Beginnings of Life

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Beginnings of Life
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Overview of evolution

• Earth formation 4.6 BYA
• Swirling ball of hot molten lava
• Gravity pulls in heavy solid nickel core
• Magma begins to cool into thin crust
• Rain begins to fall
• Harsh, hot, toxic, anaerobic (no free oxygen in
  atmosphere)

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First 4 billion years

• First life archaebacteria
• Prokaryotes no nucleus
• Dont need oxygen
• Dont produce oxygen
• thrive in harsh environments
  
  
  like deep ocean vents hot caustic
  puddles at
  Yellowstone

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First 4 billion years

• Next life photosynthesizing prokaryotes
• Cyanobacteria
• Make oxygen for a billion years

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First 4 billion years - From Prokaryotes to
eukaryotes

• Finally single-celled eukaryotes
• (have nucleus and membrane-bound organelles)
• Endosymbiont theory photosynthesizing
  prokaryotes were absorbed by other bacteria to
  become the first organelles - chloroplasts

Eukaryotic cell
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First 4 billion years

• Soft-bodied Multi-celled eukaryotes
• Began as colonies of single-celled organisms.
• Cells started to specialize and organize into
  multicellular organisms
• No backbone yet
• jelly fish
• sponges
• worms
• seaweed

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Next .5 billion years (about 500 MY)

• Cambrian explosion
• Adaptive radiation rapid speciation due to new
  opportunities
• Once life organized, and the planet was a
  comfortable living space, evolution happened in
  leaps and bounds,
• with new species diverging, rapidly filling every
  niche

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Evolve how?

• Mutations
• Some good, improve survival, so get passed down
• Mixing of genes through sexual reproduction
• Genetic drift
• Driven by Natural Selection
• Adaptive radiation
• Rememberit took billions of years to get this
  way!

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Evidence for evolution

• Fossils

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evidence
coprolite
Mosquito in amber
Dino tracks - Utah
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Evidence for evolution comparative anatomy

• Homologous structures
• Similar structures with different functions

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Evidence for evolution comparative anatomy

• Analogous structures
• Structures are different, but functions are
  similar

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Evidence comparative ANATOMY

• Vestigial structures no longer needed

Snake pelvic bones
Goose bumps
Whale pelvic bones
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evidence

• Embryonic comparison

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evidence

• Biochemical comparisons
• The more similar the DNA, the more recently two
  species branched apart.
• Many other chemical processes are similar among
  species.
• Soft tissue found inside fossilized dinosaur
  bones was found to have strikingly similar
  protein structures as those in chickens!

Can you see it?
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EVIDENCE GEOGRAPHIC DISTRIBUTION

• Fossil evidence from different continents fit
  together where continents fit together before
  Pangea broke up