Wednesday, May 07, 2008

The evolution of the eye

A nice short segment on the evolution of the eye from the National Center for Science Education. This is part of Expelled Exposed. (tip from Greg Laden's blog)



and while at it, check out this news about a squid with eyes the size of a soccer ball (hmm...fried calamari eyes...)

2 comments:

ungtss said...

So many layers of wrong in this video.

1) Non-sequitor. Titling the video "creationism disproved?" As though the presentation of a hypothesis of the evolution of one organ, the eye, could disprove the idea that the organism itself was created. Silly, if course.

2) Oversimplification. The video starts out with "light sensitive cells," as though the development of such cells was "no big deal." But let's take a closer look at this. How much genetic information is required to transform a limited number of cells into light sensitive cells? First, the cell has to hyperpolarize in light. Then, it has to have the capacity to produce various neurotransmitters depending on its state of polarization, and transmit them. And it has to be connected via nervous tissue which can transfer that neurotransmitters. And it has to have some capacity to receive the neurotransmitters. And it has to have the capacity to use this information in a way that adds survival value. All this irreducibly complex functionality, glossed over in just the "first step." All the further steps similarly oversimplify the steps of development. Like all the genetic information required to construct the "rudimentary lens," including the differentiation of lens cells, and the mechanisms required to manipulate those cells in order to make the lens useful. She skipped those steps, too. Finally, by focusing only on mollusks, she doesn't even get to the real difficult stuff -- the development of the eye BALL, which moves freely inside an eye socket.

3) Hypothesis masqueraded as science. All they have presented is a hypothesis -- not a theory -- there is in fact no evidence to prove that these various forms of eyes actually, historically, evolved from one another. The evolution of the eye could have been radically different than the process presented here. Or there could have been no such evolution at all. There is no evidence to falsify either of these other possibilities, and therefore the "just-so" story presented is not science.

4) Non-sequitur. I think my favorite quote of hers is "If it can grow, it can evolve." How beautiful is that. Growth is the process by which an organism follows the instructions encoded as genetic information preprogrammed into the organism. Evolution is the process by which genetic information is modified through the generations. Radically different processes. But she argues that if an organism can follow its preprogrammed genetic instructions, then surely those genetic instructions could be programmed into the organism without any intelligent intervention. Nice:). Like if a computer can start up, following the instructions pre-ncoded in its hardware and software, then surely those instructions can develop through random variation and non-random selection.

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