Re: [asa] Question regarding an evangelist and his "eye" biological facts (Louie Giglio)

Hi Bernie,

Optical development is different in vertebrates and invertebrates and Giglio's account is more recognizable as being somewhat closer to what happens in the later than in the former.

In human eyes, the optical nerve and retina are an outgrowth of the brain - so there is NEVER a point at which optic nerves from the eye are separated from optical nerves from the brain.

But contrast, in cephalopods (squid and octopus) the eye forms as an ingrowth of the skin the nerve cells of which then grow to form connection with the brain.

Giglio's account, then, vaguely a match for what happens in squid and octopus but is quite a misrepresentation of what happens in humans and other vertebrates - which is actually a pity because he could have made his point about the remarkable nature of optical development in the human foetus without such an error. In my assessment, he's gilding the lily in a quite unnecessary manner and while his major point is sound (we are fearfully and wonderfully made!) his science is quite wrong.

Incidentally, it's the above variation in the embryonic development of the human and octopus eyes that accounts for the oft mentioned blind-spot in the human eye and the claim that the octopus eye is a "better design". Personally, I think this to be a dumb argument on the basis that neural processing in humans combines the images from two eyes and eliminates problems caused by the blind-spot. Actually, I enjoy arguing that the blind-spot in the human eye gives us a distinct advantage - namely, that we can engage in party tricks involving the closing of one eye and the concentrated focusing on a single point. When octopus have parties, attempts to do this are met with repeated choruses of "I can still see the dot" with attendant jocularity all round. Which just shows that ANYTHING can be a "design fault" depending upon what you take the design criteria to be!

If you google "development of the eye" you'll get LOTS of hits - some of which are even marginally understandable to those without Nobel prizes in neurology or embryology! I think the below is particularly helpful if you don't mind a mental stretch;

http://www.vision.ca/eye/lobby.html

A slightly more technical account of the contrast between human and cephalopod eyes can be found at;

http://tinyurl.com/7b9ztu

Blessings,
Murray

Dehler, Bernie wrote:
> I wonder if there are any biology experts who can answer this.
>
> You may not have heard of this preacher (Louie Giglio) or his talk yet- but likely it is a fad and you will:
>
> http://www.youtube.com/watch?v=cuF629DW9kI&feature=channel
>
> My question:
>
> See his statements at time 5:03 - 5:35 (30 sec. segment)
>
> He says that when the eye is formed, millions of connections come together simultaneously, and meet from left to right. This seems outrageous to me. Can someone fact check?
>
> Yes- this is the Laminin guy... I'm sure you'll hear about that too.
>
> I'm also concerned about manipulation- check out his enthusiastic movements (likely highly rehearsed for maximum effect?) and the background music.
>
> ...Bernie
>
>
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Received on Wed Jan 14 18:08:56 2009