Reviewed Article

The Functions of Laryngeal Air Sacs in Primates: A New Hypothesis
Gwen Hewitt, Ann MacLarnon, Kate E. Jones

University of Surrey Roehampton, London, UK

Address of Corresponding Author

Folia Primatol 2002;73:70-94 (DOI: 10.1159/000064786)

  Key Words

• Air sacs
• Primates
• Hyperventilation
• Vocalisations
• Call rate ?Call duration
• Allometry
• Speech breathing
• Resting breathing rate

  Abstract

A possible function of laryngeal air sacs in apes and gibbons was investigated by examining the relationships between air sac distribution, call rate, call duration and body weight in a phylogenetic context. The results suggest that lack of sacs in the smaller gibbons and in humans is a derived feature. Call parameters in primates, such as rate and duration, scaled to resting breathing rate (and therefore to body weight) only in species without air sacs, which appear to modify these relationships. Apes and larger gibbons may be able to produce fast extended call sequences without the risk of hyperventilating because they can re-breathe exhaled air from their air sacs. Humans may have lost air sacs during their evolutionary history because they are able to modify their speech breathing patterns and so reduce any tendency to hyperventilate.

  Author Contacts

Dr. Gwen Hewitt, School of Life Sciences
University of Surrey Roehampton, West Hill
London, SW15 3SN (UK)
Tel. +44 20 8392 3524, Fax +44 20 8392 3527
E‐Mail g.hewitt@roehampton.ac.uk

  Article Information

Received: Received: October 30, 2000
Accepted after revision: April 19, 2002
Number of Print Pages : 25
Number of Figures : 5, Number of Tables : 0, Number of References : 106