Human Evolution - Anthropology APS – Unit 1 Human Evolution - Anthropology

Evolutionary Theory Charles Darwin 1809-1882 Published Origin of the Species (1859) Galapagos Islands – observed 2 species of finches Controversial !

Darwin’s Theory – Natural Selection Heritability: Organisms inherit characteristics from their parents Variation: there is a lot of variation within a species 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 (Enviro. 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 bone 3. Experiments – flake stone techniques

Human Evolution

Human Evolution hominid: is any member of the biological family Hominidae (the "great apes"), including the extinct and extant human 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: S-shaped spine Double arched foot Pelvis – shorter and wider More gluteus muscles 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

Why Bipedal – Theories! Carrying – young, food, over long distances Display – seem more impressive, scare predators Trench Coat – males who display genitals attract mates Energy efficiency – less area exposed to sunlight, cooler Scavenging – carry food and tools away from exposed areas Adaptability – gives more flexibility of movement and the means to adapt more quickly to changing situations. Habitat – a chance to safely migrate out of the trees

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 Hierarchies Silverbacks and alpha males in a group Grooming Related to the hierarchies Stress release Pair Bonding AND Group Living Humans 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 mate Who gets to mate when ties into dominance and grooming hierarchies No estrus cycle Choice in when to mate

Hominid (human), Primate differences Primates Hominids / Humans Mother – Infant relationship Long infant dependency compared to other mammals Important 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)