1. Early Earth
Chapter 19

2. A Long Time Ago…. 15,000,000,000 years ago 4,500,000,000 years ago
Big Bang
4,500,000,000 years ago
Earth formed
Fiery Ball of molten rock and ash.

4. A Long Time Ago…. 3,800,000,000 years ago 3,500,000,000 years ago
Earths crust solidifies.
Atmospheric water forms oceans.
3,500,000,000 years ago
Prokaryotes develop.

5. A Long Time Ago…. 1,500,000,000 years ago 500,000,000 years ago
Eukaryotes develop
500,000,000 years ago
Fish develop

6. A Long Time Ago…. 420,000,000 years ago 350,000,000 years ago
Millipedes develop (1st land animals)
350,000,000 years ago
Amphibians develop
Insects develop.

7. A Long Time Ago…. 250,000,000 years ago 220,000,000 years ago
Permian mass extinction
220,000,000 years ago
Pangaea breaks apart.

8. A Long Time Ago…. 200,000,000 years ago 50,000,000 years ago
Mammals develop
50,000,000 years ago
Primitive ‘primates’ develop

9. A Long Time Ago…. 4,000,000 years ago 50,000 years ago
Chimps and early humans
50,000 years ago
Homo sapiens develop

10. How Do We Know Dates? Radiometric Dating:
Radio- (radiation) -metric (measure)
Rocks have radioactivity (like a battery).
As time passes, the energy drops at specific intervals (Half-life). -

11. How Do We Know Dates? Radiometric Dating:
Half-life: The number of years it takes for the radiation (energy) to decrease by half.
We can count the number of half-life’s a rock has had and determine its age.

12. Spontaneous Origin Primordial Soup Model:
Early atmosphere full of “organic” molecules that mixed to create life.
Tested in Miller-Urey.
Developed in 1920’s.

13. Spontaneous Origin

14. Spontaneous Origin Problems: Life started earlier than believed.
Gases used couldn’t have existed because no protective ozone layer.

15. Spontaneous Origin Lerman’s Bubble Model
Underwater volcanoes released simple molecules into water.
These ‘bubbled’ to the surface.
Light heated to create amino acids.

17. Spontaneous Origin

18. Model vs. Model Miller-Urey Lerman’s Bubble Atmosphere.
Gases formed amino acids.
Sun or lightning reacted.
Underwater.
Free-floating chemicals.
Natural or lightning driven reaction.

19. Cell Walls? Microspheres formed from oils.
May have become “phospholipid bilayer”.
Bubble in a bubble.

20. Origin of DNA? Little is known. RNA became more complex.
Microsphere developed ability to copy itself.
Divide a drop of oil easy.
A lot of arguing about it!!!