How did life start? There may not be a bigger question. To learn the secret of our origins means going back beyond the earliest forms of biological life, past simple bacteria, and down to the chemistry of the building blocks that came earlier.
Most people have heard DNA’s double helix described as the blueprint for life, but its single-stranded relative RNA is also critical for transmitting genetic information. Both are present in the cells of all living organisms, and many scientists suspect that RNA was the original genetic material, coming on the scene before DNA, more than four billion years ago during a period scientists call “RNA world.”