December 08, 2011

Loss of air sacs and hominin speech

Journal of Human Evolution

Loss of air sacs improved hominin speech abilities
Bart de Boer

In this paper, the acoustic-perceptual effects of air sacs are investigated. Using an adaptive hearing experiment, it is shown that air sacs reduce the perceptual effect of vowel-like articulations. Air sacs are a feature of the vocal tract of all great apes, except humans. Because the presence or absence of air sacs is correlated with the anatomy of the hyoid bone, a probable minimum and maximum date of the loss of air sacs can be estimated from fossil hyoid bones. Australopithecus afarensis still had air sacs about 3.3 Ma, while Homo heidelbergensis, some 600 000 years ago and Homo neandethalensis some 60 000 years ago, did no longer. The reduced distinctiveness of articulations produced with an air sac is in line with the hypothesis that air sacs were selected against because of the evolution of complex vocal communication. This relation between complex vocal communication and fossil evidence may help to get a firmer estimate of when speech first evolved.



eurologist said...

That's about what you'd expect - heidelbergensis had the same if not better hunting skills compared to Neanderthals, constructed wooden throwing spears (perhaps both usable and symbolic), built tents and other structures, and made patios or work areas expertly tiled with flat stones. You don't do those kind of things without (an at least rudimentary) language.

Pascvaks said...

A "thousand words" ( a pic) on Air Sacs courtesy "Tetrapodzoology" at -

pconroy said...

To sum up:
We lost our air sacs, and became windbags