Final answer:
RNA is considered the original polymer because it can store genetic information and catalyze chemical reactions, supporting the RNA world hypothesis as the precursor to DNA and protein-based life.
Step-by-step explanation:
RNA is thought to be the original polymer because it can encode genetic instructions and some RNAs can carry out chemical reactions. The RNA world hypothesis suggests that early life was based solely on RNA and that DNA and proteins evolved later. RNA's capability to act both as a storage of genetic information and as a catalyst makes it a strong candidate for the first self-replicating system. This hypothesis is backed by the ability of RNA to form complex three-dimensional shapes that allow it to interact with other molecules and facilitate both the replication of genetic information and the catalysis of chemical reactions, essential for early life forms.
RNA molecules can create H-bonded double-stranded RNA molecules potentially capable of effective replication, which could have played a crucial role in the prebiotic chemical processes thought to precede life. Environmental factors could have helped select for RNA structures that were more stable and resistant to degradation, a process that mirrors natural selection. Consequently, only the fittest molecules would accumulate, leading to a prebiotic chemical homeostasis.