Scientists think that Earth was hostile to life until about 3.9 billion years ago.
Researchers talk about life's origin.
Self replicating, heterogeneous catalysts for redox reactions among substances that coexist metastably in the immediate environment. Dr. Eleanora Robbins is a researcher with the U.S. Geological Survey. She and Dr. Moto Sato are working to understand how life arose on Earth. But to understand life's origin, they first have to agree on what life is. It has to be carrying a memory molecule that tells it how to reproduce itself and also how to get energy.