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  Topic: Evolution of prokaryote flagella, Links to discussions, webpages, refs< Next Oldest | Next Newest >  
niiicholas



Posts: 319
Joined: May 2002

(Permalink) Posted: May 27 2003,22:50   

Reposting from II thread:
http://www.iidb.org/vbb....1005461

The author (Robin Holliday) does mention the flagellum; unfortunately s/he just kinda brushes it off:

Quote

Since the wheel has become so important for human motility and diverse other purposes, one would think that it might also be used by animals in a variety of contexts. It could be argued that the wheel can only be used effectively on smooth surfaces, and these are uncommon in nature. However, that is not true because there are salt and dry mud flats, hard damp sand on beaches, leaves and the barkof some trees. Moreover, man-made vehicles can cover rough ground very effectively. The fact of the matter is that the wheel is not found anywhere in the animal kingdom. The nearest is in the tiny rotifer, where the feeding structures appear to rotate. This is an illusion brought about be the movement of a circle of attached cilia slightly out of synchrony to create a vortex that draws water and food into the animal. The flagellae of motile bacteria that have a rotary propeller-like movement contain a single structural protein called flagellin, but could scarcely be regarded as wheel-like. However, the principle of jet propulsion is used by certain marine animals, notably the squids and octopuses, but no propellers as such are found in any aquatic multicellular organism. So how do the creationists explain why an all-powerful deity did not on any occasion design an animal incorporating the enormously advantageous rotary motion of wheels?


I think that the flagellum (and other rotary motors, e.g. the F1F0 ATPase, archaeal flagellum) are indeed valid exceptions to the "evolution can't make wheels" argument.  One might quibble that "rolling" and "spinning" aren't really valid concepts at the microscopic scale where Brownian motion is so crucial -- the "rotation" is jerky and there is no such thing as inertia -- but, to me, a rotating machine is a rotating machine.

Note that this wheel argument is old, dating at least back to Haldane (assuming the cite is right), and has been turned on the evolutionists by creos:

Quote

Design in Living Organisms: Motors
by Jonathan Sarfati
Creation Ex Nihilo Technical Journal 12(1):3–5, 1998
http://www.answersingenesis.org/docs/3799.asp

Would any evidence convince evolutionists?

The famous British evolutionist (and communist) J.B.S. Haldane claimed in 1949 that evolution could never produce ‘various mechanisms, such as the wheel and magnet, which would be useless till fairly perfect.’ [10] Therefore such machines in organisms would, in his opinion, prove evolution false. These molecular motors have indeed fulfilled one of Haldane’s criteria. Also, turtles [11] and monarch butterflies [12] which use magnetic sensors for navigation fulfil Haldane’s other criterion. I wonder whether Haldane would have had a change of heart if he had been alive to see these discoveries. Many evolutionists rule out intelligent design a priori, so the evidence, overwhelming as it is, would probably have no effect.

[...]

10. Dewar, D., Davies, L.M. and Haldane, J.B.S., 1949. Is Evolution a Myth? A Debate between D. Dewar and L.M. Davies vs. J.B.S. Haldane, Watts & Co. Ltd / Paternoster Press, London, p. 90.

11. Sarfati, J.D., 1997. Turtles can read magnetic maps.

12. Poirier, J.H., 1997. The Magnificent Migrating Monarch. Creation Ex Nihilo 20(1):28–31 (see online version). But monarchs only use the earth’s magnetic field to give them the general direction, while they rely on the sun’s position for most of their navigation.


Other sites using the same quote:

“MIRACULOUS” MOTORS
http://www.apologeticspress.org/inthenews/2003/itn-03-02.htm

The World's Tiniest Motor
http://www.answersingenesis.org/docs/207.asp

I could swear that there is another longer quote out there, from Haldane or another evolutionist, but I can't find it.  

(Does anyone have access to the Haldane-creo debate book, Is Evolution a Myth? -- it would be great to have a fuller quote)


Anyhow, you could hardly blame the creationists for pouncing on this one if everyone took the dismissive line that Holliday did on the evolution of wheels.  Unfortunately for them, Dawkins already noted the crucial difference between evolving wheels at the macro-scale and the subcellular scale:

Quote

Why don’t animals have wheels?
by Richard Dawkins
Article in The Sunday Times,  November 24th 1996
http://www.world-of-dawkins.com/Dawkins....els.htm

[...]

Now I must mention that there is one revealing exception to my premiss.  Some very small creatures have evolved the wheel in the fullest sense of the word.  One of the first locomotor devices ever evolved may have been the wheel, given that for most of its first two billion years, life consisted of nothing but bacteria (and, to this day, not only are most individual organisms bacteria, even in our own bodies bacterial cells greatly outnumber our ‘own’ cells).

Many bacteria swim using threadlike spiral propellors, each driven by its own continuously rotating propellor shaft.  It used to be thought that these ‘flagella’ were wagged like tails, the appearance of spiral rotation resulting from a wave of motion passing along the length of the flagellum, as in a wriggling snake.  The truth is much more remarkable.  The bacterial flagellum is attached to a shaft which, driven by a tiny molecular engine, rotates freely and indefinitely in a hole that runs through the cell wall.

Picture (see suggestions faxed separately to Jeremy Bayston)

The fact that only very small creatures have evolved the wheel suggests what may be the most plausible reason why larger creatures have not.  It’s a rather mundane, practical reason, but it is nonetheless important.  A large creature would need large wheels which, unlike manmade wheels, would  have to grow in situ rather than being separately fashioned out of dead materials and then mounted.  For a large, living organ, growth in situ demands blood or something equivalent.  The problem of supplying a freely rotating organ with blood vessels (not to mention nerves) that don’t tie themselves in knots is too vivid to need spelling out!

Human engineers might suggest running concentric ducts to carry blood through the middle of the axle into the middle of the wheel.  But what would the evolutionary intermediates have looked like?  Evolutionary improvement is like climbing a mountain (“Mount Improbable”).  You can’t jump from the bottom of a cliff to the top in a single leap. Sudden, precipitous change is an option for engineers, but in wild nature the summit of Mount Improbable can be reached only if a gradual ramp upwards from a given starting point can be found.  The wheel may be one of those cases where the engineering solution can be seen in plain view, yet be unattainable in evolution because its lies the other side of a deep valley, cutting unbridgeably across the massif of Mount Improbable.

The wheel may be one of those cases where the engineering solution can be seen in plain view, yet be unattainable in evolution because it lies the other side of a deep valley, cutting unbridgeably across the massif of Mount Improbable.


(Why don't we have articles like this in the newspapers in the U.S.?  Oh well...)

Still, Dawkins offers no evidence that the flagellum evolved, so this is still likely to be thoroughly undaunting to the creationist. Here in 2003 we are in a somewhat better position:

an AE thread collecting relevant info/links on the evolution of prokaryote flagella

Edited by niiicholas on May 27 2003,23:07

  
  46 replies since Nov. 28 2002,22:50 < Next Oldest | Next Newest >  

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