Editing Origin of language (section)

=== Descended larynx ===
{{More citations needed section|date=May 2021}}
[[File:Illu larynx.jpg]]

The [[larynx]] (or ''voice box'') is an organ in the neck housing the [[vocal folds]], which are responsible for [[phonation]]. In humans, the larynx is ''descended''. The human species is not unique in this respect: goats, dogs, pigs and tamarins lower the larynx temporarily, to emit loud calls.<ref>{{Cite journal |last=Fitch |first=W. T. |year=2000 |title=The phonetic potential of nonhuman vocal tracts: comparative cineradiographic observations of vocalizing animals |journal=Phonetica |volume=57 |issue=2–4 |pages=205–218 |doi=10.1159/000028474 |pmid=10992141 |s2cid=202652500}}</ref> Several deer species have a permanently lowered larynx, which may be lowered still further by males during their roaring displays.<ref>{{Cite journal |last1=Fitch |first1=W. T. |last2=Reby |first2=D. |date=August 2001 |title=The descended larynx is not uniquely human |journal=Proceedings of the Royal Society B |volume=268 |issue=1477 |pages=1669–1675 |doi=10.1098/rspb.2001.1704 |pmc=1088793 |pmid=11506679}}</ref> Lions, jaguars, cheetahs and domestic cats also do this.<ref>{{Cite journal |last1=Weissengruber |first1=G. E. |last2=Forstenpointner |first2=G. |last3=Peters |first3=G. |last4=Kübber-Heiss |first4=A. |last5=Fitch |first5=W. T. |date=September 2002 |title=Hyoid apparatus and pharynx in the lion (''Panthera leo''), jaguar (''Panthera onca''), tiger (''Panthera tigris''), cheetah (''Acinonyxjubatus'') and domestic cat (''Felis silvestris'' f. ''catus'') |journal=Journal of Anatomy |volume=201 |issue=3 |pages=195–209 |doi=10.1046/j.1469-7580.2002.00088.x |pmc=1570911 |pmid=12363272}}</ref> However, laryngeal descent in nonhumans (according to Philip Lieberman) is not accompanied by descent of the hyoid; hence the tongue remains horizontal in the oral cavity, preventing it from acting as a pharyngeal articulator.<ref>{{Cite journal |last=Lieberman |first=Philip |year=2007 |title=The Evolution of Human Speech: Its Anatomical and Neural Bases |url=http://www.cog.brown.edu/people/lieberman/pdfFiles/Lieberman%20P.%202007.%20The%20evolution%20of%20human%20speech,%20Its%20anatom.pdf |url-status=dead |journal=Current Anthropology |volume=48 |issue=1 |pages=39–66 |doi=10.1086/509092 |s2cid=28651524 |archive-url=https://web.archive.org/web/20140611203314/http://www.cog.brown.edu/people/lieberman/pdfFiles/Lieberman%20P.%202007.%20The%20evolution%20of%20human%20speech,%20Its%20anatom.pdf |archive-date=11 June 2014 |access-date=3 May 2009}}</ref>
{{Infobox anatomy
| Name        = Larynx
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| Image       = Larynx external en.svg
| Caption     = Anatomy of the larynx, [[anatomical terms of location|anterolateral]] view
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Despite all this, scholars remain divided as to how "special" the human vocal tract really is. It has been shown that the larynx does descend to some extent during development in chimpanzees, followed by hyoidal descent.<ref>{{Cite journal |last1=Nishimura |first1=T. |last2=Mikami |first2=A. |last3=Suzuki |first3=J. |last4=Matsuzawa |first4=T. |date=September 2006 |title=Descent of the hyoid in chimpanzees: evolution of face flattening and speech |journal=Journal of Human Evolution |volume=51 |issue=3 |pages=244–254 |bibcode=2006JHumE..51..244N |doi=10.1016/j.jhevol.2006.03.005 |pmid=16730049}}</ref> As against this, Philip Lieberman points out that only humans have evolved permanent and substantial laryngeal descent in association with hyoidal descent, resulting in a curved tongue and two-tube vocal tract with 1:1 proportions. He argues that Neanderthals and early anatomically modern humans could not have possessed supralaryngeal vocal tracts capable of producing "fully human speech".<ref>{{Cite journal |last1=Lieberman |first1=Philip |last2=McCarthy |first2=Robert C. |last3=Strait |first3=David |year=2006 |title=The Recent Origin of Human Speech |journal=The Journal of the Acoustical Society of America |volume=119 |issue=5 |page=3441 |bibcode=2006ASAJ..119.3441L |doi=10.1121/1.4786937}}</ref> Uniquely in the human case, simple contact between the [[epiglottis]] and [[Soft palate|velum]] is no longer possible, disrupting the normal mammalian separation of the respiratory and digestive tracts during swallowing. Since this entails substantial costs—increasing the risk of choking while swallowing food—we are forced to ask what benefits might have outweighed those costs. The obvious benefit—so it is claimed—must have been speech. But this idea has been vigorously contested. One objection is that humans are in fact not seriously at risk of choking on food: medical statistics indicate that accidents of this kind are extremely rare.<ref>M. Clegg 2001. The Comparative Anatomy and Evolution of the Human Vocal Tract Unpublished thesis, University of London.</ref> Another objection is that in the view of most scholars, speech as it is known emerged relatively late in human evolution, roughly contemporaneously with the emergence of ''Homo sapiens''.<ref>{{Cite journal |last1=Perreault |first1=C. |last2=Mathew |first2=S. |year=2012 |title=Dating the origin of language using phonemic diversity |journal=PLOS ONE |volume=7 |issue=4 |pages=e35289 |bibcode=2012PLoSO...735289P |doi=10.1371/journal.pone.0035289 |pmc=3338724 |pmid=22558135 |doi-access=free}}</ref> A development as complex as the reconfiguration of the human vocal tract would have required much more time, implying an early date of origin. This discrepancy in timescales undermines the idea that human vocal flexibility was initially driven by selection pressures for speech, thus not excluding that it was selected for e.g. improved singing ability.

==== Size exaggeration hypothesis ====
To lower the larynx is to increase the length of the vocal tract, in turn lowering [[formant]] frequencies so that the voice sounds "deeper"—giving an impression of greater size. John Ohala argues that the function of the lowered larynx in humans, especially males, is probably to enhance threat displays rather than speech itself.<ref>John J. Ohala, 2000. [http://linguistics.berkeley.edu/~ohala/papers/lowered_larynx.pdf The irrelevance of the lowered larynx in modern Man for the development of speech.] Paris, ENST: ''The Evolution of Language'', pp. 171–172.</ref> Ohala points out that if the lowered larynx were an adaptation for speech, adult human males would be expected to be better adapted in this respect than adult females, whose larynx is considerably less low. However, females outperform males in verbal tests,<ref>{{Cite journal |last1=Barel |first1=Efrat |last2=Tzischinsky |first2=Orna |date=June 2018 |title=Age and Sex Differences in Verbal and Visuospatial Abilities |journal=Advances in Cognitive Psychology |volume=2 |issue=14 |pages=51–61 |doi=10.5709/acp-0238-x |pmc=7186802 |pmid=32362962}}</ref> falsifying this whole line of reasoning.

[[W. Tecumseh Fitch]] likewise argues that this was the original selective advantage of laryngeal lowering in the human species. Although (according to Fitch) the initial lowering of the larynx in humans had nothing to do with speech, the increased range of possible formant patterns was subsequently co-opted for speech. Size exaggeration remains the sole function of the extreme laryngeal descent observed in male deer. Consistent with the size exaggeration hypothesis, a second descent of the larynx occurs at puberty in humans, although only in males. In response to the objection that the larynx is descended in human females, Fitch suggests that mothers vocalizing to protect their infants would also have benefited from this ability.<ref>Fitch, W. T. (2002). Comparative vocal production and the evolution of speech: Reinterpreting the descent of the larynx. In A. Wray (ed.), ''The Transition to Language''. Oxford: Oxford University Press, pp. 21–45.</ref>