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How does the RNA world hypothesis explain a possible early stage of life?
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A herd of African elephants (Loxodonta africana) drinking from the Chobe River, Botswana.
The RNA world hypothesis proposes that early life on Earth was based on RNA molecules that functioned as both genetic material and catalysts. This stage is thought to have preceded the emergence of DNA and protein-based life.12
Key aspects of this hypothesis include:
- Dual Functionality: Unlike proteins, which cannot replicate themselves, RNA molecules possess the potential for self-replication and enzymatic activity. These catalytic RNA molecules are known as ribozymes.123
- Evolutionary Advantage: Primitive RNA molecules that could replicate more accurately or quickly would have outmultiplied others. Cooperation between different RNA molecules—such as those catalyzing secondary reactions—likely created more effective self-replicating systems.1
- Transition to Complexity: Over time, these systems may have developed primitive mechanisms for protein synthesis, eventually leading to the formation of the first cells. As life became more complex, the more stable DNA molecule took over the role of primary genetic storage, and the direct replication of RNA was largely lost.1
This model remains a leading "self-replication-first" explanation for abiogenesis.4