APS – Unit 1

Human Evolution - Anthropology

Evolutionary Theory

Charles Darwin 1809-1882

Published Origin of the Species (1859)

Galapagos Islands – observed different species of finches

Controversial !

Darwin’s Theory – Natural Selection

1. Heritability: Organisms inherit characteristics from their parents

2. Variation: there is a lot of variation within a species

3. Environmental Fitness: Those traits that allow an individual to survive to reproductive age – to pass on to offspring

Darwin’s Finches

An example of Variation

Peppered Moth UK – example of natural selection

White and Black moths (Variation)

Food source for birds

Before Industrial Rev. most moths – white - better camouflaged against white lichen (Enviromental Fitness)

Industrial Rev – coal dust turned environment black, now black moths better camouflaged. Black moths now surviving to reproduce and pass their colour to next generation (Heritability)

Now, most moths are black (natural selection)

Evolution – evidence

Physical Anthropologists Look at:

1. Fossil, bone, stone remains (using dating techniques)2. Microscopic analysis – pollen, scratches on

bone3. Experiments – flake stone techniques

Human Evolution

Human Evolution

hominid: is any member of the biological family Hominidae (the "great apes"), including the humans, chimps, bonobos, gorillas and orangutans

Hominids

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 continued

Structural changes required for us to walk upright:

1. S-shaped spine2. Double arched foot3. Pelvis – shorter and wider4. More gluteus muscles5. 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

Hominid (human), Primate differences:

Primates Hominids / Humans

Social structures

Dominance HierarchiesSilverbacks and alpha males in a groupGroomingRelated to the hierarchiesStress release

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

Speech centre in the brain

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)

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)

Skin Colour - Legitimate Explanations for Human Variation

Darker skin provides better protection from UV rays

Darker skin is found in areas

closer to the equator where there is more and stronger sunlight (environmental Fitness)

Skin colour (variation)