Re: Airsacs (Re: Ealine Morgan

Marc Verhaegen wrote:

Op 06-09-2007 08:30, in artikel
1189060206.821340.52250@xxxxxxxxxxxxxxxxxxxxxxxxxxx, nickname
<alas_my_loves@xxxxxxxxx> schreef:
2% of modern humans have laryngocoeles (sp), located at the same
position as the laryngeal air sacs in apes. 10ma our ancestors had
lar. air sacs, later in Homo erectus they vanished (apparently) due to
the switch to horizontal backfloating/diving from vertical floating/
wading.
They still exist in modern humans, 20% of cadavers have them (not
enlarged), more common in male wind instrument players in orchestras
(enlarged), where air pressure around the voicebox increases and
decreases.
Both apiths Lucy and Selam/dik1 had lar. air sacs, based on fossil
hyoid bone. Modern great apes have them, all great apes occasionally
wade for aquatic foods, where possibility of submersion is real, and
ability to exhale used lung air into an empty pouch for flotation
would be an advantage. No great ape backfloats, Homo does, thus the
loss of the lar. air sacs and replacement with buoyant skin fat and
larger paranasal sinuses. DD

Yes, likely. Early apes (HPGPoHy), early hominids-pongids & early hominids
(HPG+apiths) had large lar.airsacs. Only Homo & small gibbons lost them.

No evidence what so ever for these sacs in early hominids.

RT
.

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