THE PRIMATES
Year 13 Biology
Achievement standard 3.7
Terms
 Arboreal – Tree-dwelling
 Binocular Vision – ability to see 3D, depth
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perception and colour
Prehensile – ability to grasp (hands, feet, tail)
Quadrapedalism – walking on all four limbs
Brachiation – use of arms to suspend body during
feeding and to move the body by arm-swinging
Bipedalism – walking on two legs (habitual)
Hominid – Humans and their ancestors
Hominoid – Group containing humans and apes
Primate Groups
 Prosimians
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Arboreal or tree living
Grasping hands and feet
Long, mobile limbs
Quadrapedal
Binocular vision
Upright sitting position
Nails instead of claws
Use scent marking to
communicate – wet nose
Primate Groups
 New World Monkeys
(Americas)
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Prehensile or grasping tail – used
as a 5th limb
Quadrapedal
Arboreal or tree living
Nostrils wide apart
E.g. spider monkey
Primate Groups
 Old world monkeys (Africa
and Asia)
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Tail not prehensile
Quadrapedal
Some are ground living
Nostrils close together – reduced
sense of smell
E.g. Baboon
Primate Groups
 Great Apes
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Some brachiating
Mostly ground dwelling
Quadrapedal
Flattened nose
Bony eye ridges
E.g. Gibbon, Gorilla, chimp,
Orangutan
Primate Groups
 Hominids
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Bipedal
Reduced canines and outer teeth
Large cerebral cortex (forebrain)
Eye ridges reduced, chin and nose
protrude
Very sensitive skin
Reduced body hair
Very complex social behaviour
Evolution of Apes and Human
(Hominoids)
Primate Skull Features
Cranial Vault
Sagittal Crest
Nuchal Crest
Brow Ridge
Heavy Malar
Zygomatic Arch
Diastema
Foramen Magnum
Protruding
Muzzle
Massive Jaw
Massive Molars
Large Canines
General Ape Characteristics
 No tail
 Y-5 Pattern on teeth.
 Quadrupedal
 Semi or fully-erect posture
 Arms long in comparison with hind limbs
 Rib cage flattened from front to back
 Larger brains
 Upper lip free from gums
 Powerful canine teeth and large incisors
Differences between Humans and
Apes
 Main physical differences between
quadrupedalism and bipedalism
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The Skull
Teeth and Jaw
The legs
The feet
The chest
Physical differences between Apes and
Humans
Physical differences between Apes and
Humans – The Skull
HUMANS
APES
Occipital Condyle forward
Occipital Condyle far back
Foramen Magnum positioned
underneath skull
Foramen Magnum positioned towards
the back
Area of attachment for neck (nuchal)
muscles is small
Area for attachment for neck (nuchal)
muscles is large. Apes also have large
sagittal crest for attachment on heavy
chewing muscles
Large Brains – 1400 cm3
Smaller Brains – 400 – 500cm3
Modern human has chin and nose that
sticks out
Apes have no chin and a flat nose
Face is flat with forehead rising up
from the eyes. Some early human had
wide cheek bones called Zygomatic
Arch.
Forehead slopes back from the eyes,
large brow ridges. Apes are
prognathic – lower face and jaw
project in front of upper parts of face.
Physical differences between Apes and
Humans – The Skull
Physical differences between Apes and
Humans – The Skull
Physical differences between Apes and
Humans – The teeth and jaw.
HUMANS
APES
Both males and females have small
incisors and canines that do not
project further than any of the other
teeth
Apes have large incisors and
canines.
Both premolars have 2 cusps
First premolar has one cusp and
second has 2 cusps.
No Diastema
Diastema in lower jaw where
canines fit.
Palate is arched and teeth shaped
like a rounded ‘V’
Palate is flat and teeth shaped like a
‘U’ with parallel sides
Physical differences between Apes and
Humans – The teeth and jaw.
Physical differences between Apes and
Humans – The pelvis and backbone
HUMANS
APES
Backbone is S shaped
Backbone is arched
Pelvis is broad, shallow from top to
bottom and bowl-shaped
Pelvis is narrow and elongated
Centre of gravity is just behind the
lower back above the legs
Centre of gravity is in the middle of
the spine.
Have large gluteus maximus
muscles to support femur and pelvis
Small gluteus maximus and support
body with arms instead.
Physical differences between Apes and
Humans – The pelvis and backbone
Physical differences between Apes and
Humans – The legs
HUMANS
APES
Head of femur is
far apart and knee
ends close
together forming
an angle (valgus
angle)
Head of femur and
knee ends in a
vertical line – no
angle
Outer condyle is
larger than inner
one in the knee
joint
Inner condyle is
larger than outer
one in the knee
joint.
Legs are longer
than arms
Arms are longer
than legs
Physical differences between Apes and
Humans – The feet
HUMANS
Foot has short toes. The big toe is
longer and lies close alongside the
other toes.
APES
Gap between the big toe and the
rest and the big toe is shorter than
the rest
Weight is taken on the outside of the Apes have flat feet.
foot. Inner side is elevated into an
arch.
Physical differences between Apes and
Humans – The chest
HUMANS
APES
Chest is broard and narrow,
flattened from front to back
Chest is flattened at the sides
Collar bone is long
Collar bone is shorter than in
humans
Shoulder blades lie on back
Shoulder blades sit along the sides
of the chest.
Bipedalism V’s Quadrupedalism
 Advantages and disadvantages of bipedal (upright)
walking
Advantages
Can see further
Free hands
Can carry babies etc
Can throw stones and wield
sticks
Can keep cooler by less sun
falling on the body and more
wind off the ground
Look larger and more menacing
Greater display of sexual organs
to members of opposite sex
Disadvantages
Back-aches
Painful birth
Takes a long time to learn to walk
Varicose veins
Why walk upright?
 In Early Africa, Apes lived in a continuous
forest and as a result were adapted for an
arboreal life.
 Climate changed (drier) and forest retreated
leaving large areas of grassland.
 Divergent evolution occurred – some
remaining in the trees and some developing
bipedalism as an adaptation for moving
between the patches of forest.