From Newsgroup: sci.anthropology.paleo


https://onlinelibrary.wiley.com/doi/10.1002/evan.70019
Rethinking Hominin Air Sac Loss in Light of Phylogenetically Meaningful Evidence

Abstract
The evolution of laryngeal air sacs in
hominins has been a subject of considerable
debate, with particular attention given to
the inferred presence of air sacs in
Australopithecus afarensis and inferred
absence in Middle and Upper Pleistocene
hominins. We challenge several assumptions
prevalent in relevant discourse and assert
that (1) while exhibiting morphological
similarity, it cannot be ruled out that
relationships between hyoid morphology and
air sac morphology in extant African great
apes may reflect convergence; (2) while the
only known A. afarensis hyoid exhibits
rCLape-likerCY bulla, this feature may have
persisted following the loss of air sacs,
and not be indicative of their presence
per se; (3) because there are currently
only five known hominin hyoid bones
represented in the fossil record (with a
single specimen predating the Middle
Pleistocene) the evidential basis for
interpreting air sac presence or absence
is minimal; and (4) inferences toward a
role of sexual selection and communicative
behavior in explicating the loss of air
sacs in the hominin lineage are undermined
by the atypical sexual dimorphism patterns
in early hominins. We advocate for a
cautious approach to interpreting hominin
behavior and evolution which prioritizes
data over speculation, and underscore the
need for rigorous evidence when constructing
evolutionary narratives about early hominin
vocal anatomy and its evolution.

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From Newsgroup: sci.anthropology.paleo


Primum Sapienti <invalide@invalid.invalid> posted:

https://onlinelibrary.wiley.com/doi/10.1002/evan.70019
Rethinking Hominin Air Sac Loss in Light of Phylogenetically Meaningful Evidence

Abstract
The evolution of laryngeal air sacs in
hominins has been a subject of considerable
debate, with particular attention given to
the inferred presence of air sacs in
Australopithecus afarensis and inferred
absence in Middle and Upper Pleistocene
hominins. We challenge several assumptions
prevalent in relevant discourse and assert
that (1) while exhibiting morphological
similarity, it cannot be ruled out that
relationships between hyoid morphology and
air sac morphology in extant African great
apes may reflect convergence; (2) while the
only known A. afarensis hyoid exhibits
rCLape-likerCY bulla, this feature may have
persisted following the loss of air sacs,
and not be indicative of their presence
per se; (3) because there are currently
only five known hominin hyoid bones
represented in the fossil record (with a
single specimen predating the Middle
Pleistocene) the evidential basis for
interpreting air sac presence or absence
is minimal; and (4) inferences toward a
role of sexual selection and communicative
behavior in explicating the loss of air
sacs in the hominin lineage are undermined
by the atypical sexual dimorphism patterns
in early hominins. We advocate for a
cautious approach to interpreting hominin
behavior and evolution which prioritizes
data over speculation, and underscore the
need for rigorous evidence when constructing
evolutionary narratives about early hominin
vocal anatomy and its evolution.

Thanks much, Primum Sapienti.

I've skimmed the full article and found some errors.

The first figure, of various gibbon hyoid bones, indicates that hoolock gibbons and nomascus gibbons have laryngeal airsacs. This is false. Only the siamang has airsacs.

The authors refer to formants being amplified by airsacs as the reason for their existence. This is false. Airsacs allow loud long calls repeatedly while preventing hyperventilation, a condition which brings about dizziness, a dangerous state for an arboreal ape contesting dominance with others far above the forest floor.

The fossil Australopithecus afarensis dikika 1, aka Selam, a 3 yr old Aa, has a chimp-like hyoid bone. Chimps have airsacs.

All Homo fossil hyoids known lack signs of bilateral laryngeal airsacs. Just like gibbons, and unlike siamangs, chimps, gorillas and orangutans.

DD
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