Sunday, August 28, 2011

Darwin and the Human Eye

Christians love to tout this line from Darwin's On The Origin of Species:

Organs of extreme Perfection and Complication.   To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree.

But, as usual, Christians are taking things out of context.  Charles Darwin wrote these words in order to draw his opponents closer so that when the punch came it would be all the more effective.  Here's how Charles Darwin explains the evolution of the human eye:

Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real. 

How a nerve comes to be sensitive to light, hardly concerns us more than how life itself first originated; but I may remark that several facts make me suspect that any sensitive nerve may be rendered sensitive to light, and likewise to those coarser vibrations of the air which produce sound. 

In looking for the gradations by which an organ in any species has been perfected, we ought to look exclusively to its lineal ancestors; but this is scarcely ever possible, and we are forced in each case to look to species of the same group, that is to the collateral descendants from the same original parent-form, in order to see what gradations are possible, and for the chance of some gradations having been transmitted from the earlier stages of descent, in an unaltered or little altered condition. Amongst existing Vertebrata, we find but a small amount of gradation in the structure of the eye, and from fossil species we can learn nothing on this head. In this great class we should probably have to descend far beneath the lowest known fossiliferous stratum to discover the earlier stages, by which the eye has been perfected. 

Charles Darwin goes on for another three pages explaining how the human eye evolved.  Charles Darwin was not confused or baffled how his theory could have encompassed the evolution of the human eye.

A very good picture is drawn by Richard Dawkins of how evolution works, and here is how it goes:

To assume that evolution is a one-step chance process is like standing at the bottom of Mt. Improbable and trying to leap to its summit ten thousand feet straight up a cliff.  This is absurd and unlikely to ever happen.  However, on the back side of the mountain is a very gradual slope.

Creationists try to convince everyone that evolution is an immediate process and that they should shy-away from ever reading about it, because Satan is trying to get into their heads.  This is a very effective way of keeping the flock ignorant, so I must admit, in the big picture, the priests are doing a great job scaring their flock.

Evolution is not chance, but genetic and behavioral changes either help a species or hurt them.  If the species is hurt, it dies off.  If the species is helped, it moves one more step up Mt. Improbable.  Over the millions of years, changes occur and little by little the evolution toward the goal, such as the human eye, gets closer.

Creationists like to talk about something called "irreducible complexity", or IC.  IC says that an object, organ or other item is irreducibly complex if the removal of one of its parts or functions causes the entire object to fail and become useless.  This assumes that there can not be degrees of complexity.

However, looking at the eye of the flatworm, which only shows light and shadow, but no shapes, it is easy to see how this eye, which could be called 25% of the human eye, benefits the flat worm.  The nautilus has a pinhole-camera eye which shows shapes and objects, but through a very dim and blurry haze.  Even then, the nautilus' eye can still easily be understood to be at least 50% of a human's eye.

The next part creationists like to talk about is that there is no clear, direct, linear evidence of how the human eye developed.  Going back to IC, let's consider a stone archway.  Archways can be built by either stacking a large pile of rocks and then carefully removing them one at a time, or by building a dirt mound or wooden frame to hold the stones in place.  Once the building is complete, this scaffolding is removed and the arch remains.  While no evidence has been found (yet) the scaffolding theory is very elegant and easy to understand.

Creationists: Evolution is not chance.  It is a gradual, selective process which is very elegant and explains biological evolution.  Learn more about it before you look silly like these people who misquoted Charles Darwin for their own gain.  Christians are supposed to be honest, but these ones are either ignorant or very dishonest indeed:

This rumor that Charles Darwin couldn't explain the human eye is 50% lie and 50% laziness.  Don't be one of the lazy, lying people like the examples above.


  1. I only read "The Evolution of the Human Eye" by Pitman MD. I'm having difficulty understanding how he is suppost to be dishonest or ignorant? From what I read he had very thought out and sound arguments why the theories he goes over are irrelevant or rather walk the line of impossibility. Having a theory on how the human eye evolved is one thing, proving it and putting it to practice is another. I quite frankly could not tell you 100% whether or not he thought it possible but what I can tell you 100% is there is no evidence to support the theory on the evolution of the human eye. There have not even been studies where the most basic of eyes has evolved into a more complex one that is advantageous and therefore passed on through generations.
    I think there is also a problem with how people try to prove this theory. They look at various eyes from various species-ranging in complexity and say this is how evolution occurred but in fact there are no links between the various species and their eyes.

    I want to comment on something you've staed as well. "Evolution is not chance". The problem is that it is. If a gene mutates, there is only at most a 50% chance of that mutation being passed on. There is also the problem of gene dominace which can further lessen the chance of that gene/mutation presenting itself. So in order for a mutation to become prominent in a population it has to be considered advantageous, the mutation has to be dominat over the gene it is replacing and it has to be passed on. Now if a species reproduce frequently the more likely the mutation is to become prominent, however if reproduction is few and far between the likelyhood of encountering this mutation is lessened. Now that is just one mutation. One step in the evolutionary ladder. In order to go from light sensitive cells to the human eye there are MILLIONS, if not even more than that, mutations that have to not only occur, but make it through the process of reproduction. To top it off each one of those mutations has to occur just right, on the right section of DNA without affecting any other function of the subject, in an I'll manner. These mutations also have to occur in specific order. If there is a mutation that occurs that allows for sight of color but there are no receptors for it this mutation becomes useless and is less likely to survive and be passed on. So I ask you, what part of the evolutionary process is not chance. It is not just about animals choosing mates with the best chance of survival-there is a cellular level to it. You stated that the persons that wrote the quoted articles in your blog to be ignorant or dishonest(which some may very well be) I believe that your statement also showed ignorance or lack of knowledge in basic biology. If evolution is not chance then there is no chance of evolution.

  2. Please forgive all of my spelling and grammatical errors in my previous post as it is late and my phone tends to auto-correct.

  3. Again you show that you haven't taken the time to understand the subject matter. Evolution is not chance. Evolution is the process by which the selection of one genetic anomaly over another is chosen and passed on. Living too close to an underwater volcanic spring spewing carcinogenic compounds which then lead to genetic mutation is chance, but that's also geology and genetics - not evolution. Living in a time where the Earth's magnetic defenses are weaker, allowing more solar radiation through - which increases the likelihood (chance) of widespread genetic mutation is astrophysics and geology, not evolution.

    Evolution does not delve into what causes genetic mutations, only the beneficial or detrimental results thereof. It is only concerned with whether or not the genetic change benefited the creature, harmed it, or made no difference at all (scaffolding).

    We have evidence of a 25% eye and even a 50% eye. Just because we don't have evidence of a 51% eye doesn't mean such an eye can't be imagined.

    Evolution would be very easy to disprove. As soon as that happened, the entire scientific world would be turned upside down and the only explanation would be God. You would see a hundred million converts overnight. Churches would be overwhelmed and would have to conduct simultaneous services in their parking lots.

    What proof? As stated by one evolutionist, "Rabbits in the Precambrian era" which could be evidenced by fossil records. That would prove, beyond a doubt, that evolution is false.

    One tiny, little scrap of evidence to even suggest it is false has yet to be discovered. A creationist might say "Oh yeah? What about the Bacterial flagellar motor? Huh? What about that?" The scientist may not be a microbiologist so he would say, "Very interesting question. I'm not sure..." to which the Creationist would interrupt, "Ha! You can't explain it, which disproves evolution! You lose. God wins." The scientist would likely be annoyed, but would then contact his peers, visit a university library to figure it out himself, or pose the question to a peer who indeed was a microbiologist.

    Creationists look for gaps in evolutionary history, and instead of thinking about them, they act like good, little sheep and fill the gap with God.

    Scientists look for gaps as a child hunts for Easter eggs. It's another excuse to do research, to learn, to explore and to explain. Scientists are bored with what we already know. They want to discover something new.

    Science discovered that the Earth was not the center of the universe. Science will likely fill-in most, if not all, of religion's most cherished gaps.

    To reiterate, if a bacteria splits 1.58cm from an underwater volcanic spout, which is exactly where it needs to be, as opposed to a long-lost relative who splits 22cm from the same spout and thus the closer one mutates, that, of course is chance. Evolution then comes into play as to whether or not the mutation is beneficial. Evolution is not concerned with how the mutation happened, just what effect it had.

  4. I understand the material just fine. It is chance. The process by which the selection of one anomaly over another is chance. Evolution is not just the end result whether it was beneficial or detrimental and it's ability to be passed on. It is the whole process, from the mutation occurring to the outcome.

    Genetic mutation does not occur soely due to environmental factors. In fact I did not bring up environmental caused mutations so I don't know where that little rant came from. You are correct in starting that environmentally wide spread genetic mutation is not evolution, but successfully passing the mutation on is.

    You are correct in stating that evolution does not delve into the causes of genetic mutations, however, it does delve into the fact that they do occur, how or why does not necesarily matter.

    Having evidence of a 25%, 50%, or even 51% eye does not prove evolution of the eye because even in these cases the subject failed to evolve-they did not pass on genetics or was not advantageous enough to affect the population.

    Evolution should be just as easy to prove as disprove. Yet it hasn't been done. If evolution was disproven I am sure churches would not be filled (though it would be wonderful). People didn't believe in God long before the theory of evolution came about. If you believe there is no God a disproven theory is not going to sway you.

    "One tiny, little scrap of evidence to even suggest it is false has yet to be discovered."

    Why does the burden of proof fall on the people who don't believe it has ever occurred? I believe you made a blog post on something similar (insert wiggly eyebrow). I can say one tiny, little scrap of evidence has yet to be discovered to suggest it has occurred-and I'm talking of macro-evolution-there is no proof that micro leads to macro over time.

    Once again you manage to put Christians in this tiny little box. It is impossible for a Christian to also be a scientist I guess. Of course creationist look for gaps in evolutionary history. It's no different than you look looking for gaps in Christian or religious history in general. I think its better to find those gaps then to ignore they are there. The difference between you and me is that I believe in God but still look to unravel lifes mysteries through science. I don't put blinders on because of either. Being a Christian does not close ones mind to science.

  5. Natasha is right:

    I can say one tiny, little scrap of evidence has yet to be discovered to suggest it has occurred-and I'm talking of macro-evolution-there is no proof that micro leads to macro over time.

    If you have a reference to some scientists research that proves that macro-evolution is more than a hypothesis, please do a post on it, and please send me an email letting me know it is out here.

  6. So, Colleen - you want me to do the footwork. You want me to search for and discover peer-reviewed research, the credentials and other works of the author and write a detailed report for you that will be awe-inspiring and completely convincing to a Christian fundamentalist who is really just trying to keep me busy? No, thank you. You can do a Google search to find the information yourself. If that's not convincing enough for you, you can visit your own university library.

    I am, with this blog, revealing evidence against god and for reality.

    When you do your Google search you might use terms like "genetic evidence for evolution" and "how natural selection works".

  7. Yeah, so I did the search, found some bloggy type stuff that says there is evidence and then the text is just about micro evolution, not macro. I don't think there is evidence nor anything that has taken it beyond what they would call a hypothesis in terms of a repeatable experiment. You don't want to do the leg work but you are sure you are on the higher intellectual ground. Interesting. Most Catholic and Christian apologetic blogs include links to some type of scholarly research. Not true with this atheist blog.

  8. I wasn't aware that I would need to write research papers using APA format, in-text citations and a reference list. However, if you believe that would make me more believable, then I don't mind doing that once in a while.

    I will rise to your challenge. :)

  9. I believe I have answered your challenge.