appearance of members of our genus,the external nose typical of
modern humans appears.
In short,substantial evidence supports the appearance of a modern
respiratory system in the hominid line beginning about 1.5 million years
ago.Chests were barrel-shaped and noses projecting,neither feature
being typical of the earliest hominids (Australopithecus) or living apes.
As shown in table 14.1,for the most part australopithecines had upper
respiratory tracts as measured by the external cranial base angle that
were also within the chimpanzee range,the exception being east Turkana
406.However,early Homohave more flexed external cranial bases and,
at least for specimens such as east Turkana 3733 and WT-15000,external
noses resembling people living today.None of this evidence establishes
language,linguistic ability,or singing,but it does suggest that hominids
for the first time had the anatomical bellows and nasal resonating cham-
bers typical of language-competent humans.Oral Chamber
The oral chamber is a crucial area for speech-sound production and one
often glossed over in studies of the evolution of language.Duchin (1990)
is a main exception.She contended that the dimensions of the oral cavity,
defined by the hard palate and mandible in skeletal material,constitute
an important component of the speech apparatus.Chimpanzees and
humans differ in palate dimensions,as shown in figure 14.5.Chimps have
relatively long,narrow maxillas,whereas human palates are shorter and
broader.In her work with radiographs of humans and chimpanzees,
Duchin documented the patterns shown in figure 14.5,demonstrating
greater mandibular and hard palate lengths in chimpanzees.She corre-
lated these skeletal differences to dissimilar muscular arrangements in
chimpanzees and humans,and concluded that the shortened oral space
in humans provides “an anatomical advantage...in that it reduces the
travel-distance to and between the articulatory target positions [so that]
...the human tongue has...a more accessible series of articulatory
positions”(1990:695).Since tongue position and the oral cavity are
crucial in the articulation of consonants (Borden,Harris,and Raphael
1994),palate dimensions are important indicators of speech and sound-
production capability.Coupled with their lack of an external nose,chim-
panzees’ inability to produce consonants is related to their long,narrow
palates.
Duchin’s technique cannot be directly repeated in fossil material,since
specimens are rarely so intact as to allow using her full complement of
measurements of the oral chamber.Thus,like other cases discussed,228 David W.Frayer and Chris Nicolay