The Incredible Journey
Recap – Natural Selection
 There is variation between individuals in a population
 Parents pass on their traits to their offspring
 The organisms with features that best suit their
environment have the best chance of survival and
reproduction
 Those organisms that are able to survive and reproduce pass
on their characteristics to their offspring
 Over time the population will become better suited to its
environment
 Let’s give it a try...
Natural Selection
 Human Adaptations that have been selected for;
 Bipedalism (position of the ‘foramen magnum’)
 Reduction in size of molar teeth
 Reduction in jaw size
 Increased cranial capacity
 Cranial ridge
Comparison of skulls
CHIMPANZEE
GORILLA
HUMAN SKULL
• What features can you identify?
• What makes the skulls different from one another?
Comparison of skulls
 Top of the skull (cranium) is smooth






There is no anterior-posterior crest to
hold huge jaw muscles
No protruding brow
No protruding jaw or teeth (ie the
teeth are vertical)
No protruding nose bone
Teeth are arranged in a parabolic
shape rather than a narrow u shape
Small canines and small incisors
Foramen magnum (hole for the
spine) is positioned directly
underneath the skull not in the back
of the skull
Australopithecus aferensis
 Location: Eastern Africa
 Cranial capacity : 375-425 cc
 Fossils discovered so far in
Tanzania, Kenya and Ethiopia
 Timeframe: 4.7 – 2.1 million years
 Fully bipedal (first!), but arms
longer than legs
 Possibly made tools out of bone
teeth and horn
(Osteodontokeratic)
Australopithecus africanus
 Location: Southern & Eastern





Africa
Cranial capacity: 420-500 cc
Timeframe: 3-2 million years
Slightly greater body size
Smaller canine teeth than A.
aferensis
Teeth structured in a more
parabolic (‘V’) shape
Australopithecus boisei (Oldoway)




Location: Eastern Africa
Cranial capacity: 500-550 cc
Timeframe: 2.5 - 1 million years
Largest teeth found in any hominid
group
 Huge jaw, small incisors & canines,
large molars & premolars, parabolic
dental structure and sagittal crest
present – (hard low quality food)
 Face is more vertically set
Homo rudolphonsis
 Earliest species of Homo (or maybe




Homo habilis?)
Cranial capacity: 775cc
Contention as to whether the fossils
are Australopithicus or Homo
Lack of crests
Smoothly rounded occipital bone
compared to Homo erectus
Homo habilis “handy man”




Location: Eastern Africa
Cranial capacity: 800 cc
2.5-1.5 million years
Short molars, small canines,
parabolic dental arcade
 Full biped, increased leg
length, decreased arm length,
shorter in stature
 Fossils accompanied by
primitive stone tools
Homo erectus
 Location: Africa, Asia, Europe
 Cranial capacity: 900-1225 cc
 Useing Acheulian tools: hand axe
culture, large game hunting,
suggestion of communication,
first to use fire
 Some scientists have split H.
erectus into three separate
species, based on the geographic
region in which specimens have
been found: H. ergaster (Africa),
H. erectus (Asia), and H.
heidelbergensis (Europe).
Homo sapien
 Location: Africa, Asian, Europe,






Australia, North America
A high, rounded cranium
Cranial capacity: 1400-1600 cc
Art & Symbolism, first to
produce fire and use language
A steep forehead
A tall and narrow nasal opening
A parabolic palate