1. Back in the day, the best evidence for a single Tree of Life, rooted in the Last Universal Common Ancestor (LUCA), was the apparent biochemical and molecular universality of Earth life…
For [Theodosius] Dobzhansky, as for all neo-Darwinians (by definition), the apparent molecular universality of life on Earth confirmed Darwin’s prediction that all organisms “have descended from some one primordial form, into which life was first breathed” (1859, 494) — an entity now known as the Last Universal Common Ancestor, or LUCA. So strong is the pull of this apparent universality, rooted in LUCA, that any other historical geometry seems unimaginable.Paul Nelson, “Sara Walker and Her Crew Publish the Most Interesting Biology Paper of 2022 (So Far, Anyway)” at Evolution News and Science Today (April 5, 2022)
Universal common ancestry was a religion, really. Create a religion, birth a heretic:
The “Laws of Life”
Theoretician Sara Walker and her team of collaborators, however, are looking for an account of what they call (in Gagler et al. 2022) the “laws of life” that would apply “to all possible biochemistries” — including organisms found elsewhere in the universe, if any exist. To that end, they wanted to know if the molecular universality explained under neo-Darwinian theory as material descent from LUCA (a) really exists, and (b) if not, what patterns do exist, and how might those be explained without presupposing a single common ancestor.
And a single common ancestor, LUCA? That’s what they didn’t find.Paul Nelson, “Sara Walker and Her Crew Publish the Most Interesting Biology Paper of 2022 (So Far, Anyway)” at Evolution News and Science Today (April 5, 2022)
Imagine Sara Imari Walker and her team having the guts to just admit that they didn’t find that a single common ancestor was the best explanation — instead of just making something up, like so many people, faced with such a challenge, would do.
It is interesting to note that this paper was edited (for the PNAS) by Eugene Koonin of the National Center for Biotechnology Information. For many years, Koonin has argued in his own work that the putative “universality due to ancestry” premise of neo-Darwinian theory no longer holds, due in large measure to what he and others have termed “non-orthologous gene displacement” (NOGD). NOGD is a pervasive pattern of the use of functional synonyms — enzyme functions being carried out by different molecular actors — in different species.Paul Nelson, “Sara Walker and Her Crew Publish the Most Interesting Biology Paper of 2022 (So Far, Anyway)” at Evolution News and Science Today (April 5, 2022)
But then, if there is no simple Tree of Life, what is the Darwin-in-the-schools lobby going to raise Cain about?
The paper is open access.
You may also wish to read: As evolutionary biologists slowly kill off Darwinism… hacking down the Tree of Life, even. Species merging. Julie Berwald: What I didn’t know then was that, even as I ambivalently placed the overhead film on the projector, the concept of the tree of life had begun to wilt. Four decades on, it’s morphed entirely.