Our last common ancestor

The shared forebearer of all life — known as the last universal common ancestor (LUCA) — lived around 4.2 billion years ago, ate carbon dioxide and hydrogen, and produced acetate that might have fed other life. Researchers inferred information about our great-great-grandblob’s genetics and biology by tracing duplicated, lost and mutated genes back up the family tree. LUCA probably possessed an early immune system, too — hinting that it lived in an established ecosystem full of microbes and pathogens.