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Originally Posted by
John Catmull
What I was trying to say was, think of the appendix hanging there off the colon on the right side. Did it just appear? Was there a need for it?
The appendix was there 10,000 years ago. I would have to look this up, but I'm reasonably sure the appendix is considered a "vestigial" organ. It has basically atrophied. Other animals have a larger version of this organ that harbors bacteria that aid in digesting things like grass.
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If so how did the body know it would be useful?
The body does not "know" if something will be useful. Something is either useful, or it is not. Neither the body, nor the cells of the body have any capacity to look into the future. (I'm not being snarky here. Just straight talk.)
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In just that position where it could sometimes catch the odd bit of food that would definitely NOT be useful because it would start an infection.
Yes. It is unfortunate for us that it can become infected. So can other things like ears, sinuses, etc. One major reason is that modern humans do not eat enough fiber. We evolved to eat much more. So we are adapted to a high fiber diet. Similarly, cows are adapted to eating grass and tend to become ill when they eat a high protein diet of grains only.
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Whether it appeared quickly or slowly how was it's function, to lubricate the colon, 'known'?
I'm not aware of this idea. I don't think it lubricates the colon, but I don't know everything about this.
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Let's have a look at the eyeball. What came first? The lens or the cones and cylinders at the rear of the eyeball? Which ever came first, they were definitely not useful then, without the whole system. Cones and cylinders would not function without various frequencies coming in. When the cones, cylinders arrived, how was it decided which would react to what frequency, without the light getting in? OK. So the lens came first. Why was it kept? There was no use for it.
Anyway, was it the correct shape for focusing, right from the start?
OK. Say the whole ball arrived, intact, by magic. It just sits there. Can't move. The six muscles haven't yet arrived. Did just one muscle arrive and it was realized, somewhere, that 5 more would be handy?
This is more questions than I can answer now. But basically, the eye has evolved over millions of years in lots of different organisms. Lots of very simple organisms possess cells that are sensitive to light, changes in light, different wavelengths, movement, etc. Once you have that, you can aim these light sensing cells by putting them in a slight pit. Then a simple lens may focus light onto the light sensing cells. A lens doesn't have to cast a perfect image in order to be useful. It just has to get more light onto the light sensitive cells. From there you can evolve sensitivity to different wavelengths of light and lenses that operate differently. Or you can evolve multiple lenses like flies have. So many ways to build a functional eye. We happened to end up with camera eyes.
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Evolution implies a purpose when there may be none.
No. This is incorrect. Evolution is not purposeful.
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Evolutionary changes appear to be a series of accidents. How could parts of the inside of a bod know before that if it, for example, ate grains [10,000 years ago ] it's blood type would change from 'O' type to 'A' type and know that it would be a positive change? Was it a positive change?
The body does not know ahead of time. The species does not know ahead of time. I am not aware that eating grains caused a change in blood type. But speaking more generally, a population of organisms exists. Let's say they run out of fruit, or they move away from where the fruit grows and can't go back. Whatever, they must now eat grains even though they are adapted to eating fruit. Many will become sick and die from disease from this diet to which they are not adapted. Sometimes the population will simply go extinct. But let's say it doesn't. Instead, a few of them are less sick because they have a gene variant that allows them to deal with grain a bit better than others in their group. So out of 50 couples, 20 die leaving no children, 20 die and leave one child, and 10 die and leave several. In the next generation, the 10 couples are over represented and their useful gene is now more common.
That's selection. Selection mean those who can't cope with a new situation have fewer offspring than those who can.
Evolution can go backward, too. In the next generation, all those kids decide to go back where the fruit grows. They migrate, eat better and the ones with the gene that helps deal with grain no longer have any advantage. So in the NEXT generation, they have no advantage and maybe even a disadvantage. The gene hangs around maybe and doesn't disappear. It's there if it's ever needed, but not so common. We have thousands of gene variants--like toolboxes full of tools that we don't know the use for until we suddenly need it and figure out how to use it.
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What was the advantage of 'A' over 'O'? How many negative changes occurred before the positive change.
I can't tell you the adaptive value of A and O. Have you tried looking it up? But, remember, they are BOTH still around. So it's not like one is good, one bad.
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I don't know - do you?
John
I've told you as much as I can off the top of my head. Are you curious? Or are you a creationist trolling? If you are genuinely interested, look up "adaptive value" of A and O blood types.