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Dawkins’s thesis that the bacterial flagellum evolved from the injectisome is no longer tenable, prof says


According to a Queen Mary U evolutionary genomics prof writing at Nature Ecology & Evolution, Richard Dawkins’s claim that the bacterial flagellum evolved from the injectisome “is no longer sustainable:

Since I wrote a blog post on the obsolescence of Dawkins’ old claim that all gene trees have the same topology, a paper has been published in Cell that contradicts another of his claims.

In his book 2006 book The God Delusion, Richard Dawkins gave prominent place to a particular scenario for the evolution of bacterial flagellar motors. Flagellar motors are highly complex structures containing many protein parts. Dawkins claimed that it was clear that the flagellar motor “commandeered” components from the injectisome in its evolution. Injectisomes are simpler structures used by some living bacteria to inject proteins into eukaryotic cells…

In the Cell paper published just a few day ago, a group of Chinese researchers published an atomic-level structure of the bacterial flagellar motor and compared it to the injectisome. These structures are shown in the figure below (kindly provided by Yonqun Zhu).

Examination of these structures shows that the components of the injectisome are far from being “very similar” to the components of the flagellar motor…

In other words, even parts of the two structures that seem to correspond to each other are very different. Thus, parts of the injectisome could not simply be “commandeered” for the flagellar motor.

You may notice another implicit contradiction of Dawkins’ scenario in the quotation above. The only ancestor-descendent scenario that the authors of the Cell paper consider to be worth mentioning is one where the injectisome is descended from the flagellum. Not the other way round.

Richard Buggs, “More obsolete Dawkinsian evidence for evolution” at Nature Ecology & Evolution (May 4, 2021)

Earlier, Buggs had taken issue with Dawkins’s claim that “Every Gene Delivers Approximately The Same Tree Of Life.” Not so, apparently.

Is it too soon to ask whether Dawkins is losing his magic dust? At one time, he could do no wrong. Now he is getting questioned within the field and Canceled by Trinity College and the American Humanist Association.

Here’s a thought: Darwinism is beginning to seem untenable to more people Canceling Darwin is unthinkable; Canceling Dawkins is not.

An alternative thesis is that people who want to defend Darwin may be considering that Dawkins has outlived his usefulness.

Which scenario is more likely?

Darwinism’s key strength is that it is much simpler and more straightforward than life forms are.

Seversky: Does Dawkin's "atheism" affect his views on biology? Are atheists "free" from bias? Is this some new law of science? PaV
Seems to me that a structure able to "commandeer" components is even MORE complicated and intelligent than an electrostatic motor. How does the not-yet-functional piece of a future motor know that it wants to be a motor? How does it decide which proteins to reach out and grab? Ockham is on the ID side here. polistra
@1 if the facts aren't on your side question the motives. But don't forget that in this case you also have to question the motives of the journal that published the article. es58
I was curious about why a professor of evolutionary genomics would take such an unscholarly delight in finding a paper that challenges the hypothesis that the Type III Secretory System offered an evolutionary explanation for the bacterial flagellum which Michael Behe claimed was an example of irreducible complexity. More specifically, I was curious about why he should use it to attack Richard Dawkins. Although Dawkins has referred to the T3SS hypothesis, as far a I can tell he did not originate it and he was far from the only member of the evolutionary biology community to promote it. Then I found that Richard Buggs is something of a rarity, an evolutionary biologist who is also a Christian creationist, which raises the inevitable questions about how he reconciles his religious beliefs with his professional career in science. Or is he, like Jonathan Wells, trying to "destroy Darwinism" by working from the inside? Seversky

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