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THE PRIMATES Powered By Docstoc

     Year 13 Biology
Achievement standard 3.7
 Arboreal – Tree-dwelling
 Binocular Vision – ability to see 3D, depth
    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
     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
     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)
     Tail not prehensile
     Quadrapedal
     Some are ground living
     Nostrils close together – reduced
      sense of smell
     E.g. Baboon
           Primate Groups
 Great Apes
     Some brachiating
     Mostly ground dwelling
     Quadrapedal
     Flattened nose
     Bony eye ridges
     E.g. Gibbon, Gorilla, chimp,
          Primate Groups
 Hominids
   Bipedal
   Reduced canines and outer teeth
   Large cerebral cortex (forebrain)
   Eye ridges reduced, chin and nose
   Very sensitive skin
   Reduced body hair
   Very complex social behaviour
Evolution of Apes and Human
   Primate Skull Features
           Sagittal Crest                    Cranial Vault

Nuchal Crest                                                     Brow Ridge

                                                                Heavy Malar

 Zygomatic Arch

Foramen Magnum                                                  Protruding
   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
 Main physical differences between
  quadrupedalism and bipedalism
     The Skull
     Teeth and Jaw
     The legs
     The feet
     The chest
Physical differences between Apes and
  Physical differences between Apes and
  Humans – The Skull
              HUMANS                                    APES
Occipital Condyle forward              Occipital Condyle far back
Foramen Magnum positioned              Foramen Magnum positioned towards
underneath skull                       the back
Area of attachment for neck (nuchal)   Area for attachment for neck (nuchal)
muscles is small                       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    Apes have no chin and a flat nose
sticks out
Face is flat with forehead rising up   Forehead slopes back from the eyes,
from the eyes. Some early human had    large brow ridges. Apes are
wide cheek bones called Zygomatic      prognathic – lower face and jaw
Arch.                                  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       Apes have large incisors and
incisors and canines that do not        canines.
project further than any of the other
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       Palate is flat and teeth shaped like a
like a rounded ‘V’                      ‘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   Pelvis is narrow and elongated
bottom and bowl-shaped

Centre of gravity is just behind the   Centre of gravity is in the middle of
lower back above the legs              the spine.

Have large gluteus maximus             Small gluteus maximus and support
muscles to support femur and pelvis    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     Head of femur and
far apart and knee   knee ends in a
ends close           vertical line – no
together forming     angle
an angle (valgus
Outer condyle is     Inner condyle is
larger than inner    larger than outer
one in the knee      one in the knee
joint                joint.
Legs are longer      Arms are longer
than arms            than legs
Physical differences between Apes and
Humans – The feet
             HUMANS                                   APES

Foot has short toes. The big toe is   Gap between the big toe and the
longer and lies close alongside the   rest and the big toe is shorter than
other toes.                           the rest

Weight is taken on the outside of the Apes have flat feet.
foot. Inner side is elevated into an
Physical differences between Apes and
Humans – The chest
             HUMANS                            APES

Chest is broard and narrow,    Chest is flattened at the sides
flattened from front to back
Collar bone is long            Collar bone is shorter than in

Shoulder blades lie on back    Shoulder blades sit along the sides
                               of the chest.
 Bipedalism V’s Quadrupedalism
  Advantages and disadvantages of bipedal (upright)
        Advantages                        Disadvantages
Can see further                    Back-aches
Free hands                         Painful birth
Can carry babies etc               Takes a long time to learn to walk
Can throw stones and wield         Varicose veins
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
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.

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