1. Trivia: How long have humans existed on Earth?
Hint: the earth has been around for 4.5 Billion years!
Life started 3.8 Billion years ago= Life has existed on Earth for 84% of its existence
200,000 years= 0.04% of Earth’s History

2. Aim: How did life form on Earth?

3. How did the Earth form? The Big Bang Theory
Scientists believe that a huge space explosion created earth and our solar system
14 BILLION Years ago

4. Earth = 4.5 Billion Years Old

5. Primitive Earth Poisons & inorganic molecules: No Oxygen !!!
Hydrogen cyanide, Hydrogen (H), Methane (CH4), Ammonia (NH3), Carbon Monoxide (CO), Carbon Dioxide (CO2), Nitrogen (N)
No Oxygen !!!

6. Water & Energy Appear
Earth cooled & thunderstorms drenched the earth with water, forming the oceans
Lightning provided an energy source for life to begin

7. Organic Compounds Form
Lightning sparks reactions with the inorganic compounds, & organic compounds are created!!!
C + H
Experiment by Stanley Miller & Harold Urey

8. Organic Compounds – the compounds of life
Examples:

9. Life begins in the Oceans
Unicellular,
Prokaryotic
Anaerobic
Heterotrophs
The first organisms on earth were simple one-celled organisms

10. Where did oxygen come from?
Some of these early forms of life changed/evolved into autotrophs.
Autotrophs: get energy from the sun & make oxygen)
The first cells were heterotrophs, anerobic prokaryotes. They had to compete for food so what adaptation would help them survive? By what process do autotrophs make their food?
What is given off by the process of photosynthesis?
So, now what gas do we have in our environment

11. Aerobic Organisms
Now that the new atmosphere has OXYGEN, aerobic organisms that use oxygen for cell respiration slowly evolved

12. Eukaryotic Cells Form
Single celled organisms in communities joined together to form the more complex eukaryotes

13. Then life took off in all different directions!

15. When did Homo sapiens first appear?
Human-Like Species Appeared 200,000 years ago

16. 9 mya: bipedal & climbed trees
Humans, Chimpanzees, and Gorillas all have a Common Ancestor: shared ancestor
9 mya: bipedal & climbed trees

17. Similar to a family tree
Descendents
Descendents
Common
Ancestor

18. Evolutionary Tree – a family tree of organisms
Species living at present time (top)
Ancestral common species (bottom)

19. Common Ancestor for all organisms – the first living thing
Unicellular
Common
Ancestor
100’s of Millions of year ago

20. Determining Relationships
Which organisms are closely related?
Those who have a recent common ancestor (a close point of intersection in a tree diagram)

21. What organisms are our closest relatives?
Chimpanzees!
-share closest branch on tree

22. Speciation
Evolution has lead to the formation of new species from different ancient organisms

23. How did so many species develop from one common ancestor?
Species have changed over time.
This is called…..Evolution

24. Creationism Why is evolution so controversial?
Evolution – species change over time
Controversy-
1) Science: Theory of Evolution by Natural Selection
* Based on Evidence
2) Religion: _____________________
* Based on beliefs
Testable! Experiments, evidence! I will give you
EVIDENCE to analyze. We can make conclusions
based on this evidence.
Can’t test with
scientific method or
provide evidence …
You are free to believe!
Creationism