The anatomical risk of the human vocal tract: An analysis of 20th
century mortality statistics

Margaret Clegg, Department of Archaeology, University of Southampton. 

E-mail:M.Clegg@soton.ac.uk

It has long been suggested that the low position of the human larynx,
with its expanded supralaryngeal tract, evolved to serve the needs of
speech (Darwin, 1868; Lieberman et al.  1971,1 972; Wind, 1976;Laitman
et al.  1979).  In contrast, all other mammals, including human infants,
have a high laryngeal position.  We are thought to be capable of
producing the sounds associated with speech only because we have a low
laryngeal position (Lieberman, 1979,1984).  Our ability to speak comes,
according to many authors, at a price; we have compromised our ability
to swallow safely.  This belief is plausible; we have all experienced
food going down the 'wrong way'.  However, little evidence is ever
produced in support of this notion.  This paper offers evidence that the
risk from choking on food may not be as great as often supposed. 

Humans have an ontogenetic descent of the larynx (Westhorpe, 1987;
Flugel & Rohen, 1991; Lieberman et al., 2001).  Therefore if we have
compromised our ability to swallow safely, we would expect infants, with
a high laryngeal position, would have a low death rate from choking on
food.  The death rate would be high at times of laryngeal descent,
around 2 years of age and again at puberty.  The death rate would then
remain high throughout the rest of life. 

These assumptions are not supported by the data.  Evidence from
mortality statistics for England and Wales for the whole of the 20th
century show a low death rate in all groups except infants. 
Furthermore, the majority of deaths from choking on food are culturally
mediated.  It is our behaviour not our anatomy that is responsible for
our lack of swallowing co-ordination. 

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