Final answer:
Scientists believe DNA was selected over RNA as the genetic material because of its greater stability, robust repair mechanisms, and double-stranded structure, which makes it more resilient to mutations. DNA's dominance in contemporary cells and its critical role in the evolutionary timeline also support its selection over RNA.
Step-by-step explanation:
The reason scientists believe DNA was selected over RNA as the most common genetic material stems from several advantages DNA has over RNA. One significant factor is DNA's stability provided by its double-stranded structure and the presence of thymine instead of uracil, which makes it less susceptible to mutations. Moreover, DNA has robust repair mechanisms that correct errors during replication, contributing to genetic fidelity.
While the RNA world hypothesis suggests that RNA may have preceded DNA as the primary genetic material due to RNA's ability to store genetic information and catalyze chemical reactions, it is thought that the evolution of DNA and proteins provided a more efficient and stable system for long-term genetic information storage and transfer. This transition is supported by the fact that all cells today store information in DNA, and its use must have occurred early in the evolutionary timeline, stemming from the common ancestor of all life forms (LUCA).
Analysis techniques also highlight the practical differences between RNA and DNA. DNA's resilience allows scientists to manipulate it more easily, whereas RNA's instability poses additional challenges. Collectively, these characteristics arguably made DNA a more robust medium for genetic information through evolutionary history.