Human Evolution

1
Human Evolution

• Our biological history

2
What is evolution?

• Evolution is change
• Biological evolution is change in the properties
  of a population over time

3
Why ?

• We discuss human evolution because
• Speculation about human history and the natural
  world plays an important role in many societies
• Culture is an expression on top of our biological
  base
• Biology and culture are intertwined complex
  brains have evolved with complex social
  organization
• Our evolutionary history is part of what it means
  to be human

4
Natural Selection

• Set of simple patterns that work together to
  change a population over generations
• Variation there is variation among members of a
  species
• Mutation variation arises from random changes
  in genetic material
• Gene flow when individuals move from place to
  place and mix genes in new gene pools, this adds
  to variation
• Genetic drift in isolation or disaster,
  whatever random genes made it through will be
  passed on to future generations

5
Natural Selection

• Set of simple patterns that work together to
  change a population over generations
• Varied reproductive success
• Not all individuals survive to reproduce
• Those that do will pass traits on to offspring
• survival of fittest

6
Our Closest Relatives

• 25 20 mya LCA with monkeys
• 13mya LCA with great apes
• 7mya LCA with chimpanzees
• All primates originated as tree dwellers
• Opposable thumbs
• Depth perception

7
Primate Social Life

• Live in social groups with strong mother/infant
  bond
• Learn by mimicking mother
• Learn by playing refine physical and social
  skills
• Dominance hierarchies reduce conflict

8
Tool Use in Primates

• Vary by group, therefore learned
• Macaques wash food
• Chimpanzees use hammerstone to break nuts
• Chimpanzees use sticks to fish for termites
• Chimpanzees use leaves as sponges

9
Evolution of Humans

• Bipedalism differentiates us from other primates
• Requires restructuring of feet, legs, hips, spine
  and skull
• Frees hands to carry objects
• Improves view of surroundings
• Can walk efficiently over long distances

10
Evolution of Humans

• Australopithecines 4 mya to 1 mya
• Gracile
• 3.55 feet tall, 65-100 pounds, brains 1/3 size
  of ours
• Eastern and southern Africa
• Omnivores fruit, vegetables, insects, small
  animals
• Robust
• Larger, much heavier skulls and jaws, bigger
  teeth
• Adapted for chewing heavy, coarse material like
  grasses, leaves and roots

11
Evolution of Humans

• Australopithecines 4 mya to 1 mya
• Gracile
• Robust
• Homo
• Homo habilis
• Larger brains, smaller teeth
• Oldowan stone tools
• Omnivores, hunted small animals, scavanged large
• May have migrated to Europe and China

12
Evolution of Humans

• Australopithecines 4 mya to 1 mya
• Gracile
• Robust
• Homo
• Homo habilis
• Homo erectus
• Larger body and brain in modern human range
• Use of tools and fire
• Omnivores, including hunting large animals
• Found in Africa, Asia and Europe

13
Evolution of Humans

• Australopithecines 4 mya to 1 mya
• Gracile
• Robust
• Homo
• Homo habilis
• Homo erectus
• Homo sapiens

14
Evolution of Humans

• Homo erectus 1.8mya 100kya
• Neanderthals 130kya 35kya
• Modern Humans 195kya
• Are Neanderthals modern humans of a separate
  species?
• Replacement model
• Multiregional model
• Hybridization model

15
Homo sapiens Culture

• Varied and efficiently made stone tools
• Compound tools ax head bound to handle
• Atlatl handle that increases power in spear
  throwing
• Symbolic and artistic artifacts
• Venus figurines 30 20kya, 40 figures
• Cave paintings
• Domestication of plants and animals
• When Ice Age populations declined people turned
  to domestication
• Dogs domesticated 10 to 14kya
• Rye farming begins in the Middle East 13kya