That’s not taxonomically correct, as neither chimpanzees nor bonobos are, strictly speaking, monkeys. But why resist a perfectly good alliteration considering how flexible the biologists have gotten to be where speciation is concerned, right?
Anyhow, one of the obvious and more shortsighted objections to MITTENS is that its formal presentation focused solely on the human-chimpanzee divergence, although literally from the moment of its origins its claims have been all-encompassing with regards to all genetic divergences between all species. I simply hadn’t gotten around to digging up the genomic evidence required to empirically anchor the math and the logic involved. One has to start somewhere, after all, and complaining that an initial test of a hypothesis is not all-inclusive is not a reasonable objection.
But now that PZ and TFG are both out, I can take some time to fill in the blanks and explore a few interesting lines of possibility, and to hunt down the various escape routes that the increasingly desperate IFLSists are attempting to find. So, I downloaded several gigabytes of data from the Great ape genome diversity program at the University of Vienna, crunched the numbers, and can now demonstrate that the expected shortfall in the fixation capacity definitely applies to the chimp-bonobo divergence as well as two intra-chimpanzee divergences.
As before, this is an approach with assumptions favorable to the post-Darwinian New Modern Synthesis, as we went with the traditional 20 years for a chimpanzee generation rather than the most recent calculation of 22 years. However, we also discovered an anomaly which is reflected in the title “The Pan Paradox: MITTENS Applied to Chimpanzee Subspecies Divergence”, because in addition to supporting MITTENS, the evidence also directly contradicts neutral theory.
The MITTENS framework (Mathematical Impossibility of The Theory of Evolution by Natural Selection) demonstrated a 220,000-fold shortfall in the fixation capacity required to explain human-chimpanzee divergence. A natural objection holds that this represents a special case—perhaps the human-chimp comparison uniquely violates the model’s assumptions. We test this objection by applying MITTENS to divergence within the genus Pan: the split between bonobos and chimpanzees, and the subsequent radiation of chimpanzee subspecies. Using genomic data from the Kuhlwilm et al. (2025) Great Ape Genome Diversity Panel comprising 67 wild Pan individuals, we identify 1,811,881 fixed differences between subspecies and calculate achievable fixations given published divergence times and effective population sizes. Using 20-year generations (shorter generations favor the standard model) and the empirically-derived Selective Turnover Coefficient d = 0.86 for wild chimpanzees, the bonobo-chimpanzee split (930,000 years, 40,000 effective generations) permits a maximum of 25 fixations—a shortfall of at least 13,000-fold against the observed fixed differences. Subspecies divergences show comparable failures: Western versus Central chimpanzees (460,000 years) fail by ~7,500-fold; Central versus Eastern (200,000 years) fail by ~3,600-fold.
You can read the whole paper here if you like. I’ve also added a link on the left sidebar to provide regular access to my open repository of science papers for those who are interested since I seldom talk about most of them here, or anywhere else, for that matter.
And we’re back with a vengeance. Thanks to everyone who has bought the book, and especially to those who have read and reviewed it. Hopefully we’ll be 1 and 2 in Biology before long.