Friday Cephalopod: This is not a mammalian eye and brain

This is an octopus eye:

Octopus-Eye

This is an octopus brain:

octopusbrain

I have to point this out because the creationist Eric Metaxas said a remarkable thing:

But the octopus isn’t the only such miracle. “Convergent evolution” is all over nature, from powered flight evolving three times to each continent having its own version of the anteater. Think about that. As one delightfully un-self-conscious “Science Today” cover put it, convergent evolution is “nature discover[ing] the same design over and over.” Well, good for nature!

But as Luskin argues, there’s a better explanation for a tentacled mollusk having a mammal’s brain and human eyes. And that explanation is common design by an intelligent Engineer. And like all good engineers, this this one reused some of His best designs.

Umm, the octopus has a retina with the photoreceptors on the inner face, unlike mammalian retinae that have the photoreceptors on the side away from the light. The octopus has no blind spot, and the axons of the eye emerge all over the back of the eye; mammalian axons have to traverse the inside of the eye and exit at a spot with no photoreceptors. The visual receptors of the octopus use the rhabodmeric transduction pathway, and mammalian photoreceptors use the ciliary pathway.

What kind of ignoramus would suggest that the octopus has human-like eyes?

Maybe the kind with a small central ganglion wrapped around their esophagus? Nah, that's an insult to molluscs.

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Ian Musgrave has just posted an excellent article on the poor design of the vertebrate eye compared to the cephalopod eye; it's very thorough, and explains how the clumsy organization of the eye clearly indicates that it is the product of an evolutionary process rather than of any kind of…
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Please stop ranting about folks who have idiotic views on biology. It is boring. I find your thoughts about real things far more compelling.

By Mark Bolton (not verified) on 11 Sep 2015 #permalink

I like the rants.

I never get tired of this. I think it's important to repeat and repeat. Thanks.

By Tim smith (not verified) on 11 Sep 2015 #permalink

Fundies can't be octopuses... because having your esophagus go through your brain makes it easy to swallow new ideas!

*rimshot*

But as Luskin argues, there’s a better explanation for a tentacled mollusk having a mammal’s brain and human eyes. And that explanation is common design by an intelligent Engineer. And like all good engineers, this this one reused some of His best designs.

The Good Lord has certainly gotten lots of reuse out of His sea squirt design.

So Eric Metaxas is apparently of the belief that a book with roots in the bronze age offers a better explanation for the development of life than does modern science. I suppose that the lesson here is something along the lines of " If you are inculcated into or otherwise fall into a rigid, successfully self perpetuating belief system, and you build your life around that belief system, and that belief system comforts and sustains you to some large or small extent, then you are unlikely to be persuaded by fact or reason to abandon that system and instead, you will use whatever tools you can find in an attempt to defend your belief system."

Since we of the Science tribe don't offer much in the way of comfort, solace, ritual, or community to those who depend on religion to provide those things, I guess that we can expect few or no rigid religionists to drop their whole belief system to suddenly embrace ours. Instead, I predict a continual series of skirmishes as each tribe trespasses on areas of belief that the other considers sacred.

How wonderfully human!