1. History of Evolutionary Thought

2. What was the view of the world and nature before Darwin?
Static Universe
The universe didn’t change through time
Problem - Fossil Evidence

3. What was the view of the world and nature before Darwin?
Static Universe
2. Earth Centred Universe
Galileo - showed that this was wrong

4. What was the view of the world and nature before Darwin?
Static Universe
Earth Centred Universe
Great Chain of Being
Problem - how do you incorporate new species?

5. What was the view of the world and nature before Darwin?
Static Universe
Earth Centred Universe
Great Chain of Being
Argument from Design
Each species was designed for a specific purpose
Problem:

6. How did this ‘traditional’ view (or Natural Theology)
apply to Biology?
Argument from Design
The design of all organisms showed that
there was an intelligent and benevolent Creator
BUT….
How do disease organisms fit into
this scheme ?
Ebola

7. How did this ‘traditional’ view (or Natural Theology)
apply to Biology?
Argument from Design
The design of all organisms showed that
there was an intelligent and benevolent Creator
OR….
Why did some species go extinct?

8. How did this ‘traditional’ view (or Natural Theology)
apply to Biology?
Argument from Design
Relationship between Species
(Great Chain of Being)
BUT ..
vulnerable to
extinction

9. How did this ‘traditional’ view (or Natural Theology)
apply to Biology?
Argument from Design
Relationship between Species
Fixed Species and Relationships
How do you incorporate new species?

10. General Summary:
The world/universe was designed by a benevolent Creator to function perfectly and its form and function were fixed through all time.

11. But Evolution is about change
What were the pre-Darwinian ideas of change through time?

12. Pre-Darwinian Ideas of Organic Change
1. Georges Louis Leclerc, Comte de Buffon ( )
Species - a distinct group maintained by
reproduction
Local Conditions
Different
species
Ancestor
Time

13. Pre-Darwinian Ideas of Organic Change
Georges Louis Leclerc, Comte de Buffon ( )
Jean-Baptiste Lamarck ( )

14. Pre-Darwinian Ideas of Organic Change
Georges Louis Leclerc, Comte de Buffon ( )
Jean-Baptiste Lamarck ( )
Lamarck’s ideas:
1. Spontaneous generation

15. Pre-Darwinian Ideas of Organic Change
Georges Louis Leclerc, Comte de Buffon ( )
Jean-Baptiste Lamarck ( )
Lamarck’s ideas:
Spontaneous generation
Ascent up the scale of nature
Different species
Complexity of the organism
Time

16. Pre-Darwinian Ideas of Organic Change
Georges Louis Leclerc, Comte de Buffon ( )
Jean-Baptiste Lamarck ( )
Lamarck’s ideas:
Spontaneous generation
Ascent up the scale of nature
Acquired characteristics

17. Originators of Modern Theories of Natural Selection
Alfred Russell Wallace
Charles Darwin

18. Voyage of HMS Beagle

19. Darwin’s Finches - Geospiza
Galapagos tortoise - Geochelone

20. Contributing Elements to Darwin’s theory
1. Charles Lyell ( )
Gradualism (Uniformitarianism)
All change through time can be explained by processes at work today
No need to invoke catastrophic events

21. Contributing Elements to Darwin’s theory
Charles Lyell ( )
Thomas Malthus ( )
Populations of organism will grow
faster than their food supply
Population
Number
Food supply
Time

22. Contributing Elements to Darwin’s theory
Charles Lyell ( )
Thomas Malthus ( )
Plant and Animal Breeders
showed that the form of a species could be changed over time

23. This differential reproduction/survival is natural selection
Logic of Darwin’s
Theory of Natural Selection
(or Descent with Modification)
Observation Deduction
All organic populations can exponentially.
In spite of Obs. 1, they don’t.
There is some kind of struggle for existence.
All members of a species are not the same.
Differences in individuals are passed to their offspring.
2. Some members of a species are better equipped to survive and reproduce than others.
This differential reproduction/survival is natural selection