Evolution of the Eye

LJP07 · 06-19-2008

Evolution provides fascinating insights into how such things like the formation of the eye, wing formation and camouflage among other great adaptations evolve. However while the theory on how these form is desirable, I can't seem to fully comprehend the understanding for the explanation of the evolution of the eye.

For example, I fully understand the wikipedia article among many which describes the same thing:

Evolution of the eye - Wikipedia, the free encyclopedia

They all claim that a group of photosensitive cells existed first with the surrounding epithelium and that a pouch formed, filled with fluid, formed a lens and became more complex. But how did the first photosensitive cells evolve and what triggered their formation in the flat epithelium?

Likewise, how did a "Pair" of eyes form and why did the photosensitive cells form in symmetrical locations, I understand why it occurred in terms of survival, but in terms of evolution why did it occur this way?

Thunderbird · 06-19-2008

Quote:

Originally Posted by LJP07

Evolution provides fascinating insights into how such things like the formation of the eye, wing formation and camouflage among other great adaptations evolve. However while the theory on how these form is desirable, I can't seem to fully comprehend the understanding for the explanation of the evolution of the eye.

For example, I fully understand the wikipedia article among many which describes the same thing:

Evolution of the eye - Wikipedia, the free encyclopedia

They all claim that a group of photosensitive cells existed first with the surrounding epithelium and that a pouch formed, filled with fluid, formed a lens and became more complex. But how did the first photosensitive cells evolve and what triggered their formation in the flat epithelium?

Likewise, how did a "Pair" of eyes form and why did the photosensitive cells form in symmetrical locations, I understand why it occurred in terms of survival, but in terms of evolution why did it occur this way?

The first part is how the cells differentiated into the group of photosensitive cells. Adaptation and natural selection are the main drivers of change, however when we attempt to gain an understanding of how these finely tuned structures could form it is apparent we need to fine tune our terms of adaptation. Terms like natural selection, adaptation, random mutation, are indeed accurate, but do not address directly how these instruments are so finely tuned to incoming information at large. Energy such as light contains variables. A spectrum. This spectrum represents and contain not only energy and information, but more aptly information about energy of the outside environment. The developing biological instruments forms around the information that flows though it, Therefore one could define an eye as a finely tuned persistent structure that can conduct information in a quantum wave form that also has its origins from that wave form, therefore only persist because of it.

As far as why their are two eyes, one needs to consider the nature of bilateral symmetry in morphology ,and how this relates to symmetry as a mathematical construct in general. Morphological geometry forms around a basic 3 dimensional axis's of movement, forward: right-left For the simple creature that begins to orient itself toward a target it needs to distinguish between dual incoming informational centers. This is why the body plan developed into two parts. The same would apply for ears. If you had only one ear you could hear but you would have no way to tell where the sound is coming from.

Thunderbird · 06-19-2008

One of the principles of self-organizing systems of evolution is a property quantum mechanics. Information in the form waves that can be split in two equal divisions but containing an equal spectrum that can be interfaced , or “braided” back together. This division and reunification creates an oscillation between the separate points of reference. These oscillations pit one system against the other to constantly seek an equilibrium. Since this equilibrium can never be reach to the fact the dual systems are separated as opposites they can only gain more information and subsequently more complexity.

Moontanman · 06-19-2008

Quote:

Evolution provides fascinating insights into how such things like the formation of the eye, wing formation and camouflage among other great adaptations evolve. However while the theory on how these form is desirable, I can't seem to fully comprehend the understanding for the explanation of the evolution of the eye.

For example, I fully understand the wikipedia article among many which describes the same thing:

Evolution of the eye - Wikipedia, the free encyclopedia

They all claim that a group of photosensitive cells existed first with the surrounding epithelium and that a pouch formed, filled with fluid, formed a lens and became more complex. But how did the first photosensitive cells evolve and what triggered their formation in the flat epithelium?

The first creatures to develop photo sensitivity did so because it was an advantage to be able to orientate them selves to the light. Either they feed on light or they feed on creatures that used light or they had to migrate from light to dark for some reason of their biology. We do see this today in many creatures that other wise would have no use for eyes or photosensitivity at all.

Quote:

Likewise, how did a "Pair" of eyes form and why did the photosensitive cells form in symmetrical locations, I understand why it occurred in terms of survival, but in terms of evolution why did it occur this way?

First it's important to understand that not all creatures have two eyes, a great many animals have lots of eyes, spiders have several, some other arthropods have more than two eyes. Two eyes are thought to be necessary to see in stereo (depth or distance) Two eyes are the minimum for stereo vision and in evolution animals seldom have more of anything than they actually need. This why cave animals are often blind, the energy necessary to grow eyes is used for other things. Two eyes in vertebrates is often thought to be universal on the earth but some reptiles have three. One in the middle of the two regular eyes, this eye is under the skin and not used for vision but it is sensitive to light. Eyes are on the head in vertebrates so an animals can see where it is going and be close to the brain. So although we have two eyes the more primitive animals often have more so the premise of why two eyes developed is not the correct idea to ask about. Two eyes did not develop from simple photosensitive cells, two eyes came later after the number of eyes had varied drastically among different life forms.

Thunderbird · 06-19-2008

Good point MoontanMan, not all creatures have two eyes such as the spider, but
they are symmetrically arranged bilaterally along the body plan. The number does not tell you as much as the geometry. This is an important point that should not be over looked.

LJP07 · 06-19-2008

Thanks all, it makes much more sense now.

Moontanman · 06-19-2008

Quote:

Originally Posted by Thunderbird

Good point MoontanMan, not all creatures have two eyes such as the spider, but
they are symmetrically arranged bilaterally along the body plan. The number does not tell you as much as the geometry. This is an important point that should not be over looked.

I hadn't thought of that, I was going to say the cyclops has only one eye but I think they have one big one and several tiny ones but I'm not sure.