Editing Origin of language (section)

== Evolutionary timeline ==
{{Human timeline}}

=== Primate communication ===
Field primatologists can give useful insights into [[great ape]] communication in the wild.<ref name="Arcadi2000" /> One notable finding is that nonhuman primates, including the other great apes, produce calls that are graded, as opposed to categorically differentiated, with listeners striving to evaluate subtle gradations in signallers' emotional and bodily states. Nonhuman apes seemingly find it extremely difficult to produce vocalisations in the absence of the corresponding emotional states.<ref name="Goodall1986" /> In captivity, nonhuman apes have been taught rudimentary forms of sign language or have been persuaded to use [[lexigrams]]—symbols that do not graphically resemble the corresponding words—on computer keyboards. Some nonhuman apes, such as [[Kanzi]], have been able to learn and use hundreds of lexigrams.<ref>{{Cite book |last1=Savage-Rumbaugh |first1=E. Sue |title=Kanzi: the ape at the brink of the human mind |last2=Lewin |first2=Roger. |publisher=Wiley |year=1994 |isbn=978-0-471-58591-6 |location=New York}}</ref><ref>{{Cite book |last1=Savage-Rumbaugh |first1=E. Sue |url=https://archive.org/details/apeslanguagehuma00sava |title=Apes, language, and the human mind |last2=Shanker |first2=Stuart. |last3=Taylor |first3=Talbot J. |publisher=Oxford University Press |year=1998 |isbn=978-0-19-510986-3 |location=New York}}</ref>

The [[Broca's area|Broca's]] and [[Wernicke's area]]s in the primate brain are responsible for controlling the muscles of the face, tongue, mouth, and larynx, as well as recognizing sounds. Primates are known to make "vocal calls", and these calls are generated by circuits in the [[brainstem]] and [[limbic system]].<ref>Freeman, Scott; Jon C. Herron., ''Evolutionary Analysis'' (4th ed.), Pearson Education, Inc. (2007), {{ISBN|0-13-227584-8}} pages 789–90</ref>

In the wild, the communication of [[vervet monkey]]s has been the most extensively studied.<ref name="Diamond1992" /> They are known to make up to ten different vocalizations. Many of these are used to warn other members of the group about approaching predators. They include a "leopard call", a "snake call", and an "eagle call".<ref>{{Cite journal |last1=Seyfarth |first1=Robert M. |last2=Cheney |first2=Dorothy L. |last3=Marler |first3=Peter |year=1980 |title=Vervet monkey alarm calls: Semantic communication in a free-ranging primate |journal=Animal Behaviour |volume=28 |issue=4 |pages=1070–1094 |doi=10.1016/S0003-3472(80)80097-2 |s2cid=53165940}}</ref> Each call triggers a different defensive strategy in the monkeys who hear the call and scientists were able to elicit predictable responses from the monkeys using loudspeakers and prerecorded sounds. Other vocalisations may be used for identification. If an infant monkey calls, its mother turns toward it, but other vervet mothers turn instead toward that infant's mother to see what she will do.<ref>{{Cite journal |last1=Arnold |first1=Kate |last2=Zuberbühler |first2=Klaus |year=2006 |title=Language evolution: Semantic combinations in primate calls |journal=Nature |volume=441 |issue=7091 |page=303 |bibcode=2006Natur.441..303A |doi=10.1038/441303a |pmid=16710411 |s2cid=4413635 |doi-access=free}}</ref><ref>{{Cite news |last=Wade, Nicholas |date=23 May 2006 |title=Nigerian Monkeys Drop Hints on Language Origin |url=https://www.nytimes.com/2006/05/23/science/23lang.html |access-date=9 September 2007 |work=[[The New York Times]]}}</ref>

Similarly, researchers have demonstrated that chimpanzees (in captivity) use different "words" in reference to different foods. They recorded vocalisations that chimps made in reference, for example, to grapes, and then other chimps pointed at pictures of grapes when they heard the recorded sound.<ref>{{Cite thesis |last=Gibbons |first=Christopher M. |title=The referentiality of chimpanzee vocal signaling: behavioral and acoustic analysis of food barks |publisher=[[Ohio State University]] |url=http://rave.ohiolink.edu/etdc/view?acc_num=osu1173219994 |year=2007}}</ref><ref>{{Cite journal |last1=Slocombe |first1=Katie E. |last2=Zuberbühler |first2=Klaus |year=2005 |title=Functionally Referential Communication in a Chimpanzee |url=http://doc.rero.ch/record/278602/files/Slocombe_K.-Functionally_refererential_20170201172432-HV.pdf |journal=Current Biology |volume=15 |issue=19 |pages=1779–1784 |bibcode=2005CBio...15.1779S |doi=10.1016/j.cub.2005.08.068 |pmid=16213827 |s2cid=6774592}}</ref>

=== ''Ardipithecus ramidus'' ===
A study published in ''HOMO: Journal of Comparative Human Biology'' in 2017 claims that ''[[Ardipithecus ramidus]]'', a hominin dated at approximately 4.5 [[Mega-annum|Ma]], shows the first evidence of an anatomical shift in the hominin lineage suggestive of increased vocal capability.<ref name="Clark2017">{{Cite journal |last1=Clark |first1=Gary |last2=Henneberg |first2=Maciej |year=2017 |title=Ardipithecus ramidus and the evolution of language and singing: An early origin for hominin vocal capability |journal=HOMO |volume=68 |issue=2 |pages=101–121 |doi=10.1016/j.jchb.2017.03.001 |pmid=28363458}}</ref> This study compared the skull of ''A. ramidus'' with 29 chimpanzee skulls of different ages and found that in numerous features ''A. ramidus'' clustered with the infant and juvenile measures as opposed to the adult measures. Such affinity with the shape dimensions of infant and juvenile chimpanzee skull architecture, it was argued, may have resulted in greater vocal capability. This assertion was based on the notion that the chimpanzee vocal tract ratios that prevent speech are a result of growth factors associated with puberty—growth factors absent in ''A. ramidus'' ontogeny. ''A. ramidus'' was also found to have a degree of [[Neck|cervical]] [[lordosis]] more conducive to vocal modulation when compared with chimpanzees as well as cranial base architecture suggestive of increased vocal capability.

What was significant in this study, according to the authors,<ref name="Clark2017" /> was the observation that the changes in skull architecture that correlate with reduced aggression are the same changes necessary for the evolution of early hominin vocal ability. In integrating data on anatomical correlates of primate mating and social systems with studies of skull and vocal tract architecture that facilitate speech production, the authors argue that [[paleoanthropology|paleoanthropologists]] prior to their study have failed to understand the important relationship between early hominin social evolution and the evolution of our species' capacities for language.

While the skull of ''A. ramidus'', according to the authors, lacks the anatomical impediments to speech evident in chimpanzees, it is unclear what the vocal capabilities of this early hominin were. While they suggest ''A. ramidus''—based on similar vocal tract ratios—may have had vocal capabilities equivalent to a modern human infant or very young child, they concede this is a debatable and speculative hypothesis. However, they do claim that changes in skull architecture through processes of social selection were a necessary prerequisite for language evolution. As they write:

{{blockquote|We propose that as a result of paedomorphic morphogenesis of the cranial base and craniofacial morphology ''Ar. ramidus'' would have not been limited in terms of the mechanical components of speech production as chimpanzees and bonobos are. It is possible that ''Ar. ramidus'' had vocal capability approximating that of chimpanzees and bonobos, with its idiosyncratic skull morphology not resulting in any significant advances in speech capability. In this sense the anatomical features analysed in this essay would have been exapted in later more voluble species of hominin. However, given the selective advantages of pro-social vocal synchrony, we suggest the species would have developed significantly more complex vocal abilities than chimpanzees and bonobos.<ref name="Clark2017" />}}

=== Early ''Homo'' ===
Anatomically, some scholars believe that features of [[bipedalism]] developed in the [[australopithecine]]s around 3.5 million years ago. Around this time, these structural developments within the skull led to a more prominently L-shaped vocal tract.<ref>{{Cite book |last1=Aronoff |first1=Mark |title=The handbook of linguistics |last2=Rees-Miller |first2=Janie. |publisher=Blackwell |year=2001 |isbn=0-631-20497-0 |location=Malden, MA <!-- There is a 2017 edition of this book, how about using that one for the missing page -->}}</ref>{{page needed|date=May 2020}} In order to generate the sounds modern ''Homo sapiens'' are capable of making, such as vowels, it is vital that Early Homo populations must have a specifically shaped voice track and a lower sitting larynx.<ref>{{Cite journal |last=Fitch |first=W. Tecumseh |year=2000 |title=The evolution of speech: a comparative review |journal=Trends in Cognitive Sciences |volume=4 |issue=7 |pages=258–267 |doi=10.1016/S1364-6613(00)01494-7 |pmid=10859570 |s2cid=14706592}}</ref> Opposing research previously suggested that [[Neanderthal|Neanderthals]] were physically incapable of creating the full range of vocals seen in modern humans due to the differences in larynx placement. Establishing distinct larynx positions through fossil remains of ''Homo sapiens'' and Neanderthals would support this theory; however, modern research has revealed that the hyoid bone was indistinguishable in the two populations. Though research has shown a lower sitting larynx is important to producing speech, another theory states it may not be as important as once thought.<ref>{{Cite journal |last=Ohala |first=John J. |date=10 September 1987 |title=Experimental Phonology |journal=Annual Meeting of the Berkeley Linguistics Society |volume=13 |page=207 |doi=10.3765/bls.v13i0.1803 |issn=2377-1666 |doi-access=free}}</ref> Cataldo, Migliano, and Vinicius report speech alone appears inadequate for transmitting stone tool-making knowledge, and suggest that speech may have emerged due to an increase in complex social interactions.<ref>{{Cite journal |last1=Cataldo |first1=D. M. |last2=Migliano |first2=A. B. |last3=Vinicius |first3=L. |date=19 January 2018 |title=Speech, stone tool-making and the evolution of language |journal=PLOS ONE |volume=13 |issue=1 |pages=e0191071 |bibcode=2018PLoSO..1391071C |doi=10.1371/journal.pone.0191071 |pmc=5774752 |pmid=29351319 |doi-access=free}}</ref>

=== Archaic ''Homo sapiens'' ===
{{redirect|Hmmmmm|Humming|Humming (disambiguation)}}
{{Further|Archaic humans}}
[[Steven Mithen]] proposed the term ''Hmmmmm'' for the pre-linguistic system of communication posited to have been used by archaic ''[[Homo]]'', beginning with ''[[Homo ergaster]]'' and reaching the highest sophistication in the [[Middle Pleistocene]] with ''[[Homo heidelbergensis]]'' and ''[[Homo neanderthalensis]]''. ''Hmmmmm'' is an acronym for ''h''olistic (non-compositional), ''m''anipulative (utterances are commands or suggestions, not descriptive statements), ''m''ulti-''m''odal (acoustic as well as gestural and facial), [[origin of music|''m''usical]], and ''m''imetic.<ref name="Mithen2006">{{Cite book |last=Mithen |first=Steven J. |title=The singing neanderthals: the origins of music, language, mind, and body |publisher=Harvard University Press |year=2006 |isbn=978-0-674-02192-1 |location=Cambridge, MA}}</ref>

==== ''Homo erectus'' ====
Evidence for ''[[Homo erectus]]'' potentially using language comes in the form of [[Acheulean]] tool usage. The use of abstract thought in the formation of Acheulean hand axes coincides with the symbol creation necessary for simple language.<ref>{{Cite journal |last1=Barham |first1=Lawrence |last2=Everett |first2=Daniel |date=1 June 2021 |title=Semiotics and the Origin of Language in the Lower Palaeolithic |journal=Journal of Archaeological Method and Theory |volume=28 |issue=2 |pages=535–579 |doi=10.1007/s10816-020-09480-9 |issn=1573-7764 |s2cid=225509049 |doi-access=free}}</ref> Recent language theories present [[recursion]] as the unique facet of human language and theory of mind.<ref>{{Cite journal |last1=Vicari |first1=Giuseppe |last2=Adenzato |first2=Mauro |date=May 2014 |title=Is recursion language-specific? Evidence of recursive mechanisms in the structure of intentional action |url=https://linkinghub.elsevier.com/retrieve/pii/S1053810014000555 |journal=Consciousness and Cognition |volume=26 |pages=169–188 |doi=10.1016/j.concog.2014.03.010 |pmid=24762973 |s2cid=206955548 |hdl-access=free |hdl=2318/154505}}</ref><ref>{{Cite journal |last=Corballis |first=Michael |date=2007 |title=The Uniqueness of Human Recursive Thinking |url=https://www.americanscientist.org/article/the-uniqueness-of-human-recursive-thinking |journal=American Scientist |volume=95 |issue=3 |page=240 |doi=10.1511/2007.65.240 |issn=0003-0996}}</ref> However, breaking down language into its symbolic parts: separating meaning from the requirements of grammar, it becomes possible to see that language does not depend on either recursion or grammar. This can be evidenced by the [[Pirahã language|Pirahã]] language users in Brazil that have no myth or creation stories, no numbers and no colors within their language.<ref>{{Cite journal |last=Everett |first=Daniel L. |date=August 2005 |title=Cultural Constraints on Grammar and Cognition in Pirahã: Another Look at the Design Features of Human Language |journal=Current Anthropology |volume=46 |issue=4 |pages=621–646 |doi=10.1086/431525 |issn=0011-3204 |s2cid=2223235 |hdl-access=free |hdl=2066/41103}}</ref> This is to highlight that even though grammar may have been unavailable, use of foresight, planning and symbolic thought can be evidence of language as early as one million years ago with Homo ''erectus''.

==== ''Homo heidelbergensis'' ====
{{See also|Homo_heidelbergensis#Language|l1=Homo heidelbergensis: Language}}
''Homo heidelbergensis'' was a close relative (most probably a migratory descendant) of ''[[Homo ergaster]]''. Some researchers believe this species to be the first hominin to make controlled vocalisations, possibly mimicking animal vocalisations,<ref name="Mithen2006" /> and that as ''Homo heidelbergensis'' developed more sophisticated culture, proceeded from this point and possibly developed an early form of symbolic language.

==== ''Homo neanderthalensis'' ====
{{See also|Neanderthal_behavior#Language|l1=Neanderthal behavior: Language}}
The discovery in 1989 of the (Neanderthal) Kebara 2 hyoid bone suggests that Neanderthals may have been anatomically capable of producing sounds similar to modern humans.<ref>{{Cite journal |last1=Arensburg |first1=B. |last2=Schepartz |first2=L. A. |last3=Tillier |first3=A. M. |last4=Vandermeersch |first4=B. |last5=Rak |first5=Y. |date=October 1990 |title=A reappraisal of the anatomical basis for speech in Middle Palaeolithic hominids |journal=American Journal of Physical Anthropology |volume=83 |issue=2 |pages=137–146 |doi=10.1002/ajpa.1330830202 |pmid=2248373}}</ref><ref>{{Cite journal |last1=D'Anastasio |first1=R. |last2=Wroe |first2=S. |last3=Tuniz |first3=C. |last4=Mancini |first4=L. |last5=Cesana |first5=D. T. |last6=Dreossi |first6=D. |last7=Ravichandiran |first7=M. |last8=Attard |first8=M. |last9=Parr |first9=W. C. |last10=Agur |first10=Anne |last11=Capasso |first11=Luigi |display-authors=8 |year=2013 |title=Micro-biomechanics of the kebara 2 hyoid and its implications for speech in neanderthals |journal=PLOS ONE |volume=8 |issue=12 |pages=e82261 |bibcode=2013PLoSO...882261D |doi=10.1371/journal.pone.0082261 |pmc=3867335 |pmid=24367509 |doi-access=free}}</ref> The [[hypoglossal nerve]], which passes through the hypoglossal canal, controls the movements of the tongue, which may have enabled voicing for size exaggeration (see size exaggeration hypothesis below) or may reflect speech abilities.<ref name="Arensburg1989" /><ref>{{Cite journal |last1=Jungers |first1=W. L. |last2=Pokempner |first2=A. A. |last3=Kay |first3=R. F. |last4=Cartmill |first4=M. |date=August 2003 |title=Hypoglossal canal size in living hominoids and the evolution of human speech. |url=http://www.baa.duke.edu/kay/site/riogallegos/PDFs/j74.pdf |url-status=dead |journal=Human Biology |volume=75 |issue=4 |pages=473–484 |doi=10.1353/hub.2003.0057 |pmid=14655872 |s2cid=30777048 |archive-url=https://web.archive.org/web/20070612035730/http://www.baa.duke.edu/kay/site/riogallegos/PDFs/j74.pdf |archive-date=12 June 2007}}</ref><ref>{{Cite journal |last1=DeGusta |first1=D. |last2=Gilbert |first2=W. H. |last3=Turner |first3=S. P. |date=February 1999 |title=Hypoglossal canal size and hominid speech |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=96 |issue=4 |pages=1800–1804 |bibcode=1999PNAS...96.1800D |doi=10.1073/pnas.96.4.1800 |pmc=15600 |pmid=9990105 |doi-access=free}}</ref><ref>{{Cite book |last=Johansson |first=Sverker |title=Evolution of Language: Sixth International Conference, Rome |date=April 2006 |isbn=9789812566560 |pages=152–159 |chapter=Constraining the Time when Language Evolved |doi=10.1142/9789812774262_0020 |access-date=10 September 2007 |chapter-url=http://urn.kb.se/resolve?urn=urn:nbn:se:du-13687 |archive-url=https://web.archive.org/web/20061015133922/http://www.tech.plymouth.ac.uk/socce/evolang6/johansson_constraining.pdf |archive-date=15 October 2006 |url-status=dead}}</ref><ref>{{Cite journal |last=Houghton |first=P. |date=February 1993 |title=Neandertal supralaryngeal vocal tract |journal=American Journal of Physical Anthropology |volume=90 |issue=2 |pages=139–146 |doi=10.1002/ajpa.1330900202 |pmid=8430750}}</ref><ref>{{Cite journal |last1=Boë |first1=Louis-Jean |last2=Maeda |first2=Shinji |last3=Heim |first3=Jean-Louis |year=1999 |title=Neandertal man was not morphologically handicapped for speech |journal=Evolution of Communication |volume=3 |issue=1 |pages=49–77 |doi=10.1075/eoc.3.1.05boe}}</ref>

However, although Neanderthals may have been anatomically able to speak, [[Richard G. Klein]] in 2004 doubted that they possessed a fully modern language. He largely bases his doubts on the fossil record of archaic humans and their stone tool kit. Bart de Boer in 2017 acknowledges this ambiguity of a universally accepted Neanderthal vocal tract; however, he notes the similarities in the thoracic vertebral canal, potential air sacs, and hyoid bones between modern humans and Neanderthals to suggest the presence of complex speech.<ref>de Boer, Bart (2017). "Evolution of speech and evolution of language". ''Psychonomic Bulletin & Review''. '''24''' (1): 158–162. [[Digital object identifier|doi]]:10.3758/s13423-016-1130-6. [[International Standard Serial Number|ISSN]]&nbsp;1069-9384.</ref> For two million years following the emergence of ''Homo habilis'', the stone tool technology of hominins changed very little. Klein, who has worked extensively on ancient stone tools, describes the crude stone tool kit of archaic humans as impossible to break down into categories based on their function, and reports that Neanderthals seem to have had little concern for the final aesthetic form of their tools. Klein argues that the Neanderthal brain may have not reached the level of complexity required for modern speech, even if the physical apparatus for speech production was well-developed.<ref>{{Cite journal |last=Klarreich |first=E. |year=2004 |title=Biography of Richard G. Klein |journal=Proceedings of the National Academy of Sciences |volume=101 |issue=16 |pages=5705–5707 |bibcode=2004PNAS..101.5705K |doi=10.1073/pnas.0402190101 |pmc=395972 |pmid=15079069 |doi-access=free}}</ref><ref>{{Cite web |last=Klein, Richard G. |title=Three Distinct Human Populations |url=http://www.accessexcellence.org/BF/bf02/klein/bf02e3.html |access-date=10 September 2007 |website=Biological and Behavioral Origins of Modern Humans |publisher=Access Excellence @ The National Health Museum}}</ref> The issue of the Neanderthal's level of cultural and technological sophistication remains a controversial one.{{Citation needed|date=May 2021}}

Based on computer simulations used to evaluate that evolution of language that resulted in showing three stages in the evolution of syntax, Neanderthals are thought to have been in stage 2, showing they had something more evolved than proto-language but not quite as complex as the language of modern humans.<ref>{{Cite journal |last=Marwick |first=Ben |year=2003 |title=Pleistocene Exchange Networks as Evidence for the Evolution of Language |journal=Cambridge Archaeological Journal |volume=13 |pages=67–81 |doi=10.1017/S0959774303000040 |s2cid=15514627 |hdl-access=free |hdl=1885/42089}}</ref>

Some researchers, applying auditory bioengineering models to computerised tomography scans of Neanderthal skulls, have asserted that Neanderthals had auditory capacity very similar to that of anatomically modern humans.<ref name="Conde-Valverde2021">{{Cite journal |last1=Conde-Valverde |first1=Mercedes |last2=Martínez |first2=Ignacio |last3=Quam |first3=Rolf M. |last4=Rosa |first4=Manuel |last5=Velez |first5=Alex D. |last6=Lorenzo |first6=Carlos |last7=Jarabo |first7=Pilar |last8=Bermúdez de Castro |first8=José María |last9=Carbonell |first9=Eudald |last10=Arsuaga |first10=Juan Luis |date=1 March 2021 |title=Neanderthals and Homo sapiens had similar auditory and speech capacities |url=https://www.nature.com/articles/s41559-021-01391-6 |journal=Nature Ecology & Evolution |volume=5 |issue=5 |pages=609–615 |bibcode=2021NatEE...5..609C |doi=10.1038/s41559-021-01391-6 |issn=2397-334X |pmid=33649543 |s2cid=232090739}}</ref> These researchers claim that this finding implies that "Neanderthals evolved the auditory capacities to support a vocal communication system as efficient as modern human speech."<ref name="Conde-Valverde2021" />

=== ''Homo sapiens'' ===
{{See also|Anatomically modern humans|Behavioral modernity}}
Anatomically modern humans begin to [[Omo remains|appear in the fossil record]] in Ethiopia some 200,000 years ago.<ref>{{Cite journal |last1=Fleagle |first1=John G. |last2=Assefa |first2=Zelalem |last3=Brown |first3=Francis H. |last4=Shea |first4=John J. |year=2008 |title=Paleoanthropology of the Kibish Formation, southern Ethiopia: Introduction |journal=Journal of Human Evolution |volume=55 |issue=3 |pages=360–365 |bibcode=2008JHumE..55..360F |doi=10.1016/j.jhevol.2008.05.007 |pmid=18617219}}</ref> Although there is still much debate as to whether behavioural modernity emerged in Africa at around the same time, a growing number of archaeologists nowadays{{When|date=May 2021}} invoke the southern African Middle Stone Age use of red ochre pigments—for example at [[Blombos Cave]]—as evidence that modern anatomy and behaviour co-evolved.<ref>{{Cite journal |last1=Henshilwood |first1=C. S. |last2=d'Errico |first2=F. |last3=Yates |first3=R. |last4=Jacobs |first4=Z. |last5=Tribolo |first5=C. |last6=Duller |first6=G. A. T. |last7=Mercier |first7=N. |last8=Sealy |first8=J. C. |last9=Valladas |first9=H. |last10=Watts |first10=I. |last11=Wintle |first11=A. G. |year=2002 |title=Emergence of modern human behavior: Middle Stone Age engravings from South Africa |journal=Science |volume=295 |issue=5558 |pages=1278–1280 |bibcode=2002Sci...295.1278H |doi=10.1126/science.1067575 |pmid=11786608 |s2cid=31169551}}</ref> These archaeologists argue strongly that if modern humans at this early stage were using red ochre pigments for ritual and symbolic purposes, they probably had symbolic language as well.<ref name="Henshilwood2009" />

According to the [[recent African origin of modern humans|recent African origins hypothesis]], from around 60,000 – 50,000 years ago<ref>{{Cite web |last=Minkel |first=J. R. |date=18 July 2007 |title=Skulls Add to "Out of Africa" Theory of Human Origins: Pattern of skull variation bolsters the case that humans took over from earlier species |url=http://www.sciam.com/article.cfm?articleID=DA5114C2-E7F2-99DF-30BBDDD4415DED90 |access-date=9 September 2007 |publisher=Scientific American.com}}</ref> a group of humans left Africa and began migrating to occupy the rest of the world, carrying language and symbolic culture with them.<ref>Chris Stringer, 2011. ''The Origin of Our Species''. London: Penguin.</ref>

=== 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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| Precursor   =
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| Artery      =
| Vein        =
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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>

=== Phonemic diversity ===
In 2011, Quentin Atkinson published a survey of [[phoneme]]s from 500 different languages as well as [[language families]] and compared their phonemic diversity by region, number of speakers and distance from Africa. The survey revealed that African languages had the largest number of phonemes, and [[Oceanic languages|Oceania]] and [[Languages of South America|South America]] had the smallest number. After allowing for the number of speakers, the phonemic diversity was compared to over 2000 possible origin locations. Atkinson's "best fit" model is that language originated in western, central, or southern Africa between 80,000 and 160,000 years ago. This predates the hypothesized [[Coastal migration|southern coastal peopling]] of Arabia, India, southeast Asia, and Australia. It would also mean that the origin of language occurred at the same time as the emergence of symbolic culture.<ref>{{Cite journal |last=Atkinson |first=Quentin |year=2011 |title=Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa |url=http://www.stat.uchicago.edu/~pmcc/prelims/2011/Atkinson-346-9.pdf |journal=Science Magazine |volume=332 |issue=6027 |pages=346–349 |bibcode=2011Sci...332..346A |doi=10.1126/science.1199295 |pmid=21493858 |s2cid=42021647 |access-date=9 July 2017}}</ref>

Numerous linguists<ref name="Cysouw2012">{{Cite journal |last1=Cysouw |first1=Michael |last2=Dediu |first2=Dan |last3=Moran |first3=Steven |date=10 February 2012 |title=Comment on "Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa" |journal=Science |volume=335 |issue=6069 |page=657 |bibcode=2012Sci...335..657C |doi=10.1126/science.1208841 |pmid=22323802 |ref=Cysouw 2012 |doi-access=free |hdl-access=free |hdl=11858/00-001M-0000-0012-1937-4}}</ref><ref name="Wang2012">{{Cite journal |last1=Wang |first1=Chuan-Chao |last2=Ding |first2=Qi-Liang |last3=Tao |first3=Huan |last4=Li |first4=Hui |date=10 February 2012 |title=Comment on "Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa" |url=https://www.science.org/doi/full/10.1126/science.1207846 |journal=Science |volume=335 |issue=6069 |page=657 |bibcode=2012Sci...335..657W |doi=10.1126/science.1207846 |pmid=22323803 |s2cid=31360222 |access-date=22 October 2023 |ref=Wang 2012}}</ref><ref name="Pereltsvaig2012">{{Cite journal |last1=Pereltsvaig |first1=Asya |last2=Van Tuyl |first2=Rory |date=10 February 2012 |title=Comment on "Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa" |url=https://www.science.org/doi/full/10.1126/science.1209176 |journal=Science |volume=335 |issue=6069 |page=657 |bibcode=2012Sci...335..657V |doi=10.1126/science.1209176 |pmid=22323804 |access-date=22 October 2023 |ref=Pereltsvaig 2012}}</ref> have criticized Atkinson's paper as misrepresenting both the phonemic data and processes of linguistic change, as language complexity does not necessarily correspond to age, and of failing to take into account the borrowing of phonemes from neighbouring languages, as some [[Bantu languages]] have done with click consonants.<ref name="Pereltsvaig2012" /> Recreations of his method gave possible origins of language in the Caucasus<ref name="Cysouw2012" /> and Turkmenistan,<ref name="Wang2012" /> in addition to southern and eastern Africa.