The things you see on Twitter… Stephen Jackson is a microbiologist at University College Cork (UCC) in Ireland. Last week, UCC held a one-day meeting on microbial evolution, and the opening talk was given by Professor James McInerney of the University of Nottingham. I’ve paid close attention to McInerney’s work for many years, given his interest in processes of horizontal gene transfer and their possible influence on reconstructing the early history of life.

Well, McInerney then went after a central evolutionary pillar — what Jackson (in a pair of tweets) called a “near-dogmatic assumption” — namely, the Tree of Life rooted in LUCA, the Last Universal Common Ancestor:

So, apparently there's no such thing as the tree of life!! Fascinating talk by James McInerney @mcinerneylab to open up Microbial Evolution Network Ireland #meni23 @UCC @UccMicrobiology pic.twitter.com/lmRplmbg2i

— Stephen Jackson (@dr_stevejackson) August 24, 2023

Near-dogmatic assumptions falling like ten-pins at #MENI2023

no tree of life

3 or more contributors to eukaryogenesis

non-triplet codons

— Stephen Jackson (@dr_stevejackson) August 24, 2023

About “non-triplet codons,” this is the paper he was referring to: “Nontriplet feature of genetic code in Euplotesciliates is a result of neutral evolution,” in PNAS.

“Design” and “Evolution” 

To gain a deeper understanding of McInerney’s skepticism about the Tree of Life, watch this fascinating YouTube presentation from September 2022 — especially the Q&A, which starts at about 47:00. McInerney quips that it’s never a good idea to combine “design” and “evolution,” signaling the doubt he shares with most of his evolutionary colleagues that intelligent design will contribute anything of value to biological knowledge.

But McInerney’s joke about ID also shows that one need not be design-motivated to question the Tree of Life topology. Early in his presentation, McInerney says that he hopes to persuade his audience that this familiar LUCA-based hypothesis “has been falsified.” But most striking is McInerney’s enthusiasm for the fruitfulness of other approaches to genomic data, demonstrating that biological research will hardly grind to a halt if the Tree of Life and LUCA go bust.

Watch the talk, along with the Q&A, and you’ll see what I mean.