1. 狂暴过去 The Violent Past: Secrets of our Past
Earth was born as a result of repeated asteroid collisions, the moon created by a single giant impact event. Then, Earth's size attracted huge meteorites, which slammed into it, causing super-high-temperature rock vapor to cover the entire surface and evaporate all ocean water. The earliest life-forms survived such infernal events by escaping deep into the ground, miraculously emerging again and again.
The Earth has gone through innumerable catastrophic events, and life has survived by acquiring new abilities to live through each crisis. Humans are part of the grand history of life's evolution, which has been closely intertwined with repeated cataclysmic events. Why was Earth able to evolve into a livable planet, but not Mars, which failed to hold its atmosphere and oceans? Find out in the opening episode of the series.
2. 冰雪地球: Snowball Earth: First Complex Life
The hypothesis "Snowball Earth" explains that ice ages, caused by the earliest life-forms, resulted in an evolutional leap — larger-sized life. Atmospheric methane created by microbes initially kept the Earth warm. As microbes that produce oxygen (photosynthesizers) emerged, atmospheric methane was lowered. As a result Earth cooled and the primeval ocean froze to 1,000 meters deep.
Most life may have become extinct during a long period of intense glaciation believed to have lasted several million years. However, some life survived, perhaps in puddles created near volcanic craters. Carbon dioxide accumulated in the air because thick ice sheets prevented ocean water from absorbing it. A green-house effect, created by carbon dioxide, finally melted the ice and fed photosynthesizers.
Hyper hurricanes raged after the great meltdown and stirred up the ocean water, creating an ideal condition for life to prosper and develop collagen. Using collagen, life-forms were able to build larger bodies, and a variety of creatures, called Ediacara biota, emerged for the first time.
3. 新边界 New Frontiers: Onto the Land
Earth provides a rich environment, and many factors continually shape the planet's condition.