Comparative Primate
Anatomy
The Hardware of Human Culture
The Hardware of Human Culture





We could not be us without. . .
A language to communicate with and to use
for learning
An ability to make and use tools
All the abilities that standing and walking on
two feet allow us
So without understanding our anatomy, we
cannot understand our culture
Comparative Hominid Anatomy




Anatomically, we are very similar to apes and
even to monkeys
But we are not identical: Humans are fully
bipedal, for example, while chimps are not.
We have two arches in our foot; chimps do
not.
Therefore we need to compare our own
anatomy with (a) other living primates and (b)
fossil hominin forms.
Overview: The Human Skeleton



You do need to know
some of the parts of
the human skeleton
Use the online
graphics (such as this)
or your printed
handouts
We make a detailed
comparison of skeletal
parts later
The Roots of Culture: The Brain




If culture is symbolic, then it is founded on
language
The source of language is located in parts of
the brain
Our ability to make and use tools is also begins
in the brain
Therefore, we start by examining the parts of
the brain
Structure of the Brain: Description I




You may want to switch back and forth between the
description in the next two slides and the diagram that
follows them in the third slide
Frontal Lobe: The lobe that allows us to think and
plan ahead
Motor Cortex: The strip along the edge of the motor
cortex that moves the facial muscles (lips, tongue,
vocalization) and the arm, hand, and finger muscles
Parietal Lobe: The lobe that enables us to touch and
taste
Structure of the Brain: Description II




Occipital Lobe: The lobe of the brain that
enables us to see
Temporal Lobe: The lobe that enables us to
hear
Olfactory Bulb: The part of the brain that
enables us to smell
Supplementary Motor Cortex: The part that
provides sensory feedback from an action
involving the motor cortex
Structure of the Brain: Diagram







Frontal Lobe and Motor
Cortex:
Cognition: Thinking Ability
Motor Abilities
Parietal Lobe: Touch and
Taste
Temporal Lobe: Hearing
Occipital Lobe: Vision
Olfactory Bulb: Smell
The Motor Cortex






The next diagram gives a schematic view of the
functions of the motor cortex or strip
Lower part: The strip regulates the facial and oral
muscles
They include the tongue, the lips, the organs for
vocalization, and the jaws
These are related to the language function
Upper part: The strip regulates the arm, the hand,
and their fingers
These are related to the tool manufacture and use
functions.
Parts of the Brain: Motor Cortex








Related to Language:
Lower Part
Lips
Tongue
Vocalization
Related to Tool Making
and Use: Upper part
Fingers and Thumb
Hand
Arm
Language Functions of the Brain:
Description I






Again, you may want to move back and forth between the
descriptions and the diagram that follows the descriptions
The language functions all occur on the left hemisphere of the
brain in most humans
Broca’s Area functions to process the generating of speech
Notice that it is located at the base of the motor cortex, which
handles the tongue, vocalization, and lip movements
Wernicke’s Area functions to process the reception of speech
Notice its location in the temporal lobe, which processes
hearing
Language Functions of the Brain:
Description II




The angular gyrus is the part that coordinates all the
sense functions housed in the brain
They coordinate the senses of sight from the occipital
lobe, of the touch and taste of the parietal lobe, of the
smell from the olfactory lobe, and of hearing from the
temporal lobe
If you smell the scent of a rose and visualize a rose in
the mind’s eye
Its function for language is to translate all the sensory
information into the sense of hearing so we can
assign meaning to speech.
Parts of the Brain: Language
Centers
Parts of Cerebrum
•
Frontal Lobe
•
Motor Cortex
•
Broca’s Area
•
Temporal Lobe
•
Auditory Cortex
•
Wernicke’s Area
•
Arcuate Fasciculus
•
Parietal Lobe
•
Occipital Lobe
•
Angular Gyrus
Comic Relief, Anyone?
(Courtesy of Geico)

So easy a caveman can do it. . . .?
So Why Do We Pick on the Bones?



With few exceptions bones are all we have to
reconstruct past human and humanlike life
forms
Therefore we have to coordinate what we
know about anatomy—human and nonhuman
primate—to reconstruct what our ancestors
might have been like.
Bottom Line: We rely heavily on inference to
trace our ancestry
Human Skill: A Description




The forehead is high, making room for the
frontal lobe
The skull is rounded, allowing a greater
volume for the entire brain
There is no brow ridge or supraorbital torus
The jaw does not jut forward; it is not
prognathous
Human Skull: Bones that Cover the
Lobes






The bones of the skull are named after the
lobes they cover
The frontal bone covers the frontal lobe
The parietal bone covers the parietal lobe
The occipital bone covers the occipital lobe
The temporal bone covers the temporal lobe
Refresh your memory: what are each of these
lobes for?
Human Skull: The Diagram







Note the following:
High forehead
Rounded skull
No brow ridge
Chin is present
Teeth are small
The bones are named
after the lobes of the
brain they cover
Comparative Primate Anatomy:
Human and Chimpanzee




In the next diagrams, the differences are significant to
biological capacity for culture
The area for brain of a chimp is more limited than
human brain because of its sloping forehead and the
heavy supraorbital torus that covers much of the
forehead
The chimp jaw has a prognathism absent in humans
Chimps have larger canine teeth than humans; so
much so that there is a diastema (gap) for the
opposite canine to fit.
Skull Morphology: Chimp and
Human





Note the following
Larger brow ridge (supraorbital torus) of chimp compared to human
Sloping forehead of chimp compared to human
More prognathous (jutting) jaw of chimp compared to human
Larger canine and gap (diastema) of chimp compared to human
Comparative Brain Structure:
Human and Chimpanzee





In the next diagram, the human brain has a Broca’s
area for processing speech.
The chimp brain has a Brodman’s area, where calls
may originate, but no speech
Our Wernicke’s area, which receives speech, is at
the same place as the planum temporale among the
chimps
The chimp brain is much smaller than humans’—400
cubic centimeters compared with our 1400 cc.
The frontal lobe of the chimp is smaller than the
human’s, partly owing to the sloping forehead
Human and Chimp Skulls
Compared: Brain Structure






Compare the following
Chimp’s brain is much smaller
(400cc vs. 1400cc)
It has reduced frontal lobe
It has no Broca’s or Wernicke’s
area
It does have Brodmann’s area
10, where calls may originate—
but no speech
It does have planum temporale,
where calls are received—but
not processed as language
What This All Means




Our brains are larger than the chimps’
We have a well-developed frontal lobe
We have well developed language areas:
Broca’s and Wernicke’s area
The motor strip is more well developed among
humans than among chimps
Comparative Primate Anatomy:
Chewing Mechanism






The next diagrams compare human dentition
(structure of teeth) with that of the chimps
Our overall dental arcade (arrangement of teeth) is
more rounded (arc-like) than the chimps
Chimpanzee have a more rectangular dental arcade,
with the back teeth more parallel
Our teeth are much smaller than the chimps’
We have small canines (jagged teeth)
Chimps have large canines, so large that they need a
gap (diastema) in the opposite jaw for them to fit
Human Dentition: Diagram





For each jaw (upper or
maxilla or lower or
mandible:
Incisors (4) in the front
for cutting food)
Canines (cuspid) (2) for
piercing
Premolars (4) for light
grinding of food
Molars (6) in back for
heavy grinding of food
Chimp and Human Dentition



Note the following:
Dental Arcade: Humans’ are arc-like; apes, parallel back
teeth
Canines and Diastema (gap): Apes have larger canines
and gaps in opposite jaw to fit them; humans do not
Comparative Primate Anatomy:
Hand Structure




Our fingers are straight; that of the chimps and
other apes are curved
We have a much longer thumb than do the
apes
Importance: we are capable of a more precise
grip than the apes
This implies that we can make finer tools than
those apes who can make and use tools
Human Hand Structure: Diagram




Note The Following:
Our digits are straight
Our thumb is opposable
The thumb is long
Ape and Human Hands:
Diagram





Hands of orangutan, chimpanzee, gorilla and human
Note the following:
Our thumbs are longer than the others’
We can make a finer grip than the others can
Less visible: apes’ digits are curved, ours are straight
Power and Precision Grip
Note the Following:
 Power grip: Fingers
and thumbs wrap
around the object
 Precision grip:
Forefingers and thumb
hold the object
 Importance: We can do
finer work compared to
nonhuman primates
Comparative Primate Anatomy:
Bipedalism vs. Quadrupedalism




Homo sapiens is the only mammal capable of
bipedalism, or the ability to stand and walk entirely
on two feet.
Kangaroos stand on two feet, but they hop rather than
walk and their forepaws are too small for any
function.
Chimpanzees can walk on two feet, but not very
efficiently; they are closer to quadrupedalism, or the
ability to move around on four feet.
What are the advantages of bipedalism over
quadrupedalism. Answer the question and then look
at the next slide.
Advantages of Bipedalism








Efficient locomotion
Freeing of hands for many proposes:
Foraging and hunting/scavenging
Tool making and use
Care and provisioning of offspring
Increased height for viewing across landscape:
Tracking migrating herds
Predator avoidance
Bipedalism: Diagram





We are the only mammals
that can stand and walk on
two feet
Apes are semi-bipedal, but
use their knuckles to get
around (top photo)
The bottom photo compares
the “quadrupedalism” of a
human with that of a chimp
Notice the human is on his
knees, not just his feet
The chimp is using its hind
feet, not its knees.
Comparative Human Anatomy:
Locomotion






You will need to make a close comparison of human
and chimp anatomy in the next diagram
Pelvis: Compare the length of the ilium of the chimp
with that of the human
Compare the arm length of the chimp with the human
Compare the leg bones of the chimp with the human
Compare the foot structure of the chimp with the
human
What are the differences between each set of
characteristics? Write your answers, then look at each
of these characteristics in detail.
Chimp and Human Locomotion
Compared
Vertebral Column and Pelvis





Note the following:
Human vertebral column
is S-shaped, supporting
the upper torso
Chimp vertebral column is
bow-shaped
Human pelvis, with ilium,
is bowl-shaped; muscles
from the thigh keep him
upright
Chimp pelvis is long, with
flat ilium
Pelvis and Femur





Note the following:
Longer ilium of chimp
Shorter, more curved
ilium of human
Straight vertical
orientation of chimp
femurs, which do not
support the upper body
well
Inward angle of human
femurs, which support
Foot Structure




Note the following:
Large toe of chimp foot
(right) is opposable to other
digits
Large toe of human foot
(left) is aligned with other
digits
Ankle bones (tarsals) of
human food are larger and
more rigid than the chimps
Foot Arch: Longitudinal and
Transverse




Note the following:
Longitudinal arch that runs
from the first metatarsal to
the calcaneus (heel bone)
Large tarsals to the rear
contribute to the rigid
structure of the foot and its
arch
Transverse arch can be
inferred from lower
placement of outside foot to
the instep
What We Have Learned





We have learned the hardware essential to culture
They include our brain, where language and tool use
originate
We have learned about our ability to stand and walk
on two feet and the importance of this ability
We have also learned about the characteristics of ape
anatomy
This comparison gives us a clue on the next phase of
this unit, human biological evolution