The biggest problem with that is their complete inability to come up with an example of a system where there is no possible set of intermediates. Three of the traditional favorites of creationists (and let's not fool our selves. IDers are creationists with a different vocabulary and the same agenda) are the Eyeball, Wasp Flowers (and other forms of misleading coloration), and Bacterial Flagellium. In the case of the eyeball the claim is that an eye has to be perfect to be worth having. First off, no it doesn't. Ask someone who has glaucoma or astigmatisim if they'd rather just have their eyes put out and be done with it. Amusingly enough, a fairly complete set of intermediate steps in the evolution of the eye can be seen through a study of mollusc eyes, going from single light sensitive cells to clusters of cells to clusters of cells in parabolic depression to a pinhole camera type eye (open to the water) to the same covered with a transparent film then a transparent mass (both of which act as protection and a lens) to the advanced eye of the squids which is essentially like our eyes without a blind spot. With camoflage/misleading colors (like the wasp pollinated flowers that trick the wasp into copulating with the flower) the claim is also that it must be all or nothing. Except that in nature there are examples of imperfect camoflage, and a little thught experiment will show that even imperfect camoflage is better than none. Looking solely at camoflage as a method of avoiding predation (but the reasoning applies elsewhere too) imagine that you are trying to hide an easter egg in the crook of a tree. If it is hot pink, people will find it immediately unless they are very far away, it is dark out, or some other impedement to their vision applies. If you change the color to something more natural (say forest green) it will still be easy to see, but conditions would have to be a bit better to find the egg (a little closer, less rain, a little lighter out) and as you grade the color of the egg closer to the brown of the tree bark, the searcher has to be closer to the tree to see it. Each little change makes the egg harder to find, until you have switched to a humming bird egg painted to look just like bark. By the same reasoning, any little improvement in camoflage gives a prey species a slightly wider range of conditions where it is safe from a preditor (and every small improvement in sight/smell/etc gives a preditor a small increase in the number of prey items it gets to eat, be them bugs, deer, fish, or black berries.)
At first glance, the flagellium thing seems intractable. After all it is a highly complex, non-robust system. There are dozens of pieces and parts that must come together just right to have a functonal flagellium (though even in this case, it isn't an all or nothing situation. A malfunctioning method of locomotion is better than nothing at all. Ask anyone with a beater that they have wired together with clothes hangers, bubble gum, and duct tape and running on a quart of oil every two days why they don't just say "top hell with it" and stay home every day.) The creationist claim is that there is no way that this complex system came together piecewise, that each of the (I believe) 20+ components of a bacterial flagellium is worthless by itself. Problem is that with further research there have been at least 15 types of bacteria (I can't remember the exact number and I don't have a copy of the paper where I first saw this) identified that use bits and pieces of the protine structure of a flagellium to do something. The one that sticks in my mind is a bacterium that uses the long sticky out bit and a small subset of the motor pieces to produce a spring loaded venomous harpoon.
There are other examples, like most of the organs and organ systems in the body (pass a comprehensive comparative anatomy course and tell me that there is no way to evolve a complex kidney or a 4 chambered, valved heart.)
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Date: 2005-08-11 05:07 am (UTC)In the case of the eyeball the claim is that an eye has to be perfect to be worth having. First off, no it doesn't. Ask someone who has glaucoma or astigmatisim if they'd rather just have their eyes put out and be done with it. Amusingly enough, a fairly complete set of intermediate steps in the evolution of the eye can be seen through a study of mollusc eyes, going from single light sensitive cells to clusters of cells to clusters of cells in parabolic depression to a pinhole camera type eye (open to the water) to the same covered with a transparent film then a transparent mass (both of which act as protection and a lens) to the advanced eye of the squids which is essentially like our eyes without a blind spot.
With camoflage/misleading colors (like the wasp pollinated flowers that trick the wasp into copulating with the flower) the claim is also that it must be all or nothing. Except that in nature there are examples of imperfect camoflage, and a little thught experiment will show that even imperfect camoflage is better than none. Looking solely at camoflage as a method of avoiding predation (but the reasoning applies elsewhere too) imagine that you are trying to hide an easter egg in the crook of a tree. If it is hot pink, people will find it immediately unless they are very far away, it is dark out, or some other impedement to their vision applies. If you change the color to something more natural (say forest green) it will still be easy to see, but conditions would have to be a bit better to find the egg (a little closer, less rain, a little lighter out) and as you grade the color of the egg closer to the brown of the tree bark, the searcher has to be closer to the tree to see it. Each little change makes the egg harder to find, until you have switched to a humming bird egg painted to look just like bark. By the same reasoning, any little improvement in camoflage gives a prey species a slightly wider range of conditions where it is safe from a preditor (and every small improvement in sight/smell/etc gives a preditor a small increase in the number of prey items it gets to eat, be them bugs, deer, fish, or black berries.)
At first glance, the flagellium thing seems intractable. After all it is a highly complex, non-robust system. There are dozens of pieces and parts that must come together just right to have a functonal flagellium (though even in this case, it isn't an all or nothing situation. A malfunctioning method of locomotion is better than nothing at all. Ask anyone with a beater that they have wired together with clothes hangers, bubble gum, and duct tape and running on a quart of oil every two days why they don't just say "top hell with it" and stay home every day.) The creationist claim is that there is no way that this complex system came together piecewise, that each of the (I believe) 20+ components of a bacterial flagellium is worthless by itself. Problem is that with further research there have been at least 15 types of bacteria (I can't remember the exact number and I don't have a copy of the paper where I first saw this) identified that use bits and pieces of the protine structure of a flagellium to do something. The one that sticks in my mind is a bacterium that uses the long sticky out bit and a small subset of the motor pieces to produce a spring loaded venomous harpoon.
There are other examples, like most of the organs and organ systems in the body (pass a comprehensive comparative anatomy course and tell me that there is no way to evolve a complex kidney or a 4 chambered, valved heart.)