Moments of Permanence - Shut up, Richard Dawkins.

From: starshadow Date: October 13th, 2009 01:48 pm (UTC) (Link)

I personally think the worst thing to happen to both science and religion was when they decided they were mutually exclusive.

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From: elspethdixon Date: October 13th, 2009 03:34 pm (UTC) (Link)

What happened to the Neanderthals.

IIRC, the current theory is competition with modern-type humans killed them off. So, basically, we happened to them.

There was a theory for a while that Neanderthals and Homo sapiens sapiens had interbred, but I think the most recent genetic evidence is against that.

I swear some of these things (the eye thing, and the single-to-multi-cell organism thing) were in my high school biology class textbook, but it's been ten years and I can't remember. I do know that not all animals have lenses and cornea in their eyes -- snails have these collections of photosensitive cells called ocelli that can only sense light and dark. I think photoreceptive cells are supposed to have developed way, way back (because there are some really primitive animals with light-sensitive eyespots, like snails and flatworms) and arthropod compound eyes and vertibrate cornea-having eyes are currently thought to have developed seperately. Oh, and chambered nautiluses have eyes with no cornea or retina that are about halfway between eyespots and actual complex eyes. Also octopus eyes (which still have no cornea) actually project a right-side-up image onto the back of the retina rather than an upside-down one like human eyes. And I'll leave the wikipedia page on cephalopods alone now.

(actually, I bet wikipedia has a page on eyes and vision that would have actual answers, but going there to fact-check the nautilus eye info already cost me about ten minutes of getting sucked into reading about giant squid).

edit: Oooh, I found an entire special issue of a scientific journal about eyes and evolution. Damn it, now I'm going to be looking this topic up in the New York Library's online databases for the rest of the day. If I get no work done, it's Richard Dawkin's fault.

Edited 2009-10-13 03:40 pm (UTC)

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From: delfinnium Date: October 13th, 2009 05:02 pm (UTC) (Link)

Yeah - basically, eyes developed from light spots - a particular chemical that the body produced is photo sensitive, and that evolved a long, long time ago, so all animals that do have any sort of photo sensitivity would possess that chemical. Now, a curved pit (eye-pit) means that directionality is much better for being able to tell the direction of light. However, it sucks for focussing an image, so the next one is a pinhole-camera eye (you know, like a normal pinhole camera, no lens, nothing else), which the nautilus actually has. But it's not a particularly good eye, since to get a sharp image you cut out a lot of light, which is why you end up with lenses.

(I'm being simplistic, there're two lines of evolution - one leading to vertebrates and they have one type of photorecptor cell, cillia based, and the other is ... something else based, which is in the mollusc/insect line.)

Now you end up with a lens which can focus a LOT of light into one particular spot on the retina, which is better than the pinhole. But then you end up with size of eyes, resolution, and sensitivity, and all that other fun stuff related to camera properties. An insect's compound eye, which has compound bits that each have its own single lens is really well suited for what it needs - eg, a dragon fly would be able to see almost a complete 360 degree field of view, plus each eyebit only needs to focus one tiny itty bit of an entire image, unlike the mammalian eye which needs to be able to use its own lens to focus both far and near and be able to adjust to focus an entire image.

Basically, the evolution of eyes goes more or less like

- need for light directionality (go to light, away from light, is something blocking light? MUST HIDE)
- need for better directionality (more eye spots, usually in a pit, now can tell whether light is coming from up, down, around, bottom, top etc)
- need for image (is that thing blocking the light FOOD or predator? is that a mate?) (these sorts of things actually only develop in places where light is abundant - animals living deep in the bottom of the ocean don't need to develop this light sensitivity at all, especially those heat vent animals.)
- and from need of image, then you get to have to deal with light properties - refraction of light in air vs refraction of light in water vs refraction of light in eyeball/lens/cornea proteins. So you see that fish and octopi actually have hit upon similar eyeball structures, the spherical lens, but the structure of eyeballs (the photoreceptors, the arrangment of retina etc) are very different. This is an example of convergent evolution, where the needs are similar, but they have different parts ot put things togehter.

It's a bit difficult to tell you what are the transitional eyeball forms ARE, but basically, it's just what is needed at the time. Eye spots are good, helps you tell directionality of light (light = more algae = more food) so you can move there. So eye pits are BETTER because you can tell direction more accurately in a smaller space. Image forming eyes are even better because now you can tell what is blocking the light. and so on and so forth.

In fact, I think (this is my graduate student/not a professor/published author opinion) that one example of transitional forms is colour blind eyes, because before, eyes just needed to be able to tell the light/dark, without discrimination of actual wavelength of light. Then it became more important for mammals to be able to tell the colours apart - be able to see fruit, see fur patterns, etc. Most mammals actually can only see two colour types - ie they only have two types of cones, while primates have three. birds have four or more, and some insects/arthropods have more than that. A mantis shrimp has a whooping 14, because it is important for it to be able to distinguish colours more easily.

so colour blind eyes are actually the form between monochromatic vision and our 'normal' trichromatic vision. I think.

Does that make sense? >.>

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From: attentive Date: October 13th, 2009 07:09 pm (UTC) (Link)

Meh.

Dawkins is a prig no doubt, and a smug one at that. He's a bit like Philip Pullman or even Bertrand Russell come to that, a very C of E, very establishment, very Oxbridge atheist quasi-rebel shouldering the burden of ridiculous amounts of privilege whilst standing brusquely on his dignity.

But Dawkins the prig with a credible intellectual pedigree is far more palatable than many, even if he's really more of a loud-mouthed populariser and advocate than a Nobel Prize winner. I tend to feel his bad press precedes him a little too much these days. If you read his writings you find stridency and the odd tendentious opinion, but relatively few outright absurdities - even when it comes to religion. He's much less of a troll (and I suspect much more widely read) than fellow travellers like Sam Harris and Christopher Hitchens.

Requiring that Dawkins, by himself, fill every explanatory gap in the theory of evolution is unfair. There aren't many entire intellectual disciplines that one person can round off - the elaboration of the existing theory will take thousands more scientific person-lifetimes and in many cases, the obtainable empirical evidence will remain inadequate and only conjecture will ever be possible.

It may be that there are the sorts of unexplained irregularities in "macroevolution" that Creationists like to point to - but even that doesn't invalidate the body of research that has been done, it only modulates it.

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From: sami Date: October 14th, 2009 06:44 am (UTC) (Link)

See, the only bad press I've seen Dawkins get is some well-deserved lambasting over the Bill Maher thing. What set off this particular rant was seeing one of his own TV specials.

The only reason I think he should be expected to fill those gaps is that he's the one who behaves as if anyone who doesn't adhere to his belief that evolution is It is patently a moron, when *he's* at the point of Bad Science, because he no longer appears to accept as a possibility the idea that his pet scientific theory could be less than utterly correct.

For good science you always have to remember the possibility that you might be wrong.

It may be that there are the sorts of unexplained irregularities in "macroevolution" that Creationists like to point to - but even that doesn't invalidate the body of research that has been done, it only modulates it.

Right, except that Dawkins brushes off the possibility of those irregularities being meaningful. This doesn't mean that the existing theories are wrong, but it does mean they're INCOMPLETE, and if you don't accept the possibility that your theory is less than perfect - which he doesn't - then you aren't going to be looking for the ways to improve them.

Mostly, I would be less bugged about it if Dick Dawkins didn't irritate me so much. He's the kind of evolution advocate who makes me want to look closer at creationism - I resent agreeing with him about anything.

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From: attentive Date: October 14th, 2009 08:00 am (UTC) (Link)

"This doesn't mean that the existing theories are wrong, but it does mean they're INCOMPLETE, and if you don't accept the possibility that your theory is less than perfect - which he doesn't - then you aren't going to be looking for the ways to improve them."

To look at this another way, in physics Newtonian mechanics, General Relativity, and the quantum mechanics/electrodynamics of Schrodinger and Feynman are all also "incomplete" theories damned by unexplained irregularities. They're all discredited as far as having a total explanatory function is concerned, in fact they've discredited each other. And after decades of effort nothing has come along to complete the picture and unify these theories in a single convincing, experimentally verifiable, and internally consistent structure.

But if you climb to the top of the Leaning Tower of Pisa and drop a cannonball and a feather, they're both accelerated towards the ground at approximately 9.8m/s^2. An incomplete, discredited scientific theory can still be an immensely powerful and constructive explanatory tool.

The reason I commented in the first instance is because I suspect you of making a fairly marginal attack on Dawkins' science - which is much less impeachable as an overall corpus of knowledge than the explanatory frameworks preferred by his ideological contenders - because you find his personality so odious!

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