1. Change through Time

2. White board activity Discuss the definition of a scientific theory
On your white boards, write the definition you all agree upon

3. Theory
A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. If enough evidence accumulates to support a hypothesis, it moves to the next step—known as a theory—in the scientific method and becomes accepted as a valid explanation of a phenomenon.
A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of knowledge that has been repeatedly confirmed through observation and experiment
Most people today use "theory" as just a hunch, guess, belief, or proposal. Science uses the original meaning of "theory": a logical, systematic set of principles or explanation that has been verified—has stood up against attempts to prove it false.

4. Isn’t evolution just a theory?
Let’s look at some of the evidence

5. Earth has been home to living things for about 3.8 billion years.
6.1
Earth has been home to living things for about 3.8 billion years.
Fossil records inform humans about the development of life on Earth.
Information from fossils can help scientists reconstruct Earth's history.
250 million years ago
70 million years ago
55 million years ago
VISUALIZATION
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Explore how fossils form.

6. Fossils - The remains of organisms preserved in the earth
Age of fossils:
Absolute age tells you when it was formed, determined by radioactive decay
Relative age is determined by a fossils location
More complex organisms develop over time

7. Unicellular organisms
3.8 billion years ago single-celled organisms lived in the ocean and were responsible for creating the oxygen in our atmosphere

8. Multicellular organisms
1.2 billion years many celled organisms appeared in the ocean

9. Life on land
The first land dwellers were simple plants and fungi

10. Mass extinctions
Huge numbers of species died or became extinct in a very short period of time
Permian extinction – 250 million years ago, 90% of the species living in the ocean became extinct and many land dwelling animals disappeared
Cretaceous extinction – 65 million years ago, dinosaur fossil record ends. At the same time, more than half of the other species living on Earth became extinct.

11. Evolution
Process through which species change over time

12. Theories Lamarck – acquired traits are inherited
Example: giraffes had to stretch their necks to reach leaves. Passed on the trait to the next generation
Darwin – natural selection: members of the same species that are better suited to their environment will survive to pass on their traits
Example: tortoises, finches

15. Species change over time.
Darwin's theory of natural selection explains evolution.
Four principals of natural selection are
• Overproduction - Organisms produce more offspring than will survive
Overproduction
adult salmon
eggs
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RESOURCES
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OUTLINE

16. Species change over time.
6.2
Species change over time.
Darwin's theory of natural selection explains evolution.
Four principals of natural selection are
• overproduction
Variation
curve
• variation – all offspring vary slightly due to differences in their genetic make-up
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RESOURCES
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OUTLINE

17. Species change over time.
6.2
Species change over time.
Darwin's theory of natural selection explains evolution.
Four principals of natural selection are
• overproduction
Adaptation
• variation
• adaptation – some differences allow for better survival rate
CHAPTER
RESOURCES
SECTION
OUTLINE

18. Species change over time.
6.2
Species change over time.
Darwin's theory of natural selection explains evolution.
Four principals of natural selection are
• overproduction
Selection
• variation
• adaptation
• selection – those preferable differences get passed on to the offspring
CHAPTER
RESOURCES
SECTION
OUTLINE

19. Speciation
Evolution of a new species from an existing species
Isolation
Contributes to a new species

20. Salamander evolution
What were the two strategies used by the salamanders to adapt to their environment?
What was the problem with the hybrid?

22. Interactives Tree of life video Tree of life interactive
Simple tree of life

23. Do Now April 29
What are the three types of evidence for evolution?

24. Evidence for evolution
Genetic – comparing DNA for similarities
Fossil – sharing a common ancestor
Biological – similarities in structure, similarities in development

25. Genetic – Comparison of chimp and human chromosomes

26. Fossil evidence
From Wolf to Whale

27. Similarities in structure
Vestigial organs – structures that at one time had a function but no longer do
Homologous structures – structures or organs that are similar from one species to another

28. Biological evidence
Homologous structures

30. Vestigial organs
Top ten

31. Embryological

32. Even a caveman can do it! brainpop Evolution of humans
Cave man challenge
Evolution of humans
What is the difference between relatives and ancestors?
What is one common way new traits are introduced?
Why Does Evolution Matter Now?