Human EvolutionThe Incredible Journey

Recap – Natural SelectionThere is variation between individuals in a populationParents pass on their traits to their offspringThe 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 SelectionHuman Adaptations that have been selected

for;Bipedalism (position of the ‘foramen magnum’)Reduction in size of molar teethReduction 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 skullsTop of the skull (cranium) is smooth

There is no anterior-posterior crest to hold huge jaw muscles 

No protruding browNo protruding jaw or teeth (ie the

teeth are vertical)No protruding nose boneTeeth are arranged in a parabolic

shape rather than a narrow u shapeSmall canines and small incisors Foramen magnum (hole for the

spine) is positioned directly underneath the skull not in the back of the skull

Australopithecus aferensisLocation: Eastern AfricaCranial capacity : 375-425 ccFossils discovered so far in

Tanzania, Kenya and EthiopiaTimeframe: 4.7 – 2.1 million

yearsFully bipedal (first!), but arms

longer than legsPossibly made tools out of

bone teeth and horn (Osteodontokeratic)

Australopithecus africanusLocation: Southern &

Eastern AfricaCranial capacity: 420-500

ccTimeframe: 3-2 million

yearsSlightly greater body sizeSmaller canine teeth than

A. aferensis Teeth structured in a more

parabolic (‘V’) shape

Australopithecus boisei (Oldoway)Location: Eastern AfricaCranial capacity: 500-550 ccTimeframe: 2.5 - 1 million yearsLargest teeth found in any

hominid groupHuge 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: 775ccContention 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 AfricaCranial capacity: 800 cc2.5-1.5 million yearsShort molars, small canines,

parabolic dental arcadeFull biped, increased leg

length, decreased arm length, shorter in stature

Fossils accompanied by primitive stone tools

Homo erectusLocation: Africa, Asia, EuropeCranial capacity: 900-1225 ccUseing 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 sapienLocation: Africa, Asian,

Europe, Australia, North America

A high, rounded craniumCranial capacity: 1400-1600 ccArt & Symbolism, first to

produce fire and use languageA steep foreheadA tall and narrow nasal

opening A parabolic palate