Adaptations:BipedalismBrain Size

Hand FunctionsTeeth – size and shape

Social StructuresReproduction

Mother-Infant RelationshipCommunication

Culture – art, religionSkin Colour

Habitual Bipedalism Bipedalism – to

habitually walk on two legs. Humans only primate with this adaptation

What had to happen for us to stand up straight?

Bipedalism… Structural changes required

for us to walk upright:

1. S-shaped spine

2. Double arched foot

3. Pelvis – shorter and wider

4. More gluteus muscles

5. Fewer head / neck muscles – therefore a bigger brain

Advantages of Being Bipedal

Free hands for carrying

Can walk longer distances

Can have a continuous good view of surroundings

Disadvantages of Being Bipedal Highly dangerous

birthing process

Offspring very dependent and weak because the skull must grow outside of the womb

Hominids and Brain Size

Humans have the largest brain for our body mass compared to other mammals

Refinements in Hand Structure -

A fully opposable thumb gives the human hand its unique power grip (left) and precision grip (right).

Tooth Size Comparison

Hominid (human), Primate differences:

Primates Hominids / Humans

Social structures

Dominance HierarchiesAlpha males in a groupGroomingRelated to the hierarchies

Pair Bonding AND Group LivingHumans are the only primates to have both social characteristics simultaneously

Hominid (human), Primate differences

Primates Hominids / Humans

Reproduction Estrus cycle (in heat)No choice of when to mateWho gets to mate when ties into dominance and grooming hierarchies

No estrus cycleChoice in when to mate

Hominid (human), Primate differences

Primates Hominids / Humans

Mother – Infant relationship

Long infant dependency compared to other mammalsImportant in learning survival skills and culture

Longest infant dependency period of all primates

Hominid (human), Primate differences

Primates Hominids / Humans

Communication Facial displays, call, touch, gestures, non-verbal cues

Speech centre in the brainDevelopment of Broca’s area of the brain (language), Frontal Cortex (abstract thought), Hyoid Bone (chin to neck bone/muscle attachment), Capacity for memory in various areas of the brain (cerebellum, prefrontal cortex, temporal lobe)

Culture

Horse in world's oldest painted prehistoric cave, 15,000-10,000 BC Lascaux, France

Dagger Carvings – Stonehengehttp://www.youtube.com/watch?v=_pXtHqAGN6E

Humanity and Our Variations

Our bodies are essentially 50 000 years old.

Now culture, not physical evolution enables us to adapt very quickly to a changing environment

Race - Cultural construct – does not physically exist

Skin Colour - Legitimate Explanations for Human

Variation

Sunlight is the best source of vitamin D (necessary for healthy bones – helps in the absorption of calcium)

Light skin absorbs vitamin D and burns more easily than darker skin Paler skin is found in areas further from the equator where there is less sunlight (environmental Fitness)

Skin colour (variation)