Exobiology and Evolutionary Biology

Evolution of Catalytic RNA and the Origins of Life

PI: Gerald Joyce

This proposal describes work that is part of a larger NASA-sponsored effort to understand the origin of life on Earth, which will guide the search for life elsewhere in the universe. It pertains to a form of RNA-based life that likely existed during Earth’s early history. RNA-based life can be simulated, and perhaps even constructed, in the laboratory through the in vitro Darwinian evolution of RNA enzymes. During the previous period of NASA-supported research, RNA enzymes were developed that catalyze their own replication and undergo Darwinian evolution in a self-sustained manner. The proposed research will substantially increase the complexity of the RNA-based evolving system so that it can bring about the invention of novel function. Large, heterogeneous populations of self-replicating RNAs will be challenged to adapt to various environmental conditions, resulting in the emergence of novel functional traits that confer selective advantage. As the environmental conditions change, further adaptations will arise through an evolutionary process that can be continued indefinitely. This work has the potential to provide the first example of a living system outside of terrestrial biology. It also will shed light on the chemical basis of life, and on the presumed ancestor of contemporary life on Earth.