Darwin

1
Darwins Daring

• Kitcher Believing Where We Cannot Prove
• Pages 332 -335

2
Darwinian History

1. Describe an ancestral population of organisms.
2. Trace modifications of the population through the
   subsequent generations, showing how
   characteristics were selected, inherited, and
   become prevalent.

3
Many Purposes

• Can describe why a trait exists
• Can describe relationships between organisms
• Can account for similarities and differences
  among species
• Can explain organisms locations
• Can try to explain extinctions
• Can be used in many broad classes of biological
  phenomena

4
Evolutionary Theory in Action Madagascar

• Island inhabited by a peculiar group of mammals,
  most of which are endemic
• tenrecs small, insectivorous mammals
• features mark them as primitive
• have specialized characteristics similar to
  other animals that do not inhabit this island
  (convergent evolution)
• Why are they found here
• and nowhere else?

5
Evolutionary Story

• In the late Mesozoic or early Cenozoic period,
  primitive mammals rafted across the Mozambique
  channel to Madagascar.
• Channel widened, preventing more advanced mammals
  from crossing.
• The tenrecs were protected.
• Without competition, they have maintained the
  simple body plan and exploited unoccupied niches.

6
Claims Subject to Independent Check Madagascar

• Madagascar drifted away from Africas east coast.
• Can check using geological criteria for the
  movement of land masses (criteria independent of
  biology)

7

• 2. Tenrecs could have rafted across the
  Mozambique channel, but that the present channel
  is a barrier to more advanced mammals.
• Test by looking to see if the animals in question
  can disperse across channels of appropriate size.

8

• 3. Specialized methods of defense are
  advantageous against predators on Madagascar.
• Study animal interactions to see if certain
  defenses are effective against local predators.

9

• 4. Tenrecs are related.
• Studies of minute features of tenrec anatomy
  should reveal common features should have
  similar protein structure.

10
Darwins theory can be compared to Newtons
Physics.

• Unified theory whose problem-solving strategies
  are used in many different areas.
• Problem solutions can be independently checked.
• Open new questions.
• History of surmounting apparent obstacles.