The pathway scientists believe best outlines the evolution of the first life on Earth is:
- Formation of organic compounds → first heterotrophs → buildup of carbon dioxide gas → first autotrophs
Explanation:
1. Formation of organic compounds: This step involves the synthesis of organic molecules, such as amino acids, nucleotides, and sugars, possibly in the prebiotic environment of early Earth.
2. First heterotrophs: The early life forms were likely heterotrophs, meaning they obtained energy and nutrients from organic molecules in their environment.
3. Buildup of carbon dioxide gas: As heterotrophs consumed organic compounds and released carbon dioxide, this gas would have accumulated in the atmosphere.
4. First autotrophs: With the buildup of carbon dioxide, early autotrophs capable of photosynthesis could evolve, using sunlight to convert carbon dioxide into organic compounds, releasing oxygen as a byproduct.
This pathway suggests a progression from simple organic molecule formation to the development of more complex life forms capable of photosynthesis, leading to the oxygenation of Earth's atmosphere.
