KingMerv00
1st March 2005, 03:00 PM
An evolution/creation debate thread has gotten beyond what I know. There are lots of smart biology people here I'm sure so I'd like to hear some of your opinions. In particular, post #1009 but they are all important.
http://forums.christianity.com/?do=post_view_flat;post=1148514;page=41;sb=post_la test_reply;so=ASC;mh=25;
I'm curious about this especially:
But what if co-option occurred more incrementally, in such a way that a system’s function evolved as parts were gradually co-opted into it (this is called coevolution)? As Allen Orr puts it, “An irreducibly complex system can be built gradually by adding parts that, while initially just advantageous, become—because of later changes—essential [i.e., indispensable]. The logic is very simple. Some part (A) initially does some job (and not very well, perhaps). Another part (B) later gets added because it helps A. This new part isn’t essential, it merely improves things. But later on, A (or something else) may change in such a way that B now becomes indispensable. This process continues as further parts get folded into the system. And at the end of the day, many parts may all be required.”
This is the most likely of the evolutionary explanations for IC systems. However, it still has its problems. Using the flagellum as an example, if it went through co-evolution, we should be able to see other systems that it evolved from, and the unique proteins found in the flagellum shouldn’t be unique (at least, not 75% of them). In fact, we haven’t found other systems with homologues (similar proteins/structures) to the flagellum, except the Type III Secretory System (TTSS), a kind of pump used to inject proteins into host cells. But the TTSS couldn’t be a precursor to the flagellum, because it requires multi-cellular organisms to act as hosts, and evolutionary biologists estimate the flagellum to have arisen before then. So there are no precursor systems and there are too many unique proteins to attribute the existence of IC systems to co-evolution.
Does that mean co-evolution couldn’t have happened? Technically, no. But it is functionally impossible. (By that I mean that it requires such a suspension of disbelief that it really isn’t reasonable to say that co-evolution is likely to account for IC systems.) You can call that an argument from ignorance if you like, but I think it’s a grounding in reality. With zero empirical evidence to support the hypothesis, it isn’t reasonable at this time to put any stock in it.
http://forums.christianity.com/?do=post_view_flat;post=1148514;page=41;sb=post_la test_reply;so=ASC;mh=25;
I'm curious about this especially:
But what if co-option occurred more incrementally, in such a way that a system’s function evolved as parts were gradually co-opted into it (this is called coevolution)? As Allen Orr puts it, “An irreducibly complex system can be built gradually by adding parts that, while initially just advantageous, become—because of later changes—essential [i.e., indispensable]. The logic is very simple. Some part (A) initially does some job (and not very well, perhaps). Another part (B) later gets added because it helps A. This new part isn’t essential, it merely improves things. But later on, A (or something else) may change in such a way that B now becomes indispensable. This process continues as further parts get folded into the system. And at the end of the day, many parts may all be required.”
This is the most likely of the evolutionary explanations for IC systems. However, it still has its problems. Using the flagellum as an example, if it went through co-evolution, we should be able to see other systems that it evolved from, and the unique proteins found in the flagellum shouldn’t be unique (at least, not 75% of them). In fact, we haven’t found other systems with homologues (similar proteins/structures) to the flagellum, except the Type III Secretory System (TTSS), a kind of pump used to inject proteins into host cells. But the TTSS couldn’t be a precursor to the flagellum, because it requires multi-cellular organisms to act as hosts, and evolutionary biologists estimate the flagellum to have arisen before then. So there are no precursor systems and there are too many unique proteins to attribute the existence of IC systems to co-evolution.
Does that mean co-evolution couldn’t have happened? Technically, no. But it is functionally impossible. (By that I mean that it requires such a suspension of disbelief that it really isn’t reasonable to say that co-evolution is likely to account for IC systems.) You can call that an argument from ignorance if you like, but I think it’s a grounding in reality. With zero empirical evidence to support the hypothesis, it isn’t reasonable at this time to put any stock in it.