TY - JOUR
T1 - Cineradiography of monkey lip-smacking reveals putative precursors of speech dynamics
AU - Ghazanfar, Asif A.
AU - Takahashi, Daniel Y.
AU - Mathur, Neil
AU - Fitch, W. Tecumseh
N1 - Funding Information:
This work was supported by the National Institutes of Health (NINDS) R01NS054898 (A.A.G.), the Pew Latin American Fellowship (D.Y.T.), the Quantitative and Computational Neuroscience Training grant NIH R90 DA 023419-01 (N.M.), and the European Research Council Advanced Grant SOMACCA: Syntax of Mind: A Comparative Computational Approach (W.T.F.).
PY - 2012/7/10
Y1 - 2012/7/10
N2 - A key feature of speech is its stereotypical 5 Hz rhythm [1, 2]. One theory posits that this rhythm evolved through the modification of rhythmic facial movements in ancestral primates [3, 4]. If the hypothesis has any validity, then a comparative approach may shed some light. We tested this idea by using cineradiography (X-ray movies) to characterize and quantify the internal dynamics of the macaque monkey vocal tract during lip-smacking (a rhythmic facial expression) versus chewing. Previous human studies showed that speech movements are faster than chewing movements, and the functional coordination between vocal tract structures is different between the two behaviors [5-9]. If rhythmic speech evolved through a rhythmic ancestral facial movement, then one hypothesis is that monkey lip-smacking versus chewing should also exhibit these differences. We found that the lips, tongue, and hyoid move with a speech-like 5 Hz rhythm during lip-smacking, but not during chewing. Most importantly, the functional coordination between these structures was distinct for each behavior. These data provide empirical support for the idea that the human speech rhythm evolved from the rhythmic facial expressions of ancestral primates.
AB - A key feature of speech is its stereotypical 5 Hz rhythm [1, 2]. One theory posits that this rhythm evolved through the modification of rhythmic facial movements in ancestral primates [3, 4]. If the hypothesis has any validity, then a comparative approach may shed some light. We tested this idea by using cineradiography (X-ray movies) to characterize and quantify the internal dynamics of the macaque monkey vocal tract during lip-smacking (a rhythmic facial expression) versus chewing. Previous human studies showed that speech movements are faster than chewing movements, and the functional coordination between vocal tract structures is different between the two behaviors [5-9]. If rhythmic speech evolved through a rhythmic ancestral facial movement, then one hypothesis is that monkey lip-smacking versus chewing should also exhibit these differences. We found that the lips, tongue, and hyoid move with a speech-like 5 Hz rhythm during lip-smacking, but not during chewing. Most importantly, the functional coordination between these structures was distinct for each behavior. These data provide empirical support for the idea that the human speech rhythm evolved from the rhythmic facial expressions of ancestral primates.
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U2 - 10.1016/j.cub.2012.04.055
DO - 10.1016/j.cub.2012.04.055
M3 - Article
C2 - 22658603
AN - SCOPUS:84863725004
SN - 0960-9822
VL - 22
SP - 1176
EP - 1182
JO - Current Biology
JF - Current Biology
IS - 13
ER -