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Saturday 29 June 2024

Yet another of the fossil records many big bangs.

 Fossil Friday: Snake Origins —Yet Another Biological Big Bang


This Fossil Friday features the “legged” snake Najash rionegrina from the Late Cretaceous of Patagonia, which is one of the oldest fossil snakes known to science. It was found in terrestrial sediments and shows a well-defined sacrum with pelvis connected to the spine and functional hind legs. Therefore it was considered as supporting an origin of snakes from burrowing rather than aquatic ancestors (Groshong 2006). I had reported about the highly controversial and hotly debated topic of snake origins in a previous article (Bechly 2023), where you can find links to all the relevant scientific literature.

Another Open Question

But  there was another open question concerning the origin of snakes: Did their distinct body plan evolve gradually as predicted by Darwinian evolution, or did snakes appear abruptly on the scene as predicted by intelligent design theory? Earlier this year a seminal new study was published by a team of researchers from the University of Michigan and Stony Brook University in the prestigious journal Science (Title et al. 2024). This study brought important new insights with the mathematical and statistical modelling of the most comprehensive evolutionary tree of snakes and lizards, based on a comparative analysis of the traits of 60,000 museum specimens and the partial sequencing of the genomes of 1,000 species (SBU 2024, Osborne 2024). The study found that all the characteristic traits of the snake body plan, such as the flexible skull with articulated jaws, the loss of limbs, and the elongated body with hundreds of vertebrae, all appeared in a short window of time about 100-110 million years ago (Rapp Learn 2024).

The authors commented in the press releases that this burst of biological novelty suggests that “snakes are like the Big Bang ‘singularity’ in cosmology” (SBU 2024; also see Cosmos 2024,Osborne 2024, Sivasubbu & Scaria 2024, Wilcox 2024). This arguably would imply that snakes became “evolutionary winners” because they evolved “in breakneck pace” (Wilcox 2024), which the senior author of the study explained with the ad hoc hypothesis that “snakes have an evolutionary clock that ticks a lot faster than many other groups of animals, allowing them to diversify and evolve at super quick speeds” (Osborne 2024). Well, that is not an explanation at all, but just a rephrasing of the problem. How could such a super quick evolution be accommodated within the framework of Darwinian population genetics and thus overcome the waiting time problem? After all, the complex re-engineering of a body plan requires coordinated mutations that need time to occur and spread in an ancestral population. Did anybody bother to do the actual math to check if such a proposed supercharged evolution is even feasible, given the available window of time and reasonable parameters for mutation rates, effective population sizes, and generation turnover rates? Of course not. We just have the usual sweeping generalizations and fancy just-so stories.

The Fatal Waiting Time Problem

My prediction is that this will prove to be another good example of the fatal waiting time problem for neo-Darwinism. In any case we can add the origin of snakes to the large number of abrupt appearances in the history of life (Bechly 2024), and I am happy to embrace the name coined by the authors of the new study for this remarkable event: The macroevolutionary singularity of snakes. This does not sound very Darwinian, does it? So what do the authors suggest as causal explanation? They have none and the press release from Stony Brook University (SBU 2024) therefore concludes with this remarkable admission: “The authors note that the ultimate causes, or triggers, of adaptive radiations is a major mystery in biology. In the case of snakes, it’s likely there were multiple contributing factors, and it may never be possible to fully define each factor and their role in this unique evolutionary process.” It other words, it was a biological Big Bang and they have no clue what caused it. But of course it must have been unguided evolution, no intelligence allowed!

References

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