Comment: 18:44 - 19:17 (00:33)
Source: Annenberg/CPB Resources - Earth Revealed - 2. The Restless Planet
Keywords: "James Sadd", atmosphere, life, oxygen, water, algae
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Our transcription: The most significant difference between Earth and the other planets in our Solar System is that Earth has the conditions to support life as we know it.
The abundance of water on Earth was critical to the origin of life.
Water also helped moderate the temperature of a planet's surface to a range which enabled life to evolve.
Oxygen gas, however, was not part of this primitive atmosphere.
It wasn't until the development of primitive algae about 1.8 billion years ago that free oxygen became an important part of the atmosphere of the Earth.
This paved the way for development of more complex life forms.
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Geology School Keywords
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