We now know that all extant living creatures derive from a single common ancestor, called the ‘Last Universal Common Ancestor’ (LUCA). It’s hard to think of a more unifying view of life. All living things are linked to a single-celled creature, the deepest root to the complex-branching tree of life. If we could play the movie of life backward, we would find this microscopic primogenitor at the starting point of biological evolution, the sole actor in what would become a very dramatic story, lasting some 3.5 billion years leading to us.