Analysis of PrimatesAnalysis of PrimatesComparisons of Human, Ape, Comparisons of Human, Ape,

and Australopithecineand Australopithecine

Characteristics of PrimatesCharacteristics of Primates

HominidsHominids Bones of more than 500 early Bones of more than 500 early

hominids have been foundhominids have been found From these bones, we have gained a From these bones, we have gained a

broad understanding of these related broad understanding of these related speciesspecies

By 3mya most hominids were bipedalBy 3mya most hominids were bipedal These hominids had a pelvis similar These hominids had a pelvis similar

to humansto humans

Comparison of Pelvis and Foot Comparison of Pelvis and Foot BonesBones

Hominid pelvis (like human pelvis) became shorter Hominid pelvis (like human pelvis) became shorter and bowl-shapedand bowl-shaped

This made the pelvis more stable for upright walkingThis made the pelvis more stable for upright walking Early hominid leg and foot bones also more similar to Early hominid leg and foot bones also more similar to

human’s human’s

Hominid LocomotionHominid Locomotion Bipedal locomotion is an adaptation for living in Bipedal locomotion is an adaptation for living in

open grasslandsopen grasslands Bipedal adaptation was selected for because it Bipedal adaptation was selected for because it

was easier to see far and move fartherwas easier to see far and move farther Upright posture also gets rid of excess body Upright posture also gets rid of excess body

heatheat Over many years hominid legs became strongerOver many years hominid legs became stronger Over many years hominid feet developed Over many years hominid feet developed

arches for efficient support of their body weightarches for efficient support of their body weight Over many years hominid hands became better Over many years hominid hands became better

at manipulating objects such as food and toolsat manipulating objects such as food and tools

Hominid HeadHominid Head Early hominid heads were very Early hominid heads were very

different than ours (evolutionary different than ours (evolutionary forces were slower in making forces were slower in making changes to heads)changes to heads)

Adult brain was 1/3 size of oursAdult brain was 1/3 size of ours The widest part of skull was below The widest part of skull was below

the brain casethe brain case

Hominid SkullsHominid Skulls

Australopithecus boisei Modern HumanAustralopithecus boisei Modern HumanEarly hominids had big teeth, large jaws, large Early hominids had big teeth, large jaws, large

zygomatic archeszygomatic archesEarly hominids had a sagittal crest (jaw muscle Early hominids had a sagittal crest (jaw muscle

attachment area)attachment area)(In modern humans, jaw muscles are smaller and (In modern humans, jaw muscles are smaller and

attach to skull in temple region)attach to skull in temple region)

Comparisons of SkullsComparisons of Skulls Modern humans have large cranial Modern humans have large cranial

capacity, relatively small teeth, less capacity, relatively small teeth, less prominent brow ridges, small zygomatic prominent brow ridges, small zygomatic arches, small jaw, no sagittal crestarches, small jaw, no sagittal crest

Comparisons of SkullsComparisons of Skulls As a transitional species, (intermediate between modern As a transitional species, (intermediate between modern

humans and apes) Australopithecines had less cranial humans and apes) Australopithecines had less cranial capacity, larger teeth, prominent brow ridges, larger capacity, larger teeth, prominent brow ridges, larger zygomatic arches, larger jaw, sagittal crestzygomatic arches, larger jaw, sagittal crest

Below is an Australopithecine afarensis skull (like Lucy)Below is an Australopithecine afarensis skull (like Lucy)

Comparisons of SkullsComparisons of Skulls

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

Comparison of Spinal CordsComparison of Spinal Cords Ape spinal cord exits the Ape spinal cord exits the

rear of the skullrear of the skull Australopithecus, lower Australopithecus, lower

left, spinal cord (like left, spinal cord (like human) exits the bottom human) exits the bottom of skullof skull

Skeletal ComparisonsSkeletal Comparisons

Dental ComparisonsDental Comparisons Gorilla lower jaw is Gorilla lower jaw is

parallel, and canine parallel, and canine teeth are very teeth are very pointedpointed

Australopithecus Australopithecus lower jaw is more lower jaw is more angledangled

Modern human Modern human lower jaw is even lower jaw is even more angledmore angled

Dental ComparisonsDental Comparisons Australopithecus Australopithecus

afarensis (4.0-2.9 afarensis (4.0-2.9 mya) (Lucy) canine mya) (Lucy) canine teeth were relatively teeth were relatively large and pointed, large and pointed, similar to apessimilar to apes

Australopithecus Australopithecus africanus (3.3-2.3 africanus (3.3-2.3 mya) canine teeth did mya) canine teeth did not project out—teeth not project out—teeth more like humans than more like humans than afarensisafarensis

Branches of the Hominid Branches of the Hominid Evolutionary TreeEvolutionary Tree

Hominid Species in Order of Hominid Species in Order of Appearance in Fossil RecordAppearance in Fossil Record

(oldest to newest)(oldest to newest) Ardipithecus ramidusArdipithecus ramidus Australopithecus anamensisAustralopithecus anamensis Australopithecus afarensis (Lucy)Australopithecus afarensis (Lucy) Australopithecus africanusAustralopithecus africanus Australopithecus aethiopicusAustralopithecus aethiopicus Australopithecus robustusAustralopithecus robustus Australopithecus boiseiAustralopithecus boisei Homo habilisHomo habilis Homo erectusHomo erectus Homo sapien (archaic)Homo sapien (archaic) Homo sapien neanderthalensisHomo sapien neanderthalensis Homo sapien sapien (modern)Homo sapien sapien (modern)

For tomorrow, below and reviewFor tomorrow, below and review Big Neanderthal debateBig Neanderthal debate