Final answer:
The RNA World Hypothesis suggests that RNA, capable of storing genetic information and catalysing reactions, predates DNA. DNA likely evolved from RNA due to its greater chemical stability, resolving the 'DNA or RNA first' question.
Step-by-step explanation:
The debate around whether DNA or RNA came first in the evolutionary history of life is framed within what is known as the origin of life or the 'information system' discussion. The RNA World Hypothesis is popular among scientists, proposing that RNA was the first nucleic acid to evolve, due to its ability to store genetic information and catalyse chemical reactions. This hypothesis provides a potential solution to the 'chicken-and-egg' problem of which component came first, the information storage of DNA or the catalytic functionality of proteins.
While all modern cells utilize DNA to store genetic information, the simplicity and versatility of RNA suggest that an RNA world may have given rise to DNA. It is believed that DNA became the primary information storage molecule due to its chemical stability compared to RNA. The transition from RNA to DNA is a critical aspect of early cellular evolution, though specific details remain to be clarified.