Analysis of Primates

1
Analysis of Primates

• Comparisons of Human, Ape, and Australopithecine

2
Characteristics of Primates
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Hominids

• Bones of more than 500 early hominids have been
  found
• From these bones, we have gained a broad
  understanding of these related species
• By 3mya most hominids were bipedal
• These hominids had a pelvis similar to humans

4
Comparison of Pelvis and Foot Bones

• Hominid pelvis (like human pelvis) became shorter
  and bowl-shaped
• This made the pelvis more stable for upright
  walking
• Early hominid leg and foot bones also more
  similar to humans

5
Hominid Locomotion

• Bipedal locomotion is an adaptation for living in
  open grasslands
• Bipedal adaptation was selected for because it
  was easier to see far and move farther
• Upright posture also gets rid of excess body heat
• Over many years hominid legs became stronger
• Over many years hominid feet developed arches for
  efficient support of their body weight
• Over many years hominid hands became better at
  manipulating objects such as food and tools

6
Hominid Head

• Early hominid heads were very different than ours
  (evolutionary forces were slower in making
  changes to heads)
• Adult brain was 1/3 size of ours
• The widest part of skull was below the brain case

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Hominid Skulls

• Australopithecus boisei Modern
  Human
• Early hominids had big teeth, large jaws, large
  zygomatic arches
• Early hominids had a sagittal crest (jaw muscle
  attachment area)
• (In modern humans, jaw muscles are smaller and
  attach to skull in temple region)

8
Comparisons of Skulls

• Modern humans have large cranial capacity,
  relatively small teeth, less prominent brow
  ridges, small zygomatic arches, small jaw, no
  sagittal crest

9
Comparisons of Skulls

• As a transitional species, (intermediate between
  modern humans and apes) Australopithecines had
  less cranial capacity, larger teeth, prominent
  brow ridges, larger zygomatic arches, larger jaw,
  sagittal crest
• Below is an Australopithecine afarensis skull
  (like Lucy)

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Comparisons of Skulls

• Skulls of Apes (see above gorilla skulls) had
  small cranial capacity, large teeth, prominent
  brow ridges, large zygomatic arches, large jaw,
  sagittal crest

11
Comparison of Spinal Cords

• Ape spinal cord exits the rear of the skull
• Australopithecus, lower left, spinal cord (like
  human) exits the bottom of skull

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Skeletal Comparisons
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Dental Comparisons

• Gorilla lower jaw is parallel, and canine teeth
  are very pointed
• Australopithecus lower jaw is more angled
• Modern human lower jaw is even more angled

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Dental Comparisons

• Australopithecus afarensis (4.0-2.9 mya) (Lucy)
  canine teeth were relatively large and pointed,
  similar to apes
• Australopithecus africanus (3.3-2.3 mya) canine
  teeth did not project outteeth more like humans
  than afarensis

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Branches of the Hominid Evolutionary Tree
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Hominid Species in Order of Appearance in Fossil
Record(oldest to newest)

• Ardipithecus ramidus
• Australopithecus anamensis
• Australopithecus afarensis (Lucy)
• Australopithecus africanus
• Australopithecus aethiopicus
• Australopithecus robustus
• Australopithecus boisei
• Homo habilis
• Homo erectus
• Homo sapien (archaic)
• Homo sapien neanderthalensis
• Homo sapien sapien (modern)

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• For tomorrow, below and review
• Big Neanderthal debate