Precambrian EraPrecambrian Era

4,600,000,000 years ago to 570,000,000 years ago4,600,000,000 years ago to 570,000,000 years ago

85% of Earth’s History85% of Earth’s History

Simple life starts in the oceans

The Earth FormsThe Earth Forms

4.6 BYA4.6 BYA

Surface cools, forming the crust

Oldest rock found in Western Australia primitive atmosphere forms from volcanic

eruptions (No Free oxygen gas).

Oceans form (from water vapor released in eruptions & maybe comets)

4.3 BYA4.3 BYA

A molten Earth forms

Comparison of AtmospheresComparison of Atmospheres

3.5 BYA3.5 BYA

Oldest fossils of bacteria (prokaryotes).

Simple & small with no nucleus

Miller/Urey Experiment (1953)Miller/Urey Experiment (1953)

Tried to create life from a simulated primitive atmosphere.

Instead created complex molecules, but no cells.

What does it mean to be living?What does it mean to be living?

Be able to reproduce

Uses energy

Composed of one or more cells

Contains genetic information

Where did Life Start?Where did Life Start?

Oceans (nutrient rich, possibly with complex molecules)

Ice (opportunity for organization)

Meteorites (rich with building blocks of life)

First Cells?First Cells?

complex molecules (RNA) replicating inside coacervates (similar to cell membrane).

3.0 BYA3.0 BYACyanobacteria (blue-green algae)

evolve creates energy from photosynthesis giving off oxygen gas (beginning to

form the atmosphere of today). Form large stromatolites (below)

1.5 BYA1.5 BYA Eukaryotes (complex, larger,

single celled organisms) evolve from prokaryotes (bacteria).

630 MYA630 MYA Multicellular organisms evolve with soft bodies

Species include: jelly fish; coral stalks; segmented worms; algae