How did life emerge

1. How did life emerge By Crby cr steussy Most material from CS Brown’s “Big History”

2. Earth • About 4.6 bil yrs ago a supernova exploded in the Milky Way • From the debris our star, the sun, and planets, including earth appeared.

3. Earth • About 4 billion years ago as the earth cooled bubbles formed in the molten lava

4. Early Earth • From 3.8 to 1.8 billion years ago a sort of blue-green bacteria spread across the cooling earth. • The first form of life.

5. Early Earth • The earliest cells (right) had no nuclei. • eukaryotic cells with nuclei began about 1.9 billion years ago • The “Goldilocks conditions”

6. not so- Early Earth • Around 600 Million (with an M) the first soft tissues sea creatures, about the width of 5 human hairs, appeared. • Goldilocks conditions

7. not so- Early Earth • Between 400-600 Million years ago animals with “hard parts” like trilobites emerged, as did plants and something like a sow bug (right) crawled from the sea. • The so-called “Cambrian explosion”

8. not so- Early Earth • Around 250 million years ago a mass extinction occurred. • Fungus ruled the earth of pangea afterwards

9. not so- Early Earth • 200 million years ago reptiles appeared that evolved into dinosaurs • Flowering plants and hardwood trees emerged 100 million years ago

10. Earth • Around 65 million years ago a massive asteroid impact caused the extinction of the dinosaurs. • In its wake mammals began to flourish