Maybe viruses did originate by reducing from ancient cells, but cells of a sort no longer present on Earth. That is, not from either the Bacteria or the Archaea domains, or even from whatever cellular ancestor those two shared, but from Microbe Lineage X, still another domain of life that went extinct… except for its remnant form, viruses. That’s a little like the paleontologist’s cheerful reminder: Dinosaurs didn’t go completely extinct; they’re still here, but we call them birds. Abergel and Claverie don’t speak of Microbe Lineage X. They refer instead, in their papers, to a kind of
...more
