Is the eye, respiratory, nervous, or digestive system even possible with evolution?

Question

So many elements have to be present at the same time for them to function at all. So how did they have a chance to evolve slowly without all components, they would be useless and would not be beneficial to the evolutionary process (evolution would expel them before they were useful).Imagine yourself without half of the elements for you nervous system you would not be possible.

Answer 1

Yes, evolution explains these systems. The problem (as illustrated in your last sentence) only arises if you take a complete working system, and then think of *removing* elements. Of course, that would cripple the existing system.

But the system did not evolve that way ... a biological organ system is not a collection of separate (and independently useless) parts that evolved separately and then somehow came together to finally become something useful. Humans look at a completed system and see separate parts ... but nature honors no such separation.

For example, it is not necessary for the retina and the lens in the eye to both evolve independently to completion before they can serve some useful function when combined. Instead, the retina and lens both evolved from far more primitive structures that could barely be called "retina" and "lens". Then, improvements in one structure led to improvements in the other.

Another way to put it ... the problem is separating things into *parts* instead of *functions* which is far closer to the way nature works. Functions can evolve from practically nothing ... as long as the function (a) serves some advantage, and (b) can be incrementally improved using slight modifications to structure, then it will evolve ... and together, several functions (detecting light, focusing light, filtering light, communicating light to the brain, etc. etc.) will all improve together.

Answer 2

Yes, of course. Very primitive eye spots containing cells sensitive to light exist in a number of present-day species. They are quite useful to these organisms, and, given enough time, could gradually evolve into more specialized structures. The most difficult part of evolution for some people seems to be the idea of probability, and combining that with the vast time span (billions of years) that life has existed on this planet.

A simple example - if you toss a coin enough times, eventually it will land on its edge and stay there. If a chance event happens, and it is beneficial to the organism, it will be kept.

Answer 3

There are a few answers to the "irreducible complexity" argument. One of them is simply that the complexity isn't irreducible. The primitive eyes that the other respondent mentioned, for example. Another answer is "disappearing scaffolding." It's possible that an irreducibly complex system may have been reducible previously, but certain components disappeared through evolution, leaving a seemingly irreducibly complex system. Picture a skyscraper. How did they build it that high? Well, they used scaffolding, but they took it away when they were finished.

Answer 4

Very simply, you are wrong. There are animals with simpler forms of eyes, respiratory, nervous and digestive systems than we have. Right down to the Euglena, with a light sensitive spot, which is so simple, it is used only to guide itself to sources of light. Look into the other systems in simple organisms such as flat worms, starfish, sponges etc, then come back and make your claim again. After all, they have survived with these simpler systems longer than we have; about 1 billion years longer, in fact.
Read Richard Dawkin's book "An Ancestor's Tale" for further enlightenment.

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Answer 5

No. The organs in our bodies did not evolve from or into anything. They have always been the same organs from the beginning. God created us this way. You point is correct. It is impossible for the organs to evolve individually and completely function. It seems like you answered your own question with confidence. It is easier and more correct to believe humans were created, rather than evolved.

Answer 6

yes it is possible --- i am not a biologist just interested and there are many examples today of how the development of various unrelated body functions evolved --- we nor any other creature sprung fully formed from the foliage --- check out some books on biology or genetics and see --- have fun