How life evolved from a mix of chemicals on the young planet Earth is one of science's most enduring mysteries, which biochemists are attempting to solve by recreating the earliest building blocks of life in the laboratory. Earth's biology is based on DNA, which carries all an organism's genetic information in a molecule that takes the shape of a spiraling ladder. RNA, the molecule that facilitates protein manufacturing, has a simpler shape--it's a single strand, as opposed to DNA's double strand--leading some biologists to propose the RNA world hypothesis in which RNA evolved first and eventually gave rise to DNA. But trying to imagine the assembly of RNA from its chemical components poses its own problems. How could RNA, which encodes proteins,