Human Evolution

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Chapter 12

• Human Evolution

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1. Paleoanthropologist

• scientist who study human evolution
• Deals with fossils makes inferences from
  subtle clues
• Constructs models

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• Louis and Mary Leakey searched the Olduvai
  Gorge for evidence of hominids (our
  ancestors)
• Olduvai Gorge is 1000 miles from Asia
• Hominid migration followed the waterways of
  the Tigris, and Euphrates Rivers into
  Mesopotamia

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2. Primates

• monkeys, apes, humans, lemurs, tarsier
• Characteristics
• Highly movable fingers/toes with nails not
• claws
• Good vision-depth perception
• Binocular vision each eye sees a
• slightly different view of the same scene,
  the brain merges the two images into a 3D
  image providing depth perception
• Vertical position of the body

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3. Prosimian primates

• before monkeys lemur, tarsier
• Characteristics
• Night time hunters
• Large eyes for seeing at night
• Small body size

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4. Anthropods

• monkeys, apes, humans
• Characteristics
• Developed clavicle
• Rotating shoulder joints
• Rotating elbow joints
• Opposable thumbs precision grip flexibility
• Opposable big toe (in most) precision
  grasping
• Large brain for body size (cranial capacity)
• Color vision

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5. Humans

• Characteristics
• Bipedalism
• Pelvic difference supports organs
• Foot difference body weight distribution
• Jaw differences change in diet
• Teeth differences change in diet
• Large cranial capacity average 1400cm3

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6. Hominid evolution

• Homo sapiens our immediate ancestors
• (humans)

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• Australopithecus genus name meaning southern ape

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1. A. aferensis

• 1974 the remains were found in Eastern Africa
  oldest found 3-3.5 myo called Lucy
• Shorter than modern humans
• Fossil footprints/pelvic and leg bones
  indicate bipedalism
• Cranial capacity
• 380 450 cm3
• Heavy brow ridge

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2. A. africanus

• 3-2.2 myo
• Little taller and heavier than A. aferensis
• Cranial capacity 430 550 cm3
• More rounded jaw

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3. A. robustus A. boisei

• 1-2 myo
• Heavier skulls/ larger back teeth molars used
  for grinding, indicates diet of plants
• Cranial capacity 450 600 cm3
• Evidence indicates these are not in our direct
  line of ancestors

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Homo genus name meaning man
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4. Homo habilis (handy man)

• First in the human species (Homo)
• Cranial capacity 600 800 cm3
• Speech area of brain developed
• Meat eater
• Used stone tools for hunting/cooking

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5. Homo erectus (upright man)

• 0.5 1.6 myo
• Cranial capacity 700 1250 cm3
• Possibly as tall as modern humans
• Mainly hunters and gatherers
• Used tools/fire

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6. Homo sapiens Neanderthals

• 35,000 130,000 yo
• Inhabited Europe, Asia, Africa
• Cranial capacity 1450 cm3
• 5 feet tall/ stocky
• Cave dwellers
• Used tools
• Evidence indicates these are not in our direct
  line of ancestors

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7. Homo sapien sapien (wise man)

• Cro-Magnon 35,000 yo
• Inhabited France, Africa, Asia, Australia
• Cranial capacity 1400 cm3
• 6 feet tall
• Evidence of culture/tools/paintings
• Lacked brow ridge, had a high fore head with
  prominent chin
• Modern man

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7. Migration of Man

• 2 hypothesis

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Multi-regional Evolution

• H. erectus spread throughout the world and
  parallel lines of evolution created the modern
  populations.
• There was gene flow between populations
  preventing speciation.

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Europe Africa Asia Australia
Present 500,000 ya 1,000,000 ya
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Recent-Africa-origin hypothesis

• most widely supported
• modern H. sapiens originated in Africa and
  migrated to other areas displacing populations of
  H. erectus

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• evidence mitochondrial DNA is different from
  that in the nucleus.
• Mitochondrial DNA from all populations are
  similar. Mutation occurs at a predictable rate.
  Scientists think it took only 100,000 to
  200,000 yrs for the genes to change as they have.

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