The Tree of Life vies with the Origin of Life for a position of highest significance among biological concerns. Those who write about it (bioarborists?) have much to say about its anatomy. Does it consist of simple branches, as per Darwin’s sketch, or is it anastomosed into a bramble of connected branches? This matters. By one scheme, ancestry can be directly discerned, by the other, much extra information is required. Genealogists know how hard it is to trace family trees when some DNA found its way into the lineage by, shall we say, a supplementary route.
But here is food for those who want to be enlightened. A special issue of the journal Biology and Philosophy is entitled The Tree of Life. Edited by the British biophilosopher (is there such a term?) Maureen O’Malley, it consists of fifteen chapters written by experts in the field. Microbiologists will find this to be an important addition to their long list of things to read, being that some 90% of evolution took place while life was solely microbial.