Early Life-forms and Earth’s Atmosphere
Paragraph 1: Why has life flourished on Earth? This question has a two-part answer. First, Earth has been a cradle for life because of its position relative to the Sun. Second, once life began on Earth, simple early life-forms (photosynthetic bacteria) slowly but inexorably altered the environment in a manner that not only maintained life but also paved the way for later, complex life-forms. These changes allowed later organisms to evolve and thrive. Humans and other higher organisms owe their life-supporting environment to these early life-forms.
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