Rare 'universal paralog' genes may reveal a pre-LUCA evolutionary record

All life on Earth shares a common ancestor that lived roughly four billion years ago. This so-called "last universal common ancestor" (LUCA) represents the most ancient organism that researchers can study. Previous research on the last universal common ancestor has found that all the characteristics we see in organisms today, like having a cell membrane and a DNA genome, were already present by the time of this ancestor. So, if we want to understand how these foundational characteristics of life first emerged, then we need to be able to study evolutionary history prior to the last universal common ancestor.