The facial muscles of 3 african primates contrasted with those of papio ursinus


Pellatt, A.

South African Journal of Science 75(10): 436-440

1979


The facial muscles of single specimens of vervet monkey (Cercopithecus aethiops), bushbaby (Galago senegalensis) and chimpanzee (Pan troglodytes) are described and contrasted with the Chacma baboon, (Papio ursinus). Those of the bushbaby, a member of the infraorder Lorisiformes which arose during the Paleocene, are far more primitive than those of the baboon; the vervet monkey belonging, with the baboon, to the superfamily Cercopithecoidea of Oligocene origin, has an almost identical facial musculature; while the chimpanzee, whose pongid ancestry dates back only to Miocene times, shows notable advances which help to confirm its inclusion in the superfamily Hominoidea.

mo
7
436
South
African
Journal
of
Science
Vol.
75
October
1979
The
Facial
Muscles
of
Three
African
Primates
Contrasted
with
Those
of
Papio
ursinus
A.
Pellatt
Department
of
General
Anatomy,
School
of
Dentistry,
University
of
the
Witwatersrand,
Johannesburg
2001.
The
facial
muscles
of
single
specimens
of
vervet
monkey
(Cercopithecus
aethiops),
bushbaby
(Galago
senegalensis)
and
chimpanzee
(Pan
troglodytes)
are
described
and
contrasted
with
those
of
the
Chacma
baboon,
(Papio
ursinus).
Those
of
the
bushbaby,
a
tnember
of
the
infraorder
Lorisiformes
which
arose
dur-
ing
the
Palaeocene,
are
far
more
primitive
than
those
of
the
baboon;
the
vervet
monkey
belonging,
with
the
baboon,
to
the
superfamily
Cercopithecoidea
of
Oligocene
origin,
has
an
almost
identical
facial
musculature;
whilst
the
chimpanzee,
whose
pongid
ancestry
dates
back
only
to
Miocene
times,
shows
notable
advances
which
help
to
confirm
its
inclusion
in
the
superfamily
Hominoidea.
In
an
earlier
communication'
the
facial
muscles
of
the
Chacma
baboon
(Papio
ursinus)
were
described.
It
was
noted
that
they
show
both
primitive
and
advanced,
or
specialised,
features
and
that
their
combination
correlates
well
with
the
taxonomic
position
of
this
lower
anthropoid.
Single
specimens
of
vervet
monkey
(Cercopithecus
aethiops),
bushbaby
(Galago
senegalensis)
and
chimpanzee
(Pan
troglodytes)
have
also
been
studied
and
their
facial
muscles
are
here
compared
and
contrasted
with
those
previously
described
in
the
baboon.
Materials
and
methods
The
vervet
monkey
and
the
bushbaby,
both
males,
were
available
as
preserved
specimens
in
the
department,
but
their
region
of
origin
in
South
Africa
is
unknown.
The
chimpanzee
head
(of
an
im-
mature,
3.85
kg
female)
was
procured
from
the
Yerkes
Primate
Center,
but
its
previous
history
is
not
available.
Preservation
in
all
three
specimens
was
good.
Dissection
and
recording
procedures
were
identical
with
those
for
P.
ursinus.'
Observations
Galago
senegalensis
(Figs
1,
2
and
3)
Muscles
of
the
scalp
(Figs
2
and
3)
Occipitalis
(os/op)
is
unilaminar,
arises
from
the
external
oc-
cipital
protuberance
and
inserts
into
the
scalp
over
the
vertex
and
into
the
base
of
the
auricle,
thus
combining
features
of
occipitalis
profundus
and
occipitalis
superficialis
of
P.
ursinus.
Auricularis
superior
(as)
is
small
but
not
essentially
different
from
that
in
P.
ursinus.
Auricularis
anterior
(aa)
is
a
well
defined
muscle
which
orginates
on
the
superior
bony
margin
of
the
orbital
aperture
and
inserts
into
the
scalp
at
the
base
of
the
auricle.
Although
partly
occupying
the
position
offrontalis
in
Papio,
it
can
have
no
effect
on
the
eyelid
since
it
has
no
periorbital
soft
tissue
attachment.
In
fact,
frontalis
is
not
present
in
this
animal,
which
is
not
surprising
because
the
almost
circular
palpebral
'fissure'
could
not
be
opened
any
more
widely
by
the
raising
of
an
eyebrow
indeed
no
eyebrow
is
present.
Auricularis
posterior
(ap).
Three
bellies
are
present
instead
of
the
two
seen
in
Papio.
Periorbital
muscles
(Figs
1
and
2)
Orbicularis
oculi
(o
oc)
is
markedly
developed,
extending
from
midway
between
orbit
and
auricle
above
to
the
upper
parotid
region
below
and
almost
to
the
oral
angle
anteriorly.
Two
thin
extensions
pass
to
the
auricular
helix:
the
lower
one
may
represent
an
incipient
malaris
or
zygomaticus
(?zy
and
?ma).
No
differentiation
into
orbital
and
palpebral
parts
is
discernible
and
neither
depressor
nor
corrugator
supercilii
is
present.
Oronasal
muscles
(Figs
1
and
2)
Maxillonasolabialis
(mn)
is
absent
over
the
dorsum
of
the
snout,
only
its
labial
part
being
apparent.
Levator
anguli
oris
(la)
is
hardly
identifiable;
orbicularis
oris
(o
or)
is
small;
nasalis
and
mentalis
re
Fig.
1.
The
facial
muscles
of
Galago
senegalen-
sis.
Lateral
view.
Note
the
connecting
band
(cb)
between
platysma
(plc)
and
the
panniculus
car-
nosus
(pc);
also
the
great
size
of
orbicularis
oculi
(o
oc)
and
the
relatively
poor
development
of
the
perioral
musculature.
?am,
?auriculoman-
dibularis;
dh,
deep
head
of
platysma;
la,
levator
anguli
oris;
?ma
?zy,
?malaris,
?zygomaticus;
mn,
maxillonasolabialis;
o
or,
orbicularis
oris;
pla,
mental
part
of
platysma;
plg
modiolar
part
of
platysma;
sh,
superficial
head
of
platysma,
turned
anteriorly.
South
African
Journal
of
Science
Vol.
75
October
1979
437
7-
4
7-
-
sL
O
.ate
;
.
11\
X.
ti
Fig.
2.
The
facial
muscles
of
Ga/ago
senegalensis.
Dorsofrontal
view.
Note
the
absence
of
frontalis
and
the
numerous
muscular
bands
passing
to
the
auricle.
aa,
auricularis
anterior;
ap,
auricularis
posterior;
as,
auricularis
superior;
mn,
maxillonasolabialis;
o
oc,
orbicularis
oculi;
os/op,
occipitalis.
could
not
be
identified.
Buccinator
(not
shown)
is
well
developed.
Platysma
(Figs
1
and
3)
The
ventral
region
of
this
muscle,
although
more
weakly
developed,
differs
little
from
that
in
P.
ursinus.
The
dorsal
or
nuchal
part
is
much
reduced;
the
deep
head
(dh)
is
a
thin
muscular
strap
lying
in
series
with,
and
immediately
below,
the
three
bellies
of
auricularis
posterior
(ap).
The
superficial
head
(sh)
is
a
very
small
fan
of
fibres
which
originate
over
the
shoulder.
A
small
band
also
arises
on
the
tragus
of
the
auricle
and
may
represent
auriculo-
mandibularis
(?am)
of
subprimate
forms.
Most
interesting
of
all
is
a
muscular
band
(cb)
which
unites
the
deep
head
(dh)
of
platysma
to
the
panniculus
carnosus
(pc)
in
fascicular
continuity.
In
dorsal
view
this
causes
a
distinctly
`sleeveless
vest'
appearance
(Fig.
5).
as
1,1
.;avop'
sd
b
c
Fig.
3.
the
facial
muscles
of
Galago
senegalensis.
Dorsooccipital
view.
Note
the
three
bands
of
auricularis
posterior
(ap)
and
the
band
(cb)
which
connects
platysma
(plc)
and
the
panniculus
carnosus
(pc),
giving
a
'sleeveless
vest'
appearance.
aa,
auricularis
anterior;
as,
auricularis
superior;
dh,
deep
head
of
platysma;
sh,
superficial
head
of
plarysma;
o
oc,
orbicularis
oculi;
os/op,
occipitalis.
Si
I
l
1.
'
ti'
438
South
African
Journal
of
Science
Vol.
75
October
1979
The
periorbital
muscles
orbicularis
oculi
(o
oc)
and
frontalis
(fr)
and
the
scalp
muscles
auricularis
superior
et
anterior
(asa),
auricularis
posterior
(ap),
occipitalis
profundus
(op)
and
occipitalis
superficialis
(os)
likewise
hardly
differ
from
those
in
the
baboon.
Platysma
(pla-g)
is
substantially
similar
to
that
in
P.
ursinus.
Notable
differences
are
that
the
deep
head
(dh)
originates
from
the
trapezius
(tz)
epimysium
lateral
to
rather
than
in
the
median
nuchal
sulcus.
No
division
into
upper
and
lower
portions,
such
as
that
seen
in
Papio,
is
present
and
the
fan
of
decussated
fasciculi
(plb)
which
foreshadows
the
depressor
anguli
oris
of
higher
anthropoids
is
more
extensive
and
reaches
the
angle
of
the
mouth.
iY
r
-
et
.
;
-
Fig.
4.
The
facial
muscles
of
Cercopithecus
aethiops.
Lateral
view.
Note
the
general
similarity
to
those
of
P.
ursinus.'
asa,
auricularis
superior
et
anterior;
bu,
buccinator;
bup,
buc-
cinator
pouch;
fr,
frontalis;
ma,
malaris;
mn,
max-
illonasolabialis;
o
oc,
orbicularis
oculi;
o,
orbital
part;
p,
palpebral
part;
o
or,
orbicularis
oris;
pl-,
parts
of
platysma;
pla,
mental
part;
plb,
decussated
part;
plc,
cervical
part;
pld,
parotid
part;
ple,
nuchal
part;
plf,
buccal
pouch
part;
plg,
modiolar
part;
Zy,
zygomaticus.
Cercopithecus
aethiops
(Figs
4
and
5)
The
facial
muscles
of
this
animal
are
almost
identical
with
those
of
P.
ursinus.
In
particular,
the
oronasal
muscles,
max-
illonasolabialis
(mn),
malaris
(ma),
zygomaticus
(zy)
and
or-
bicularis
oris
(o
or),
show
no
notable
difference
in
spite
of
a
less
well-developed
muzzle.
The
deeper
muscles
in
this
group
(not
shown),
levator
anguli
oris,
nasalis,
mentalis
and
the
incisivi,
are
also
very
similar
to
those
of
P.
ursinus.
op
r
h,.
dh
T.
Fig.
5.
The
facial
muscles
of
Cercopithecus
aethiops.
Dorsal
view.
These
are
virtually
identical
with
those
of
P.
ursinus.'
ap,
auricularis
posterior;
as,
auricularis
superior;
dh,
deep
head
of
platysma,
ple;
op,
occipitalis
profundus;
os,
oc-
cupitalis
superficialis;
scm,
sternocleidomastoid;
sh,
superficial
head
of
platysma;
te,
temporalis,
tz,
trapezius.
Pan
troglodytes
(Figs
6,
7
and
8)
Muscles
of
the
scalp
(Figs
7
and
8)
Occipitalis
superficialis
(osf)
is
represented
by
only
a
fibrous
sheet
which
extends
from
the
nuchal
region
to
blend
with
the
epicranial
aponeurosis
over
the
vertex.
Occipitalis
profundus
(op)
arises
from
the
whole
extent
of
the
nuchal
crest
in
the
depths
of
the
nuchal
intermuscular
sulcus.
A
uricularis
superior
et
anterior
(asa)
and
frontalis
(fr)
are
essentially
as
seen
in
P.
ursinus.
Muscles
of
the
face
(Figs
6
and
7)
Orbicularis
oculi.
A
band
(s),
which
on
the
left
side
joins
this
muscle
to
the
levator
labii
superioris,
may
represent
an
incipient
zygomaticus
minor.
The
muscle
otherwise
does
not
differ
from
that
of
P.
ursinus.
Corrugator
supercilii
(not
shown).
Surprisingly,
this
is
barely
distinguishable
in
Pan,
although
the
living
animal
may
show
a
well-
developed
frown.
Zygomaticus
major
(Zy).
This
simple
strap-shaped
muscle
shows
no
sign
of
bifurcation
as
seen
in
P.
ursinus.
Malaris
(ma)
is
easily
separable
from
zygomaticus
laterally
and
from
orbicularis
oculi
(o
oc)
and
levator
labii
superioris
(11s)
medially.
Levator
labii
superioris
is
well
differentiated
from
its
neighbours,
levator
labii
superioris
alaeque
nasi
(11san)
and
malaris
(ma).
Levator
anguli
oris
(not
shown)
is
poorly
developed.
Depressor
anguli
oris
(dao)
passes
from
the
lower
margin
of
the
mandible
to
the
region
of
the
modiolus
labii
and
is
strongly
interlaced
with
platysma.
Depressor
labii
inferioris
(not
shown)
is
not
differentiated
from
platysma
but
some
fasciculi
appear
to
arise
from
bone
where
platysma
in
part
inserts.
Mentalis
(not
shown)
is
small
but
distinct.
Orbicularis
oris
(o
or)
is
well
developed
and
receives
contribu-
tions
from
the
labial
elevators
and
depressors.
Peripheral
and
marginal
parts
are
not
clearly
differentiated.
Buccinator
(
not
shown)
is
small
in
this
immature
specimen
and
no
trace
of
a
buccal
pouch
is
seen.
Platysma
(Fig.
7)
Since
only
the
head
of
the
animal
was
available,
the
thoracoacromial
parts
of
platysma
could
not
be
studied.
No
trace
of
a
nuchal
part
exists,
the
most
dorsalward
part
of
origin
lying
over
the
upper
part
of
sternocleidomastoid
(scm).
The
muscle
is
unilaminar,
thin
and
much
reduced
when
compared
with
that
of
P.
ursinus,
even
bearing
in
mind
that
the
specimen
was
immature.
It
inserts
into
the
modiolus
labii,
the
lower
lip,
the
mental
skin
and
subcutis,
but
only
slightly
into
the
adjacent
bone.
Although
the
two
platysmae
lie
adjacent
in
the
neck,
midline
decussation
is
minimal.
Discussion
The
Lorisiformes,
to
which
group
the
genus
Galago
belongs,
probably
diverged
from
the
insectivore-primate
stock
during
the
Palaeocene,
50
60
million
years
ago;
the
Cercopithecoidea,
which
includes
the
genera
Papio
and
Cercopithecus,
in
the
Oligocene
some
30
million
years
ago;
whilst
the
Pongidae,
represented
by
the
fossil
Proconsul,
are
first
noted
in
the
lower
Miocene,
approx-
imately
20
million
years
ago
.2
orf
oat
439
South
African
Journal
of
Science
Vol.
75
October
1979
Fig.
6.
The
facial
muscles
of
Pan
troglodytes.
Frontal
view.
Note
procerus
(pr)
levator
labii
superioris
(11s),
levator
labii
superioris
alaeque
nasi
(11san)
and
depressor
anguli
oris
(dao).
Malaris
(ma)
is
still
present.
asa,
auricularis
superior
et
anterior;
fr,
frontalis;
o
or
orbicularis
oris;
pla,
mental
part
of
platysma;
plg,
modiolar
part
of
platysma;
s,
slip
from
or-
bicularis
oculi
to
labial
levators;
Zy,
zygomaticus.
Fig.
7.
The
facial
muscles
of
Pan
troglodytes.
Lateral
view.
Note
absence
of
nuchal
part
of
platysma.
asa,
auricularis
superior
et
anterior;
dao,
depressor
anguli
oris,
fr,
frontalis,
llsan,
levator
labii
superioris
alaeque
nasi;
ma,
malaris;
o
oc,
orbicularis
oculi;
o,
orbital
part;
p,
palpebral
part;
o
or,
or-
bicularis
oris,
op,
occipitalis
profundus;
osf,
fascial
vestige
of
occipitalis
superficialis;
pla,
mental
part
of
platysma;
plc,
cer-
vical
part
of
platysma;
plg,
modiolar
part
of
platysma;
s,
slip
from
orbicularis
oculi
to
labial
levators;
scm,
ster-
nocleidomastoid,
tz,
trapezius,
Zy,
zygomaticus.
1
'
yl
Oor
/
,
4
,?
,
!//t!
Pt
S.
dao
These
three
groups
do
not
form
a
linear
evolutionary
series,
being
better
deemed
side
branches
on
the
tree
of
primate
ascent.
Nonetheless,
it
is
instructive
to
consider
whether
the
facial
musculatures
of
the
species
described
here
correlate
with
their
generally
accepted
taxonomic
positions
because
the
primates,
in
ad-
dition
to
general
mammalian
features
of
liveliness
and
exploratory
activity
which
they
display
par
excellence,
have
elaborated
facial
and
vocal
communication
to
a
high
degree,
resulting
in
increasingly
complex
social
life
and
culminating
in
the
subtle
facial
expression
and
speech
of
man.
Concomitant
facial
muscular
differentiation
is
shown
to
advan-
tage
by
the
very
limited
number
of
four
animals
studied.
Further-
more,
because
their
predominantly
arboreal
habits
make
good
fossil
material
tantalizingly
rare,
more
attention
must
be
paid
to
soft-tissue
structure
in
the
primates
than
in
groups
which
provide
abundant
fossils.
'0.
senegalensis
The
obviously
more
primitive
facial
musculature
of
the
bushbaby
correlates
well
with
its
assignment
to
the
Lorisiformes,
a
group
nearly
twice
as
old
as
the
Cercopithecoidea.
The
muscles
are
poorly
differentitated,
particularly
over
the
muzzle,
whilst
zygomaticus
and
melaris
as
separate
entities
are
absent.
The
absence
of
frontalis,
the
very
large
orbicularis
oculi
and
the
three-
bellied
auricularis
posterior
are
probably
specializations
for
control
of
the
large
eye
and
ear,
although
Huber
3
seems
to
concur
with
the
alternative
view
that
these
features
may
represent
a
basic
lemuri
form-insectivore
pattern.
Corrugator
et
depressor
supercilii
are
not
differentiated:
bushbaby
'eyebrows'
are
not
signal
transmitters
as
are
those
of
higher
primates.
Especially
interesting
is
the
fascicular
continuity
between
platysma
and
the
panniculus
carnosus.
Platysma
derives
from
second
branchial
arch
mesoderm
supplied
by
the
facial
nerve,
whilst
the
panniculus
develops
from
postbranchial
mesoderm
and
is
supplied
segmentally
by
spinal
nerves.
Nonetheless,
as
noted
in
the
discussion
on
the
facial
muscles
of
P.
ursinus,
1
the
view
of
Gegenbaur
4
that
the
two
muscular
sheets
have
a
common
origin
and
Huber's
observations
that
monotreme
facial
musculature
fuses
in
part
with
the
panniculus,
seem
to
be
confirmed
in
G.
senegalensis
by
the
'sleeveless
vest'
appearance
of
the
platysmal
and
pannicular
connexion.
C.
aethiops
The
facial
musculature
of
the
vervet
monkey,
evolved
some
20
30
million
years
later
than
that
of
Galago,
shows
marked
ad-
vances.
Platysma
now
maintains
its
erstwhile
linkage
only
to
the
Fig.
8.
The
facial
and
upper
cervical
musculature
of
Pan
troglodytes.
Dorsooccipital
view.
Note
the
wide
lateral
expansion
of
occipitalis
profun-
dus
(op)
and
the
fascia!
vestige
of
occipitalis
superficialis
(osf)
(rolled
up
on
right
side).
Platysma
is
not
visible
in
this
view
but
may
be
vestigially
represented
by
the
so-called
transver-
sus
nuchae
(tn).
asa,
auricularis
superior
et
anterior;
ap,
auricularis
posterior;
fr,
frontalis;
op,
occipitalis
profundus;
osf,
fascial
vestige
of
occipitalis
superficialis;
scm,
sterno-
cleidomastoid;
spl,
splenius
capitis;
ssc,
sernispinalis
capitis;
tz,
trapezius.
440
South
African
Journal
of
Science
Vol.
75
October
1979
panniculus
by
a
fascial
sheet.
The
muzzle
muscles
are
well
differen-
tiated
and
a
true
modiolar
area
is
apparent.
Zygomaticus
is
distinct,
as
is
malaris
at
least
from
origin
to
midbelly.
Corrugator
and
depressorsupercilii
are
in
the
process
of
separating
from
orbicularis
oculi,
now
that
the
eyebrows
have
signal
value.
P.
ursinus
Apart
from
the
quantitative
changes
which
the
doglike
elonga-
tion
of
the
muzzle
of
P.
ursinus
has
imposed
on
its
covering
muscles
and
on
platysma,
the
basic
plan
is
identical
with
that
of
C.
aethiops,
no
new
muscles
being
differentiated
(with
the
possible
exception
of
an
incipient
depressor
anguli
oris,
foreshadowed
by
the
fan
of
decussated
platysmal
fasciculi
to
the
modiolar
region)
and
no
old
ones
eliminated.
The
close
taxonomic
status
of
these
allometrically
dissimilar
cercopithecoids
is
thus
confirmed
by
the
essential
sameness
of
their
facial
musculature.
P.
troglodytes
A
member
of
a
group
some
10
million
years
younger
than
the
cer-
copithecoids,
the
chimpanzee
shows
marked
differences
in
its
facial
muscles.
These
are
partly
due
to
reduction
of
the
external
nasal
skeleton,
with
concomitant
reduction
in
the
primitive
sheetlike
muscular
cover,
and
partly
to
increasingly
subtle
use
of
the
face
in
communication.
Maxillonasolabialis
is
replaced
by
its
separate
derivatives,
levator
labii
superioris
alaeque
nasi,
and
levator
labii
superioris
(proprius),
although
no
zygomaticus
minor
is
differen-
tiated.
Malaris
and
zygomaticus
(major)
are
distinct
right
into
the
upper
lip.
Depressor
anguli
oris,
characteristic
only
of
hominoid
primates
has
appeared
and
depressor
labii
inferioris
is
identifiable.
All
these
changes
are
associated
with
much
more
finely
graded
use
of
the
lips
than
occurs
in
lower
forms.
Incisivus
inferior,
especially
well
developed
in
P.
ursinus,
has
virtually
disappeared,
its
modiolar
setting
function
being
taken
over
by
the
newly
developed
depressor
anguli
oris.'
The
virtual
disappearance
of
occipitalis
superficialis
and
reduction
of
auricularis
posterior
reflect
the
lesser
importance
of
scalp
and
auricular
mobility
in
Pan.
Disappearance
of
the
nuchal
part
of
platysma
is
also
typical
of
the
Hominoidea,
and
is
to
be
correlated
with
the
relative
reduction
in
size
of
the
jaws.
The
undoubtedly
higher
evolutionary
status
of
the
chimpanzee
is
thus
well
reflected
in
its
facial
musculature,
with
greatly
enhanced
potential
for
visual
communication.
Facial
movements
Just
as
the
facial
musculatures
of
these
four
animals
correlate
with
their
taxonomic
ranking,
so
do
the
movements
generated
by
them.
Andrew'•'
considers
the
facial
expressions
of
all
mammals
to
be,
fundamentally,
protective
responses.
In
lower
forms
these
are
gross
grimacings
which
accompany
strong
emotion
-
the
'agonistic
faces'
of
Van
Hoof.'
In
higher
forms,
more
fleeting,
non-
agonistic
movements,
involving
only
a
single
muscle
or
group
of
muscles,
become
increasingly
important.
The
facial
activity
of
G.
senegalensis
consists
almost
exclusively
of
mass-reflex
protective
movements,
isolated
mouth
corner
withdrawal
sometimes
occuring
in
peaceful
social
contact.'
The
facial
movements
of
P.
ursinus
and
C.
aethiops
are
also
mostly
very
primitive.
Exceptions
are
the
fear/threat
signal
of
eyebrow
raising
common
to
both
species
and
the
characteristic
lip-
smacking
of
P.
ursinus.
Eyebrow
raising
exposes
the
pale
signal
skin
of
the
upper
eyelid
and
is
used
to
dominate
an
inferior
or,
in
association
with
auricular
flattening
and
retraction,
to
indicate
fear
of
a
superior.
Lip-smacking,
a
rapid
opening
and
closing
of
the
slightly
protruded
lips
which
is
both
visible
and
audible,
is
a
placatory
behaviour
used
to
facilitate
non-hostile
approach
bet-
ween
individuals.
P.
troglodytes,
in
addition
to
its
gross
'agonistic
faces',
shows
a
range
of
isolated
and
more
subtle
facial
signals.'
It
may
smile
faintly
or
give
a
definite
grin.
High
intensity
grinning
may
even
be
accom-
panied
by
vocalisations
reminiscent
of
human
laughter.
The
chim-
panzee
also
has
graded
expression
with
which
to
indicate
discon-
tent:
from
initial
simple
drooping
of
lip
corners,
through
a
stage
of
lip
puckering
to
final
shrieking
with
mouth
wide
open
-
a
sequence
very
similar
to
that
in
the
crying
human
baby.
The
chimpanzee
also
shows
a
true
frown
and
is
able
to
express
longing,
especially
for
food,
by
means
of
lip
pouting,
a
ritualised
movement
derived
from
suckling.'
Summary
and
conclusions
The
facial
muscles
of
G.
senegalensis,
C.
aethiops
and
P.
troglodytes,
distantly
related
African
primates,
are
described
and
considered
in
relation
to
those
of
P.
ursinus,
which
Lightolleri°
pro-
posed
as
the
standard
for
study
of
the
facial
musculature.
It
is
clear
that
they
can
be
arranged
in
a
time
series
of
increasing
differentia-
tion
and
complexity
which
corresponds
with
the
taxonomic
classification
of
these
animals.
Furthermore,
the
movements
generated
by
these
muscles
also
demonstrate
a
progressive
evolutionary
refinement,
from
almost
total
reliance
by
the
(Palaeocene)
lorisiform
G.
senegalensis
on
mass-reflex
facial
responses;
through
partial
emancipation
from
these
of
at
least
some
of
their
expression
elements
to
form
more
isolated
non-agonistic
facial
signals
of
subtler
communicatory
value
in
the
(Oligocene)
cercopithecoids
C.
aethiops
and
P.
ursinus;
to
the
wide
range
of
graded
facial
activity
seen
in
the
(Miocene)
pongid
P.
troglodytes.
It
is
emphasized
that
these
species
are
not
a
linear
series,
but
the
structure
and
functioning
of
their
facial
musculatures
are
clearly
correlated
in
a
general
way
with
their
evolutionary
status.
P.
troglodytes,
man's
nearest
hominoid
relative
(with
the
possible
ex-
ception
of
P.
paniscus
11
),
indeed
shows
something
of
the
niceties
of
human
facial
communication,
albeit
in
relatively
crude
fashion.
Received
21
June;
accepted
11
September
1979.
I.
Pellatt,
A.
(1979).
The
facial
muscles
of
Papio
ursinus.
S.
Afr.
J.
Sri..
75,
30
-
37.
2.
Young,
J.
Z.
(1962).
The
Life
of
Vertebrates.
Oxford
University
Press,
Lon-
don.
3.
Huber,
E.
(1930).
Evolution
of
facial
musculature
and
cutaneous
field
of
N.
trigeminus.
Quart.
Rev.
Biol.,
5,
133
-
154.
4.
Gegenbaur,
C.
(1883).
Lehrbuch
der
Anatomie
des
Menschen.
Leipzig.
5.
Huber,
E.
(1931).
Evolution
of
Facial
Musculature
and
Facial
Expression
Johns
Hopkins
Press,
Baltimore.
6.
Nairn,
R.
1.
(1975).
The
circumoral
musculature:
structure
and
function.
Brit.
dent.
J.,
138,
49
-
56.
7.
Andrew,
R.
J.
(1963).
The
origin
and
evolution
of
the
cells
and
facial
expres-
sions
of
the
primates.
Behaviour.
20,
Part
2,
5-109.
8.
Andrew,
R.
J.
(1963).
Evolution
of
facial
expression.
Science,
142,
1034
-
1041.
9.
Van
hooff,
J.
A.
R.
A.
M.
(1962).
Facial
expressions
in
higher
primates.
Symp.
Zoo!.
Soc.
Lond.,
8,
97
-
125.
10.
Lightoller,
G.
S.
(1928).
The
facial
muscles
of
three
orang-utans
and
two
Cer-
copithecidae.
J.
Anal.,
63,
19
-
81.
11.
Zihlman,
A.
L.
(1979).
Pygmy
chimpanzee
morphology
and
the
interpretation
of
early
hominids.
S.
Afr.
J.
Sci.,
85,
165
-
168.