1. The Evolution of Living Things
Chapter 7
The Evolution of Living Things

2. Review What is a hypothesis?
A possible explanation or answer to a question
What is a theory?
A unifying explanation for a broad range of hypotheses and observations that have been supported by explanation
What is a law?
Theories that are proven time and time again

3. What is Evolution? Evolution is a widely accepted theory.
It is not a law.
You don’t need to believe anything I say in this chapter.
However you need to know the information behind the theory to pass you SOL’s next year.

4. Change over time
These three frogs all look different but live in the same habitat

5. Differences Among Species
All three frogs have different adaptations that help them survive
Adaptation
A characteristic that helps an organism survive and reproduce in its environment
Can include structures for finding food, for protection and movement

6. Stegosaurus

7. Dimetrodon

8. Brontosaurus

9. Species
Groups of organisms that can mate with one another and produce fertile offspring
Share same characteristics and adaptations
Mule vs. horse vs. donkey

10. Do Species Change Over Time?
Scientist estimate the Earth is 4.6 billion years old
Did the same animals and plants always live here?

11. Evolution
Process by which populations accumulate inherited changes over time
Because of evolution, scientists think all living organisms have a common ancestor

12. Evidence of Evolution Fossils
The solidified remains or imprints of once living organisms are found in the layers of the earth’s crust
Mold – imprint
Cast – mold filled in with sediment

14. Fossil Record
A historical sequence of life indicated by fossils found in the layers of the Earth’s crust

17. Vestigial Structures Remnants of once-useful structures
Hind limb bones in whales
Other examples
Wings on flightless birds (ostriches, rheas)
Human tail bone
Erector pilli muscles and body hair
Wisdom teeth

18. Comparing Organisms
Bones in the human arm and a bat’s arm are similar even though they are used in different ways
Indicates a common ancestor but the bones have evolved to perform different functions

19. Birds Walk on Their Toes

20. Comparing DNA All living things made from the same genetic material
The more similar the species (closely related) the more similarities in DNA codes

21. Comparing Embryonic Structures