Human sound systems are shaped by post-Neolithic changes in bite configuration
The first fricatives
In 1985, the linguist Charles Hockett proposed that the use of teeth and jaws as tools in hunter-gatherer populations makes consonants produced with lower lip and upper teeth (“f” and “v” sounds) hard to produce. He thus conjectured that these sounds were a recent innovation in human language. Blasi et al. combined paleoanthropology, speech sciences, historical linguistics, and methods from evolutionary biology to provide evidence for a Neolithic global change in the sound systems of the world's languages. Spoken languages have thus been shaped by changes in the human bite configuration owing to changes in dietary and behavioral practices since the Neolithic.
Science, this issue p. eaav3218
Structured Abstract
INTRODUCTION
Human speech manifests itself in spectacular diversity, ranging from ubiquitous sounds such as “m” and “a” to the rare click consonants in some languages of southern Africa. This range is generally thought to have been fixed by biological constraints since at least the emergence of Homo sapiens. At the same time, the abundance of each sound in the languages of the world is commonly taken to depend on how easy the sound is to produce, perceive, and learn. This dependency is also regarded as fixed at the species level.
RATIONALE
Given this dependency, we expect that any change in the human apparatus for production, perception, or learning affects the probability—or even the range—of the sounds that languages have. Paleoanthropological evidence suggests that the production apparatus has undergone a fundamental change of just this kind since the Neolithic. Although humans generally start out with vertical and horizontal overlap in their bite configuration (overbite and overjet, respectively), masticatory exertion in the Paleolithic gave rise to an edge-to-edge bite after adolescence. Preservation of overbite and overjet began to persist long into adulthood only with the softer diets that started to become prevalent in the wake of agriculture and intensified food processing. We hypothesize that this post-Neolithic decline of edge-to-edge bite enabled the innovation and spread of a new class of speech sounds that is now present in nearly half of the world’s languages: labiodentals, produced by positioning the lower lip against the upper teeth, such as in “f” or “v.”
RESULTS
Biomechanical models of the speech apparatus show that labiodentals incur about 30% less muscular effort in the overbite and overjet configuration than in the edge-to-edge bite configuration. This difference is not present in similar articulations that place the upper lip, instead of the teeth, against the lower lip (as in bilabial “m,” “w,” or “p”). Our models also show that the overbite and overjet configuration reduces the incidental tooth/lip distance in bilabial articulations to 24 to 70% of their original values, inviting accidental production of labiodentals. The joint effect of a decrease in muscular effort and an increase in accidental production predicts a higher probability of labiodentals in the language of populations where overbite and overjet persist into adulthood. When the persistence of overbite and overjet in a population is approximated by the prevalence of agriculturally produced food, we find that societies described as hunter-gatherers indeed have, on average, only about one-fourth the number of labiodentals exhibited by food-producing societies, after controlling for spatial and phylogenetic correlation. When the persistence is approximated by the increase in food-processing technology over the history of one well-researched language family, Indo-European, we likewise observe a steady increase of the reconstructed probability of labiodental sounds, from a median estimate of about 3% in the proto-language (6000 to 8000 years ago) to a presence of 76% in extant languages.
CONCLUSION
Our findings reveal that the transition from prehistoric foragers to contemporary societies has had an impact on the human speech apparatus, and therefore on our species’ main mode of communication and social differentiation: spoken language.
Labiodentals depend on bite configuration.
Biomechanical modeling shows that labiodental sounds like “f” are easier to produce (and to accidentally arise) under overbite and overjet (A) than under the edge-to-edge bite (B) that prevailed before the Neolithic (C). Overbite and overjet persisted only when exposed to the softer diets that became characteristic with food production (D versus E) and more recently with intensified food processing (F). Both developments led to a spread of labiodental sounds.
Abstract
Linguistic diversity, now and in the past, is widely regarded to be independent of biological changes that took place after the emergence of Homo sapiens. We show converging evidence from paleoanthropology, speech biomechanics, ethnography, and historical linguistics that labiodental sounds (such as “f” and “v”) were innovated after the Neolithic. Changes in diet attributable to food-processing technologies modified the human bite from an edge-to-edge configuration to one that preserves adolescent overbite and overjet into adulthood. This change favored the emergence and maintenance of labiodentals. Our findings suggest that language is shaped not only by the contingencies of its history, but also by culturally induced changes in human biology.
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Supplementary Material
Summary
Supplementary Text
Figs. S1 to S33
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Published In
Science
Volume 363 • Issue 6432 • 15 March 2019
History
Received: 26 September 2018
Accepted: 6 February 2019
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Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.
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NWO VIDI: 276-70-022
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EURIAS:
RE: Regarding eLetter "RE: Some remarks on the analysis of labiodentals in Indo-European" posted by Alexander Piperski.
We have posted a response on OSF:
https://osf.io/fhprd/
Best,
- The authors
RE: RE: Labiodental fricatives /f v/ are less present in languages having a small number of consonants
This eLetter is based on a Technical Comment by Berthommier and Boë that was rejected by the editors of Science after we (the authors) of the original manuscript were given the chance to respond.
In short and in light of B & B's false criticisms, we did:
1. Control for the number of segments
2. Discuss the case of Australia (at length)
3. Discuss various other misunderstandings in their comment
Therefore, we have updated our original response and made it available on OSF (where we published our supplementary materials, data, and code):
https://osf.io/s45bx/
- The authors
RE: Regarding eLetter "RE: 2 reasons to refute Hockett's hypothesis that bite configuration affects human sound evolution" posted by Sergei Tarasov.
We have posted a response on bioRxiv:
https://doi.org/10.1101/2020.02.27.965400
Best,
- The authors
RE: Regarding eLetter "RE: Labiodental mechanics" posted by Maziar Tajick
Regarding eLetter "RE: Labiodental mechanics" posted by Maziar Tajick
We have posted a response on OSF:
https://osf.io/m8jb3/
Best,
- The authors
RE: 2 reasons to refute Hockett's hypothesis that bite configuration affects human sound evolution
Blasi et al. ground their conclusion on evidence from ethnography, historical linguistics and speech biomechanics. We reanalyze the data in Blasi et al. and demonstrate that the first 2 sources do not support their findings and Hockett's hypothesis -- that languages of hunter-gatherers are less likely to develop labiodentals sounds. The negative association between labiodentals and hunter-gatherers instead appears to be an artifact of labiodental decline with increasing distance from Africa, which is a general trend of language phonemes.
Read our detailed study at https://www.biorxiv.org/content/10.1101/2020.02.20.957407v1
RE: Labiodental fricatives /f v/ are less present in languages having a small number of consonants
Abstract: We have found a significant relationship between the consonant inventory size and labiodentals /f v/. The geographical distribution of small inventory size languages overlaps with Hunter-Gatherers populations, leading to a possible confusion. The particular characteristics of Australia are detailed because symptomatic of this confusion.
In Blasi et al. (Fig. S3, Research Article, 15 March 2019), it is shown that pseudo-BMA weights capture more than 90% in models including subsistence mode and having all non-labiodental segments as reference, « thus lending support to the notion that subsistence plays a role in accurately predicting labiodental counts ». We have found by another approach that the frequency of the two main labiodental segments /f v/ strongly depends on the count of all segments. The conditional probability of having phoneme /f/ or /v/ given the consonant inventory size, P(/x/|Size) was calculated from counts in UPSID451 (Figure 1A https://doi.org/10.6084/m9.figshare.8846216.v1). We have divided the set of 451 languages into 2 classes (Small/S and Average+Large/AL) from the 5 classes described in WALS (4), with a limit set at 19 consonants (S < 19; AL >= 19). S-class languages (n=164; average number=14.6) have a lower probability of having /f/ or /v/ compared to AL languages with a medium or large consonant inventory (n=287; average number=27) (P(/f/|S)=0.21; P(/f/|AL)=0.51; Percentage comparison test: p<0.001; P(/v/|S)=0.07; P(/v/|AL)=0.29; p<0.001). This suggests that consonant inventory size is a possible confounding factor. The geographical distribution of language classes S and AL established in WALS (Figure 1B https://doi.org/10.6084/m9.figshare.8846216.v1) confirms that S-Class languages overlap with Hunter-Gatherers (HG) populations. S-class distribution is similar to this of "no labiodental" in figures D and E of the abstract of (1) whatever the subsistence class. HG populations are located mainly in Oceania and America. We also checked locally that labiodental fricative frequency is comparable to world means in Papua-New-Guinea (P(/f/|S)=0.19 and P(/v/|S)=0.03 for the 37 S-class languages in UPSID451 (2)) and South America (P(/f/|S)=0.11 and P(/v/|S)=0.05 for the 44 S-class languages). This is well established that phonetic diversity decreases according the distance from Africa (3). This leads to small inventory sizes in distant regions and consequently there is a selective pressure to decrease at the same time the labiodental count. It arises that if most HG have S-Class languages then HG have less labiodental fricatives. Consequently, the subsistence type could be a proxy for evaluating the labiodental count. We suspect that the capture of 90% weight by the subsistence mode models is related to this link between the HG type and the number of segments (which is given when all non-labiodental segments are taken as reference).
It is also shown in (Fig. S3, (1)) that pseudo-BMA weights are greatly increased in the fricative as control condition for the baseline model (about 65% in AUTOTYP and about 30% in the GMR dataset) in which subsistence is not included. First, we see in figures D and E (provided in the abstract of (1)) that food producers and HG have similar "no labiodental/labiodentals(s)" proportions in America and Oceania, with exclusion of Australia having HG only. The number of "no labiodental" points is much higher. Subsistence type appears as a non informative parameter in these regions. Second, we established as for /f v/ that the frequency of non-labiodental fricatives also depends on the consonant inventory size. We have found similar and significant S/AL differences for /z ʃ/ and tendencies for /s ʒ/. Then, we suspect a close relationship between these two observations combined and the increase of the pseudo-BMA weights of the baseline model (without subsistence information) in the fricative as control condition. In this case, non-labiodental fricatives could be a proxy for evaluating the labiodental fricative count, better than the subsistence type as seen before. Let remark that Australia could strongly contribute to this effect since labiodental fricatives are extremely rarely present without non-labiodental fricatives.
A systematic count of the 22 pulmonic fricatives /ɸ β f v θ ð s z ʃ ʒ ʂ ʐ ç ʝ x ɣ χ ʁ ħ ʕ h ɦ/ was carried out with PHOIBLE (5) in the n=343 Australian languages. Apart from the 2 reported labiodental fricatives /f/, a total of 81 non-labiodental fricatives were observed. However, this is mainly composed of 65 /β ð ɣ/ segments and these are not uniformly distributed throughout Australia. 61 of the non-labiodental fricatives are present in the northern Queensland region as well as one reported /f/ in Kunjen language. This has /f/ not in isolation but together with /ð ɣ/. We conclude that the use of fricative manner of articulation is rare but significant only in the northern regions of Australia. Then, the absence of labiodental fricatives has to be considered as a consequence of the absence of fricatives and not in isolation. We agree there is no general constraint against fricatives but we assume that this pattern is a typical consequence of structural constraints existing in linguistic systems, enhanced by the small size of the consonant inventory (6).
Because the absence of fricatives is not explained by the subsistence factor, the relationship between the absence of labiodentals and the presence of HG in Australia has to be carefully considered. Blasi et al. (1) argue that non fricative labiodentals « are options that could have easily arisen in Australia if there were no bias against labiodentals and only a bias against fricatives ». In Australian languages, we find features including nasal, approximant, tap/flap, trill, and lateral approximant (5,7). First, trill and lateral approximant are never associated with labiodentals articulation. The nasal /ɱ/ and tap/flap /ⱱ/ are only present in African languages furthermore having large consonant inventories. Similarly, the approximant /ʋ/ is mostly present in Indo-European AL-class languages. Thus, their adoption in Australian S-Class languages could not be as "easy".
In UPSID451 we observe a rarefaction of labiodental fricatives /f v/ as well as other fricatives such as /z ʃ/ when the size of the consonant inventory decreases. The production of the latter is obviously not related to the bite configuration. Another hypothesis is to consider that linguistic factors (phoneme selection and general mechanisms for constructing phoneme inventories) are the main drivers of language evolution rather than anatomical factors. The observations could be a by-product of an overlap between HG populations and S-class languages influenced by these linguistic factors. Therefore, to rule out this hypothesis, analyses might be performed using the same standardized phonetic sets.
References
[1] D. E. Blasi, S. Moran, S. R. Moisik, P. Widmer, D. Dediu, B. Bickel, Human sound systems are shaped by post-Neolithic changes in bite configuration. Science 363, 3432 (2019). doi:10.1126/science.aav3218
[2] I. Maddieson, K. Precoda, Updating UPSID. UCLA Working Papers in Phonetics 74, 104-111 (1990)
[3] Q. Atkinson, Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa. Science 332, 346-9 (2011). doi: 10.1126/science.1199295
[4] I. Maddieson, Consonant Inventories. In The World Atlas of Language Structures Online, M. S. Dryer, M. Haspelmath, Eds. (Leipzig: Max Planck Institute for Evolutionary Anthropology, 2013)
[5] S. Moran, D. McCloy, R. Wright, PHOIBLE Online (Max Planck Institute for Evolutionary Anthropology, Leipzig, 2014); https://phoible.org/.
[6] B. Lindblom, I. Maddieson, Phonetic Universals in Consonant Systems. In Language, Speech and Mind, C. Li, L. M. Hyman, Eds. (London: Routledge, 1988), pp. 62-78.
[7] E. Gasser, C. Bowern, in Proceedings of the 2013 Annual Meeting on Phonology (2014). doi: http://dx.doi.org/10.3765/amp.v1i1.17
RE: Labiodental fricatives /f v/ are less present in languages having a small number of consonants
Abstract: We have found a significant relationship between the consonant inventory size and labiodentals /f v/. The geographical distribution of small inventory size languages overlaps with Hunter-Gatherers populations, leading to a possible confusion. The particular characteristics of Australia are detailed because symptomatic of this confusion.
In Blasi et al. (Fig. S3, Research Article, 15 March 2019), it is shown that pseudo-BMA weights capture more than 90% in models including subsistence mode and having all non-labiodental segments as reference, « thus lending support to the notion that subsistence plays a role in accurately predicting labiodental counts ». We have found by another approach that the frequency of the two main labiodental segments /f v/ strongly depends on the count of all segments. The conditional probability of having phoneme /f/ or /v/ given the consonant inventory size, P(/x/|Size) was calculated from counts in UPSID451. We have divided the set of 451 languages into 2 classes (Small/S and Average+Large/AL) from the 5 classes described in WALS (4), with a limit set at 19 consonants (S < 19; AL >= 19). S-class languages (n=164; average number=14.6) have a lower probability of having /f/ or /v/ compared to AL languages with a medium or large consonant inventory (n=287; average number=27) (P(/f/|S)=0.21; P(/f/|AL)=0.51; Percentage comparison test: p<0.001; P(/v/|S)=0.07; P(/v/|AL)=0.29; p<0.001). This suggests that consonant inventory size is a possible confounding factor. The geographical distribution of language classes S and AL established in WALS (which is compatible with UPSID451) confirms that S-Class languages overlap with Hunter-Gatherers (HG) populations. S-class distribution is similar to this of "no labiodental" in figures D and E of the abstract of (1) whatever the subsistence class. HG populations are located mainly in Oceania and America. We also checked locally that labiodental fricative frequency is comparable to world means in Papua-New-Guinea (P(/f/|S)=0.19 and P(/v/|S)=0.03 for the 37 S-class languages in UPSID451 (2)) and South America (P(/f/|S)=0.11 and P(/v/|S)=0.05 for the 44 S-class languages). This is well established that phonetic diversity decreases according the distance from Africa (3). This leads to small inventory sizes in distant regions and consequently there is a selective pressure to decrease at the same time the labiodental count. It arises that if most HG have S-Class languages then HG have less labiodental fricatives. Consequently, the subsistence type could be a proxy for evaluating the labiodental count. We suspect that the capture of 90% weight by the subsistence mode models is related to this link between the HG type and the number of segments (which is given when all non-labiodental segments are taken as reference).
It is also shown in (Fig. S3, (1)) that pseudo-BMA weights are greatly increased in the fricative as control condition for the baseline model (about 65% in AUTOTYP and about 30% in the GMR dataset) in which subsistence is not included. First, we see in figures D and E (provided in the abstract of (1)) that food producers and HG have similar "no labiodental/labiodentals(s)" proportions in America and Oceania, with exclusion of Australia having HG only. The number of "no labiodental" points is much higher. Subsistence type appears as a non informative parameter in these regions. Second, we established as for /f v/ that the frequency of non-labiodental fricatives also depends on the consonant inventory size. We have found similar and significant S/AL differences for /z ʃ/ and tendencies for /s ʒ/. Then, we suspect a close relationship between these two observations combined and the increase of the pseudo-BMA weights of the baseline model (without subsistence information) in the fricative as control condition. In this case, non-labiodental fricatives could be a proxy for evaluating the labiodental fricative count, better than the subsistence type as seen before. Let remark that Australia could strongly contribute to this effect since labiodental fricatives are extremely rarely present without non-labiodental fricatives.
A systematic count of the 22 pulmonic fricatives /ɸ β f v θ ð s z ʃ ʒ ʂ ʐ ç ʝ x ɣ χ ʁ ħ ʕ h ɦ/ was carried out with PHOIBLE (5) in the n=343 Australian languages. Apart from the 2 reported labiodental fricatives /f/, a total of 81 non-labiodental fricatives were observed. However, this is mainly composed of 65 /β ð ɣ/ segments and these are not uniformly distributed throughout Australia. 61 of the non-labiodental fricatives are present in the northern Queensland region as well as one reported /f/ in Kunjen language. This has /f/ not in isolation but together with /ð ɣ/. We conclude that the use of fricative manner of articulation is rare but significant only in the northern regions of Australia. Then, the absence of labiodental fricatives has to be considered as a consequence of the absence of fricatives and not in isolation. We agree there is no general constraint against fricatives but we assume that this pattern is a typical consequence of structural constraints existing in linguistic systems, enhanced by the small size of the consonant inventory (6).
Because the absence of fricatives is not explained by the subsistence factor, the relationship between the absence of labiodentals and the presence of HG in Australia has to be carefully considered. Blasi et al. (1) argue that non fricative labiodentals « are options that could have easily arisen in Australia if there were no bias against labiodentals and only a bias against fricatives ». In Australian languages, we find features including nasal, approximant, tap/flap, trill, and lateral approximant (5,7). First, trill and lateral approximant are never associated with labiodentals articulation. The nasal /ɱ/ and tap/flap /ⱱ/ are only present in African languages furthermore having large consonant inventories. Similarly, the approximant /ʋ/ is mostly present in Indo-European AL-class languages. Thus, their adoption in Australian S-Class languages could not be as "easy".
In UPSID451 we observe a rarefaction of labiodental fricatives /f v/ as well as other fricatives such as /z ʃ/ when the size of the consonant inventory decreases. The production of the latter is obviously not related to the bite configuration. Another hypothesis is to consider that linguistic factors (phoneme selection and general mechanisms for constructing phoneme inventories) are the main drivers of language evolution rather than anatomical factors. The observations could be a by-product of an overlap between HG populations and S-class languages influenced by these linguistic factors. Therefore, to rule out this hypothesis, analyses might be performed using the same standardized phonetic sets.
[1] D. E. Blasi, S. Moran, S. R. Moisik, P. Widmer, D. Dediu, B. Bickel, Human sound systems are shaped by post-Neolithic changes in bite configuration. Science 363, 3432 (2019). doi:10.1126/science.aav3218
[2] I. Maddieson, K. Precoda, Updating UPSID. UCLA Working Papers in Phonetics 74, 104-111 (1990)
[3] Q. Atkinson, Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa. Science 332, 346-9 (2011). doi: 10.1126/science.1199295
[4] I. Maddieson, Consonant Inventories. In The World Atlas of Language Structures Online, M. S. Dryer, M. Haspelmath, Eds. (Leipzig: Max Planck Institute for Evolutionary Anthropology, 2013)
[5] S. Moran, D. McCloy, R. Wright, PHOIBLE Online (Max Planck Institute for Evolutionary Anthropology, Leipzig, 2014); https://phoible.org/.
[6] B. Lindblom, I. Maddieson, Phonetic Universals in Consonant Systems. In Language, Speech and Mind, C. Li, L. M. Hyman, Eds. (London: Routledge, 1988), pp. 62-78.
[7] E. Gasser, C. Bowern, in Proceedings of the 2013 Annual Meeting on Phonology (2014). doi: http://dx.doi.org/10.3765/amp.v1i1.17
RE: Labiodental mechanics
Was it considered that without an overbite it would be easier to produce labiodentals using the lower teeth and upper lip instead?
These results are certainly fascinating, but perhaps rather than the sounds not existing, they could also have been produced differently as well.
RE: Emergent labiodentals are no factor in language evolution
Blasi and colleagues (1) argue that Hockett's conjecture is correct that "labiodentals are overwhelmingly absent in languages whose speakers live from hunting and gathering" (2). On their view, a relatively effortless articulation of labiodentals was facilitated by a post-Neolithic reduction of tooth wear following the production of soft food (1), resulting in the "post-Neolithic emergence of overbite and overjet persistence and reduced effort when producing labiodentals" (1). From this they conclude that a "uniformitarian assumption" cannot be relied upon when making claims about language universals and language evolution. On this account, language is shaped by culturally induced changes in human biology, here a change in subsistence from hunting-gathering to agriculture, leading to a modified articulatory base with less tooth wear.
If correct, the authors' major empirical claim seems to be the debunking of the Flintstone myth. Lacking the necessary overbite configuration, pre-Neolithic Wilma could not have pronounced her husband's name Fred or the family name without great effort. Furthermore, the worldwide association between subsistence type and labiodentals, accounting for the relative absence of labiodentals in languages spoken by hunter-gatherers, and the relative increase of labiodentals during the history of Indo-European, matching the spread of agriculture in early Indo-European societies, both fall into place (1).
While this attempted confirmation of Hockett's conjecture may well be an interesting and informative empirical result, its theoretical significance for language or the evolution of language remains essentially nil. Contrary to the authors' position, a century-old consensus view is that the basic units of phonological structure are not the speech segments of human language (e.g., labiodental "f" or "w"), but rather the distinctive features (e.g., Labial, Coronal, Continuant, Voice) by which the motor articulators like tongue, lips, and larynx assemble such sounds (3). Crucially, this scientific consensus holds that rules of phonology do not apply randomly to individual sounds or collections of segments but rather apply specifically to the natural classes characterized by one or more distinctive features (4), just as the possible chemical elements and their associated possible chemical reactions and bonds are naturally grouped by the number of electrons to complete each atom's outer shells. As a result, the emergence of labiodental fricative /v/ engenders no theoretical significance since its constituent distinctive features, [Voice, Labial, Continuant], already comprise a universal part of the phonetic faculty of humans, and occur world-wide in the speech sounds (5). 'Voice' is a distinctive feature of, e.g., the sounds of plosives /b/, /d/, and /g/; 'Labial' is a property of the bilabials /p/ and /b/ and nasal /m/; and 'Continuant' is a feature of, e.g., sibilant /s/, interdental /θ/, palato-alveolar /š/, or velar fricative /x/. Consequently, the constitutive distinctive features of labiodental fricative /v/ are each represented in different segments that all must very plausibly have existed in pre-Neolithic times. Just as no new elements with some new number of electrons in its outer shells has ever been chemically created, the set of possible distinctive features has more plausibly remained fixed since pre-Neolithic times, and this part of human genetic endowment for language (sometimes called "UG") was never modified.
In fact, throughout the Neolithic, children and adolescents of hunter-gatherer populations must have been fully capable of articulating labiodentals before tooth wear became sufficiently substantial to make articulation effortful in adulthood. To put the matter in perspective, 19th-century Dutch farmers wearing wooden shoes have been shown to develop osteochondritis dissecans (6), a joint disorder that mostly affects foot and knee bones and causes catching and locking in the joints during movement. A change from clogs to soft footwear simply avoids the problem. Surely, no biologist would seriously want to argue that a culturally-induced change in footwear has been a factor in the evolution of bipedal locomotion in modern humans. We conclude, therefore, that the change in bite configuration was a factor exogenous to the language faculty that led only to a slightly different selection from a fixed set of distinctive features for use of an unchanged phonetic faculty, rather than a change in the basic set of distinctive features itself, and therefore was of absolutely no relevance for the evolution of language or language universals, since these latter did not evolve at all in this situation.
In brief, there has been no change in the possible array of distinctive features, but only in the range of their use, due to a factor tangential to the human phonetic faculty. The putative "cultural evolution" merely resulted in some additional exploitation of an already existing trait of the universal phonetics of human speech without altering the design of language (7). Therefore, the authors' suggestion that their result should prompt a total revision of our view on the nature of evolution of language and language universals seems like misleading over-reach at best, and a red herring at worst (7-9).
References
[1] C. F. Hockett, Distinguished lecture: F. Am. Anthropol. 87, 263–281 (1985). doi:
10.1525/aa.1985.87.2.02a00020
[2] D. E. Blasi, S. Moran, S. R. Moisik, P. Widmer, D. Dediu, B. Bickel, Human sound systems are shaped by post-Neolithic changes in bite configuration. Science 363, 6432 (2019): eaav3218. doi: 10.1126/science.aav3218
[3] R. Jakobson, G. Fant, M. Halle, Preliminaries to Speech Analysis: the Distinctive Features and their Correlates (MIT Press, 1952).
[4] M. Halle, On distinctive features and their articulatory implementation. Nat. Lang. Linguist. Theory 1, 91-105 (1983). https://www.jstor.org/stable/4047515
[5] P. Ladefoged, I. Maddieson, The Sounds of the World's Languages (Blackwell, 1996).
[6] I. Vikatou, M. L .P. Hoogland, A. L. Waters-Rist, Osteochondritis Dissecans of skeletal elements of the foot in a 19th century rural farming community from The Netherlands. Int. J. Paleopathol 19: 53-63 (2017). doi: 10.1016/j.ijpp.2017.09.005
[7] N. Chomsky, What kind of creatures are we? (Columbia University Press, 2016).
[8] R. C. Berwick, N. Chomsky, Why Only Us: Language and Evolution (MIT Press, 2016).
[9] M. A. C. Huybregts, Phonemic clicks and the mapping asymmetry: How language emerged and speech developed. Neurosci. Biobehav. Rev. 81, 279–294 (2017). doi: 10.1016/j.neubiorev.2017.01.041
Some remarks on the analysis of labiodentals in Indo-European
I think that Blasi et al. managed to discover and prove the existence of a very interesting connection between linguistics, biology, anthropolgy, and other fields of study. I am not arguing against the main points of the paper, but, as a linguist, I would like to focus on the section entitled "Increase of labiodentals during the history of Indo-European" and raise some concerns about it.
Historical linguistics is a forensic enterprise to a significant extent, especially when it deals with sparse data from earlier times. Given this nature of historical linguistics, a statement like "This sound should be reconstructed as /a/ rather than /o/ based on the spelling of two words in some manuscript and on a loanword from a neighboring language" is more informative and meaniningful than a statement like "This sound was an /a/ with a probability of 20% or an /o/ with a probability of 80%", even though the latter statement is seemingly more scientific. For this reason, a reconstruction of the Proto-Indo-European phonological system based on stochastic character mappping is hardly able to give us any new insights. Indo-European is a good testing ground for statstical models of language change adapted from biology, because the history of this family is well-known. If a model yields plausible results for Indo-European, it is justified to apply it to lesser-studied language families; if it contradicts the general opinion on some aspect of Indo-European, it is most likely that the result provided by the model is simply wrong. This is not surprising given that any such model works with a limited amount of data presented in a specific format, whereas many generations of Indo-Europeanists have carefully analyzed the whole body of evidence coming from all kinds of sources. For instance, Blasi et al. say that Proto-Indo-European /w/ might have been labiodental or not with the probabilities of 50%. However, the status of this Proto-Indo-European sound as a glide corresponding to /u/ (i.e., a bilabial or labiovelar approximant rather than a labiodental) is confirmed by the fact that it alternates with /u/, and this alternation was omnipresent in Proto-Indo-European inflexion and word-formation: e.g., /wed-ōr/ ~ /ud-nes/ 'water' (nominative singular ~ genitive singular) (Meier-Brügger 2010: 338). What is more, the correspondence sets used by the authors of the paper are based on the reconstruction of Proto-Indo-European that includes bilabial /w/, bilabial /bʰ/, etc. One might say that symbols like /bʰ/ are merely algebraic shorthands for these correspondence sets rather than realistic reconstructions, but "[i]n actual practice, <…>, reconstruction involves more than just an algebraic matching" (Weiss 2014: 128), which means that the correspondence sets might look differently under the assumption that some of these sounds were labiodental. So, making any conclusion about the presence or absence of labiodentals in Proto-Indo-European using the methods of Blasi et al. is less reliable than reconstructing Proto-Indo-European phonology in a traditional manner.
Another issue concerns Figure 7A showing presence or absence of labiodental reflexes for individual correspondence sets in the daughter languages of Proto-Indo-European. The chart is not erroneous, but somewhat biased and misleading. The bias manifests itself in the fact that the authors include not only systematic cases where labiodentals regularly arose from the reconstructed proto-sound, but also very rare and idiosyncratic cases. For instance, the only examples of Indo-European /kʲ/ turning into a labiodental come from Albanian and Modern English. In Albanian, this change occurs in the consonant cluster /skʲ/ in the Geg dialect and in a few cases in Standard Albanian and in the consonant cluster /kʲl/ before a front vowel, the latter sound change being supported by a single example (Schumacher & Matzinger 2013: 275, 237). In English, the velar fricative /x/ changed into /f/ after back (i.e., labialized) vowels in cases like "enough", but this change was restricted to a small number of words (Minkova 2013: 114). Another questionable example comes from Swedish, where a labiodental sound, namely /f/, is said to represent Proto-Indo-European /b/ in the verb form "grifs" 'is grabbed (pass.)', but this form is actually "grips" in Modern Standard Swedish, /p/ being the normal reflex of Proto-Indo-European /b/. Admittedly, Middle Swedish /p/ did change into /f/ before /t/ and /s/ and "grīfs" is cited as a form occurring in a manuscript from around 1500 (Noreen 1904: 206). However, pieces of evidence like these three supporting the red (labiodental) color in the chart are definitely not comparable to the amount of evidence behind such red cells as the one for the Swedish continuation of Proto-Indo-European /p/, where almost every instance of this sound changed into /f/ in Proto-Germanic. Obviously, if one is trying to prove that labiodentals are becoming more widespread over time, it is not advisable to make use of the marginal cases one can find in detailed historical grammars of well-described languages; it would be better to focus on more general changes resulting in the emergence of labiodentals. Otherwise, a similar chart with numerous red cells indicating an increase in frequency can be composed for any other type of segments, not only labiodentals.
Most importantly, the presentation of Blasi et al. does not mention the fact that the emergence of labiodental sounds is often part of some more general process, where the stops across all places of articulation turn into corresponding fricatives, with bilabial stops becoming labiodental fricatives. In fact, this is what happened to Greek and Germanic, listed as two out of three branches (along with Italo-Celtic) with the most pronounced preference for labiodentals. In Greek, voiceless aspirated stops /pʰ/, /tʰ/, and /kʰ/ turned into fricatives /f/, /θ/, and /x/, respectively, and voiced stops /b/, /d/, and /g/ turned into /v/, /ð/, and /ɣ/. In Proto-Germanic, voiceless stops /p/, /t/, /k/, and /kʷ/ became /f/, /θ/, /x/, and /xʷ/, respectively, whereas voiced aspirated stops /bʰ/, /dʰ/, and /gʰ/ became /v/, /ð/, and /ɣ/. This raises the question why labiodental fricatives are preferred over bilabial fricatives /ɸ/ and /β/ and whether this is linked to bite configuration, but the paper does not answer these questions, focusing on the comparison of labiodental fricatives to bilabial stops and the bilabial approximant. Thus, the preference for /f/ and /v/ over /ɸ/ and /β/ together with a tendency to fricativize stops is a good explanation for the abundance of labiodental sounds in Greek and Germanic, and maybe even in younger Indo-European as a whole; however, the question remains: is this preference actually explained by bite configuration and its cultural and socioeconomic consequences or not?
References
M. Meier-Brügger, Indogermanische Sprachwissenschaft (De Gruyter, 2010).
D. Minkova, A Historical Phonology of English (Edinburgh University Press, 2014).
A. Noreen, Altschwedische Grammatik mit Einschluss des Altgutnischen (Niemeyer, Halle, 1904).
S. Schumacher, J. Matzinger, Die Verben des Altalbanischen (Harrassowitz, Wiesbaden, 2013).
M. Weiss, The Comparative Method, in C. Bowern & B. Evans (eds.), The Routledge Handbook of Historical Linguistics (Routledge, 2014).
RE: Human oral anatomy preadapted to the production of consonants
Very interesting thinking, thanks a lot. This reminds of our proposal (Vaneechoutte 2011) that human oral anatomy, probably at least since Homo erectus (small oral opening, fleshy lips, incisiform canines, closed tooth-row, globular tongue, vaulted and smooth palate, descended hyoid - as opposed to ape oral anatomy), preadapted to the production of consonants.
Human speech has different preadaptations (duetting, voluntary breathing, vocal learning, brain enlargement, oral closures) which evolved at different times. When early-Pleistocene Homo dispersed intercontinentally along African and Eurasian coasts and rivers (continental shelf hypothesis), their lifestyle included bipedal wading and shallow diving for littoral foods, which are extremely rich in brain-specific nutrients such as DHA (Cunnane 2005). Littoral foods such as shellfish - which had to be opened with stone tools, and had to be sucked, not chewed - not only help explain archaic Homo's stone tool technology and brain enlargement, but also our small dentition and mouth (Hockett 1967) and masticatory reduction (MYH16 gene inactivation, probably begin-Pleistocene); which allowed our oral passage to be closed at different places (labial, dental, palatal etc.) which later became the articulation places for producing consonants, one of the preadaptations for human speech.
For references, google e.g. "Seafood, diving, song and speech 2011 Vaneechoutte" or "Speech originS 2017 Verhaegen".