Evolution of sensory organs - I don't want to just throw this away...

[bascule]

Well, I guess the thread this guy posted to got deleted and he probably got banned, after I had typed up a whole response at that! So here's what I had to say in reply...

 

So I began to ask my professors' date=' “How could the whole complex system evolve which would include thousands of additional mutations resulting in a system that would end up working together in unison to provide sight to the organism by random changes alone when each step along the way infers no benefit and thus natural selection breaks down?”

 

Their answer, “Well the answer is no one really knows for sure but it happened so it must be possible, isn’t it amazing?” As I furthered this line of thought I realized that there are many such systems like this (sexual reproductive systems, auditory, tactile, taste, smell, etc.)[/quote']

 

Maybe you should look for some better answers. There are literally hundreds of books dedicated to answering these kinds of questions. I think Dawkins' The Ancestor's Tale is a great starting point for answering all of these kinds of questions about evolution, because for any given topic he runs down a list of about a dozen books dealing with any particular issue he's addressing at a given time. He had multiple sections throughout the book on the evolution of eyes (something which occured 40 times independently throughout evolutionary history)

 

There's a newly released book on molecular evolution, The Plausibility of Life, which shows how complex structures can arise through selective stages of repurposing. I'd wholeheartedly recommend that (haven't yet read it myself but it's received some excellent reviews). It's supposed to be something of a definitive volume debunking "irreducible complexity" arguments, and will hopefully have all the answers to the questions you are asking about the evolution of complex sensory organs (which is the primary topic it deals with, I believe)

 

The easiest way to explain anything like this is that originally there was no connection between the photosensitive cells and the brain; the photosensitive cells served some other, unrelated purpose and a mutation brought about a neural connection between these cells and the brain. The information gleaned through this approach was enough to afford a reproductive advantage to this individual, and things simply spread from there. Vision affords an enormous advantage to those who have it over those who don't, and is thusly favored quite well by natural selection.

 

Neurons are very good at analyzing feedback responses. For example there have been experiments conducted where blind people were equipped with a grid of tactile stimulators which were attached to their back. A low resolution camera was used to drive the tactile stimulators. The camera was then head mounted on the blind people. After using the devices for awhile the blind people could begin to "see" to the point that they were able to navigate their way around rooms without assistance. Apparently one inadvertently adjusted the zoom setting of his camera, and when his "visual" field lurched forward he instinctually lurched backward and covered his face with his arms.

[DV8 2XL]

bascule, I agree with everything you wrote, and yes it would have been a shame to lose such a devastating bit of prose. But I suspect you are (we all are) barking up the wrong tree when we attempt to make see the light this way.

 

In my experience, the two concepts they fail to grasp is the scale of time that these process work in, and just how small the steps need be. It's like some sort of learning handicap. They just can't conceptualise it, even abstractly.

[Myelin]

Have you read "The Blind Watchmaker?" Probably so, it is a very common book on this subject. I found it to be unfulfilling, very basic.

[bascule]

Have you read "The Blind Watchmaker?" Probably so, it is a very common book on this subject. I found it to be unfulfilling, very basic.

 

Yes, I've read the Blind Watchmaker, along with the Selfish Gene, the Extended Phenotype, and River out of Eden... and just yesterday I finished The Ancestor's Tale.

[Myelin]

What do you recommend? I have read the Selfish Gene and I found it was a better "thought book" the the Watchmaker. But I have not read the others.