In a new peer reviewed analysis, scientists quantify amino acids before and after our “last universal common ancestor.”The last universal common ancestor is the single life form that branched into everything since. For a while, there’s been a consensus about the order in which the building-block amino acids were “added” into the box of Lego pieces that build our genes. Our understanding of these extremely ancient times will always be incomplete, but it’s important for us to keep researching early Earth. amino acids) date back four billion years—to the last universal common ancestor (LUCA) of all life on Earth. “[A]biotic synthesis of aromatic amino acids might be possible in the water–rock interface of Enceladus’s subsurface ocean,” the scientists explain.