First DNA Life: From chemical reactions before 4 billion years ago to replicating molecules about 4 billion years ago to DNA based life then to LUCA, the only DNA based branch to survive. Meaning, DNA based life likely started before LUCA, and LUCA is the only branch to survive the test of time. From LUCA to humans, RNA and DNA are essentially the same as today. They serve as the tools for genetic information storage, transmission, and expression through prokaryotes to eukaryotes, underpinning the diversity and complexity of life on Earth. The last universal common ancestor (LUCA) is estimated to have lived approximately 3.5 to 3.8 billion years ago. It is the organism from which all current life on Earth descended from. Your greatest grandparents.

Imagined image: LUCA in a variety of shapes that they might have resembled, set in an ancient, deep-sea hydrothermal vent environment.