How did Evolution produce Symmetry?

Fair enough, old chap (chapess?) I just took exception to DOTF thinking we needed to be told that ten fingers means five each side, and the ludicrously panglossian ideas he offered. I mean, not having an asymmetrical head with an extra eye on one side being a problem for evolution?! As I thought I made (oxmoronically) implicitly obvious, that would leave you (extra-)eyeless on the other side!Put those things together in the same short paragraph, and I -- perhaps too quickly -- pegged him as low-grade creationist nitwit. It's a hazard of discussing these matters too much I'm actually delighted on the rare occasions when a creationist asks genuine questions, seeking knowledge, trying to see who is right. But that's not the general habit: they start absolutely certain that, no matter what they are told, that they are right nevertheless. (For a classic example, see Philip’s reference to ‘excellencies’ in this very thread. Fingers in the ears and singing LA-LA-LA-LA at the top of his inefficient (see below) lungs.) The general habit is Argument from Incredulity. When one is deficient in knowledge of a subject, to then use that argument smacks of -- hell, is -- a form of arrogance.So, sorry DOTF. By all means prove me wrong! Please. I insist.Ref old Dr Pangloss, I found it amazing that DOTF expected such best of all possible worlds to be produced by evolution... when in fact the concept of there being a vastly intelligent designer -- his own concept -- is by its nature utterly panglossian.'Look how perfectly so-and-so is/works! Look at how great bilateral symmetry is, two perfectly aligned eyes pointing forward!' and so on. And so the irony meter goes fzzzt-BANG! when evolution is expected to put eyes all over the body. If that would be better, then why did god not do that?!This is actually a damned good question. There are many instances of not if X is better why didn't god give us it, but since X is demonstrably better, why did god not do it?Here's an example.Birds have through-flow lung ventilation, whereby the air travels a circuit through their bodies. Mammals have a tidal system: the air goes in and out through the same tubing. The mammalian system therefore mixes the used air with the fresh, and some of it is re-breathed. Because the bird system does not mix the fresh air with the used, it is demonstrably, measurably, massively more efficient than the mammal system -- one website says it is ten times more efficient.Now, the creationist might say "So? God can do it however he likes." But on the one hand, we humans are allegedly the pinnacles of creation. Are there no instances when better -- much better -- breathing would be useful to us? How about just running?And on the other hand, there seems no functional logic to which creatures got which system. All birds have through-flow; fair enough for hawks and hummingbirds, peregrines and pigeons. But ostriches? Penguins? Kiwis? Sure, it's good that they’ve got it, I'm sure they're very pleased to have it. But if -- not if, but since -- through-flow is so much better, one has to wonder why no mammal was deemed to have needed better breathing than it’s got. No long-distance runner, like wolves or hunting dogs, have it; no sprinter like cheetahs have it. And crucially, no bat has it. What makes bat lifestyle so different from bird lifestyle that a bat could not immediately benefit from avian through-flow respiration?And another example, pinched from what I wrote for the EvoWiki:

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As photographers will tell you, a 'pinhole camera' is an effective way to form an image out of light; the small aperture at the front forms an image on the screen behind it. The smaller the hole, the sharper the image. The down side is that the smaller the aperture, the less overall light gets in. To solve the problem, camera designers add a lens. A lens is an obvious improvement, since it allows both a sharp and bright image. We might therefore expect the Intelligent Designer of organisms to use lenses in eyes.

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And the 'designer' did. Octopus and squid eyes have lenses... vertebrate eyes have lenses.

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There is however one cephalopod mollusc, the nautilus (Nautilus pompilius), which is considered more primitive than octopuses and squid, since it has an external shell. And it lives at considerable depths, where light is at a premium.

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The nautilus has a very good pinhole camera eye; considerable thought presumably went into its design. But the designer apparently saw fit not to give that eye a lens. Its eyes are therefore far less efficient than it easily could have been. Did the designer just forget?

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Erm, sorry, I appear to have wandered off topic Okay, butterfly pattern formation. There’s tons of stuff about this, and while (as with everything) we don’t know everything about it, it ain’t no Black Box for evolution. The best place I’ve found to start is here. This page gives a load of references, including pdfs of the actual papers. I’d only seen one of these papers before, and it’s why I mentioned Hox genes. (Incidentally, it is the homeobox Ultrabithorax that is also involved -- not surprisingly, really -- in the formation of fly halteres, and a mutation in Ubx is what can turn these impressive balancing organs back into what they once were, ie wings.As to why they tend to be symmetrical: it’s the way genes get expressed. In short, genes work in cascades, with one set controlling the next level, and those the next. All cells (yeah yeah, red blood cells etc etc, smartarses! ) contain all the genes, and it is the cascades that arrange which are switched on in which cells where to form the required tissue, by reference to the cells already around it. This means that in practice, a particular cell gets told something like ‘if you find yourself at the end of a limb bud / in a wing / in a liver / whatever, do this’.So when a limb is forming, the left hand doesn’t need to know what the right hand is doing. They are both doing the same thing, automatically and generally symmetrically, just in opposite directions out from the starting point. Same with butterfly wings.And thanks for the references, Mammuthus! Fascinating!Cheers, DT

Hi WK, nice to see you over here!"Way forward"? Nah, it's simply the formula:'Idiotic post' --> 'Short, sharp response'. 'Fraid this is nearly Pavlovian with me. I know it's a bad habit, but ring my bell and my fangs get bared.The better formula is:'Ignorant but open post' --> 'Detailed, hopefully informative response'. This too is nearly Pavlovian. I suppose it amounts to the old "Ask a stupid question..."As to referring people to a load of textbooks... well, just where do you start when ignorance runs so deep?When someone says 'evolution can't explain X', the first thing one should say -- and soooo often, you don't realise it should have been the first thing till much later -- is not 'yes it can because this this and this', but rather, 'what do you know about evolution?' If the answer is already obviously the square root of f**k all, what should one do? Give them a course in evolutionary biology before you can even attempt to answer the specific point? Sod that. Tell them to go away, sit down with a straightforwad textbook on the matter, then come back if they still have a problem.The alternative -- a detailed response -- will simply not be understood. I've had such responses plain ignored and followed by a restatement of the alleged problem ('you didn't answer my question!'), and sometimes thrown back at me for being deliberately complicated -- when the matter is complicated and/or relies on a load of other knowledge.So, the point is seriously made: if the amount that needs to be explained to answer the point is beyond the sensible capacity of anyone on a bulletin board to provide, go read a textbook.And as to Hox genes, they are a bit like shielding in chemistry. A large proportion of the answers will come from them. Sure, Hox genes aren't the be-all and end-all of butterfly wing patterning (or anything else genetic-developmental). But in looking up that bit of the basics, the answers and/or where to look for them should become apparent.Cheers, DT (Oolon Colluphid)

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a fish with two eyes on one side and none on the other would be vulnerable to attack from the side with no eyes,

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...unless, of course, the fish was a flounder, and spend most of it's life lying flat, buried in the sand at the bottom of the ocean.Then it's good to have both eyes on one side of your head.

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How could random events (or elements) produce harmony, symmetry, and proportion, PER SE?

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...um, physics?

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True, propagations and rebirths (micro-ToE events) should aide somewhat in maintaining these excellencies

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Please define "micro-ToE event."Please define "excellencies".

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on biological levels as per your ToE speculators.

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But speaking PER SE on cosmic excellencies of symmetry, harmony, and proportion does beg (strongly infer) awesome design (ID) to be sure, so that it seems pointless to argue the matter.

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So, your argument boild down to, "It's really impressive to me, so Godidit!"

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Most of us infer that a potter fashions the pottery, an artist the painting, etc.

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That's because we all can see, touch, and hear potters and painters.

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How much more might I (we) infer an excellent universe, quantum chemical science, life-form, and/or person to be directly fashioned by an awesome Maker.

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You tell us.

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Albeit doubts and fears must always taunt me (us) in this matter. A real curse of sin and blindness in my (our) mind(s) which repeatedly refuses to acknowledge the glorious truth of cosmic design.

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So, Philip, how do we tell the difference between an Intelligently Designed system and a natural one which we1) do not currently understand but may in the future, and/or2) do not have the intelligence to ever understand?

You are, of course, correct. There are several (many?) exceptions to the general rule of animal symmetry; I'd considered discussing this in my original post, but felt it would over-complicate matters. What is interesting is that asymmetry always occurs for functional reasons as well.

Right. Unlike our body, there are no Framsticks genes that effect both the left and right side of the body. And yet, if you leave them for long enough, you still tend to get rough symmetry - final forms often end up like spiders, snakes, or "fast crawling" creatures. I've got a speed one going right now, and my fastest creature is an "inchworm" (a fork, with a long body ahead of it; it uses the fork to push itself along). It's a bit curved, but as you mentioned, in Framsticks you can go in circles and still get credit for velocity.------------------
"Illuminant light,
illuminate me."[This message has been edited by Rei, 10-24-2003]

Hi ReiOkay, I've looked at the Framsticks thingybob site. Looks rather more clever than my old DarwinPond (though my five-year-old daughter likes feeding and killing the swimmers ). Which version / option should one download to just play with it a bit?Cheers, DT

You probably use Windows; I use Linux, so I haven't used any of the windows ones. It is really fun to play around with, though ------------------
"Illuminant light,
illuminate me."

Don't you need to register it to get the graphics out of it? Because I can't figure out a thing. They're all just sticks.------------------
Ia! Cthulhu fhtagn!

In linux, I use framsview.- Karen------------------
"Illuminant light,
illuminate me."

Yes, I did sound a little patronising up there. As [Mr Jack?] assumed, I was emphasising symmetry. Five fingers on each side, not four and six or three and seven. Everyone knows that! It's good to restate it sometimes for the purpose of bolstering your argument.Just a quick note before I sign off for the night - I noticed something schrafinator said a while back: What about the artists responsible for, say, the Easter Island carvings? We cannot see, touch or hear them, and (as far as I know) we have no evidence for their existence apart from their art. Yet we still infer their work is the product of intelligent design.

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What about the artists responsible for, say, the Easter Island carvings? We cannot see, touch or hear them, and (as far as I know) we have no evidence for their existence apart from their art. Yet we still infer their work is the product of intelligent design.

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But we have reasons for that inference.We have the surviving inhabitants of the island, some of whom have demonstrated at least partial knowledge of the processes by which their ancestors carved and transported the moai. We can gather used toki (stone adzes) by the hundreds at the foot of the slope where unfinished moai still lie, and refuse pits and oven remains indicate the presence of many human workers. We also have history since the first Western arrival (Roggeveen) where the natives lost the social organization to produce them, and each clan turned to knocking down the other's statues, demonstrating their significance to the people (as each represents a specific dead ancestor and was presumably commissioned by him/her while they were alive). In short, we do not just take somebody's word for it, nor do we pull our ideas out of thin air. We can see material evidence of the processes involved in creating the art.Can you cite some evidence of processes used by an intelligent designer to create a specific organism?

I'm still waiting to hear how an intelligent designer can fashion very stupid designs, and still be called intelligent.DT

Does this mean, Zephyr, that if we had no evidence concerning the history of the moai, we could assume they are not the product of intelligent design?

As we knew less and less about the background we would have a harder and harder time infering intelligent design. However, the statues are still of a kind that we recognize as the kind of thing humans produce and would infer things from that.This does become a real problem. As we probe back into paleoanthropology the tools that our ancestors made become more and more simple and less like those we recognize as like known intelligently designed and made tools. At some point it starts to become controversial whether they are products of design or nature and takes significant care to try to distinguish them. When we can't attach them to known designers we start to be unable to distinguish them from "undesigned" objects.