Evolution?

[germdoc]

Considering the theory of the evolution of the eye, and all the steps of all the generations and whatever mutations were involved, one would think the eye has really improved. Why then considering my contribution to the evolution, my eyesight gets worse the older I get?

The same thing that makes hair grow on your palms makes your eyesight worse. To quote the title of a book by the late humorist Lewis Grizzard, "Can I Do It Until I Just Need Glasses"?

[prlundberg]

Slik Geek: This is how the eye is believed to have evolved from a scientific standpoint. This is taken from pbs.org, http://www.pbs.org/wgbh/evolution/li.../l_011_01.html

"Darwin acknowledged from the start that the eye would be a difficult case for his new theory to explain. Difficult, but not impossible. Scientists have come up with scenarios through which the first eye-like structure, a light-sensitive pigmented spot on the skin, could have gone through changes and complexities to form the human eye, with its many parts and astounding abilities.

Through natural selection, different types of eyes have emerged in evolutionary history -- and the human eye isn't even the best one, from some standpoints. Because blood vessels run across the surface of the retina instead of beneath it, it's easy for the vessels to proliferate or leak and impair vision. So, the evolution theorists say, the anti-evolution argument that life was created by an "intelligent designer" doesn't hold water: If God or some other omnipotent force was responsible for the human eye, it was something of a botched design.

Biologists use the range of less complex light sensitive structures that exist in living species today to hypothesize the various evolutionary stages eyes may have gone through.

Here's how some scientists think some eyes may have evolved: The simple light-sensitive spot on the skin of some ancestral creature gave it some tiny survival advantage, perhaps allowing it to evade a predator. Random changes then created a depression in the light-sensitive patch, a deepening pit that made "vision" a little sharper. At the same time, the pit's opening gradually narrowed, so light entered through a small aperture, like a pinhole camera.

Every change had to confer a survival advantage, no matter how slight. Eventually, the light-sensitive spot evolved into a retina, the layer of cells and pigment at the back of the human eye. Over time a lens formed at the front of the eye. It could have arisen as a double-layered transparent tissue containing increasing amounts of liquid that gave it the convex curvature of the human eye.

In fact, eyes corresponding to every stage in this sequence have been found in existing living species. The existence of this range of less complex light-sensitive structures supports scientists' hypotheses about how complex eyes like ours could evolve. The first animals with anything resembling an eye lived about 550 million years ago. And, according to one scientist's calculations, only 364,000 years would have been needed for a camera-like eye to evolve from a light-sensitive patch."

Now, this is not concrete scientific law, but you can't discuss absolutes on either side of this debate.

[ragswl4]

Slik Geek: This is how the eye is believed to have evolved from a scientific standpoint. This is taken from pbs.org, http://www.pbs.org/wgbh/evolution/li.../l_011_01.html

"Darwin acknowledged from the start that the eye would be a difficult case for his new theory to explain. Difficult, but not impossible. Scientists have come up with scenarios through which the first eye-like structure, a light-sensitive pigmented spot on the skin, could have gone through changes and complexities to form the human eye, with its many parts and astounding abilities.

Through natural selection, different types of eyes have emerged in evolutionary history -- and the human eye isn't even the best one, from some standpoints. Because blood vessels run across the surface of the retina instead of beneath it, it's easy for the vessels to proliferate or leak and impair vision. So, the evolution theorists say, the anti-evolution argument that life was created by an "intelligent designer" doesn't hold water: If God or some other omnipotent force was responsible for the human eye, it was something of a botched design.

Biologists use the range of less complex light sensitive structures that exist in living species today to hypothesize the various evolutionary stages eyes may have gone through.

Here's how some scientists think some eyes may have evolved: The simple light-sensitive spot on the skin of some ancestral creature gave it some tiny survival advantage, perhaps allowing it to evade a predator. Random changes then created a depression in the light-sensitive patch, a deepening pit that made "vision" a little sharper. At the same time, the pit's opening gradually narrowed, so light entered through a small aperture, like a pinhole camera.

Every change had to confer a survival advantage, no matter how slight. Eventually, the light-sensitive spot evolved into a retina, the layer of cells and pigment at the back of the human eye. Over time a lens formed at the front of the eye. It could have arisen as a double-layered transparent tissue containing increasing amounts of liquid that gave it the convex curvature of the human eye.

In fact, eyes corresponding to every stage in this sequence have been found in existing living species. The existence of this range of less complex light-sensitive structures supports scientists' hypotheses about how complex eyes like ours could evolve. The first animals with anything resembling an eye lived about 550 million years ago. And, according to one scientist's calculations, only 364,000 years would have been needed for a camera-like eye to evolve from a light-sensitive patch."

Now, this is not concrete scientific law, but you can't discuss absolutes on either side of this debate.

According to the forum rules there is only one side of this debate, which means it isn't a debate at all. All unproven theory no matter what side a person might be on.

[leehljp]

Phil: Now, this is not concrete scientific law, but you can't discuss absolutes on either side of this debate.

And for this forum, This is called "Wisdom."

Interestingly, one of the most contemporary uses of the name "Darwin" is "The Darwin Awards," in which so many people eschew wisdom and common sense.
. . . which reminds me of a Red Neck's famous last words: "Hey y'all, watch this!"

Application: . . . wisdom and restraint when in community and around the coffee pot. If it ain't a concrete scientific law, continue using wisdom.

[cgallery]

All this talk about evolution and I just wanna say that I still can't fly. Every time I watch "Heroes" I'm reminded that some people are progressing in their evolution at a faster rate than I.

NOT thrilled with this.

[ragswl4]

All this talk about evolution and I just wanna say that I still can't fly. Every time I watch "Heroes" I'm reminded that some people are progressing in their evolution at a faster rate than I.

NOT thrilled with this.

Rudy you are not alone, in fact I believe I am regressing.

[Kristofor]

Biology is a science but it is a very different science than thermodynamics. A large part of biology is categorization and memorization of the cateogries. Valuable stuff but different from the formation and testing of scientific theories. I think that is part of the reason that evolution is held to so strongly by many biologists. They are somewhat unique as scientists by not having to ability to do scientific testing of their theories in many cases. We can neither prove nor disprove the theory of evolution. In many fields, a theory like that would die away.

Jim

Well... Scientists work with the tools they have at the time. Look back a few hundred years and the chemists had no real concept of the atom and it's structure. Instead these folks would develop categories and describe the properties and affinities of various materials. Many of their categorizations were useful, but many were also wrong and there was no way to test the underlying assumptions, only the macro properties that could be observed.

This is much the same with biology. The basic understanding of how genetic material is stored in DNA is less than a century old. With the ability to sequence that material biologists now have the tool to make much more direct investigation into organisms. Indeed they can even conduct experiments directly by modifying this material. There are plenty of ethical questions raised by these abilities (is it right to make glow in the dark fish, transparent frogs, etc.) but it should make for much more definitive relationships between organisms.

Of course none of the above really has much impact on the existence or lack of a supreme being. The ability to create people or the base components of the universe out of nothing would both be pretty neat!

Kristofor.

[Alex Franke]

Just a thought: Wouldn't it be fun if everyone in the world agreed to only mate with people with polythelia (extra nipples)?

Also, if evolution advances linearly and medicine/technology advance exponentially, certainly we would run into a lot of cases -- specifically particular to old age -- in which the theory of evolution by natural selection seems to break down.

In any case, no matter how man originally came to be, I don't think there's anything that says we can't change over time...

[ragswl4]

Also, if evolution advances linearly and medicine/technology advance exponentially, certainly we would run into a lot of cases -- specifically particular to old age -- in which the theory of evolution by natural selection seems to break down.

Quite the contrary in my opinion. The advancement of medicine/technology is part of human evolution. It is what made mankind the king of the animals on this earth. I don't see how we can separate medicine and technology from our evolution to the next level or extinction as the case may be. The theory is that the ape evolved to human and one of the reasons was the creation of tools. We are doing the same thing now except we call the tools computers, space shuttles, nuclear weapons and toilet paper.

We are where we are in the food chain because of our brains and what has been invented by those brains.

[JimD]

Sigma147,

I've thought of this a fair bit and I sense you have too. I doubt either of us will change our minds but I appreciate your sharing of points supporting your view.

I noticed in the one posted link the following statement:

"These questions have, as yet, only tentative answers"

The context was addressing my point about what positive mutations and specifically addressing how and whether they happen. I must admit I did not study the references you provided in detail but I did read through the one. I can also tell from the title of several others that they are not necessarily talking about mutations of genes. If we see individuals that are more resistant to AIDS, for instance, we do not know if that is due to a gene sequence they had before they were exposed to AIDS and a gene sequence that their parents also had or if somewhere along the way the genes changed. Even if we knew that it was a new and different gene sequence, did it arise due to the simple combining of genetic material from the parents or was it a mutation? The combining of genetic material form the parents is what I would call micro evolution and it clearly exists. I did not see a reference to macro evolution. I believe that adaptive changes to existing species clearly take place but there is no clear evidence of significant changes in capabilities.

I believe your point was in reference to my comment about positive mutations. I can see why you could look upon some of this material as supportive of a view that these occur. I look at the same information and think it supports my belief that both natural selection and micro evolution are real but macro evolution and positive mutations are just theories - as was kind of stated in one of your references.

An issue that I did not initially raise that troubles me relative to evolution is the theory that the earth is very old and thus there was a lot of time for evolution to occur. My main issue is that I do not think positive mutations either occur at all or at least occur at such a low rate that there is no way to create new species through that process. The answer usually given to this is that there was a lot of time available. One of the reasons that is references is carbon dating of materials. Carbon dating depends on the material having been created at one point and then gradually decaying in a constant radiation background. We do not know that the material was either created all at once (big bang is another unprovable theory) or that the radiation field has been constant. The sun gives off much more radiation than our bodies experience due to the atmosphere. The suns also varies in its radiation. If the atmosphere was not constant, or the sun was not relatively constant, or if some of the carbon 14 atoms were introduced into the system at varying times, our carbon dating system is horribly inaccurate. I brought this up only to point out that there are more issues with evolution than I initially raised.

I think it still comes down to an unprovable theory to me that I consider very improbable due to these issues. Evolution is, however, the best theory for the origin of man that does not depend on the existance of God.


Jim

[dkerfoot]

Just as a point of (hopefully) clarification, many people who don't believe in evolution have no trouble with natural selection or adaptation. In intelligent design circles you may hear this expressed as Micro vs Macro evolution.

Natural selection, where those best adapted to a given environment will survive and reproduce young that have similar traits, is rarely a matter of debate.

It is the leap to becoming an entirely different species that is more often questioned.

One famous example is the finches on Daphne Major. The birds with the larger beaks survived a drought because they could crack and eat tougher seeds when the preferred ones ran out. The surviving birds had babies that also had larger beaks. No real debate there.

The debate happens when we go way back in time and ask if the finches used to be fish.

So, generally speaking - no one argues about antibiotic resistant strains of bacteria. If a medicine kills 99.9 percent of a given strain of germ, it stands to reason that if the 0.1% remaining is able to reproduce, their kids are going to be pretty special.

People begin to argue when you go on to say that in 4 billion years those germs will then grow up to become scientists. Personally, I find that notion ridiculous. I am quite certain they will NEVER make it past the grade school gym teacher stage.

[jseklund]

DKERFOOT: Does that imply that the existence of grade school gym teachers PROVES the reality of evolution (and possible limitations)?

I think you bring a very good point up. I, personally, cannot imagine how some people refuse to believe in evolution- and that's not a knock- it's just that it seems so likely to ME, it is hard to imagine another view. But I try- because perseption can be tricky. Perhaps the people who question evolution see SOMETHING that will either disprove or aid in the tweaking of the theory. Questions are king.

Your point about it being the mechanism itself that leads to the change is a good one. I think this is the spot where
1. We need more understanding and
2. People have the hardest time grasping what we already do hypothesize.

It is a big jump to imagine a new species entirely evolving from this, but not as big, perhaps, as we think. We see anomalies in humans every day when babies are born. We "correct" them with our technology, but what if it were allowed to run free?

[DonHo]

Well I'll stick my toe in the water once more. I agree with Doug's post. To say if I believe in evolution, I first have to know how evolution is defined. I agee that new breeds of dogs and cattle have come about, I've watched that happen. If that's evolution I've even helped it along by practicing selective breeding with show guppies and bettas.
On the other hand I don't believe any of my ancestors were single cell organisms. I also haven't heard of and don't believe there is any proof of one species changing into another species. You may can start with a black and white spotted cat and thru selective breeding produce both solid black and solid white cats but I don't think you'd ever get dogs.

DonHo

[diamondman]

Education

I guess you didn't learn this stuff where you grew up. Evolution can be thought of as an upside down tree. As new species evolve they separate into new branches which move in their own direction and again branch out. Somewhere back in time some apes separated into a brand new species called Homo. They continued to evolve (e.g. Homo Habilus, Homo Erectus ) all the way to Homo Sapien. Apes and other primates continued to evolve too, but along different branches of the tree. Thus today we see a wide variety of primate species, all related to men by virtue of an ancient common ancestry.

[JimD]

diamondman,

Another issue I have with macro evolution is illustrated by your comment. If there is a clear path from single celled organisms to us, why do the transitional forms not show up in the fossil record? All of the animals currently on earth appear in the fossil record at about the same time. If they were around for millions or billions of years, why can't we see clear evidence of that?

It's realatively easy to postulate how macro evolution might work, its pretty hard to find evidence it happened or is still happening.

Jim