tive by the fact that these same three lines show trends for increased
cranial capacity over time.Hypoglossal Canal Size
Research by Kay,Cartmill,and Balow (1998) provides additional evi-
dence for language capacity going back at least as far as Neanderthals.
This work concerns the size of the hypoglossal canal,which is a bony
chamber located on the base of the skull,just superior to the foramen
magnum.It transmits the twelfth cranial nerve,which is responsible for
innervation of the tongue.Dimensions of the canal were measured in
chimpanzees,gorillas,and modern humans,and in a small sample of fossil
hominids.Compared with modern humans,apes had significantly smaller
canals (and by inference,smaller hypoglossal nerves) in absolute dimen-
sions or relative to palate size.Australopithecines and earliest Homo
from South Africa fell within or below the ape range in hypoglossal canal
size,and a small sample of Neanderthals and other archaic hominids
from Africa and the Levant were completely within the modern Homo
sapiensrange.In agreement with work reviewed here,this evidence is
consistent with an early origin for linguistic capacity.Respiratory System
The respiratory system of the earliest hominids does not resemble that
of modern humans.Rather,both the source of the air stream (the lungs,
as determined by the shape of the rib cage) and one of the potential
exits (the nose,as measured by the bony nasal surfaces) of the earliest
hominids strikingly resemble modern chimpanzees.For lungs,early aus-
tralopithecines (as represented by Australopithecus afarensis) have a rib
cage that continuously expands from the first to the last rib.This funnel-
shaped or lampshade pattern (Jellema,Latimer,and Walker 1993) is
typical of modern chimpanzees and deviates from all modern humans,
which have a barrel-shaped thoracic cage shape (figure 14.3).The earli-
est appearance of the modern human rib cage pattern occurs at about
1.5 million years ago with the Nariokotome boy from west Turkana,
Kenya.This specimen (WT-15000) has a rib cage described as “in almost
all respects indistinguishable from those of modern humans”(Jellema,
Latimer,and Walker 1993:324).Another study of the same specimen
(MacLarnon 1993) corroborated the modernity of the vertebral column
of WT-15000.However,vertebral arches (which enclose the spinal cord)
have diameters smaller than expected,and this may indicate deficiencies
in fine muscular control of intercostal (interrib) muscles.Based on this225 Fossil Evidence for the Origin of Speech Sounds