Earth is a planet born in fire and baptized in ice. Earth grew from the collision of many smaller planets, drawn together by Earth' s gravitational force and melted together from the force and heat of the impact.
Over the ages, continents have shifted their positions, wind and rain shaping and reshaping the surface. Scientists believe that at least two total ice ages have occurred, each lasting for millions of years.
From microbes to the first complex creatures, life was always searching for new frontiers. By 450 million years ago, Earth had become a less violent planet - no longer bombarded by giant meteors from space and the great ice ages had passed.
The dinosaurs would roam the Earth and ruled for millions of years, until a disaster from space wiped them out and cleared the way for the mammals to rise and dominate the planet.
The human race is here today because of its ability to adapt. Our ancestors, the earliest mammals, survived low oxygen levels. Later primates developed sharp eyesight and hands that could clasp for nocturnal life in trees.
Earth provides a rich environment, and many factors continue to shape the planet's condition. This episode is a summary of the previous five, condensed into a single hour.
