Can anyone describe the evolutionary stages of development?

Question

of a lobster eye. I currently hold to Intelligent Design and am interested in feedback on criticisms of ID. I know the development of the lobster eye is used by ID scientists as an example of irreducible complexity, but I want to get a Darwinian's feedback.

Answer 1

OK I know this is long ... but evolutionary development by definition is a *looooooooooong* process, so bear with me. The lobster eye, of course, didn't evolve starting with the lobster ... but goes way back to earlier life forms from which the lobster evolved. So the description below is about the eye in general.

All we need to show, to refute the "irreducible complexity" argument, is that each structure of the eye could have emerged in a primitive stage, through incremental steps that each produced an incremental advantage.

1. The development of photopigments. These are proteins that react to light (they literally change shape when a photon of light strikes them). Chlorophyll is an example, but they are relatively common in nature.

2. Dorsal photo-areas. Those individuals who had these pigments more concentrated on the top of their bodies, can now tell the direction of the surface of the water, which is where food is coming from.

2. Eyespots. Those individuals who had these pigments concentrated in certain spots, were able to detect changes in light, and survived slightly better, and produced slightly more offspring. Millions of generations of this produced individuals with distinct eyespots (places on the body where cells containing these pigments are concentrated).

3. Eye cups. Slight indentations which produced better detection of the direction of light, leading to more cup-shaped eyespots.

4. Closing into openings. Cup-shaped eyespots with a smaller opening for better directionality, with the light-cells concentrated on the back of the cup (a primitive retina).

5. Formation of the lens. Secretion of some mucusoid fluid at the opening of the cup that is slightly denser than the surrounding water producing better focus of the light on the light-sensitive cells in the back, all produced the ability to not only sense the direction of light, but movement as well. Then membranes that help keep the fluids at the opening and in the cup. Then slightly better and better control of the membrane-bound fluid in the opening using controlled secretions, leading to primitive lens.

6. Focusing. Then primitive muscles to adjust the aperture of the opening, or the focal length of the lens.

7. Better retina. While all this is happening, the "eyespot" is constantly getting better ... improvements to the lens (focusing) produce improvements to the retina, and improvements to the retina lead to an increased advantage for focusing. So the retina is improving, sharpening, developing edge-detection capabilities.

8. And so on, and so on. Ever more complex features over thousands of generations, each change a *slight* improvement.

All that matters is the basic fact of nature ... SLIGHTLY BETTER EYESIGHT PRODUCES SLIGHTLY BETTER SURVIVAL AND THEREFORE SLIGHTLY MORE OFFSPRING. That's fact is all that's needed to explain a constant incremental improvement over millions and millions of years. Turn that basic law of nature loose for that long, and you can have all sorts of complex eye 'designs' that we see today in nature ... complete with examples of al these primitive intermediate stages (such as eyespots in flatworms and jellyfish, to cup-shaped narrow-opening eyes in molluscs like the chambered nautilus ... all the way up to focusing camera-style eyes we find in ourselves).

And the other important point I'm trying to make is that these are not "separate" steps. The retina doesn't stop developing when the lens starts to develop ... but instead, both are constantly developing together ... each driving improvements to the other ... and the two together driving improvements to the optic nerve, to the visual centers of the brain, to motor coordination, etc.

Things *look* "irreducible" to us, because we can't separate these structures, but these structures did not evolve separately, they are closely interrelated because they *evolved* together.

The reason "irreducible complexity" is not a concept accepted by almost any scientist, is that every single example given so far can be similarly shown to be "reducible" ... i.e. reducible into incremental steps of development, each of which has enough incremental advantage that it is explainable by natural selection.

So "irreducible complexity" fails as a refutation of natural selection.

Answer 2

"i'm not putting forward that ANY evolutionist or Darwinist claims that a chimp is the instant make sure of the human,..." Um, yet it really is strictly what you wrote, above. you wrote "2 chimps beginning a human." that is hard to appreciate what you're asking in the journey that your words do not honestly mean what they look to intend. besides, there look a good number of issues incorrect with your questioning. as an example: (o) *each and every* organism is a transitional organism, and each and each and every new fossil discovery creates 2 new lacking hyperlinks. (o) Evolution is *not* a "incontrovertible truth." What that is, is a valid, unique medical idea. (you should study the meanings of "truth," "idea," and "hypothesis" in case you want to have any credibility in a medical debate.) the idea of evolution explains how a unmarried spark of existence may have developed into all the diverse varieties that we see on the prompt. the shown truth that it nonetheless is the reigning idea says that that is in truth the finest clarification that everybody's arise with, and no human being has yet found any irrepairable flaw in it. (o) Mutation does not reason someone of one species to develop right into a diverse species. (o) people are literally not imagined to have developed from chimpanzees or vice versa. both species are heavily proper, and likely have a complication-loose ancestor someplace more effective than some million years in the past.

Answer 3

Hi. I'd be more interested in why a water breathing fetus has a tail during it's development. I feel it is because our evolution brought us through an enormous number of iterations before 0 BC. Crayfish have eyes as well, but not the ones which evolved in a light less cave. I respect your belief, but it takes an enormous amount of blind faith.