1. Evolution: Change Over Time
The Evidence
The Evidence
Evolution: Change Over Time
Evolution: Change Over Time
The Evidence
The Evidence

2. Fossil Record Defined: Collection of every known fossil
Most fossils found in sedimentary rock
Age determined by depth
Law of Superposition: new rock forms on top of older rock
A.k.a. Relative Dating
Evidence Conclusions:
1) Newer fossils are more complex
2) Common ancestors: similarities between ancient & modern life

3. Missing Link Fossils AKA: Transition Fossils
Whale Evidence
Long spine
Found in dried up oceans
Reptile Evidence
Teeth
Bony tail
Fish evidence
Scales
Fins
Found in dried-up oceans
Amphibian evidence
Eyes on top of head
Wrist bones
Land Evidence
Wolf-like teeth
Hind legs
Bird Evidence
Wishbone
Feathers
AKA: Transition Fossils
Archaeopteryx: shares both bird & reptile features
Basilosaurus: shares whale & land mammal features
Tiktaalik: shares fish & amphibian features
Evidence Conclusion : Indicates common ancestry

5. Comparing old fossils to modern life shows change
Ancient Kelp
Modern Kelp

6. #3: How do we know evolution happens?

7. Radiometric Dating
Helps determine age of fossils. More accurate than relative dating.
Isotopes: atoms of the same element with differing neutrons
Ex: 12C and 14C
12C = 6 protons + 6 neutrons
14C = 6 protons + 8 neutrons
Organisms collect carbon throughout their lifetime.
When organism dies: 14C starts to decay into 14 N at a known rate (half-life)
Fossil age determined by comparing ratio of C to N
Wider ratio = older sample
Both are Carbon

9. Dating Fossils

10. The study of geography provides evidence of evolution.
island species most closely resemble nearest mainland species
populations can show variation from one island to another

11. Embryo Development Different species show similar development patterns
Different body plans become noticeable later in development
Evidence Conclusion : Indicates common ancestry
Embryo
Development

12. flipper arm leg wing Homologous Structures walking grasping swimming
flight
Defined: similar body structures with very different functions
Different environments lead to adaptations
Ex: The forelimbs of animals
Evidence Conclusion : Indicates common ancestry

13. Homologous structures are different than analogous structures
Analogous structures have similar functions but different structures.
Human hand
Bat wing
Mole foot
Fly wing
Analogous structures are not evidence of a common ancestor.

14. Vestigial Structures
Defined: Organs or structures which have lost most or all their original function
Vestigial Human Parts:
Gill slits = once used to breathe oxygen in water
Yolk sac = once used to nourish developing embryo
Tailbone = once used for balance
Appendix = once used to digest plants
Wisdom teeth = once used to grind plant tissue
Evidence Conclusion : Indicates common ancestry

15. Human Embryo w/ Vestigial Structures

16. Pythons have tiny femurs (leg bone)

17. Biochemical Evidence DNA, RNA, proteins compared
Genetic code same for most life
More related species have more similar biochemistry
Evidence Conclusion : Indicates common ancestry

18. Video: Part 5- Did humans evolve?

19. Review How do the following lines of evidence show change over time?
Fossils
Homologous structures
Vestigial structures
Resistant organisms
Embryo development
Biochemical (molecular) evidence
Fossil age can be determined two ways. What are they?
Which type of anatomical structures do not show evidence of common ancestry?