Comment by jjk166
3 years ago
Flagella only exist as components of something, they do not need to and shouldn't exist by themselves. If flagella spontaneously popped into existence and cells picked them up, that would be quite difficult to explain without design, but cells producing flagella because they are useful components makes perfect sense on its own.
I think he's saying, random mutation wouldn't produce all required components at once. One mutation gives you a bit of a flagella, another gives you bit of a nose, but how does the flagella mutation survive to coexist with the nose mutation that makes it useful.
I suspect the answer is that having flagella without a nose is still better than having no flagella. If so it suggests evolution isn't good at accessing groups of mutations that aren't individually beneficial.
Evolution doesn't produce 1st part of the flagellum, second part of the flagellum, third part of the flagellum.
It produces shitty flagellum, better flagellum, good flagellum.
But the problem is we don't see the intermediate forms. So right now you might see a complicated flagellum that has a lot of highly specialized parts that all need eachother, but that is merely a refinement that took place after all the pieces were already there. Like once an arch is complete, all the scaffolding that was holding it up is now vestigial and if it is removed the arch will remain standing.
It seems you may have misunderstood the original argument. The iterative approach suggests increments so minute at each step that they wouldn't significantly impact an organism's survival at any given time. Also given the extremely slow process of evolution and the relatively short number of iterations it is infeasible to suggest such a solution. If a person would like to create an iPhone it's easy to tell them to start with a shitty scrap of metal and work from there. You can make that sort of argument as a solution for creating anything but it is clearly not feasible.
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>Evolution doesn't produce 1st part of the flagellum
So this isn't exactly 100% true. Quite often the encoding of these things can sit in our DNA not activated and then pop up out of nowhere.
Scishow did an episode on this recently.
https://www.youtube.com/watch?v=YzWOjP7hm2w
I understand that, but it seems like even the MVP "shitty" flagellum would require many mutations that individually have no benefit. But I suppose with enough generations/parallelism you get enough stacking of useless mutations to reach the useful ones.
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> cells producing flagella because they are useful components makes perfect sense on its own.
But that's the thing, this sort of implies that a complete flagellum can be spontaneously produced because it's useful, which sort of collides with the parent comment on systems evolving by combining previously useful components.
Flagella aren't useful until they are complete. So intermediate forms should be lost, right?
Would this leave us in a scenario where a single combination of several mutations at the same time suddenly gives you a complete, functional flagellum?