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)