2. CONTRIBUTORS TO SOLVING LIFE’S ORIGIN PUZZLE

3. SWAMMERDAM late 1600’s Dutch Proposed the seeds of life were formed when Earth was formed. Each generation was contained in the one before like nesting boxes.

4. REDI 1668 Redi disproved spontaneous generation by doing a controlled experiment using rotting meat. This proved living flies did not come from non-living meat.

5. BONNET late 1700’s Suggested preformation Each egg contained a tiny preformed creature which contains a tiny preformed creature inside it and so on.

6. COMTE DE BUFFON late 1700’s French Proposed life originated on the warm primitive earth. But he also believed the Earth had formed about 60,000 years ago.

7. PASTEUR mid 1800’s He showed that providing broth was not contaminated with microorganisms it would not spoil for years. Pasteur proved biogenesis and disproved abiogenesis

8. OPARIN 1930 He proposed the widely accepted hypothesis that life began in the early oceans. He envisioned chemical reactions occurring in the atmosphere and the products raining down into the oceans forming the primordial soup

9. UREY AND MILLER 1953 Primitive earth’s atmosphere had H 2, NH 3, CH 4, and water vapor, no OXYGEN Urey and Miller set up an experiment to show that simple compounds could form organic compounds such as amino acids and sugars, when subjected to an electric spark and kept at the correct temperature.

10. FOX late 1950’s He showed how chains of amino acids could form protocells. Protocells look like living cells and are sometimes mistaken for bacteria because they grow, divide and metabolize. They do not show all the characteristics of life so they are not considered as living.

11. Oxygen from photosynthetic prokaryotes paved the way for aerobic eukaryotes The original organisms were thought to be anaerobic, heterotrophic prokaryotes As a result of competition for nutrients some organisms became autotrophs using the CO 2 in the air to make organic compounds. The autotrophs released O 2 into the air allowing aerobic organisms to develop.

12. MARGULIS 1962 She developed the idea that eukaryotes evolved through a symbiotic relationship between primitive prokaryotes.