1. Origin of Life Hypotheses

2. I. Earth History
4.5 bya: Earth Forms

3. I. Earth History
- Earliest Atmosphere - probably of volcanic origin
Gases produced were probably similar to those created by modern volcanoes (H2O, CO2, SO2, CO, S2, Cl2, N2, H2) and NH3 and CH4

4. I. Earth History
4.5 bya: Earth Forms
4.0 bya: Oldest Rocks

5. I. Earth History
4.5 bya: Earth Forms
4.0 bya: Oldest Rocks
3.5 bya: Oldest Fossils

6. I. Earth History
4.5 bya: Earth Forms
4.0 bya: Oldest Rocks
3.5 bya: Oldest Fossils
Stromatolites - communities of layered 'bacteria'

7. I. Earth History
bya: Oxygen in Atmosphere
4.5 bya: Earth Forms
4.0 bya: Oldest Rocks
3.4 bya: Oldest Fossils

8. I. Earth History
bya: Oxygen
1.8 bya: first eukaryote
4.5 bya: Earth Forms
4.0 bya: Oldest Rocks
3.4 bya: Oldest Fossils

9. I. Earth History
bya: Oxygen
1.8 bya: first eukaryote
0.9 bya: first animals
4.5 bya: Earth Forms
4.0 bya: Oldest Rocks
3.4 bya: Oldest Fossils

10. I. Earth History
bya: Oxygen
1.8 bya: first eukaryote
0.9 bya: first animals
0.5 bya: Cambrian
4.5 bya: Earth Forms
4.0 bya: Oldest Rocks
3.4 bya: Oldest Fossils

11. I. Earth History
bya: Oxygen
1.8 bya: first eukaryote
0.9 bya: first animals
0.5 bya: Cambrian
0.24 bya:Mesozoic
4.5 bya: Earth Forms
4.0 bya: Oldest Rocks
3.4 bya: Oldest Fossils

12. I. Earth History
bya: Oxygen
1.8 bya: first eukaryote
0.9 bya: first animals
0.5 bya: Cambrian
0.24 bya:Mesozoic
0.065 bya:Cenozoic
4.5 bya: Earth Forms
4.0 bya: Oldest Rocks
3.4 bya: Oldest Fossils

13. I. Earth History
4.5 million to present
(1/1000th of earth history)
bya: Oxygen
1.8 bya: first eukaryote
0.9 bya: first animals
0.5 bya: Cambrian
0.24 bya:Mesozoic
0.065 bya:Cenozoic
4.5 bya: Earth Forms
4.0 bya: Oldest Rocks
3.4 bya: Oldest Fossils

14. II. Origin of Life Hypotheses
- Oparin-Haldane Hypothesis (1924):
- in a reducing atmosphere, biomonomers would form spontaneously
Aleksandr Oparin
( )
J.B.S. Haldane
( )

15. II. Origin of Life Hypotheses
- Oparin-Haldane Hypothesis (1924):
- in a reducing atmosphere, biomonomers would form spontaneously
- Miller-Urey (1953)
all biologically important monomers have been produced by these experiments, even while changing gas composition and energy sources

16. II. Origin of Life Hypotheses
- Oparin-Haldane Hypothesis (1924):
- in a reducing atmosphere, biomonomers would form spontaneously
- Miller-Urey (1953)
- Sydney Fox polymerized protein microspheres

17. II. Origin of Life Hypotheses
- Oparin-Haldane Hypothesis (1924):
- in a reducing atmosphere, biomonomers would form spontaneously
- Miller-Urey (1953)
- Sydney Fox polymerized protein microspheres
- Cairns-Smith ( ) - clays as templates for non-random polymerization
Murcheson meteorite - amino acids present; some not found on Earth. To date, 74 meteoric AA's.
Szostak - clays could catalyze
formation of RNA's

18. III. Acquiring the Characteristics of Life
A. Three Primary Attributes:
- Barrier (phospholipid membrane)
- Metabolism (reaction pathways)
- Genetic System

19. III. Acquiring the Characteristics of Life
B. Barrier (phospholipid membrane)
- form spontaneously in aqueous solutions

20. A B C D E III. Acquiring the Characteristics of Life
C. Metabolic Pathways
- problem:
how can pathways with useless intermediates evolve? These represent 'maladaptive valleys', don't they? A B C D E
How do you get from A to E, if B, C, and D are non-functional?

21. A B C D E III. Acquiring the Characteristics of Life
C. Metabolic Pathways
- Solution - reverse evolution A B C D E

22. E III. Acquiring the Characteristics of Life C. Metabolic Pathways
- Solution - reverse evolution
suppose E is a useful molecule, initially available in the env. E

23. E III. Acquiring the Characteristics of Life C. Metabolic Pathways
- Solution - reverse evolution
suppose E is a useful molecule, initially available in the env.
As protocells gobble it up, the concentration drops. E

24. D E III. Acquiring the Characteristics of Life C. Metabolic Pathways
- Solution - reverse evolution
Anything that can absorb something else (D) and MAKE E is at a selective advantage... D E

25. D E III. Acquiring the Characteristics of Life C. Metabolic Pathways
- Solution - reverse evolution
Anything that can absorb something else (D) and MAKE E is at a selective advantage...
but over time, D may drop in concentration... D E

26. C D E III. Acquiring the Characteristics of Life C. Metabolic Pathways
- Solution - reverse evolution
So, anything that can absorb C and then make D and E will be selected for... C D E

27. A B C D E III. Acquiring the Characteristics of Life
C. Metabolic Pathways
- Solution - reverse evolution A B C D E
and so on until a complete pathway evolves.