1. The Theory of Evolution by Natural Selection
Charles Darwin
The Origin of Species

2. 1. Overproduction & Struggle for Existence
Individuals produce more offspring
than the environment can support.
Individuals must compete …the struggle for existence.

3. 2. Variation and Adaptation
Individuals in a population have variations.
Some variations make an organism
better adapted….adaptation.

4. 3. Survival of the Fittest
Individuals with the best adaptations are better suited
to their environment (have greater fitness),
as a result they can survive and reproduce.

5. 4. Natural Selection
Organisms with variations most suited to their environment survive and leave more offspring.
The environment (nature) “selects”
which organisms will survive.

6. EVIDENCE OF EVOLUTION

7. THE AGE OF THE EARTH FOSSILS ANATOMY Evolution takes a long time.
Earth is about 4.5 billion years old.
FOSSILS
Fossils offer the most direct evidence of evolution.
ANATOMY
similar arrangement of bones…
evidence of common ancestor.

8. Some organisms have structures that are no
longer useful buthad important function
in the organism’s ancestor.

9. EMBRYOLOGY
Very different animals have similar structures during development. The similar features of embryos in very different organisms suggest evolution from a common ancestor.

10. Biological Molecules
Many proteins in bacteria are similar in structure and function to proteins in animals.
DNA Sequences: The more similar the nucleotide sequence in a gene the more closely related the organisms.

11. GENETIC CODE All living things use the same genetic code.
This genetic code is nearly identical in almost all organisms, from bacteria to animals.

12. Evolutionary Trees

13. An evolutionary tree represents the evolutionary relationships among a group of organisms.  
Evolutionary relationships among organisms are based on physical features and the DNA sequences of their genes.

14. Which is more closely related?
A & B or
B & C

15. Which is more closely related?
B & D or
C & E

16. Which is more closely related?
B & D or
D & E

17. Which is more closely related?
Amphibian & Reptiles
Reptiles & Mammals

18. Human Evolution
Homo sapien - “wise man”

19. Upright bipedal walking
- allowed the hands to be freed for other
things such as tool/weapon use.

20. Smaller, blunt canines
- suggests a change in diet.

21. Increase in brain size

22. Opposable thumbs help:
monkeys and apes climb trees.
grasp objects such as tools and weapons.