thanny said:
...
And i see where you are coming from WereKitten, but in my opinion that doesn't really explain the majority of instances. The eye would have had to have many working parts to be useful as anything - As would many functions of the body. As for having a photosensitive area, I can see how that would make sense in terms of natural selection, but that in itself is not at all 'simple' and would not be formed in one mutation.
|
Mine wasn't meant to be an exhaustive explanation, just pointing the general way to tackle the issue. The development of the eye was actually often taken as a subject in evolution vs ID debates, and you'll find a lot of literature about it if you research.
Your opinion on the majority of instances is hardly worth anything, sorry if it sounds harsh but of course the same is true for mine, since neither of us is an accomplished physiologist/paleontologist/genetist. Since Darwin's times it was very well known that if a biological structure was found for which it was impossible to find a building path through adaptively favourable mutations then the whole natural selection mechanism theory would be in trouble.
Since then, many examples of tentative irreducible complexity were brought forth, and none stood under closer exam by the scientific community at large. So much so that there's a lot of inner debate about the details of the natural selection mechanisms, but very little about the scaffolding.
PS: you seem to have a restricted, teleological point of view about the smaller mutations. There was no "useless leg stump" mutation, the whole idea of calling it a "leg" foreshadows its future use. But that's not how it works. A primitive limb good enough to walk on earth could evolve by a mutation that changed the muscles or shape of ventral fins that were good enough for a fish to crawl on seabed. Those could have reached that additional use through mutations from ventral fins that originally were only good to stabilize swimming.
In the bacterial flagella example, the same proteins that work the "rotor" part are those used in other phyla to move the parts of an expulsion structure.
You seem to focus too much on the endgame, but selection operates very locally.