Analysis of Primates
Comparisons of Human, Ape, and
Australopithecine
Characteristics of Primates
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
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Comparison of Pelvis and Foot
Bones
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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
human’s
Hominid Locomotion
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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
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)
Comparisons of Skulls
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Modern humans have large cranial capacity,
relatively small teeth, less prominent brow
ridges, small zygomatic arches, small jaw, no
sagittal crest
Comparisons of Skulls
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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)
Comparisons of Skulls
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Skulls of Apes (see above gorilla skulls) had
small cranial capacity, large teeth, prominent
brow ridges, large zygomatic arches, large jaw,
sagittal crest
Comparison of Spinal Cords
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Ape spinal cord exits the
rear of the skull
Australopithecus, lower
left, spinal cord (like
human) exits the bottom
of skull
Skeletal Comparisons
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
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Australopithecus afarensis
(4.0-2.9 mya) (Lucy)
canine teeth were
relatively large and
pointed, similar to apes
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Australopithecus
africanus (3.3-2.3 mya)
canine teeth did not
project out—teeth more
like humans than
afarensis
Branches of the Hominid
Evolutionary Tree
Hominid Species in Order of
Appearance in Fossil Record
(oldest to newest)
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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)
For tomorrow, below and review
 Big Neanderthal debate