Neandertal vocal tract reconstructions: A critical appraisal

D. B. Burr Department of Anthropology, University of Colorado, Boulder, Colorado 80302, U.S.A. Received 2 May 1975 and accepted 2 July 1975

Neandertal Vocal Tract Reconstructions : A Critical Appraisal Although numerous arguments have been advanced against Lieberman & Crelin’s hypothesis that Neandertal man lacked fully developed human speech, few of these have been noted in the recent literature. Fewer still have criticized Lieberman & Crelin specifically on their anatomical approach. This is, however, perhaps the weakest point in the hypothesis. The method of vocal tract reconstruction used by Lieberman & Crelin was not accurate due to the use of casts which are stylized models rather than accurate representations. Their comparisons of human newborns and adult Neandertal can be criticized on many grounds. Furthermore, their attempt to analyze the total functional complex underlying speech fails because of their inability to use parallel resonators in the acoustic analysis. Their method of placement of the larynx may be subject to errors due to deformation of the fossil, drying of the skull, and effects of fossilization. Relations between the tongue and larynx upon which Lieberman & Crelin’s conclusions are partly based are totally invalid. Their conceptions of the posture of fossil men are also in error. Although Lieberman & Crelin retreat from the usual formation of hypotheses based on speculation alone, the anatomic reconstructions are a weak link in their hypothesis. Until this weakness can be corrected, their contribution towards solving the question of speech in Neandertals remains limited.

Although numerous arguments have been advanced against Lieberman & Crelin’s hypothesis that certain Neandertals lacked fully human articulation, few of these have been presented in the recent literature. Kolata (1974: 619) states: “The anatomical arguments against the proposed articulatory limitations of Neandertals are advanced by those who doubt that a correct model of the vocal tract of a fossil can be constructed from the physical characteristics of its skull.”

None of the anatomical arguments which may be advanced against Lieberman & Crelin’s work, however, need have its foundation in the above assumption. The purpose of this paper is to identify the anatomical arguments against the hypothesis. Although Siegel & Carlisle (1974) and LeMay (1975) have been notable in their criticism of Lieberman & Crelin, this paper attempts to expand their criticisms and to maintain a strictly anatomical approach to the problem. Lieberman & Crelin compared measures of functional aspects of the cranial base of certain Neandertals with those of the skull bases of six infants and fifty adults. Based on these comparisons of cranial base morphology they reconstructed the soft parts of the vocal anatomy. Using a computerized model, they analyzed the reconstructed vocal tracts acoustically, concluding that some “Classic” Neandertals did not have fully articulate speech. One of the foremost problems with the work of Lieberman & Crelin lies in the method of measurement from which the reconstruction of the La Chapelle vocal tract was made. For these measurements three major sources were used: casts from the University of Pennsylvania, photographs, and the original specimen in Paris (Lieberman & Crelin, Journal of Human Evolution (1976) 5, 285-290

286

D.

B.

BURR

1971). The original, however, could not be used for the modelling procedure, and my own examination of the University of Pennsylvania casts of the La Chapelle specimen has indicated that they are of poor quality. The reconstructions of the nasal passages could not have been accurately modelled directly from the cast since these airways are not open. Lieberman & Crelin based the reconstruction of the nasal region on the length and posterior inclination of the vomer, and on the angle of the basi-occipital between the foramen magnum and the sphenoid. The cast, however, is not an accurate representation of this region. In the original specimen the sphenoid bone is entirely missing, and between the reconstructed sphenoid and the vomer there is a gap of nine millimeters. In the Pennsylvania cast, the sphenoid and the basi-occipital meet at the synchondrosis in a perfectly shaped shallow arch. From this, Lieberman h Crelin conclude that La Chapelle had a shallow nasopharyngeal arch. What in fact has happened is that the sphenoid has been lowered and the cranial base artifically shaped. Consequently, the angle of the basi-occipital just posterior to the synchondrosis is lowered. Lieberman & Crelin’s reconstruction of the Neandertal vocal tract was also based on observed differences between it and the skulls of six human newborns (Lieberman & Crelin, 1971). This is a risky basis for reconstruction. Le Gros Clark (1959) points out that if comparisons were made between infant apes and adult human skulls, the conclusion might be drawn that the infant ape had articulate speech. Allometric growth negates any justification for comparisons across certain age barriers; characteristics appear at certain ages in response to certain selective pressures. While Lieberman & Crelin (197 1) have accounted for differences in relative size, the large correlation between shape and absolute size is not considered. Though the skull bases may be only slightly affected by tooth eruption and muscular forces, “aspects of total mandibular growth are directly affected by muscular function, the eruption of the teeth, and the growth of the condylar region of the mandible” (Gray, 1957: 619). Is it valid, then, to compare specimens in which these forces have had the chance to act, and those in which they have not, and to conclude on the basis of some morphological similarities that similarities existed in function? There are a number of morphological similarities between the skulls of Neandertal and human newborns. However, some of these similarities, such as the lack of well developed mastoid processes or lack of a chin (Lieberman, Crelin & Klatt, 1972) have no relation to articulate speech (Siegel & Carlisle, 1974). Lieberman & Crelin have replied that such likenesses illustrate similarities in the total anatomical complex of human newborn and adult Neandertal cranial base morphology (1974). The question can be raised: what bearing do these characteristics have on the total anatomical complex related to articulated speech? They are, in my opinion, not functionally related to speech, and are therefore of little value in this context. Lieberman & Crelin have, in effect, concluded that since there are observable similarities in the two crania, the speech capabilities of each must be similar. By basing their reconstruction of La Chapelle’s vocal tract even partly on resemblances to the newborn human, they have effectively drawn their conclusion before performing the acoustic analysis. The comparison of newborns and Neandertal is further endangered by conclusions which can be, but ought not to be, drawn on the basis of the old axiom “ontogeny recapitulates phylogeny”. Lieberman & Crelin (197 1)) Crelin (personal communication) and Lieberman (1972) feel that the law is a valid basis for conclusions concerning the phylogenetic history of H. sapiens. It requires only a meagre knowledge of evolutionary

NEANDERTAL

VOCAL

TRACT

REcONSTRGCT~~NS

287

theory to understand that if evolution were directed by past failures rather than by what is selectively advantageous at the moment, this world would be devoid of life entirely. Morphologically, man has changed in the last 40,000 years. The infant is no exception. Many researchers have indicated the danger of falling into the trap of recapitulation. Wind (1970: 111) stated: “Problems in comparing phylogeny with ontogeny may arise from lack of reliable means of comparison . . . . reasonable comparison in a Haeckelian sense between phylogeny and ontogeny is only possible when there is a comparable stage discernible between the two processes.”

A modern human infant and an adult Neandertal can hardly be considered “comparable stages.” Simpson (1966) and Siegel & Carlisle (1974) have made similar points. Lieberman & Crelin used a computerized acoustic analysis to determine the limits of sound production for the reconstructed Neandertal vocal apparatuses. Although this allowed them to suppose a variable pharyngeal size, it could not accommodate parallel resonators. Yet researchers have noted that the maxillary sinuses and nasal airways are important to sound production (Greene, 1957). Others have noted that the nasal cavity may serve as a resonator only for high pitched tones, while the sinuses may add to the forced vibration of the tone in this case (Kaplan, 1960). It is interesting to note in this regard that the sinuses enlarge and differentiate rapidly at the time of puberty, during which the quality of the voice-both in men and women-also changes drastically. Therefore, it would be valuable to analyze acoustically the effect that the nasal airways, large sinuses, and thick facial bones of the Neandertais had on resonation. Perhaps Lieberman & Crelin’s (1971) suggestion that La Chapelle had a “nasal or seminasal” quality in his speech would be changed. At any rate, it is clear that Lieberman & Crelin have drawn some of their conclusions concerning the quality of Neandertal vocalization prematurely, on the basis of only part of the evidence, and have failed in their attempt to analyze the total functional complex underlying articulate speech. While Lieberman & Crelin quite correctly point out the importance of the position of the larynx in determinations of pharynx and tongue size, their method of placement leaves much to be desired. Since the stylohyoid muscle attaches at one end to the styloid process, and to the moveable hyoid bone at the other, the angle of the styloid plate, they hypothesize, should provide an accurate measure of the angle of this muscle in a fossil individual. This in turn allows the assessment of the localization of the larynx and epiglottis (Lieberman & Crelin, 1971). Three questions present themselves regarding the use of this method in fossil individuals: What effect does drying the skull have upon the angulation of the styloid process, and what effects occur as a result of fossilization? To my knowledge, neither of these questions is answerable at present. With specific regard to the La Chapelle specimen, what effect would an artificially crushed base have on the angulation of the styloid process ? This question can be answered. Common sense tells us that if the skull base were flattened in the direction of the cranial vault, the angle of the styloid would decrease with respect to the cranial base. Consequently, the larynx would appear to have been positioned higher than it actually was. This is, in fact, what Lieberman & Crelin found. Earley, 1975) notes that the position of the larynx Crelin (personal communication; is a function of the length of the tongue. He suggests that in the La Chapelle specimen localization of the laryngeal-pharyngeal juncture as in man would imply a tongue too

D.

288

B. BURR

If the larynx were placed higher this would not allow free long for efficient articulation. vibration of the glottis or freedom for the velum, and it would shorten the pharyngeal resonating cavity. What Crelin fails to note is that the length of the tongue is of little importance culation.

Keaster

(1940:

256) pointed

in arti-

out:

“ . . . speech is the least impaired of all the functions in cases of tongue amputation . . . . The patients studied have difficulty in deglutition and mastication, but they can and do speak without a tongue.” Greene

(1937 : 1970) also suggests that the tongue is not essential in speech:

‘L. . . . it has been demonstrated many times that defects of the tongue very often produce only minor defects of speech. Even with the total loss of the tongue, it has been shown that one can speak fairly well, though some of the sounds will be missing.” Froeschels

(1933)

came

cases in which limited standable

to the same conclusion, tongue movement

The importance

speech.

point out, lies in changing

Siegel

& Carlisle is restricted

material.

(1974)

as Lieberman,

Crelin

& Klatt

This tinction

cavity.

report

and under(1972)

is performed

a very long tongue would not necessarily

note that the choice

and clearly

Although

sample

Lieberman

& Crelin

Puccioni

is representative

rather

negate

(1974)

(19 14) and Morant

(1936)

skulls by Lieberman

some Australian

have countered of human

both found significant of the mandible,

&

aboriginal

with the fact that they

than with isolated measures,

for the wide range

groups in the form and structure

has pointed

of the modern

does not take into account

are dealing with a total complex

racial

(1944)

to adequate

articulation.

Crelin

their

of the tongue, Thus,

& Moser

no hindrance

the shape of the pharyngeal

with the root of the tongue only. efficient

while Frowine

presents

it is still doubtful

vocal

tract

variations

if

morphology;

between

while Brosnahan

various

(1961:

76)

out that

‘I . . . the no less observable fact of differences in the vocal apparatuses of individuals has tended to be neglected. . . . Like every bodily apparatus this is subject to differences between individuals and groups in respect to its bones, muscles, . . . structure and organization as a whole, and its pattern of functioning.” Underlying concerning Keith’s larynx (1949:

the work of Lieberman the

upright

reconstructions relative

posture

of the Rhodesian

to the pharynx

& Crelin

of certain

seems to be a basic misunderstanding

Neandertals.

man

Lieberman

as evidence

in Neandertals.

These

(1968)

presents

for the high position

are taken

directly

from

of the Negus

190) who states:

“Neanderthal man had a greater palate area for use in grinding food, but he had a higher larynx because of his slouching attitude and more prominent snout; the total was that he approximated more closely to the type of Apes.” Lieberman assessment

& Crelin by Keith

have reconstructed

the Rhodesian

and Negus that the Rhodesian

man vocal

individual

tract

based on the

possessed a sloping verte-

bral column.

Yet, according to Sergi (1930-1932), the position of the foramen magnum in the Rhodesian individual, which in other characters is highly divergent from modern men, scarcely differs at all from modern populations; Straus & Cave (1957) have shown that the posture of Neandertals was in no way deviant from that of modern populations. Sloping posture might be associated with a change in the size and cephalo-caudal orientation

of the pharynx.

Although

Lieberman

(personal

communication)

discounts

NEANDERTAL

VOCAL

TRACT

RECONSTRUCTIONS

289

the effect of upright posture, Bosma & Fletcher (1961) note that human crania-vertebral angulation allows the rectilinear relation of the meso-pharynx and nasopharynx so important in articulated speech. Sloping posture would have affected the Broken Hill individual’s ability to articulate by decreasing this angle of the vocal tract. It is only natural, then, that any vocal tract reconstruction which is based on an inaccurate skull base reconstruction must be unreliable. Given the ability to reconstruct accurately the soft tissue anatomy from the hard one, Lieberman & Crelin’s anatomical reconstructions can be criticized on numerous valid grounds. Though their work signals a breakthrough in that it retreats from mere conjectural hypotheses concerning the development of early hominid vocalization, their anatomic reconstructions are a weak link in an otherwise strong hypothesis. Yet these reconstructions, the premise upon which their work is based, are vital to the validity of Lieberman & Crelin’s conclusions. Until doubt concerning these reconstructions is removed their conclusions cannot readily be accepted. The author expresses his appreciation to Dr Gordon W. Hewes and Dr Dennis P. Van Gerven for criticisms and suggestions in the early stages of this investigation, and to Dr Alice M. Brues for comments upon the final manuscript. References Bosma, J. F. & Fletcher, S. G. (1961). The upperpharynx, a review. Part I: embryology and anatomy. Annals of Otology, Rhinology, and Laryngology 70, 53-73. Brosnahan, L. F. (1961). The sounds of language. An inquiry into the role of genetic factors in the development of sound systems. Cambridge: Heffers. Earley, K. (1975). The voice of Neanderthal. The Sciences 15, 1 l-15. Froeschels, E. (1933). Speech Therapy. Boston: Expression Co. Frowine. V. K. & Moser. H. (1944). Relationship of dentition to speech. Journal of the American Dental Association 31, 1081-1096. . Gray, G. W. (1957). Speech sound formation. In Handbook of Speech Pathology. (L. E. Travis, ed.). New York: Appleton-Century-Crofts, Inc. Greene, J. S. (1937). Speech defects and related oral anomalies. Journal of the American Dental Association, Dental Cosnws 24, 1969-1974. Greene, M. C. L. (1957). The Voice and Its Disorders. New York: The Macmillan Company. Kaplan, H. (1960). Anatomy and Physiology of Speech. New York: McGraw-Hill Book Company, Inc. Keaster, J. (1940). Studies in the anatomy and physiology of the tongue. LatyngoscOpe50, 222-257. was language a factor? Science 186, 618-619. Kolata, G. B. (1974). The demise of the Neandertals: LeGros Clark, W. E. (1959). The Antecedents of Man. New York: Harper and Row, Publishers. LeMay, M. ( 1975). The language capability of Neanderthal man. American Journal of Physical Anthropology 42,9-14. Lieberman, P. (1968). Primate vocalizations and human linguistic ability. Journal of the Acoustical Society of America 44, 1574-1584. Lieberman P. (1972). The Speech of Primates. The Hague: Mouton. Lieberman, P. & Crelin, E. S. (1971). On the speech of Neanderthal man. Linguistic Inquiry 2, 203-222. Lieberman, P. & Crelin, E. S. (1974). Speech and Neanderthal man: a reply to Carlisle and Siegel. American Anthropologist 76,323-325. Lieberman, P. Crelin, E. S. & Klatt, D. H. (1972). Phonetic ability and related anatomy of the newborn and adult human, Neanderthal man, and the Chimpanzee. American Anthropologist 74, 287-307. Morant, G. (1936). A biometric Study of the human mandible. Biometrika 28,84-122. Negus, V. E. (1949). The Comparative Anatomy and Physiology of the Larynx. London: William Heinemann Medical Books, Ltd. Puccioni, N. (1914). Morphologie du maxillaire inferieur. Anthropologic 25, 291-321. Sergi, S. (1930-1932). La posizione e la inclinazione de1 forame occipitale nel crania neandertaliano di Saccopastore. Rivista Anthropologia 29, 563-657. Siegel, M. I. & Carlisle, R. C. (1974). Some problems in the interpretation of Neanderthal speech capabilities: a reply to Lieberman. American Anthropologist 76, 319-323. 4

290

D.

B. BURR

Simpson, G. G. (1966). The biological nature of man. Science 152,472478. Straws, W. L. & Cave, A. J. E. (1957). Pathology and posture of the Neanderthal man. Qwrferb Reoinu of Biology 32,348-363. Wind, J. (1970). On the Phylogeny and Ontogeny of the Human Larynx: A Morphological and Functional Study. Groningen: Walters-Noordhoff PubIishing.