I would like to thank David, the creationist, who commented on my blog. Often it is difficult to know what you are doing until you have something to compare yourself to, light needs darkness to define itself with; the water world of the ocean needs the air to define its surface and to show that it is indeed something more. I needed David to link all those wonderful sites so I could see what the other side is saying. So I could address some of their faulty ideas.
Many of the sites focus on the development of the eye as proof that there was a designer behind the animal and all life. How could something so complex have evolved naturally the first time so perfectly? Simple, someone made it that way. I love that answer it is so simple that it must be true, right? If the fossil eye was the epitome of eye biotechnology, then yes it would make sense that someone designed it, but it is not true.
The Trilobite first evolved in the Cambrian Explosion and it had a compound eye. The people who described the eye did only that, they described what they saw, because that is all they could do. They could not see through the eye, so they did not know how it worked or even how well it worked. Al they could see is that it had the structure of a compound eye.
What is a compound eye? What is an eye? An eye is an organ that senses light and when I say organ I mean a collection of cells that perform that function and most people would say that only animal have eyes. That is true, only animals have eyes, but it is not true that only animals can sense light. Plants sense light, some flowers are only open during the day, some only at night, some track the Sun's position and many plants grow so that they increase their exposure to the light, but we do not say that they have eyes, even though it is clear they can tell where the light is coming from.
Okay plants don't have "eyes", but they can detect light. Plants do not think, so they must be reacting to the light. The flower that folds its petals up at night must be moving the petals by growing one side in preference to the other, or by moving water out of some key cells, thus closing the flower. The entire petal does not collapse so we know that it must have specialized cells, light sensitive cells. A sunflower turns its head to follow the sun. It does not turn the entire plant, so it must be a specialized group of cells. You start to see where I am heading I hope.
There is this lizard that lives on the south tip of New Zealand, or some other out of the way location. What is odd about this lizard is that it is in the process of evolving a third eye. Ouch, the way I said that, was like the lizard was taking a hand in its own development; this is not true. The third eye is a patch scales that are photo sensitive. That is it. What is an eye, it is a collection of photosensitive cells, so this too is an eye. But it gives an answer to the question of what a eye could have looked like.
Here is a thought experiment, a string of ideas of how I think a compound eye might evolve from nothing:
-A cell that is sensitive to light rises towards or sinks away from the light.
-a multicellular organism with light sensitive skin moves up or down the water column otherwise blind
-light sensitive skin at the front of the animal can differentiate degrees of light and sense movement (shadows) and either attack or flee
-light sensitive skin is in fixed locations and can detect movement in one direction per location, multiple locations give the animal an idea of the shadows size, speed, distance, other relevant features
That last one would be a compound eye for underwater, where something on the seabed would not need colour, would need warning from predators or that pray was near. It is simple and it is nothing like an eye but would be detectable in a fossil as an eye. To continue:
-the cell specializes to see light and shadow and discrete wavelengths of light, infrared, red, green, blue and ultra violet (some eyes see red through blue like us, some see orange through ultra violet there is a diversity in the ranges and as implied, some see the infrared -pit-vipers, poisonous snakes see temperature with their pits to find where the poisoned pray has gone)
-light sensitive cells shrink and group together allowing more representation to occur
-translucent film develops as protection
-different film shapes aid image clarification
- fixed lens shape allows silage resolution at a fixed distance to increase chances of getting or getting away
- a shutter develops to decrease the amount of light getting to the light sensitive cells
-fixed lens becomes a changing lens that allows multiple distance focusing.
What I hope you are seeing is that the eye that we have today is the result of many incremental changes that worked in our ancestors favour, so that they passed their genes down to us. The eye is the result of these incremental changes. Oh and one more thing, our eye is not the best eye, it is a good eye for where we came from. It cannot see as far as an eagle can, we can not see temperature like a snake, ultra violet light is lost to us, our night vision sucks, a great many of us cannot read properly because we are far sighted, some are near sighted, all going to the proof there are multiple plans for getting around to the same thing.
In conclusion, finding a fossilized eye means little, only that the eye has been with us for a long time. It does not show any of the possible sophistication, nor any of it's lack of sophistication. That you cannot see a more primitive eye, does not mean that it does not exist; it just may look like something else.
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