Reconstructing the Last Universal Common Ancestor

Abstract

There is general agreement that bacteria, archaea, and eukarya share common ancestry. However, tracing back extant lineages to reconstruct the ancestral gene set of the three domains has proven to be non-trivial, as there is little unambiguous signal this far back in time. In this chapter, I explain the basic principles behind reconstruction of the Last Universal Common Ancestor (LUCA) and summarise a few of the challenges associated with reconstruction. Finally, I consider whether a mid-resolution LUCA might be the most achievable goal, particularly from the perspective of the classes of chemistry available to early life.