The 10,000 generations of budding yeast tracked in a Harvard lab showed massive evolution of complex new features, right? Wrong:
From the paper:
…we observe widespread parallelism across strains and environments at the level of genes and pathways: populations predictably adapt through loss-of-function mutations in the adenine biosynthesis pathway, sterility-associated genes, and negative regulators of the Ras pathway.” (p. 14)
“We note that once a population has fixed an upstream loss-of-function mutation, it requires reversion of both the original ade2-1 mutation and the upstream mutation to find the higher fitness genotype. While this is possible in principle, both mutations have single-codon target sizes and when they occur alone are likely neutral and deleterious respectively, making this evolutionary path extremely improbable. We do not observe any populations that move from the lower fitness genotype to the higher fitness genotype even after 10,000 generations of evolution. (P. 10)Milo S Johnson, Shreyas Gopalakrishnan, Juhee Goyal, Megan E Dillingham, Christopher W Bakerlee, Parris T Humphrey, Tanush Jagdish, Elizabeth R Jerison, Katya Kosheleva, eLife 2021;10:e63910 DOI: 10.7554/eLife.63910
Note these “populations predictably adapt through loss-of-function mutations” and “We do not observe any populations that move from the lower fitness genotype to the higher fitness genotype even after 10,000 generations of evolution.”
Wait. What’s this “predictably” stuff?
If the authors could have predicted adaptation through loss-of-function mutations, why didn’t they let high school textbook authors and pop science presenters in on the secret?: Michael Behe is right: Darwin devolves. Evolution is mostly about devolution.
Does that maybe make sense in a universe where entropy is growing? But where does it leave Darwin? At the bus stop after the last bus has left?
The paper is open access.
See also: A forthright admission of how the lamprey larvae change official vertebrate history. Lamprey paper first author: “Once fortified with historical inertia, just-so stories are difficult to interrogate.” Just-So stories in science are not just difficult to interrogate but risky! People fear the questioner Doubts the Narrative and That Is Not Allowed. The essay is charming and it is heartening to read someone in science who is prepared to let evidence, not Narrative, be the guide.