Khan Academy Static

Earth is over 4.5 billion years old. How do we know this? When did life first emerge? From the dawn of Earth as a planet to the first primitive life forms to our "modern" species, this tutorial is an epic journey of the history of life on Earth.

10693_First_living_things_on_land_clarification.html

10692_Biodiversity_flourishes_in_Phanerozoic_eon.html

10689_Earth_formation.html

10691_Ozone_layer_and_eukaryotes_show_up_in_the_Proterozoic_eon.html

10690_Beginnings_of_life.html