Evolution

1
Evolution

• Fossil Record as Fair Test

2
Theory of Evolution

• All life on Earth descended from a common
  ancestor
• Life originated as a simple form, and became more
  diverse and complex over time

3
Fossil Record

• Represents 4,000,000,000 year long record of
  the natural history of our planet

4
Law of Superposition

• States that the older strata are the lower strata
  ( vice versa)

5
Fossil Record

• Each layer of sedimentary rock provides us with
  fossilized snapshots of the life-forms of that
  era
• The more snapshots (fossils) we find, the more
  complete our record of the history of life on our
  planet.
• Remember the Checks lab?(the more data we
  collected, the more complete our record, the more
  confident we become in the story which we
  generated)

6
Competing Hypotheses

• Hypothesis A Life forms do not change over
  time. Each species is fixed(traditional
  view)
• Hypothesis B Life forms change over time.
• Could our fossil record have supported either of
  these hypothesis?(Is the fossil record a FAIR
  test of these competing ideas?)

7
Competing Hypotheses(Variation)

• Hypothesis A Life forms do not change over
  time. Each species is fixed(traditional
  view)
• Hypothesis B Life forms change over
  time.Variation 1 Life has changed, but with no
  discernable pattern
• Variation 2 Life forms have changed from
  simple to complex