I am curious about the very first sentences in Lane’s book. Why the qualifier “complex” in “All complex life on earth shares a common ancestor ...”? What sorts of simple ‘life’ might be excluded from Lane’s study? Crystals are a difficult to exclude from many life definitions and indeed crystals or clays have been proposed as not only the first replicators but even as potential ancestors of RNA life. I suspect that viruses arose from the same original autocatalytic event that led to us. The parents of the first virus remain murky however.

“We do know that this common ancestor was already a very complex cell.” But where did that cell come from? Perhaps this is a fair claim because the very patterns of ancestor were murky when we were little more than puddles of autocatalytic chemicals, or even with lipid cell walls to protect those puddles.

Aha: Lane seems to exclude bacteria as simple life. That’s a fair category to study. We shall consider the eukaryotes. I find it highly plausible that we had a single eukaryote ancestor—a single particular cell!