Correlates of Vocal Tract Evolution in Late Pliocene and Pleistocene Hominins

https://link.springer.com/article/10.1007/s12110-025-09487-9
Correlates of Vocal Tract Evolution in
Late Pliocene and Pleistocene Hominins
Abstract
Despite decades of research on the
emergence of human speech capacities,
an integrative account consistent with
hominin evolution remains lacking. We
review paleoanthropological and
archaeological findings in search of a
timeline for the emergence of modern
human articulatory morphological
features. Our synthesis shows that
several behavioral innovations coincide
with morphological changes to the
would-be speech articulators. We find
that significant reductions of the
mandible and masticatory muscles and
vocal tract anatomy coincide in the
hominin fossil record with the
incorporation of processed and
(ultimately) cooked food, the appearance
and development of rudimentary stone
tools, increases in brain size, and
likely changes to social life and
organization. Many changes are likely
mutually reinforcing; for example,
gracilization of the hominin mandible may
have been maintainable in the lineage
because food processing had already been
outsourced to the hands and stone tools,
reducing selection pressures for robust
mandibles in the process. We highlight
correlates of the evolution of
craniofacial and vocal tract features in
the hominin lineage and outline a
timeline by which our ancestors became
‘pre-adapted’ for the evolution of fully
modern human speech.