An expansion:
It is not possible to firmly believe in intelligent design without a fundamental misunderstanding of the mechanisms of evolution, so here goes:

The traditional argument against evolution, as first put forward by William Paley in his magnum opus "Natural Theology" of 1802, is that of the proposed evolution of the eye.

"How can an eye have evolved?" ask the doubters. "It takes so many different parts, and if you remove any of them it ceases to work". In the case of the eye, it needs a lens, a complex arrangement of ciliary muscles, a very precise arrangement of an optic nerve and so on. Proponents of intelligent design began their movement with this example, turning Paley's original arguments into a cry of "What use is half an eye?". This argument is wrong and misleading.

It assumes that the only way an eye can possibly have evolved is in one lump. But suppose that in the far distant past, an organism just happened, through random mutation (in the same way some people are bigger or more hairy than others) to develop a patch of cells somewhere on its body that were at least partially sensitive to light? It's not beyond the bounds of possibility. A huge number of organic molecules are sensitive to light - just look at the way skin tans under UV light.

In reality, this first creature almost certainly died without breeding. But sooneer or later, thet co-incidence would have happened again and again, until a creature survived to breed. If, somehow, this patch of cells provided some advantage (possibly it would cause the creature to become partially nocturnal, when there were fewer predators) then its offspring would be more likely to survive long enough to breed than those creatures without the light sensing area - which might well be just a few cells out of billions in its body.

If it turned out that being able to detect light and dark conferred some sort of advantage, then over time those creatures that (again, through random mutation) were somehow able to do so more efficiently than their peers would be more likely, over a large population, to survive to breed.

Eventually, you would end up with the entire population of organisms able to detect light and dark on a rudimentary level. They were blind, and now they can see. Now let's say that one of them develops a mutation that allows it to tell the difference between some two colours (blue and red are furthest apart in the visible spectrum, so we will use these). Again, this is not too unlikely. To dip into Physics for a moment, the energy carried by light is not related to the intensity of the light, but rather to the wavelength of the light. Blue light carries more energy per photon than red light does, so it's not a wild speculation that blue light would affect chemical reactions in a different way to red light.

Now we have a creature that can distinguish between light and dark, and between strong colours - and every step in the process has been logical and clear. As time goes on, the ability of these creatures to distinguish colours might improve - say that their main predator is a yellow colour. The creatures that are best at seeing yellow will be those that are most able to see this predator coming and escape it, surviving to breed.

Now let's suppose that a creature develops a mutation that causes a very small amount of fluid to collect on or near the light sensing area. If you hold a glass of water up to a light, you will see how light reflects though it and, from some angles, the view through the water is made clearer or bigger. This isn't a lens yet, but if you've dissected an eye then you'll be aware that the lens is made of a thick, springy, jelly like substance. It's not too great a leap of imagination to see that over time chemicals could be introduced into the water, allowing it to take on a thicker texture. There are plenty of bodily fluids to choose from - not all of them are thin and watery, are they?

Now we'll suppose that a particular arrangement of facial muscles allows the animal to slightly change the shape of the light sensing area... I think that, by now, you see where I'm going with this.


I hope that in the above discussion, I have shown logically how an eye could evolve. The intelligent designers have got wise to this one - there's such a weight of evidence that eyes can and did evolve that they've pretty much conceded the point. Then they ask "What use is half a bacterial flagellum" and show that they have entirely misunderstood the argument.

Bacterial flagellum? This is the new rallying point of the ID movement. The man responsible for this new argument is a biologist called Michael Behe, who has made the observation that a flagellum (a mode of transport used by some bacteria) is a hugely complex thing using over forty proteins. Remove any of them, and it fails to work. This argument is supposedly backed up by mathematics from William Dembski, who describes "complex specified information". A biological assemblage is "complex and specified" if it contains three or more parts which cannot be removed without the assemblage ceasing to work. So what's the problem with this argument?

Well, "ceases to work" is a tricky sentence. Remove some of the proteins and you won't necessarily get a working flagellum, but you might well get something else. The flagellum very closely resembles types of secretory systems used as defences against other types of bacteria. Remove certain proteins, and you may well have a working secretory system. Remove a few more and you'll have something else. Even if you remove proteins until it absolutely ceases to perform any useful function, that's not to say that particular assemblage wouldn't perform a function if the rest of the bacterium was also subtly changed - as you would expect it to over the course of the thousands or millions of generations evolution reqires.



That's the mechanics of it. But some people would say "How is it that a creature 'Knows' what to do?". Well the answer is that it doesn't. No creature has a built-in DNA timer that says "Now is a good time to develop an eye". Creatures are constantly accumulating random mutations in their genetics. If one of thse mutations is beneficial then the creature is more likely to survive. If the mutation is harmful then the creature will be less likely to survive. There might be local examples of these probabilities being reversed, but over thousands of generations and years, everything will average out. Evolution has no sense of purpose - to use Richard Dawkin's words, it is an entirely blind process.

As for the creation of new species, that's not overly complicated either. If one part of a species is entirely isolated from another (no interbreeding possible, for whatever reason - maybe there's a mountain range or an ocean in the way) then it will still accumulate random mutations at the same rate as the rest of the species, but these mutations are under no compulsion to be identical. Suppose you stand in the middle of a field with a line of a thousand people to your left, and another thousand to your right. Now play a game of Chinese whispers. When you get to the end of each line you certainly don't expect your message to be uncorrupted, but you also don't expect it to be the same at both ends of the line. In fact, you'd be amazed if it was.

Now take the lines of people as successive generations of a reproductively isolated species. Given enough time the descendants wil not only be unrecognisable as descendants of the original organisms, bu the two populations will be so different from each other that they bear almost no resemblance. They will have shifted enough that they are no longer able to interbreed. One species has split into two.


Evolution can also be very subtle - if a predator is too efficient then it will eat too many prey, killing them all off. In this case the creatures that are less able to hunt effectively have the advantage.


I hope this explanation has been clear, though I'm not under the illusion that it will change anyone's mind. I just think it's important that people understand the proposed means of evolution, even if they don't believe it happens.
( MatJ LOOK, Thu 18 Mar 2010, 19:29, 7 replies)

WOW
What is your view on hair? Will we end up bald? With central heating and air con, will we no longer need it? No need to answer, my hairline is retreating as I type this so I must be evolving, but now that`s got me thinking about hereditary traits, are they an advantage, or a hindrance? Or both and neither?
*goes to clean blood from ears*
(Sadarse works like Mist condensing mud flaps, Thu 18 Mar 2010, 22:11, closed)

Hair as we know it is the result of sexual selection: those with great looking lids get more women, have more sex, and thus have more babies. In theory, anyway...
(Merrep, Thu 18 Mar 2010, 22:37, closed)

But by what criteria do we judge it as attractive?

( Bob Todd whee, Thu 18 Mar 2010, 23:28, closed)

hence - Russell Brand
(BigAndyBee, Fri 19 Mar 2010, 11:04, closed)

I recommend Dawkins' Climbing Mount Improbable for eye evolution;
it has a whole chapter about eye evolution, and another about wing evolution.
( Bob Todd whee, Thu 18 Mar 2010, 22:19, closed)

For the "Half an eye people"
Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve-Karl Popper
(Sadarse works like Mist condensing mud flaps, Fri 19 Mar 2010, 1:03, closed)

but, but . . .
"It is not possible to firmly believe in intelligent design without a fundamental misunderstanding of the mechanisms of evolution"

Isn't that the whole point? They don't misunderstand it, they reject it.

My favourite lunacy is the argument that the grand canyon was created one weekend by a rather large rainstorm.

This all gets filed in the 'funny shit' part of my brain.
( Not Pineapple anymore, Fri 19 Mar 2010, 10:27, closed)

My personal favourite is the "peanut butter" video.
I never did find out if it was a spoof or just collossal ignorance. I think in some ways I'd rather not know the truth.
( Mockingbird Practitioner of SCIENCE, Fri 19 Mar 2010, 10:32, closed)

.
By the way, your explanation is actually a bit light on the mechanics of it all.

There's a catch to this 'creature who senses light' argument. If this creature manages to breed, he's going to breeed with a similar creature, but one who probably doesn't have these traits.

It's not specifically the physical advantage that drives evolution. It's dominant genes.
( Not Pineapple anymore, Fri 19 Mar 2010, 10:39, closed)

Slightly light perhaps
But I was off to the pub, and had already spent far too long on it.
( MatJ LOOK, Sat 20 Mar 2010, 2:15, closed)

Very well written
I can recommend "Expelled: No Intelligence Allowed" if you want to get really annoyed at these people.
(bill, Fri 19 Mar 2010, 13:03, closed)

Here! Here!
Apologies if I'm paraphrasing anyone else - too much to read, whilst not being noticed, at work.
My lifelong argument with the people who believe in intelligent design is that there whole argument actually proves itself wrong!
If there had to be an "intelligent being" to create us, then who created that being? That becomes an endless circle of an unanswerable question.
Usually reponded to with some mumbling and use of the word faith!
(ape_hots, Mon 22 Mar 2010, 15:50, closed)