produced the same array of sounds that living humans can (16, 17, 26). They were not apish mutes; they were just not identical to us.” - Jeffrey Laitman et al. (1996), Commentary; What the nose knows: New understandings of Neanderthal upper respiratory tract specializations.
A similar note was presented by Philip Lieberman:
The Lieberman and Crelin (1971) Neanderthal study is often cited to support claims that speech evolved abruptly at a recent date. 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 matter of language-origin dating will be revisited in coming passages. On the note of revisiting, let's recall the issue of SVT(h) and SVT(v) components of the vocal tract. Daniel Lieberman's observations on the morphological forms of the vocal tract brings up another dimension to the discussion of language developmental capacities, particularly in terms of the different physiological players like the aforementioned roles of the flexure of the basicrania and the position of the larynx in the neck. It looks like as a result of this, researchers like Philip Lieberman have either revised their perspectives or fine-tuned it. See:
The absence of computer-implemented digital image analysis technology in the 1970s precluded accurate measurements of tongue position by George; the perceptual-magnet phenomenon documented by Kuhl and her colleagues was not apparent until almost two decades later. In short, cranial-base flexure in itself cannot be used to predict whether a fossil had an adult human supralaryngeal vocal tract.
At the time, however, a close relationship between vocal tract development and cranial-base angle was accepted by our and other research groups. Studies followed that linked the cranial-base angle and the length of the basicranium (which indicates oral-cavity length) with the vocal tracts of living nonhuman primates and fossil hominids (Laitman, Heimbuch, and Crelin 1978, 1979; Laitman and Heimbuch 1982). Their conclusion was that Neanderthals and earlier fossil hominids did not have human vocal tracts. The studies of Boe and his colleagues (Boe, Maeda, and Heim 1999; Boe et al. 2002) reached an opposite conclusion. Reconstructions of the vocal tracts of fossils based on cranial-base angles are problematic. When Daniel Lieberman and McCarthy (1999) reexamined the Denver series they found that the tongue and larynx continued to descend after cranial flexure stabilized and that SVTh and SVTv did not achieve their adult 1:1 proportions until age five to six years. Fitch and Giedd (1999), using MRIs, reached the same conclusion. - Philip Lieberman, 2007, The Evolution of Human Speech; Its Anatomical and Neural Bases.
The last bit should particularly be a focus of attention, by those who press forward the idea that kids as young as 8 years are able to speak effectively, supposedly as a means of countering what they interpreted from work of the likes of Laitman, who reported that human infants featured relatively flatter basicrania, and hence, higher positioning of the larynx in the neck. Talk about overlooking the meaning of "infant"! Apparently, said researchers are referring to human young who are not yet able to speak effectively.
Nevertheless, as the above passages from Philip Lieberman point out, primary reliance on the angle of the basicranium is "problematic" for the reasons stated. Rather, as Daniel Lieberman et al.'s findings suggest, the volume of the vocal tract within which the tongue has to maneuver coupled with the "reshaping" and associated movement of the tongue, appear to be a stronger determinant of the positioning of the larynx than the flexure of the basicranium...
The low position of the human larynx is a reflex of the human tongue’s reshaping and moving down into the pharynx. It is closely coupled to tongue displacement (Negus 1949; Bosma 1975; D. Lieberman and McCarthy 1999; Nishimura et al. 2003). As the tongue descends into the pharynx, it carries the larynx down with it.
The human tongue, as it turns out, retains the length of tongue seen in the more prognathous or forward face projecting apes and hominids. However, recent humans having flatter "snouts," and hence faces, means that there is nowhere else for the tongue to go but to descend down the neck! While the likes of Daniel Lieberman and co. have observed a correlation between the descent of the tongue and and that of the larynx, thereby stimulating renewed attention towards the relationship between tongue displacement and the positioning of the larynx, the understanding had been around for quite a while, albeit perhaps not afforded the same attention that it now gets:
There is no prognathous snout . . . . The [human] tongue however retains the size it had in Apes and more primitive types of Man, and in consequence it is curved, occupying a position partly in the mouth and partly in the pharynx. As the larynx is closely approximated to its hinder end, there is of necessity descent in the neck; briefly stated, the tongue has pushed the larynx to a low position, opposite the fourth, fifth, and sixth cervical vertebrae. - Victor Negus, 1946.
Neanderthals, if recalled, tend to have greater mid-facial protrusion than recent humans, but the mouth area is actually not as prognathous as those seen in apes and other "primitive" hominids. On the basis of this, it might be tempting to predict a similar development of the tongue in Neanderthals as recent humans. Not so fast, if one considers the following; as noted earlier, several research teams likened the structure of Neanderthal vocal tract to those of recent human "infants":
in 1971, Edmund Crelin and I attempted to reconstruct the supralaryngeal vocal tract of the Neanderthal fossil from La Chapelle-aux-Saints (Boule 1911–13). We compared the skeletal features of the skull and mandible that support the soft tissues of the vocal tract in human newborns and in the Neanderthal fossil and noted a number of similarities between them. In addition to basicranial flexure, which became the focus of many subsequent studies, there were similarities in skeletal features supporting the muscles that move the tongue such as the pterygoid process of the sphenoid bone, the total length of the basicranium, and the distance between the end of the palate and the foramen magnum (into which the spinal column is inserted). On the basis of these findings, a range of vocal tract area functions similar to those of newborns in the cineradiographic study of Truby, Bosma, and Lind (1965) was modeled using Henke’s (1966) computer-implemented algorithm, which established the relationships between vocal tract shapes and formant frequencies, and the computed formant-frequency vowel patterns were compared with those measured by Peterson and Barney (1952). Speech was possible because most vowel and consonant formant-frequency patterns could be produced, but the formant-frequency patterns that convey the quantal vowels of human speech could not be produced. - Philip Lieberman, 2007, The Evolution of Human Speech; Its Anatomical and Neural Bases.
These physiological findings are consistent with the observable fact that recent human infants and recent human adults exhibit different speech capacities, notwithstanding the relatively "flat snouts" in both. Though equivocal by some accounts, given that similarities in vocal tract form were drawn between Neanderthals and recent human infants, the speech qualities of the latter may give some insights into the speech-potential of Neanderthals. Differences in vocal tract proportions—alluded to earlier—may provide a clue to this:
The reconstructed Neanderthal’s tongue rested for the most part in the oral cavity, and this precluded its producing the abrupt 10:1 area-function vocal-tract midpoint discontinuities required. - P. Lieberman
In contrast:
The adult-like human supralaryngeal vocal tract has a tongue with an almost circular sagittal (midline) contour forming two segments, a horizontal oral cavity (SVTh) and a vertical pharyngeal cavity (SVTv) of almost equal length (1:1 proportions) positioned at a right angle (fig. 1). Movements of the undistorted tongue in the space defined by the oral cavity and the pharynx can produce the abrupt midpoint 10:1 area-function discontinuities on which the format-frequency patterns of the quantal vowels [i], [u], and [a] depend.
The above thus maintains that Neanderthal's tongue was stored mostly in the oral cavity, in contrast to the more extensive descent of the tongue in the neck of recent human adults. This has been facilitated in Neanderthals due to the relatively longer SVT(h). Most physiological reconstructions of the Neanderthal feature relatively short necks; it seems that the three Neanderthal specimens studied by McCarthy et al. did not fair differently [translating into a shorter SVT(v)]. This coupled with the long SVT(h), meant that Neanderthal vocal tract proportions did not conform to the 1:1 ratio that characterize adult recent human vocal tract:
We can determine whether Neanderthals and other fossil hominids could have had 1:1 SVTh/SVTv proportions by examining their basicrania, which provide a measure of SVTh, and their cervical vertebrae, which provide a measure of the length of their necks. McCarthy et al. (n.d.) determined these metrics for a sample of 62 specimens of Pan troglodytes, the WT 15000 fossil Homo ergaster, 3 Neanderthal fossils, and 82 specimens of H. sapiens, including the Middle Paleolithic Skhul V fossil, 8 Upper Paleolithic fossils, and 73 contemporary humans from seven different populations. The data show that Neanderthal necks were too short to accommodate human vocal tracts. McCarthy and his colleagues arrive at a Neanderthal neck length estimate of 120 mm in contrast to the 134–127-mm averages for two modern human samples; the short neck and long Neandertal SVTh would place the cricoid cartilage behind the sternum, permitting human speech but precluding eating. (A similar conclusion was reached by Lieberman [1984, 290–96].)
The conflicting estimations of Neanderthal larynx location between one team of researchers and other groups is obviously the direct result of limitations of reliance on fossilized data. This situation, as noted earlier, surfaces in the measurements of the La Chapelle-aux-Saints Neanderthal remain.Where does that leave us then? For one, this is bound to happen from excessive reliance on both a single [prehistoric] specimen as opposed to multiple specimens, so as to look for trends, and a single determinant. In addition to the case of the La Chapelle-aux-Saints specimen, the single Neanderthal hyoid bone, assigned to the KMH2 Kebara specimen, has been afflicted by the same problem. Absence of a relatively more comprehensive study in the development pattern featured in samples, i.e. from infants or children to adults and/or between males and females, can add to uncertainty about a series, particularly for prehistoric specimens where the probability of paucity of data can be fairly high. One team voiced this concern, for example, from Schwartz and Tattersall (2005):
How does one apply such concept to Neanderthals as an example? read on:
This kind of study of development has been appreciated, when it comes to recent humans in the study of the growth pattern of the basicranium and vocal tract proportions from infants and/or juveniles to adults, but what about Neanderthals? Obviously sample accessibility in this respect is narrower in the Neanderthal context, given limited number of specimens, but going by clues provided by the Le Moustier 2 specimen for instance (Gunz et al., 2011), much of the developmental features of the basicranium found in Neanderthal neonates is retained in the adult stage. There is more visible transformation in recent humans, from the neonatal stage to the adult stage. It was estimated that as far as the cranial base was concerned, "shape differences between the Le Moustier 2 specimen and recent human neonates were "extremely subtle"." (Gunz et al.) By most accounts, lower basicranial flexure is seen in adult Neanderthals, however, compared to that seen in adult recent humans. Gunz et al. (2011) note, for instance:
The shape differences between Le Moustier 2 and modern human neonates in the cranial base are extremely subtle. Around the time of birth modern humans and Neanderthals have very similar endocranial shapes and volumes. Our EV estimates for Le Moustier 2 range between 408–428 cc. Our reconstruction of Le Moustier 2 shows that most facial differences between modern humans and Neanderthals develop prenatally as they are already established at the time of birth. Most shape differences in the braincase between modern humans and Neanderthals, however, develop after birth.
The authors go onto note:
Studying the endocranial shape changes of modern humans and Neandertals from birth to adulthood, we could show that modern human braincases undergo a “globularization-phase” in the first year of life. The shape changes during the first year of life comprise a relative expansion of the parietal bone, the occipital bone and flexion of the cranial base (Neubauer et al. 2009; Neubauer et al. 2010). This phase is absent from Neandertals, and appears to be unique to modern humans (Gunz et al. 2010; Neubauer et al. 2010).
These findings suggest that the relatively modest changes, if any, in bascranial flexure within the Neanderthal context, from the neonatal stage to adulthood, as compared against the recent human context, is reflective of the derived states of Neanderthals and recent humans respectively, amongst other such differences.
Having said that, the weight of evidence, as it stands, is slanted towards the crowd which maintains that there were differences in the vocal tract shape and/or proportions, between Neanderthals and recent humans. Soft tissues like the tongue and vocal tract muscles are not normally preserved in fossils, and so, people are compelled to rely on the next best thing to provide clues, which for the most part are bones. In this respect, the basicranium, possibly the mandible (esp. when the basicranium is not available), and the cervical vertebrae, serve as particularly useful clues in vocal tract structure. As it turns out, neither the shape/position of the hyoid bone nor the location of the larynx are good predictors of speech capacity! It can be argued that the angle of the basicranium in of itself is of little use in this determination as well; rather, physiologically, the proportions of the vocal tract coupled with the shape and displacement of the tongue are stronger markers of speech capabilities.
A smaller but loud crowd argues for identical vocal tract development between recent humans and Neanderthals, which happens to be the pattern seen in adult recent humans. These primarily rely on measurement of basicranial flexure, producing results which are inconsistent with results of the same standard applied by others. The advocates have often relied on single specimens, mainly adult, to make a blanket statement about these features in Neanderthals. In one such occasion, the research team failed to even note a clear difference between neonatal and adult vocal tract proportions, which might well provide insights to why their findings in a Neanderthal specimen falls within the adult human range:
The biological mechanisms that regulate the descent and reshaping of the human tongue are unknown, and tongue position and shape cannot be inferred from the basicranial angle. Boe and his colleagues (Boe, Maeda, and Heim 1999; Boe et al. 2002) nonetheless base their Neanderthal reconstruction on the cranial-base angle of the La Chapelle-aux-Saints fossil as reconstructed by Heim (1989). The basicranial flexure of Heim’s Neanderthal skull reconstruction is within the human range, but that does not signify an adult human vocal tract. Although the studies of D. Lieberman and McCarthy (1999) and Fitch and Giedd (1999) are cited, Boe and his colleagues ignore their findings and fit a vocal tract with the adult human proportions noted by Honda and Tiede (1998) to the fossil.
The relationships between skulls, jaws, and soft tissue noted by Honda and Tiede (1998) hold for adult humans; they do not apply to young children, human neonates, apes, or monkeys. Genetic evidence (Krings et al. 1997; Ovchinnikov et al. 2000) shows that Neanderthals diverged from humans about 500,000 years ago, and their skeletal morphology differs from that of modern humans (Howells 1976, 1989; D. Lieberman 1995). Adult human vocal-tract morphology therefore cannot arbitrarily be bestowed on them. Nonetheless, Boe and his colleagues model the vocal-tract shapes that adult human speakers use to produce vowels. Not surprisingly, these configurations produce the full range of human vowels. They also model a putative human infant vocal tract that does not resemble any newborn vocal tract documented by Negus (1949), Truby, Bosma, and Lind (1965), Bosma (1975), Laitman and Crelin (1976), or anyone else. Its SVTh/SVTv ratio is close to that of the five-to-six-year-old children documented by Lieberman and McCarthy (1999) and Fitch and Giedd (1999). Similar flaws mark other studies that have proposed human vocal tracts for Neanderthals (see Lieberman (1984, 2000, 2006c for reviews). - Philip Lieberman, 2007, The Evolution of Human Speech; Its Anatomical and Neural Bases.
To sum things up briefly, the shape of the vocal tract [of course, including movement and shape of the tongue within] and the proportions that it assumes, are key physiological factors in facilitating the oral motor skills of recent humans in implementing complex speech, as opposed to merely the location of the larynx, although the positioning of the larynx still plays an important role in the time management of the flow of air and opening of the larynx between or during the different roles the mouth has come to assume, namely eating, breathing, and communicating.
Visual aids are in order; courtesy of Philip Lieberman (2007):
A relatively more detailed breakdown of underlying physiological factors at work in the development of complex speech by recent humans from P. Lieberman:
...studies of the ontogenetic development of the human vocal tract reveal other factors:
1. The skeletal structure that supports the roof of the mouth rotates toward the back of the skull, effectively shortening the mouth and SVTh, during the first two years of life; the human face is flat compared with those of prognathous present-day apes and early hominids such as the australopithecines (D. Lieberman, Ross, and Ravosa 2000).
2. The human tongue gradually descends into the pharynx, changing its shape from relatively long and flat to posteriorly rounded. This yields the 1:1 SVTh/SVTv proportions seen in figure 1. This unique human developmental process is not complete until age six to eight years (D. Lieberman and McCarthy 1999). As the human tongue descends, it carries the larynx down with it.
3. The human neck gradually lengthens (Mahajan and Bharucha 1994). Neck length is critical in that a larynx positioned below the neck at the level of the sternum (collarbone) would make it impossible to swallow (Palmer et al. 1992; D. Lieberman et al. 2001).
As is the case in nonhuman primates throughout life, the tongue is positioned almost entirely in the mouth in human neonates. In the course of human ontogenetic development, the tongue moves down into the pharynx, carrying the larynx down with it.
To help with dating the origin of complex speech capability of recent humans, specimens ranging from the prehistoric ancestral hominid, Neanderthals, early "anatomically modern humans" from the Middle Paleolithic and Upper Paleolithic to contemporary humans came in handy. Included, were some nonhuman specimens of 62 Pan troglodytes. The measurements applied for this task are the SVT(h) and SVT(v) proportions. P. Lieberman for instance, noted that the Skhul V specimen exhibited vocal tract horizontal and vertical proportions that placed it outside the characteristic fully modern adult human vocal tract proportion of 1:1 (SVT(h)/SVT(v)); vocal tracts that can confidently be placed under the adult recent human proportion only started to appear in samples dating to from around 50ky ago among the test samples:
Surprisingly, a similar constraint [as applied to Neanderthal specimens] rules out a human vocal tract in the Middle Pleistocene fossil Skhul V (McCowan and Keith 1939), which has often been thought to be fully modern. McCarthy and his colleagues estimate the cervical spine length of Skhul V to be 109 mm, at the bottom of the adult modern human range. Skhul V’s SVTh is relatively long, and therefore its short neck precludes its having a fully human vocal tract with 1:1 SVTh/SVTv proportions. Fully modern speech anatomy is not evident in the fossil record until the Upper Paleolithic, about 50,000 years ago.
Using vocal tract proportions as an indicator of complex language capability, these results would suggest that the Skhul V individual would not have been very effective in performing the complex language skills of contemporary humans. The problem with the above analysis of course, is that only one early modern human specimen from the Middle Paleolithic was tested. Hardly enough to ascertain a pattern in human physiology at the time. The same can be said of the lone ancestral hominid specimen of the WT 15000 Homo Egarster fossil. The Neanderthal sample was also small, but at least more than 2 individuals. In any case, if these specimens are representative of a group, community or population of their respective eras, then the finding is interesting in how relatively late of a date it is, with respect to vocal tract proportions as an indicator of complex speech capability, when one considers the duration modern humans have been around.
The 50ky ago mark interestingly coincides with the often-cited age for OOA (Out of Africa) dispersions of modern humans. Even if such a prospect were taken at face value, one would have to take it that complex speech capability occurred on the African continent prior to any notable migratory events which led to territories outside of Africa now being populated by modern humans. Given language diversity across modern human populations, and undoubtedly, many languages had disappeared over the ages, it is not inconceivable that complex language development would have stabilized and would have already been widely distributed on the African continent for a considerable time before the subsequent expansion of modern humans to other landmasses. It should also be kept in mind, that many of the existing modern human languages around the world belong to language families, which in turn form larger clusters, according to estimated linguistic relationship, under larger language superstructures which themselves end up at a starting point on the African continent. In taking these observations into consideration, complex language emergence in modern humans would have been around for much longer than 50 kya.
Whatever maybe said of the accuracy of dating, a relatively late complex language capacity of modern humans, i.e., when stacked against how long modern humans have been around, is an intriguing revelation. More of this matter will be looked at later on, but it takes some steam off the question of what would have kept modern humans from having the capacity for complex language very early on in their evolution, if not upon the species' emergence.
Aside from the location of the larynx ("voice box"), another possible marker allegedly tied to the ability to perform spoken language comes from DNA analysis: the gene involved is the so-called "FoxP2," located on region 3 of the long arm of chromosome number 7. It is said to be an "essential ingredient" in the ability of speech. In this instance, however, both Neanderthals and recent humans reportedly possess it. The gene plays an indirect role in the language capacities of humans, in that it codes for embryonic development of brain elements that regulate motor control, cognition and emotion among its other roles, e.g., in the development of lung tissue and other structures (Lieberman, 2007). That it is not the only gene implicated in brain development, may be worth pointing out.
Other mammals have the gene too, with a similar function to that of a human's, but of nucleotide versions different from that of a human. Perhaps as a way to communicate this difference, researchers use lower case lettering for the equivalent gene in other mammals, e.g., foxp2. For instance, the mouse version is said to be removed from the human version by 3 mutations, while the chimpanzee version is removed from the human counterpart by 2 mutations (Lieberman, 2007 via Lai et al., 2003). The Neanderthal variant is claimed to be "identical" to that of recent humans; exactly how identical, one would need to independently confirm that, but it is safe to say that it is likely to be much closer to the recent human counterpart than a chimpanzee's.
The FoxP2's link to speech ability was the culmination of research targeted at isolating the underlying factors behind the cognitive deficits and acute orofacial movement and speech impairment afflicting the so-called KE extended family. Studies using MRI (magnetic resonance imagining) techniques have revealed that elements of this family possess an abnormally small [bilaterally] caudate nucleus, and the unilaterally abnormal putamen, globus pallidus, angular gyrus, cingulated cortex, and Broca's area of the brain (Lieberman, 2007).
Speaking of the brain, of all the physiological elements implicated above in complex language capability, the brain obviously plays a central role. It's not just enough to have the right vocal tract shape and proportions, without a brain designed to facilitate complex language-associated cognition and motor control. A such, it would be presumptuous to take it for granted that Neanderthals, or any of our hominid relatives, had complex language ability merely on the account that they are related to us, and/or they had a brain-size similar to or larger than modern human. The Neanderthals would have had to have a brain featuring "neural population" (closely linked neural circuits) setups that performed equivalent functions as the modern human brain.
Any allegations made with regards to the neural circuitry layout in Neanderthal brain would remain in the realm of deep speculation, because, quite simply, the brain doesn't fossilize; the only thing that is left to work with is the braincase. Among the very few estimations that can be made with some degree of objectivity and relevance, are those which would have been drawn from extensive study of inter-species comparisons of brain neural circuitry layout, involving various non-primate and primate creatures; for instance, common features of neural circuitry layout between, say, Pan troglodytes and modern humans, might hint to inheritance of said features from our common recent ancestor. Such aspects of the brain can be estimated, with comparatively little doubt, to have also been part of the Neanderthal brain design.
Feature commonality can go even beyond our closest living relatives, like the chimpanzees, and be shared with a wide range of species, like mice, felines, etc. Those occasions too can hint to, with very little room for doubt, certain aspects of the Neanderthal brain. Other than such type of markers for assessment, i.e., using living creatures as opposed to relying on fossil data, the only other marker type that can be used to draw any reasonable conclusion about the Neanderthal neural substrate is genetic material, as has been seen with the so-called FoxP2 gene. To kind of put these matters into perspective:
It is clear that human speech entails having neural capabilities that are absent in closely related living species. Although a chimpanzee’s vocal tract would suffice to establish vocal language, it cannot talk, despite the fact that acoustic analyses (e.g., Lieberman 1968) reveal “bound” formant-frequency patterns in chimpanzee calls similar to those that convey different words in human speech. These sounds could be used to differentiate words if the chimpanzees could voluntarily reorder the motor commands used to generate them. Chimpanzees could establish “protospeech,” producing everything save for quantal sounds, if they were able to freely reiterate—to reorder and recombine the motor commands underlying speech. Chimpanzee calls in the state of nature appear to be stereotyped and fixed (Goodall 1986). The neural circuits that confer the reiterative abilities necessary for human speech appear to be absent in chimpanzees and other nonhuman primates.
The reiterative quality of these human neural circuits extends to other aspects of behavior, including syntax. - Lieberman, 2007.
To reiterate, it simply cannot be taken for granted that Neanderthals were predisposed to speaking like modern humans, simply because they appeared to be very close to the latter from fossil data and via some assessments, like genetic data. Yes, it can be said that the Neanderthal were more than likely closest to modern humans than our closest living relatives, like chimpanzees, but the driving point is to instill mindfulness to the limitations of osteological data. The differences between the Neanderthal and modern humans are thus expected to pale in comparison to that between chimps and modern humans, but that does preclude neural differences between Neanderthals and modern humans. As noted above, based on osteological estimation alone, even chimps appear to have the potential to talk, but obviously chimps are living proofs that this is clearly not the case. Having the potential to talk does not automatically lend itself to the ability to perform complex language.
Returning to the matter of genetic material serving as a useful marker for assessing certain aspects of neural capacity...
The basal ganglia through different anatomically segregated neural circuits also reiterate cognitive pattern generators conferring cognitive flexibility and take part in associative learning. The evolutionary significance of the regulatory FOXP2 gene, which has erroneously been identified as a “language gene,” rests in the fact that it governs the embryonic development of the basal ganglia and other subcortical elements of these neural circuits (see Lieberman (2000, 2002, 2006a and the studies noted below).
Genetic material, however, usually only confirms the presence or absence of certain trait or feature; it doesn't necessarily tell us how that feature or trait may have actually functioned, or to put it another way, the exact underlying mechanism(s) behind a trait, without having to rely on extrapolation from how a particular gene is determined to be functioning in living organisms. Needless to say, link between genes and phenotype is almost always via correlation; researchers generally take in a wide range of samples sporting noticeable variations of a case-study-phenotype, note the gene types and frequencies and then tie that in with phenotype patterns within or across samples, to determine if there are clear correlations between gene type & frequency and a phenotype. The FoxP2 gene itself can serve as such an example:
The discovery of FOXP2 results from a sustained study of a large extended family marked by a genetic anomaly. A syndrome—a suite of speech and orofacial movement disorders and cognitive and linguistic deficits—occurs in afflicted members of the KE family (Vargha-Khadem et al. 1995, 1998; Lai et al. 2001; Watkins et al. 2002). Afflicted individuals are unable to protrude their tongues while closing their lips. They have difficulty repeating two-word sequences. They have significantly lower scores on standardized intelligence tests than their non-afflicted siblings.
The mutation on the FoxP2 gene of the KE family members was useful in isolating the affected individuals from the non-affected individuals, i.e., a matter of deductive correlation between gene type & frequency and phenotype. The deductive correlation, however, weakened a bit, when it came to tying the mutation on the gene to IQ scores; read on:
Some have higher nonverbal IQ scores than unaffected members of the family, suggesting to some investigators that FOXP2 does not affect intelligence. However, as the different nonverbal IQs for the non-affected members of the KE family show, intelligence is derived from the interaction of many neural systems and life experiences. It is impossible to know what the nonverbal IQs of an affected individual would have been absent the genetic anomaly, but the low mean nonverbal IQ of the affected members (86, with a range of 71-11) versus a mean of 104 (with a range of 84–119) for unaffected family members suggests that FOXP2 anomalies are responsible for generally lower intelligence. - Lieberman, 2007.
Both the cortical and sub-cortical regions of the brain are tasked with regulating cognition, emotion, and motor control. However, what's interesting, is that a number of studies have revealed that the sub-cortical regions of the brain are particularly vital. That's not to say other components of the brain are not vital, but why the emphasis on the sub-cortical regions?
The traditional model for the neural bases of speech and language posits linguistic functions localized in Broca’s and Wernicke’s cortical areas. The theory derives from studies of damage to the brain that result in aphasia—permanent loss of various aspects of language. However, current studies show that aphasia does not occur in the absence of subcortical damage. Moreover, subcortical damage can result in aphasia without any cortical damage. The studies that I briefly reviewed, including hypoxic insult to the brain in climbers ascending Mount Everest and studies of Parkinson’s disease, show that basal ganglia dysfunction yields linguistic deficits similar to those traditionally attributed to damage to Broca’s area. Fecteau and Theoret claim that a “healthy Broca’s area is necessary for proper speech,” but the clinical record clearly shows that persons with major damage to Broca’s area recover in the absence of subcortical damage. The reason seems to rest in the plasticity of cortical areas. As Fecteau and Theoret themselves note, behavior can be restored when a cortical area is destroyed because “the rest of the brain is capable of sustaining function following a brain lesion, and brain plasticity plays a major role in behavioral recovery.” Studies such as Pascual-Leone et al. (2005) and Sanes et al. (1995) show that cortex is redundant and extremely malleable. In contrast, the subcortical brain structures that support cortical-striatal-cortical circuits regulating motor control, language, emotion, and other aspects of behavior (Cummings 1993) are few and do not appear to be capable of restructuring. - Lieberman, 2007.
With this, the discussion will be carried over to the next entry: Click here.
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Neanderthal in the News:
Neanderthal Cloning Project
To recap:
Were contemporary modern humans [the species that lives on to this day] responsible for the Neanderthals' demise? Or did everything that was working fine for the Neanderthals' survival, prior to the arrival of "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 aforementioned fronts.
There have been suspicions within the scientific community about the role of modern humans in the demise of Neanderthals for quite a while now, although there seemed to have been 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 to abrupt environmental shifts as the prime suspect in the demise of the Neanderthals, supposedly 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:
The discussion will pick up from where the previous segment left. In the first segment, the matter of the changing direction of the wind, in terms of how the Neanderthal is perceived in academia, was briefly looked at, and the launch of an examination of whether so-called "anatomically modern" humans had any role in the former's demise. Naturally, one of the first things to look at in pursuit of the answer(s), is the determination of any role of differences in either intellectual capacity and/or culture at the sub-species level in the way the evolutionary paths of the two human species have manifested. It is obviously hard to overlook the fact that the 'anatomically modern' human is the only human species that lives on to this day. It therefore follows that modern humans had the benefit of something that gave their sub-species an evolutionary upper hand.
There is an emerging segment in academia which is getting more vociferous about the prospect of neither the intellectual nor behavioral capacity of the Neanderthal being significantly different or inferior to that of their 'anatomically modern' human contemporaries. If we were to give it the benefit of doubt and put the aspect of intellectual capacity aside, then one will have to explore the role played by culture and/or the impact of ecology. To this end, the discussion in the first segment looked at the possible role of technology. In the Upper Paleolithic context, much evidence of this is in the form of a variety of stone tools found in occupation sites that have been subject to archaeological scrutiny.
In the last segment, the role of the interplay between respective technological peculiarities and body plan was analyzed. Osteological examinations of post-cranial remains have provided clues to a very real possibility that Neanderthals and their 'anatomically modern' counterparts adopted different hunting strategies. Additionally, species-specific morphological patterns of Neanderthals and recent human bodies provide insights into certain behavioral capacities of these two closely related but distinct species of humans; extrapolation of what were the fortes of either species, and what could have been their limitations just from the restrictions and degree of freedom dictated by stature and body build alone. This discussion led to a look at various osteological distinctions between Neanderthals and recent humans at the sub-species level.
It is true that prejudice and bias in academia had, and still do to some extent, clouded objective assessment about the intelligence and behavioral capacity of Neanderthals and how these beings have been visually portrayed. This doesn't, however, mean that acknowledging systematic differences between Neanderthals and recent humans is tantamount to such prejudice against Neanderthals and in favor of recent humans. There are very real anatomical differences between Neanderthals and humans that cannot simply be ignored.
Some of these anatomical differences, whether we, as observers, like it or not, have had some impact on what either human species were able to do or how far they were able to undertake a particular activity. Intelligence itself cannot be ascertained by osteological data alone without outside factors—as determined by tangible evidence—taken into consideration. Neurological capacities can only tentatively be assumed from size or capacity of the neuro-cranium, from the osteological standpoint. Outside of that, evidence of behavioral capacity through art, tool making and possible patterns in prehistoric handling of pre-historic burial sites are much more tangible clues of behavioral complexity or sophistry.
There are sufficient clues to suggest that 'anatomically modern' humans attained an edge of some degree over the Neanderthals at some point; before then, the two human species had identical levels of behavioral sophistry for a considerable amount of time. What could have brought about this shift in technological capacities, which, from the looks of things, seemed to have tilted more favorably towards 'anatomical modern' humans?
Some have talked about the possibility of language having a prominent role. Measuring the neuro-cranium obviously does not discern this, but researchers have turned to another osteological [indirect] clue: the position of the hyoid bone. For instance, by comparing the throat bones of Neanderthals against those of modern humans, anatomist Dr. Jeffrey Laitman, of Mount Sinai School of Medicine, estimated that the location of the larynx likely played a role in the development of spoken language.
Adult modern humans have the larynx down the throat, which enables them to produce a number of important sounds, particularly vowels. In contrast, osteological reconstructions have determined that Neanderthals would have had the larynx at a higher location in the throat than the case was/is for modern humans (Laitman, Clash of The Cavemen). Interestingly, infantile humans are said to have the larynx high up the throat—to facilitate simultaneous swallowing and breathing; a lower larynx allows a smooth transition from breathing to swallowing and vice versa, thus removing the necessity of simultaneous breathing and swallowing. Henceforth, Neanderthals wouldn't have been able to make certain vowel sounds, like for example, the "oo" sound.
The hyoid bone aside, another possible marker of the situation of the larynx, is the shape of the skull base. Neanderthal's skull base was determined by Jean Louis Heim (1989), of the Natural Museum of Natural History, to be angled in such a way that speaks to the placement of the larynx low in the neck, thereby contradicting earlier findings which put forward that earlier hominids feature a comparatively "flattened base" relative to recent humans, and that the Neanderthal shared this trait. Subsequent findings (e.g., Laitman et al. 1992) stick to the general premise of the earlier observations. A comparatively flattened base is said to be indicative of a positioning of the larynx that would be higher than that in an adult modern human.
Things to keep in mind about the aforementioned findings: 1) University of Kansas paleo-anthropologist David Frayer's (1992) case about identical Neanderthal-recent human speech capability relied on two separate lines of evidence from two separate specimens: the skull of the La Chapelle Neanderthal skull for basicranial analysis (Jean Lois Heim, 1989), and the hyoid bone of only one specimen--the incomplete Kebaran specimen, dubbed both as "KMH2" and as the "most complete Neanderthal skeleton", which lacks a skull--save for the remnant of the mandible, for neck analysis.
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| Image caption: The Kebaran Neanderthal specimen, referred to as "KMH2", is reputed with "coming closer to completion than any other Neanderthal specimen" to date. A piece of the mandible of the specimen appears to have been located, but the rest of the cranium is missing. |
Click on the image for higher resolution.
2) The researchers implicated here, with respect to the speech capabilities of Neanderthals vs. modern humans, arrived at essentially opposite conclusions around the very same specimen, namely, the La Chapelle skull. Laitman's computer reapplication of Heim's measurements for simulation, for instance, reportedly suggested a pattern more similar to an infantile than an adult human. The rationale is that the larynx positioned with respect to the degree to which cranial base flexes (Daniel Lieberman, The Evolution of the Human Head):
“...modern human infants have a flat (extended) cranial base and a high, intra-narial larynx (see Figure 8.7), and that the larynx descends as the cranial base flexes (George, 1978). These correlated changes were argued to be related casually by two factors. First, because the larynx is partially suspended by muscles that originate on the basioccipital, a flexed (lower) basioccipital might position the larynx lower relative to the palate. Second, the basicranial flexion would shorten the anteroposterior distance between the back of the palate and the vertebral column. As the cranial base flexed, this would leave insufficient space for the larynx, requiring it to descend to keep a patent airway. Because Neanderthals had flatter cranial bases, like those of infants, the CLL group [aka Ed Crelin, Philip Lieberman, and Jeffrey Laitman] reasoned that they probably also had high larynxes, which, in combination with longer faces, would lead to SVT(h):SVT(v) ratios other than 1:1 [SVT = supra-laryngeal vocal tract, i.e. airway from the larynx to the lips]. If that was the case, Neanderthals would have had difficulty in articulating a full range of acoustically distinct vowels, especially vowels such as /i/...” - Daniel Lieberman, The Evolution of the Human Head.
Besides reiterating the case about the influence of the basicranial flexure on the relative positioning of the larynx in the neck, as put forward by researchers like Crelin, Lieberman [Philip] and Laitman, Daniel Lieberman raises another interesting matter in this subject, namely, SVT(h) and SVT(v). These two concepts will be revisited in the coming passages. Daniel Lieberman's insights bring a dimension to this subject matter that is different from the aforementioned reliance on basicranial flexure.
It is not certain though, that an inability of producing such sounds like vowels would necessarily have meant that Neanderthals lacked language. However, it does suggest that they would have had considerable difficulty in how far they would have been able to systematize language and allow it to have the capacity to possess a fairly large, complex and flexible vocabulary.
With regards to the hyoid, we are told the following, courtesy of The Free Library webpage:
In their new study, the Mount Sinai investigators took measurements of hyoid shape and size from a variety of mammals, including humans, apes, gibbons, baboons, dogs, sheep, pigs, rabbits, rats, dolphins, and whales.
Considerable variation in hyoid shape appeared, both among species and among individuals in the same species, Reidenberg says. Even within species that exhibit little variation in the neck position of the hyoid, individuals display marked differences in the bone's shape, suggesting that the shape of a single hyoid offers no clues as to where it sat in the neck, she asserts.
Further analysis found marked overlap between human and pig hyoids on four of six measures of shape and size, Reidenberg says. Pig hyoids overlap with the Neandertal specimen on two of those measures, she holds.
The discoverers of the Neandertal hyoid reported that the specimen overlaps with modern human hyoids on five of the same six measures (SN: 7/8/89, p. 24).
Despite the anatomical ties between pig and human hyoids, only humans possess a voice box positioned low in the neck and a vocal tract capable of producing speech sounds, Reidenberg says. Thus, researchers should not assume that the fossil hyoid's shape announces an advanced capacity for speech among Neandertals, she concludes.
On the other hand, ...
Frayer also compared pig and human hyoids. Shape differences are readily apparent and seem to stem from the bone's contrasting functions in pigs and humans, he argues. Reidenberg and Laitman's focus on a few discrete features rather than the whole bone may mask these divergences, in his view.
The Neandertal hyoid is "indistinguishable" from those of modern humans, Frayer contends.
The fossil's shape does not establish where the Neandertal voice box lay, he adds. But Frayer deems Reidenberg and Laitman's data "irrelevant." - Neandertal neck bone sparks cross talk, courtesy of The Free Library .com.
Well, it can be argued that if there are overlaps in the morphology of the "whole bone," which is what Frayer argues should be the focus, i.e., between humans and various other animals, then differences in impact of the hyoid bone's shape and metrics in the positioning of the "voice box" ought to be the result of the "few discrete features". However, Frayer argues that the "overlaps in morphology" in this case, are due to what he sees as "arbitrary" discriminants chosen by researchers, for the sake of trying to find relations between recent human hyoid bone and various other animal hyoid bones; rather, the "overall shape" should be the overriding determinant around which to draw the final conclusion about the relationship between recent human and other animals' respective hyoid bones vs. that between recent human and Neanderthal respective hyoid bones.
Frayer latches onto the idea that shape differences are "readily apparent" between pig and human hyoid bones, but it should be pointed out that no argument has been put forward for a lack of differences between pig and human hyoid bones. What was put forward, rather, is that there were "overlaps" in shape and/or size. Furthermore, this idea does not confront the finding that "considerable" variation in hyoid bone shape was found not only across species, but between individuals of the very same species, thereby rendering highly questionable, the drawing of a fairly broad conclusion based on a single prehistoric hyoid bone!
For all the criticism directed at using variables in studying the significance of hyoid bone shape and size on the location of the larynx, it is noted that the discoverers of the KMH2 remains—aka the Neanderthal specimen whose hyoid bone was found--used the VERY SAME "six measures" of shape and size applied by the Mt. Sinai analysts, so as to claim that the Neanderthal hyoid bone overlapped with recent human counterparts on "five" of those six measures. In other words, Frayer's protest against usage of variables as opposed to the singular factor of "overall shape" or "whole bone" was with respect to the conclusions of the Mt. Sinai team, with which he apparently disagrees, but in an ironic twist, the discoverers of KMH2 used the very same variables as the Mt. Sinai team to draw a conclusion that is more in line with Frayer's own viewpoint.
It is therefore unlikely that Frayer would have rejected the usage of said variables in assessing relationships in shape and size, had the discoverers' conclusion been the only one out there around such variables. Furthermore, conceding that the shape of the hyoid bone "does not establish where the Neanderthal voice box lay" only undermines Frayer's position.
Some have interpreted the conclusions of the so-called CLL group, aka Philip Lieberman, Ed Crelin and Jeffrey Laitman, as supposedly professing "speech inability" of Neanderthals. From around the web, one such interpretation was put forth along with this reference, which was presented as supporting "counter" material against the interpretation attributed to the said group of researchers:
"The discovery of the first fossil hominid hyoid bone from Kebara provides important insights into the vocal tract of Middle Palaeolithic hominids, because a previously unknown portion of the anatomy is available for study and its anatomical relationships can be evaluated.
The bone itself is not notably different, in either size or morphology from that of modern human hyoids. The relations of the hyoid to the mandible and cervical vertebrae probably did not differ from the modern pattern; the Kebara neck appears to be anatomically and proportionally similar to that of living peoples.
These new data strongly suggest that Middle Palaeolithic people shared structural relationships with modern humans in terms of their vocal tracts. They appear to be as 'anatomically capable' of speech as modern humans when hyoid positioning and supralaryngeal space are the critera considered.
The hyoid bone from Kebara is a 'singular' discovery, yet the evidence for marked similarities of this bone to those of living peoples cannot be easily dismissed; this research has demonstrated that it is a component in a suite of morphological relationships that collectively display a modern human configuration." ~ B. Arensburg et al, "A Reappraisal of the Anatomical Basis for Speech in Middle Palaeolithic Hominids," American, Journal of Physical Anthropology 83:137-146, p. 145.
Apparently in an effort to set the record straight and dispel such interpretations of his and colleagues' position, Laitman et al. notes:
“The general picture of the Neanderthal upper respiratory tract that has emerged over the last few decades by those attempting to reconstruct it has been of a region which differed somewhat from that in living humans. Both our own (15, 16, 24) and other studies (17, 18, 25) have emphasized that some Neanderthals (such as the "Classic" western European specimens) would have exhibited a larynx slightly higher in the neck than that of modern humans, with these Neanderthals having a more limited oropharyngeal segment with a greater portion of the tongue occupying the oral cavity. When one factors in their large external nose and sizable paranasal sinuses, the overall Neanderthal anatomy suggests a group that relied more heavily upon the nasal rather than the oral route for respiration then do living humans. These specializations were very possibly due to respiratory-related adaptations to their environment. A by-product of this respiratory-driven anatomical configuration would be that Neanderthals could not have produced the same array of sounds that living humans can (16, 17, 26). They were not apish mutes; they were just not identical to us.” - Jeffrey Laitman et al. (1996), Commentary; What the nose knows: New understandings of Neanderthal upper respiratory tract specializations.
A similar note was presented by Philip Lieberman:
The Lieberman and Crelin (1971) Neanderthal study is often cited to support claims that speech evolved abruptly at a recent date. 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 matter of language-origin dating will be revisited in coming passages. On the note of revisiting, let's recall the issue of SVT(h) and SVT(v) components of the vocal tract. Daniel Lieberman's observations on the morphological forms of the vocal tract brings up another dimension to the discussion of language developmental capacities, particularly in terms of the different physiological players like the aforementioned roles of the flexure of the basicrania and the position of the larynx in the neck. It looks like as a result of this, researchers like Philip Lieberman have either revised their perspectives or fine-tuned it. See:
The absence of computer-implemented digital image analysis technology in the 1970s precluded accurate measurements of tongue position by George; the perceptual-magnet phenomenon documented by Kuhl and her colleagues was not apparent until almost two decades later. In short, cranial-base flexure in itself cannot be used to predict whether a fossil had an adult human supralaryngeal vocal tract.
At the time, however, a close relationship between vocal tract development and cranial-base angle was accepted by our and other research groups. Studies followed that linked the cranial-base angle and the length of the basicranium (which indicates oral-cavity length) with the vocal tracts of living nonhuman primates and fossil hominids (Laitman, Heimbuch, and Crelin 1978, 1979; Laitman and Heimbuch 1982). Their conclusion was that Neanderthals and earlier fossil hominids did not have human vocal tracts. The studies of Boe and his colleagues (Boe, Maeda, and Heim 1999; Boe et al. 2002) reached an opposite conclusion. Reconstructions of the vocal tracts of fossils based on cranial-base angles are problematic. When Daniel Lieberman and McCarthy (1999) reexamined the Denver series they found that the tongue and larynx continued to descend after cranial flexure stabilized and that SVTh and SVTv did not achieve their adult 1:1 proportions until age five to six years. Fitch and Giedd (1999), using MRIs, reached the same conclusion. - Philip Lieberman, 2007, The Evolution of Human Speech; Its Anatomical and Neural Bases.
The last bit should particularly be a focus of attention, by those who press forward the idea that kids as young as 8 years are able to speak effectively, supposedly as a means of countering what they interpreted from work of the likes of Laitman, who reported that human infants featured relatively flatter basicrania, and hence, higher positioning of the larynx in the neck. Talk about overlooking the meaning of "infant"! Apparently, said researchers are referring to human young who are not yet able to speak effectively.
Nevertheless, as the above passages from Philip Lieberman point out, primary reliance on the angle of the basicranium is "problematic" for the reasons stated. Rather, as Daniel Lieberman et al.'s findings suggest, the volume of the vocal tract within which the tongue has to maneuver coupled with the "reshaping" and associated movement of the tongue, appear to be a stronger determinant of the positioning of the larynx than the flexure of the basicranium...
The low position of the human larynx is a reflex of the human tongue’s reshaping and moving down into the pharynx. It is closely coupled to tongue displacement (Negus 1949; Bosma 1975; D. Lieberman and McCarthy 1999; Nishimura et al. 2003). As the tongue descends into the pharynx, it carries the larynx down with it.
The human tongue, as it turns out, retains the length of tongue seen in the more prognathous or forward face projecting apes and hominids. However, recent humans having flatter "snouts," and hence faces, means that there is nowhere else for the tongue to go but to descend down the neck! While the likes of Daniel Lieberman and co. have observed a correlation between the descent of the tongue and and that of the larynx, thereby stimulating renewed attention towards the relationship between tongue displacement and the positioning of the larynx, the understanding had been around for quite a while, albeit perhaps not afforded the same attention that it now gets:
There is no prognathous snout . . . . The [human] tongue however retains the size it had in Apes and more primitive types of Man, and in consequence it is curved, occupying a position partly in the mouth and partly in the pharynx. As the larynx is closely approximated to its hinder end, there is of necessity descent in the neck; briefly stated, the tongue has pushed the larynx to a low position, opposite the fourth, fifth, and sixth cervical vertebrae. - Victor Negus, 1946.
Neanderthals, if recalled, tend to have greater mid-facial protrusion than recent humans, but the mouth area is actually not as prognathous as those seen in apes and other "primitive" hominids. On the basis of this, it might be tempting to predict a similar development of the tongue in Neanderthals as recent humans. Not so fast, if one considers the following; as noted earlier, several research teams likened the structure of Neanderthal vocal tract to those of recent human "infants":
in 1971, Edmund Crelin and I attempted to reconstruct the supralaryngeal vocal tract of the Neanderthal fossil from La Chapelle-aux-Saints (Boule 1911–13). We compared the skeletal features of the skull and mandible that support the soft tissues of the vocal tract in human newborns and in the Neanderthal fossil and noted a number of similarities between them. In addition to basicranial flexure, which became the focus of many subsequent studies, there were similarities in skeletal features supporting the muscles that move the tongue such as the pterygoid process of the sphenoid bone, the total length of the basicranium, and the distance between the end of the palate and the foramen magnum (into which the spinal column is inserted). On the basis of these findings, a range of vocal tract area functions similar to those of newborns in the cineradiographic study of Truby, Bosma, and Lind (1965) was modeled using Henke’s (1966) computer-implemented algorithm, which established the relationships between vocal tract shapes and formant frequencies, and the computed formant-frequency vowel patterns were compared with those measured by Peterson and Barney (1952). Speech was possible because most vowel and consonant formant-frequency patterns could be produced, but the formant-frequency patterns that convey the quantal vowels of human speech could not be produced. - Philip Lieberman, 2007, The Evolution of Human Speech; Its Anatomical and Neural Bases.
These physiological findings are consistent with the observable fact that recent human infants and recent human adults exhibit different speech capacities, notwithstanding the relatively "flat snouts" in both. Though equivocal by some accounts, given that similarities in vocal tract form were drawn between Neanderthals and recent human infants, the speech qualities of the latter may give some insights into the speech-potential of Neanderthals. Differences in vocal tract proportions—alluded to earlier—may provide a clue to this:
The reconstructed Neanderthal’s tongue rested for the most part in the oral cavity, and this precluded its producing the abrupt 10:1 area-function vocal-tract midpoint discontinuities required. - P. Lieberman
In contrast:
The adult-like human supralaryngeal vocal tract has a tongue with an almost circular sagittal (midline) contour forming two segments, a horizontal oral cavity (SVTh) and a vertical pharyngeal cavity (SVTv) of almost equal length (1:1 proportions) positioned at a right angle (fig. 1). Movements of the undistorted tongue in the space defined by the oral cavity and the pharynx can produce the abrupt midpoint 10:1 area-function discontinuities on which the format-frequency patterns of the quantal vowels [i], [u], and [a] depend.
The above thus maintains that Neanderthal's tongue was stored mostly in the oral cavity, in contrast to the more extensive descent of the tongue in the neck of recent human adults. This has been facilitated in Neanderthals due to the relatively longer SVT(h). Most physiological reconstructions of the Neanderthal feature relatively short necks; it seems that the three Neanderthal specimens studied by McCarthy et al. did not fair differently [translating into a shorter SVT(v)]. This coupled with the long SVT(h), meant that Neanderthal vocal tract proportions did not conform to the 1:1 ratio that characterize adult recent human vocal tract:
We can determine whether Neanderthals and other fossil hominids could have had 1:1 SVTh/SVTv proportions by examining their basicrania, which provide a measure of SVTh, and their cervical vertebrae, which provide a measure of the length of their necks. McCarthy et al. (n.d.) determined these metrics for a sample of 62 specimens of Pan troglodytes, the WT 15000 fossil Homo ergaster, 3 Neanderthal fossils, and 82 specimens of H. sapiens, including the Middle Paleolithic Skhul V fossil, 8 Upper Paleolithic fossils, and 73 contemporary humans from seven different populations. The data show that Neanderthal necks were too short to accommodate human vocal tracts. McCarthy and his colleagues arrive at a Neanderthal neck length estimate of 120 mm in contrast to the 134–127-mm averages for two modern human samples; the short neck and long Neandertal SVTh would place the cricoid cartilage behind the sternum, permitting human speech but precluding eating. (A similar conclusion was reached by Lieberman [1984, 290–96].)
The conflicting estimations of Neanderthal larynx location between one team of researchers and other groups is obviously the direct result of limitations of reliance on fossilized data. This situation, as noted earlier, surfaces in the measurements of the La Chapelle-aux-Saints Neanderthal remain.Where does that leave us then? For one, this is bound to happen from excessive reliance on both a single [prehistoric] specimen as opposed to multiple specimens, so as to look for trends, and a single determinant. In addition to the case of the La Chapelle-aux-Saints specimen, the single Neanderthal hyoid bone, assigned to the KMH2 Kebara specimen, has been afflicted by the same problem. Absence of a relatively more comprehensive study in the development pattern featured in samples, i.e. from infants or children to adults and/or between males and females, can add to uncertainty about a series, particularly for prehistoric specimens where the probability of paucity of data can be fairly high. One team voiced this concern, for example, from Schwartz and Tattersall (2005):
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| Source: Schwartz and Tattersall, 2005, The Le Moustier adolescent: A description and interpretation of its craniodental morphology. |
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| Source: Schwartz and Tattersall, 2005, The Le Moustier adolescent: A description and interpretation of its craniodental morphology. |
Click on all images for higher resolution.
This kind of study of development has been appreciated, when it comes to recent humans in the study of the growth pattern of the basicranium and vocal tract proportions from infants and/or juveniles to adults, but what about Neanderthals? Obviously sample accessibility in this respect is narrower in the Neanderthal context, given limited number of specimens, but going by clues provided by the Le Moustier 2 specimen for instance (Gunz et al., 2011), much of the developmental features of the basicranium found in Neanderthal neonates is retained in the adult stage. There is more visible transformation in recent humans, from the neonatal stage to the adult stage. It was estimated that as far as the cranial base was concerned, "shape differences between the Le Moustier 2 specimen and recent human neonates were "extremely subtle"." (Gunz et al.) By most accounts, lower basicranial flexure is seen in adult Neanderthals, however, compared to that seen in adult recent humans. Gunz et al. (2011) note, for instance:
The shape differences between Le Moustier 2 and modern human neonates in the cranial base are extremely subtle. Around the time of birth modern humans and Neanderthals have very similar endocranial shapes and volumes. Our EV estimates for Le Moustier 2 range between 408–428 cc. Our reconstruction of Le Moustier 2 shows that most facial differences between modern humans and Neanderthals develop prenatally as they are already established at the time of birth. Most shape differences in the braincase between modern humans and Neanderthals, however, develop after birth.
The authors go onto note:
Studying the endocranial shape changes of modern humans and Neandertals from birth to adulthood, we could show that modern human braincases undergo a “globularization-phase” in the first year of life. The shape changes during the first year of life comprise a relative expansion of the parietal bone, the occipital bone and flexion of the cranial base (Neubauer et al. 2009; Neubauer et al. 2010). This phase is absent from Neandertals, and appears to be unique to modern humans (Gunz et al. 2010; Neubauer et al. 2010).
These findings suggest that the relatively modest changes, if any, in bascranial flexure within the Neanderthal context, from the neonatal stage to adulthood, as compared against the recent human context, is reflective of the derived states of Neanderthals and recent humans respectively, amongst other such differences.
Having said that, the weight of evidence, as it stands, is slanted towards the crowd which maintains that there were differences in the vocal tract shape and/or proportions, between Neanderthals and recent humans. Soft tissues like the tongue and vocal tract muscles are not normally preserved in fossils, and so, people are compelled to rely on the next best thing to provide clues, which for the most part are bones. In this respect, the basicranium, possibly the mandible (esp. when the basicranium is not available), and the cervical vertebrae, serve as particularly useful clues in vocal tract structure. As it turns out, neither the shape/position of the hyoid bone nor the location of the larynx are good predictors of speech capacity! It can be argued that the angle of the basicranium in of itself is of little use in this determination as well; rather, physiologically, the proportions of the vocal tract coupled with the shape and displacement of the tongue are stronger markers of speech capabilities.
A smaller but loud crowd argues for identical vocal tract development between recent humans and Neanderthals, which happens to be the pattern seen in adult recent humans. These primarily rely on measurement of basicranial flexure, producing results which are inconsistent with results of the same standard applied by others. The advocates have often relied on single specimens, mainly adult, to make a blanket statement about these features in Neanderthals. In one such occasion, the research team failed to even note a clear difference between neonatal and adult vocal tract proportions, which might well provide insights to why their findings in a Neanderthal specimen falls within the adult human range:
The biological mechanisms that regulate the descent and reshaping of the human tongue are unknown, and tongue position and shape cannot be inferred from the basicranial angle. Boe and his colleagues (Boe, Maeda, and Heim 1999; Boe et al. 2002) nonetheless base their Neanderthal reconstruction on the cranial-base angle of the La Chapelle-aux-Saints fossil as reconstructed by Heim (1989). The basicranial flexure of Heim’s Neanderthal skull reconstruction is within the human range, but that does not signify an adult human vocal tract. Although the studies of D. Lieberman and McCarthy (1999) and Fitch and Giedd (1999) are cited, Boe and his colleagues ignore their findings and fit a vocal tract with the adult human proportions noted by Honda and Tiede (1998) to the fossil.
The relationships between skulls, jaws, and soft tissue noted by Honda and Tiede (1998) hold for adult humans; they do not apply to young children, human neonates, apes, or monkeys. Genetic evidence (Krings et al. 1997; Ovchinnikov et al. 2000) shows that Neanderthals diverged from humans about 500,000 years ago, and their skeletal morphology differs from that of modern humans (Howells 1976, 1989; D. Lieberman 1995). Adult human vocal-tract morphology therefore cannot arbitrarily be bestowed on them. Nonetheless, Boe and his colleagues model the vocal-tract shapes that adult human speakers use to produce vowels. Not surprisingly, these configurations produce the full range of human vowels. They also model a putative human infant vocal tract that does not resemble any newborn vocal tract documented by Negus (1949), Truby, Bosma, and Lind (1965), Bosma (1975), Laitman and Crelin (1976), or anyone else. Its SVTh/SVTv ratio is close to that of the five-to-six-year-old children documented by Lieberman and McCarthy (1999) and Fitch and Giedd (1999). Similar flaws mark other studies that have proposed human vocal tracts for Neanderthals (see Lieberman (1984, 2000, 2006c for reviews). - Philip Lieberman, 2007, The Evolution of Human Speech; Its Anatomical and Neural Bases.
To sum things up briefly, the shape of the vocal tract [of course, including movement and shape of the tongue within] and the proportions that it assumes, are key physiological factors in facilitating the oral motor skills of recent humans in implementing complex speech, as opposed to merely the location of the larynx, although the positioning of the larynx still plays an important role in the time management of the flow of air and opening of the larynx between or during the different roles the mouth has come to assume, namely eating, breathing, and communicating.
Visual aids are in order; courtesy of Philip Lieberman (2007):
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| Image caption: On the left: Figure 1. The adult human supralaryngeal vocal tract, showing the almost circular posterior contour of the tongue. The SVTh portion and the SVTv portion are almost equal in length. There is a natural discontinuity formed by the intersection of SVTh and SVTv that permits abrupt changes in the cross-sectional area of the human supralaryngeal vocal tract at its midpoint. On the right: Figure 2. Midsagittal views of an adult human supralaryngeal vocal tract for the quantal vowels [i], [a] and [u] and the resulting formant-frequency patterns, showing the peaks in the frequency spectrum that follow from the convergence of two formant frequencies. The 10:1 discontinuity at the midpoint of the vocal tract allows speakers to be imprecise and still generate vowels that have spectral peaks. |
Click to enlarge.
A relatively more detailed breakdown of underlying physiological factors at work in the development of complex speech by recent humans from P. Lieberman:
...studies of the ontogenetic development of the human vocal tract reveal other factors:
1. The skeletal structure that supports the roof of the mouth rotates toward the back of the skull, effectively shortening the mouth and SVTh, during the first two years of life; the human face is flat compared with those of prognathous present-day apes and early hominids such as the australopithecines (D. Lieberman, Ross, and Ravosa 2000).
2. The human tongue gradually descends into the pharynx, changing its shape from relatively long and flat to posteriorly rounded. This yields the 1:1 SVTh/SVTv proportions seen in figure 1. This unique human developmental process is not complete until age six to eight years (D. Lieberman and McCarthy 1999). As the human tongue descends, it carries the larynx down with it.
3. The human neck gradually lengthens (Mahajan and Bharucha 1994). Neck length is critical in that a larynx positioned below the neck at the level of the sternum (collarbone) would make it impossible to swallow (Palmer et al. 1992; D. Lieberman et al. 2001).
As is the case in nonhuman primates throughout life, the tongue is positioned almost entirely in the mouth in human neonates. In the course of human ontogenetic development, the tongue moves down into the pharynx, carrying the larynx down with it.
To help with dating the origin of complex speech capability of recent humans, specimens ranging from the prehistoric ancestral hominid, Neanderthals, early "anatomically modern humans" from the Middle Paleolithic and Upper Paleolithic to contemporary humans came in handy. Included, were some nonhuman specimens of 62 Pan troglodytes. The measurements applied for this task are the SVT(h) and SVT(v) proportions. P. Lieberman for instance, noted that the Skhul V specimen exhibited vocal tract horizontal and vertical proportions that placed it outside the characteristic fully modern adult human vocal tract proportion of 1:1 (SVT(h)/SVT(v)); vocal tracts that can confidently be placed under the adult recent human proportion only started to appear in samples dating to from around 50ky ago among the test samples:
Surprisingly, a similar constraint [as applied to Neanderthal specimens] rules out a human vocal tract in the Middle Pleistocene fossil Skhul V (McCowan and Keith 1939), which has often been thought to be fully modern. McCarthy and his colleagues estimate the cervical spine length of Skhul V to be 109 mm, at the bottom of the adult modern human range. Skhul V’s SVTh is relatively long, and therefore its short neck precludes its having a fully human vocal tract with 1:1 SVTh/SVTv proportions. Fully modern speech anatomy is not evident in the fossil record until the Upper Paleolithic, about 50,000 years ago.
Using vocal tract proportions as an indicator of complex language capability, these results would suggest that the Skhul V individual would not have been very effective in performing the complex language skills of contemporary humans. The problem with the above analysis of course, is that only one early modern human specimen from the Middle Paleolithic was tested. Hardly enough to ascertain a pattern in human physiology at the time. The same can be said of the lone ancestral hominid specimen of the WT 15000 Homo Egarster fossil. The Neanderthal sample was also small, but at least more than 2 individuals. In any case, if these specimens are representative of a group, community or population of their respective eras, then the finding is interesting in how relatively late of a date it is, with respect to vocal tract proportions as an indicator of complex speech capability, when one considers the duration modern humans have been around.
The 50ky ago mark interestingly coincides with the often-cited age for OOA (Out of Africa) dispersions of modern humans. Even if such a prospect were taken at face value, one would have to take it that complex speech capability occurred on the African continent prior to any notable migratory events which led to territories outside of Africa now being populated by modern humans. Given language diversity across modern human populations, and undoubtedly, many languages had disappeared over the ages, it is not inconceivable that complex language development would have stabilized and would have already been widely distributed on the African continent for a considerable time before the subsequent expansion of modern humans to other landmasses. It should also be kept in mind, that many of the existing modern human languages around the world belong to language families, which in turn form larger clusters, according to estimated linguistic relationship, under larger language superstructures which themselves end up at a starting point on the African continent. In taking these observations into consideration, complex language emergence in modern humans would have been around for much longer than 50 kya.
Whatever maybe said of the accuracy of dating, a relatively late complex language capacity of modern humans, i.e., when stacked against how long modern humans have been around, is an intriguing revelation. More of this matter will be looked at later on, but it takes some steam off the question of what would have kept modern humans from having the capacity for complex language very early on in their evolution, if not upon the species' emergence.
Aside from the location of the larynx ("voice box"), another possible marker allegedly tied to the ability to perform spoken language comes from DNA analysis: the gene involved is the so-called "FoxP2," located on region 3 of the long arm of chromosome number 7. It is said to be an "essential ingredient" in the ability of speech. In this instance, however, both Neanderthals and recent humans reportedly possess it. The gene plays an indirect role in the language capacities of humans, in that it codes for embryonic development of brain elements that regulate motor control, cognition and emotion among its other roles, e.g., in the development of lung tissue and other structures (Lieberman, 2007). That it is not the only gene implicated in brain development, may be worth pointing out.
Other mammals have the gene too, with a similar function to that of a human's, but of nucleotide versions different from that of a human. Perhaps as a way to communicate this difference, researchers use lower case lettering for the equivalent gene in other mammals, e.g., foxp2. For instance, the mouse version is said to be removed from the human version by 3 mutations, while the chimpanzee version is removed from the human counterpart by 2 mutations (Lieberman, 2007 via Lai et al., 2003). The Neanderthal variant is claimed to be "identical" to that of recent humans; exactly how identical, one would need to independently confirm that, but it is safe to say that it is likely to be much closer to the recent human counterpart than a chimpanzee's.
The FoxP2's link to speech ability was the culmination of research targeted at isolating the underlying factors behind the cognitive deficits and acute orofacial movement and speech impairment afflicting the so-called KE extended family. Studies using MRI (magnetic resonance imagining) techniques have revealed that elements of this family possess an abnormally small [bilaterally] caudate nucleus, and the unilaterally abnormal putamen, globus pallidus, angular gyrus, cingulated cortex, and Broca's area of the brain (Lieberman, 2007).
Speaking of the brain, of all the physiological elements implicated above in complex language capability, the brain obviously plays a central role. It's not just enough to have the right vocal tract shape and proportions, without a brain designed to facilitate complex language-associated cognition and motor control. A such, it would be presumptuous to take it for granted that Neanderthals, or any of our hominid relatives, had complex language ability merely on the account that they are related to us, and/or they had a brain-size similar to or larger than modern human. The Neanderthals would have had to have a brain featuring "neural population" (closely linked neural circuits) setups that performed equivalent functions as the modern human brain.
Any allegations made with regards to the neural circuitry layout in Neanderthal brain would remain in the realm of deep speculation, because, quite simply, the brain doesn't fossilize; the only thing that is left to work with is the braincase. Among the very few estimations that can be made with some degree of objectivity and relevance, are those which would have been drawn from extensive study of inter-species comparisons of brain neural circuitry layout, involving various non-primate and primate creatures; for instance, common features of neural circuitry layout between, say, Pan troglodytes and modern humans, might hint to inheritance of said features from our common recent ancestor. Such aspects of the brain can be estimated, with comparatively little doubt, to have also been part of the Neanderthal brain design.
Feature commonality can go even beyond our closest living relatives, like the chimpanzees, and be shared with a wide range of species, like mice, felines, etc. Those occasions too can hint to, with very little room for doubt, certain aspects of the Neanderthal brain. Other than such type of markers for assessment, i.e., using living creatures as opposed to relying on fossil data, the only other marker type that can be used to draw any reasonable conclusion about the Neanderthal neural substrate is genetic material, as has been seen with the so-called FoxP2 gene. To kind of put these matters into perspective:
It is clear that human speech entails having neural capabilities that are absent in closely related living species. Although a chimpanzee’s vocal tract would suffice to establish vocal language, it cannot talk, despite the fact that acoustic analyses (e.g., Lieberman 1968) reveal “bound” formant-frequency patterns in chimpanzee calls similar to those that convey different words in human speech. These sounds could be used to differentiate words if the chimpanzees could voluntarily reorder the motor commands used to generate them. Chimpanzees could establish “protospeech,” producing everything save for quantal sounds, if they were able to freely reiterate—to reorder and recombine the motor commands underlying speech. Chimpanzee calls in the state of nature appear to be stereotyped and fixed (Goodall 1986). The neural circuits that confer the reiterative abilities necessary for human speech appear to be absent in chimpanzees and other nonhuman primates.
The reiterative quality of these human neural circuits extends to other aspects of behavior, including syntax. - Lieberman, 2007.
To reiterate, it simply cannot be taken for granted that Neanderthals were predisposed to speaking like modern humans, simply because they appeared to be very close to the latter from fossil data and via some assessments, like genetic data. Yes, it can be said that the Neanderthal were more than likely closest to modern humans than our closest living relatives, like chimpanzees, but the driving point is to instill mindfulness to the limitations of osteological data. The differences between the Neanderthal and modern humans are thus expected to pale in comparison to that between chimps and modern humans, but that does preclude neural differences between Neanderthals and modern humans. As noted above, based on osteological estimation alone, even chimps appear to have the potential to talk, but obviously chimps are living proofs that this is clearly not the case. Having the potential to talk does not automatically lend itself to the ability to perform complex language.
Returning to the matter of genetic material serving as a useful marker for assessing certain aspects of neural capacity...
The basal ganglia through different anatomically segregated neural circuits also reiterate cognitive pattern generators conferring cognitive flexibility and take part in associative learning. The evolutionary significance of the regulatory FOXP2 gene, which has erroneously been identified as a “language gene,” rests in the fact that it governs the embryonic development of the basal ganglia and other subcortical elements of these neural circuits (see Lieberman (2000, 2002, 2006a and the studies noted below).
Genetic material, however, usually only confirms the presence or absence of certain trait or feature; it doesn't necessarily tell us how that feature or trait may have actually functioned, or to put it another way, the exact underlying mechanism(s) behind a trait, without having to rely on extrapolation from how a particular gene is determined to be functioning in living organisms. Needless to say, link between genes and phenotype is almost always via correlation; researchers generally take in a wide range of samples sporting noticeable variations of a case-study-phenotype, note the gene types and frequencies and then tie that in with phenotype patterns within or across samples, to determine if there are clear correlations between gene type & frequency and a phenotype. The FoxP2 gene itself can serve as such an example:
The discovery of FOXP2 results from a sustained study of a large extended family marked by a genetic anomaly. A syndrome—a suite of speech and orofacial movement disorders and cognitive and linguistic deficits—occurs in afflicted members of the KE family (Vargha-Khadem et al. 1995, 1998; Lai et al. 2001; Watkins et al. 2002). Afflicted individuals are unable to protrude their tongues while closing their lips. They have difficulty repeating two-word sequences. They have significantly lower scores on standardized intelligence tests than their non-afflicted siblings.
The mutation on the FoxP2 gene of the KE family members was useful in isolating the affected individuals from the non-affected individuals, i.e., a matter of deductive correlation between gene type & frequency and phenotype. The deductive correlation, however, weakened a bit, when it came to tying the mutation on the gene to IQ scores; read on:
Some have higher nonverbal IQ scores than unaffected members of the family, suggesting to some investigators that FOXP2 does not affect intelligence. However, as the different nonverbal IQs for the non-affected members of the KE family show, intelligence is derived from the interaction of many neural systems and life experiences. It is impossible to know what the nonverbal IQs of an affected individual would have been absent the genetic anomaly, but the low mean nonverbal IQ of the affected members (86, with a range of 71-11) versus a mean of 104 (with a range of 84–119) for unaffected family members suggests that FOXP2 anomalies are responsible for generally lower intelligence. - Lieberman, 2007.
Both the cortical and sub-cortical regions of the brain are tasked with regulating cognition, emotion, and motor control. However, what's interesting, is that a number of studies have revealed that the sub-cortical regions of the brain are particularly vital. That's not to say other components of the brain are not vital, but why the emphasis on the sub-cortical regions?
The traditional model for the neural bases of speech and language posits linguistic functions localized in Broca’s and Wernicke’s cortical areas. The theory derives from studies of damage to the brain that result in aphasia—permanent loss of various aspects of language. However, current studies show that aphasia does not occur in the absence of subcortical damage. Moreover, subcortical damage can result in aphasia without any cortical damage. The studies that I briefly reviewed, including hypoxic insult to the brain in climbers ascending Mount Everest and studies of Parkinson’s disease, show that basal ganglia dysfunction yields linguistic deficits similar to those traditionally attributed to damage to Broca’s area. Fecteau and Theoret claim that a “healthy Broca’s area is necessary for proper speech,” but the clinical record clearly shows that persons with major damage to Broca’s area recover in the absence of subcortical damage. The reason seems to rest in the plasticity of cortical areas. As Fecteau and Theoret themselves note, behavior can be restored when a cortical area is destroyed because “the rest of the brain is capable of sustaining function following a brain lesion, and brain plasticity plays a major role in behavioral recovery.” Studies such as Pascual-Leone et al. (2005) and Sanes et al. (1995) show that cortex is redundant and extremely malleable. In contrast, the subcortical brain structures that support cortical-striatal-cortical circuits regulating motor control, language, emotion, and other aspects of behavior (Cummings 1993) are few and do not appear to be capable of restructuring. - Lieberman, 2007.
With this, the discussion will be carried over to the next entry: Click here.
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Neanderthal in the News:
Neanderthal Cloning Project
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