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Source: (consider it)
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Thread: The Death of Darwinism
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Crœsos
Shipmate
# 238
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Posted
quote:
Originally posted by Ramarius:
quote:
Originally posted by Pre-cambrian:
Not necessarily. The arguments between punctuated equilibrium and phyletic gradualism are basically about the speed and temporal regularity at which evolutionary change takes place. That's a different question to whether the results of evolutionary change, when it happens, are haphazard.
Is the discussion between the puncs and grads roughly this?
Gould suggested that sometimes mutations happen that have no immediate benefit; but that they nonetheless remain in the gene pool because they are not harmful. They remain in the gene pool and may subsequently become part of a later beneficial mutation. This is "Historical contingency” which simply means, “it depends upon something that happened in the past.”
Gould’s opponents say that the *environment* drives evolution to a particular solution, (so it doesn’t depend on past changes paddling away lazily in the gene pool) and that a mutation conferring no immediate benefit will probably disappear from the gene pool before it is eventually "needed."
No. There's no one working in the life sciences today who doesn't accept the reality of neutral mutations. You're conflating questions of gradualism (slow, incremental changes over time) vs. punctuated equilibrium (rapid changes over short periods of time followed by long periods of relative stability) with the question of how deterministic a given environment is towards a few, very specific solutions. These are separate, and only marginally related, questions.
To go back to the Lenski experiment, we see that certain evolutionary solutions are adopted by all strains (larger cell volumes, lower maximum population, specialized glucose metabolism). This seems to be consistent with both gradualism and environmental determinism and probably represents the mutational "low hanging fruit".
On the other hand, the true breakthrough in adaptation (the ability to metabolize citrate) is consistent with both punctuated equilibrium (once Cit+ evolved, it rapidly took over population Ara-3) and contingency (no other strain developed Cit+, Ara-3 ancestor strains could also evolve Cit+, but only if taken from generation 20,000 or later).
At any rate, going back to the question of human-level intelligence, it seems to me to be more akin to developing Cit+ (a very rare series of contingent mutations) than to the "low hanging fruit" mentioned above (which would probably include things like certain coloration patterns or refractive lens eyes). Given about four and a half billion years of life (and about six hundred million years of complex multicellular life) only one known species (us) has managed the trick, compared with a lot of convergently evolved eyes, wings, camoflage, etc.
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Humani nil a me alienum puto
Posts: 10706 | From: Sardis, Lydia | Registered: May 2001
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Dafyd
Shipmate
# 5549
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Posted
quote:
Originally posted by Ramarius:
Is the discussion between the puncs and grads roughly this?
Yes and no. I think you've roughly characterised one area in which Gould disagreed with other evolutionart theorists. But it's not the area of punc vs grad.
Punctuated evolution means that evolutionary changes tends to happen fast in bursts, in response to fast changes in the environment, and then settle down to stretches of nothing much happening (because all the organisms in an ecosystem are pretty much as well adapted to the environment and each other as they can be). Gradualism is the belief that evolutionary change ticks over slowly and steadily with no sudden bursts.
It so happens that Gould and Lewontin, who proposed punctuated equilibrium as the most widely applicable model of evolution, are also well-known proponents of other semi-controversial positions. But that doesn't mean that there is a necessary connection between all those debates.
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we remain, thanks to original sin, much in love with talking about, rather than with, one another. Rowan Williams
Posts: 10567 | From: Edinburgh | Registered: Feb 2004
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mousethief
Ship's Thieving Rodent
# 953
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Posted
Can one of you help me? I'm having (don't ask why) something of a debate with a creationist over on Facepalm, and he made the statement that "scientists are abandoning evolution and big bang cosmology in droves." What on earth is he talking about? Is this some new wrinkle in the creationist bullshit? Some article that some absurd creationist journal published? Where does this come from?
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This is the last sig I'll ever write for you...
Posts: 63536 | From: Washington | Registered: Jul 2001
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Crœsos
Shipmate
# 238
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Posted
quote:
Originally posted by mousethief:
Can one of you help me? I'm having (don't ask why) something of a debate with a creationist over on Facepalm, and he made the statement that "scientists are abandoning evolution and big bang cosmology in droves." What on earth is he talking about? Is this some new wrinkle in the creationist bullshit? Some article that some absurd creationist journal published? Where does this come from?
Actually it's very old creationist bullshit. I can't say what's kicked off the recent spate of "evolution is on its last legs" that you've come across, but creationists have been predicting the imminent collapse of Darwinian evolution (and before that, geology) for literally centuries now.
Any . . . minute . . . now! ![[Roll Eyes]](rolleyes.gif)
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Humani nil a me alienum puto
Posts: 10706 | From: Sardis, Lydia | Registered: May 2001
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Palimpsest
Shipmate
# 16772
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Posted
quote:
Originally posted by mousethief:
Can one of you help me? I'm having (don't ask why) something of a debate with a creationist over on Facepalm, and he made the statement that "scientists are abandoning evolution and big bang cosmology in droves." What on earth is he talking about? Is this some new wrinkle in the creationist bullshit? Some article that some absurd creationist journal published? Where does this come from?
Old nonsense. Ask him to name two of the droves. I bet he can't.
Posts: 2990 | From: Seattle WA. US | Registered: Nov 2011
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ken
Ship's Roundhead
# 2460
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Posted
quote:
Originally posted by mousethief:
... he made the statement that "scientists are abandoning evolution and big bang cosmology in droves."
OK, its obviously not true, but what do they back themselves up with when challenged?
In my experience they pull in three kinds of support for this contention about evolution (I can't talk about the cosmology)
1) they quote stuff from a small number of rather clever physicists or mathematicians or philosophers who simply don't understand modern biology (i.e. post-Darwin) and bring up absurd objections to the idea of evolution. The best known of these is perhaps the late Fred Hoyle, who was a cosmic super-genius of the first order, and a hero, and ought to have got the Nobel Prize, and was a pretty decent SF writer too, but who knew fuck all about biology. Others have had similar failures. The root cause of their misunderstanding seems to me to be a sort of philosophical essentialism, which maybe helps with physics and other such sciences but misses the point entirely in biology. (Well, not just me so much as me channeling Ernst Mayr...)
2) they quote stuff from the so-called "Eclipse of Darwinism" period, when a large number of biologists accepted the fact of evolution and the great age of the Earth but rejected natural selection as a main driver of evolution, and some of the main consequences of that. Again it kicked off with essentialism, and a big dose of what the Germans called "Naturphilosophie". It was reinforced later by widley held misunderstandings about the supposed incompatibility of Mendelian genetics and Natural Selection leading to odd ideas about saltationism and some handwaving stuff about life-forces and essences.
This was common from maybe the 1870s to about the 1920s, with a considerable long hangover from it going up to the 1940s or even 1950s, especially among German-speaking biologists, and among botanists. That period was brought to a close by the so-called "New Synthesis" which explained, pretty clearly, how population genetics, natural selection, speciation, and phylogeny did all fit together. After the 1920s pretty much all English-speaking and Russian-speaking biologists were Darwinians again (though the Russians got kicked back by Stalin later) and most continental Europeans got on board by the 1940s.
The "eclipse" coincided with the rise of YEC in America, so lots of the early YECcies quoted anti-Darwinian biologists from the 1900s in their books. And the quotes got transmitted from YEC to YEC, even if their originators had long been disproived, or changed their own minds.
3) Some polemical YECs are in the habit of taking disputes between biologists about the nature or course of evolution and treating them as casting doubt on the fact of evolution. They have had great fun with the punctuation vs. gradualism thing, with pattern cladism, with the recent re-recognition by some biologists of some place for group selection or saltation, with the argumetns abotu so-called "selfish genes". What they don't admit is that all these are disputes within the broad world-view of the neo Darwinisist synthesis and that (almost) none of the participants actually disbelieve in tghe great age of the earth or in the fact that new species originate through natural selction.
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Ken
L’amor che move il sole e l’altre stelle.
Posts: 39579 | From: London | Registered: Mar 2002
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Ramarius
Shipmate
# 16551
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Posted
Looking at some reviews of the Lenski experiment I've been surprised at just how limited the experiment has been (hardly a re-run of evolution). For example, no new metabolic function evolved - the ability to digest citrate was already there. What was lacking was the ability to * transport* the citrate from the outside environment through the cell membrane into the interior.
As Lenski himself puts it in his ipaper “The only known barrier to aerobic growth on citrate is its inability to transport citrate under oxic conditions” (para 5). And getting e-Coli to use the citrate was a pretty tortuous process. Lenski again '..none of the 12 LTEE populations evolved the capacity to use the citrate that was present in their environment for over 30,000 generations. During that time, each population experienced billions of mutations (22), far more than the number of possible point mutations in the _4.6-million-bp genome. This ratio implies, to a first approximation, that each population tried every typical one-step mutation many times. It must be difficult, therefore, to evolve the Cit_ phenotype, despite the ecological opportunity'
So after over 20years of selective pressure over some 360,000 generations ( 12 x 30,000) has produced a minor novel trait. The experiment shows a change at micro level only (no macro evolutionary changes) and is hardly representative of a natural environment (no dead cells to scavenge, no contaminant, no other bacteria involved). Hardly surprising that both Conway Morris and Behe cite the results to support their own divergent views on evolution.
Basically we get the results we get because an intelligent agent created specific conditions and ensured they were maintained without contamination (no random influences allowed to interfere) until certain results pertained.
Posts: 950 | From: Virtually anywhere | Registered: Jul 2011
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ken
Ship's Roundhead
# 2460
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Posted
Its quite possible that no completely new significant metabolic pathways have evolved for a few hundred million years. Not since green plants developed lignin and some ways of building complex stuctures with phenols and other aromatic compounds, and one major group of fungi evolved ways to eat them. Sometime before that animals learned a few clever tricks with steroids. Thats about all there is that bacteria can't do, and the things that bacteria can do they swap betweem themselves in ways that we mostly don't. So what's the chance of getting a new one in only a few years? Think of the scale!
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Ken
L’amor che move il sole e l’altre stelle.
Posts: 39579 | From: London | Registered: Mar 2002
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ken
Ship's Roundhead
# 2460
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Posted
quote:
Originally posted by Ramarius:
During that time, each population experienced billions of mutations (22), far more than the number of possible point mutations in the _4.6-million-bp genome. This ratio implies, to a first approximation, that each population tried every typical one-step mutation many times.
Of course. Think if the scale! If even such a tiny experiment as this can do all that, what could happen in the wild, with much larger numbers, much more diverse genomes, and other bacteria to swap genes with, the chance of larger mutations or of two mutations coming together, is much greater.
quote:
So after over 20years of selective pressure over some 360,000 generations ( 12 x 30,000) has produced a minor novel trait.
Which is bloody amazing! If evolution worked that fast in the wild - well, it would be staggering.
Think of the scale.
The bacteria we have now might have had about about two billion years to develoip the range of metabolic capabilities that they had when the first prokaryotes evolved - no-one really knows because its impossible to tell from fossils exactly when the earlier organisms had settled down into what is now the standard pattern , and almost as hard to tell when things other than bacteria evolved. But lets estimate two billion. So that is one hundred million times longer than the experiment - 10^8 times more time.
No-one knows how many bacteria there are in the world. Estimates vary from maybe a tenth of thge biomass of the whole planet to almost all of it. No-one knows for sure what the biomass of the planet is. Also no-one knows how much of it is dormant and how much actively growing (the latter obviously more likely to both mutate and be selected) Also things work very different on land (where organisms tend to hang around for a long time and build complex structures) in the seas (where turnover and primary production is higher than biomass) and in sediments and under the surface (where most life is probably dormant much of the time - but this is the great unknown of mega-scale ecology)
A conservative estimate for biomass might be a trillion tonnes, 10^15 kilos - so guess 10^15 times the size of the experiment.
But the genetic diversity of the world is very great compared to the experiment. No-one knows how many broadly distinct baterial species there are - in fact the question ins probably meaningless because bacteria don't form distinct species in the way we do, their whole population genetics is qute different. There are less than ten thousand known to traditional microbiology, some researches estimate there might be a trillion different bacterial species (according to some dodgy definitions). What really counts is the number of differently organised genomes. Lets make a very conservative estimate of a million - much less than the probable number of different animal species! Thats 10^6
So the size of the "experiment" that led to the bacterial world we have now is, at an extremely conservative estimate 10^8 * 10^15 * 10^6 times larger than the lab experiment. That's 10^29 times bigger.
Its kind of hard to get over quite how big a number 10^29 is. But if it only takes one little experiment evolve a "minor novel trait", 10^29 times more than that is going to evolve an awful lot. I mean you thought space was big...
In real life of course its even bigger an more complicated than that because the whole world is partitioned into vast mumbers of micro-climates and little envirtonments in which different things happen. And far more for bacteria than for us. Compared to a bacterium the body of a large animal (such as a human) is about the same size as a small planet like Vesta or the Moon or Mars is to us. Except that they don't just live on the surface of the "planet" they live all through it on all the internal structures and membranes - at the level even of organs such as lungs and livers and blood vessels thats's thousands of times bigger than the outer surface of the body and wehn you bring in cell membranes its vastly biuggger than that - so to bacteria each of us presents a living space as large and diverse as the whole Solar System would be to us if we could get there. Which is one reason each of us hosts trillions of bacteria with perhaps thousands of different kinds of genome organisation.
Oh, and viruses... there are a loit of genes in viruses. And there are millions, perhaps billions of them in each cubic centimetre of seawater. And lots of other bits and pieces of genetic material floating about. Plasmids and weird stuff and things that look like dormant genomes of dead bacteria. All over the bloody place. And bacteria, or at lest some of them, go around grabbing hold of these things, taking DNA out of them, and trying it out to see what it does. (Really - do a Google search for "transformation competence"). So whenever anything new turns up in the way of genes, sooner or later it will be paired with pretty much everything else. So all those little mutations will have the chance to be combined into larger ones. Which is how bacterial genetics mostly works now and why its not driven by brand new genes so much as by the vast availablility of old ones. The infinite number of monkeys don't need to re-write the worlkd of Shakespeare because they are already living in the Library of Babel. And of course its why in real life we'd expect bacterial evolution to move faster than in the experiment because of the diversity of genetic material in any one environment, and because things are exported between environments.
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Ken
L’amor che move il sole e l’altre stelle.
Posts: 39579 | From: London | Registered: Mar 2002
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Johnny S
Shipmate
# 12581
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Posted
quote:
Originally posted by ken:
1) they quote stuff from a small number of rather clever physicists or mathematicians or philosophers who simply don't understand modern biology (i.e. post-Darwin) and bring up absurd objections to the idea of evolution. The best known of these is perhaps the late Fred Hoyle, who was a cosmic super-genius of the first order, and a hero, and ought to have got the Nobel Prize, and was a pretty decent SF writer too, but who knew fuck all about biology.
That's a really good point and right on the money.
To be fair, though, it works both ways. When I studied Chemistry it was generally accepted among the physical sciences that biologists weren't very good at Maths!
Then again, it probably stemmed from envy too ... the biology dept. had all the good looking girls. Correction. The biology department had girls.
Posts: 6834 | From: London | Registered: Apr 2007
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Soror Magna
Shipmate
# 9881
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Posted
quote:
Originally posted by Johnny S:
... To be fair, though, it works both ways. When I studied Chemistry it was generally accepted among the physical sciences that biologists weren't very good at Maths!
...
Yeah, but they're evolving due to environmental changes. Universities and colleges started requiring all Bi majors to take statistics, because it's essential to any sort of population analysis, and now there's bioinformatics. There's a whole new subspecies of biologist that is really good at math and computers. ![[Big Grin]](biggrin.gif) OliviaG
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"You come with me to room 1013 over at the hospital, I'll show you America. Terminal, crazy and mean." -- Tony Kushner, "Angels in America"
Posts: 5430 | From: Caprica City | Registered: Jul 2005
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ken
Ship's Roundhead
# 2460
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Posted
quote:
Originally posted by OliviaG:
]Yeah, but they're evolving due to environmental changes. Universities and colleges started requiring all Bi majors to take statistics...
Hey, us biologists invented most of the statistics that the rest of everybody uses! Pearson and Fisher and Spearmen and Kendall and Mr so-called Student and the rest of them weren't physicists!
Biologists sensu latoanyway.
quote:
Originally posted by OliviaG:
...and now there's bioinformatics
What I have an MSc in ![[Biased]](wink.gif)
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Ken
L’amor che move il sole e l’altre stelle.
Posts: 39579 | From: London | Registered: Mar 2002
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Ramarius
Shipmate
# 16551
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Posted
@ken. Thanks for the info above. As you may know from previous discussions on cosmology I'm fascinated by mind-boggling numbers...
The issues Lenski's experiment raises are different though. You can have as much variation in the system as you like - the question is what it takes to enable those variations to combine to bring about beneficial adaptations. Two points on that. The first (and repeating what I said above) to get the e-Coli to a place where it could digest citrate, necessitated that specific conditions prevail, and continue to prevail over an extended period of time. The implication of that is the more variables you introduce, the less likely you are to get a beneficial adaptation since there's more that can go wrong.
The second point reinforces that, since along with beneficial there were also a significant number (may turn out to be as many as half) mutations that were degretative - they eliminate a gene or its protein function.
Put that together and the evidence from this experiment is it's incredibly difficult to create the conditions for a beneficial adaptation on the basis of our current understanding of the evolutionary process.
And just to add to that, on the basis of Lenski's results to date, there's no indication that these changes are on the way to building a new *complex* system.
Obviously the whole science of evolution won't be re-written on the basis of this experiment, but it's throwing up challenges to our understanding of evolutionary theory to which we need to give proper consideration.
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Crœsos
Shipmate
# 238
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Posted
quote:
Originally posted by Ramarius:
So after over 20years of selective pressure over some 360,000 generations ( 12 x 30,000) has produced a minor novel trait. The experiment shows a change at micro level only (no macro evolutionary changes) and is hardly representative of a natural environment (no dead cells to scavenge, no contaminant, no other bacteria involved).
First off, how do you distinguish between "micro" and "macro" when dealing with organisms that are themselves microscopic? Bacteria don't really have a "macro" level. Similarly, what's the threshold for a "major" novel trait? Membrane permeability is a pretty major function as far as bacteria are concerned. And why do you ignore the several other novel traits that are indisputably minor (e.g. greater cell volume, optimized glucose metabolism)?
quote:
Originally posted by Ramarius:
Hardly surprising that both Conway Morris and Behe cite the results to support their own divergent views on evolution.
Behe's response demonstrates about equal parts chutzpah and avoidance given that Lenski's work demonstrates that one of the cornerstones of Behe's position is incorrect. Here's the relevant section:
quote:
One of the major points of [my] book [The Edge of Evolution] was that if only one mutation is needed to confer some ability, then Darwinian evolution has little problem finding it. But if more than one is needed, the probability of getting all the right ones grows exponentially worse. "If two mutations have to occur before there is a net beneficial effect -- if an intermediate state is harmful, or less fit than the starting state -- then there is already a big evolutionary problem." And what if more than two are needed? The task quickly gets out of reach of random mutation.
Lenski's work pretty clearly shows that the development of Cit+ is the result of at least two separate mutations, which is why the Ara-3 ancestral line can only re-evolve it using samples taken from generation 20,000 or later. There was some mutation there that didn't grant Cit+, but which was a necessary its development 10,000 generations later. In short, random mutation can do exactly what Behe claims it can't do.
quote:
Originally posted by Ramarius:
Basically we get the results we get because an intelligent agent created specific conditions and ensured they were maintained without contamination (no random influences allowed to interfere) until certain results pertained.
Yeah, it's what most scientists call "controlling outside variables". It's usually considered a strength, not a flaw. The whole point of the Lenski experiment was to see if random mutation working with selective pressure is sufficient to evolve new traits. As such great care was taken to eliminate outside sources of genetic material, going as far as making sure to use E. coli strains that don't engage in bacterial conjugation. And I'm not sure that the distinction between a man-made selective regime and a naturally occurring one. Do you have any evidence that bacteria change their mutation rates when they know scientists are watching?
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Humani nil a me alienum puto
Posts: 10706 | From: Sardis, Lydia | Registered: May 2001
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ken
Ship's Roundhead
# 2460
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Posted
What Croesos just said.
And also:
quote:
Originally posted by Ramarius:
The implication of that is the more variables you introduce, the less likely you are to get a beneficial adaptation since there's more that can go wrong.
This misses the point entirely. Natural selection isn't aiming for a particular beneficial adapation. It is selecting for adaptations that happen to work well enough to get along in the particular situation a population of organisms happens to be in.
So the more variation there is the more likely it is that something, or some combination of things, will happen to work. Overwhelmingly so. There is a combinatorial explosion.
quote:
The second point reinforces that, since along with beneficial there were also a significant number (may turn out to be as many as half) mutations that were degretative - they eliminate a gene or its protein function.
So? Why is that relevant? I'd be surprised if it was anywhere near as few as half to be honest - the odds are more likely hundreds to one. But so what?
quote:
Put that together and the evidence from this experiment is it's incredibly difficult to create the conditions for a beneficial adaptation on the basis of our current understanding of the evolutionary process.
The other way round. The evidence is that successful adaptations are incredibly likely. Just look at the numbers.
Are you making the golf-ball and blade of grass mistake?
A golfer hits a ball. It lands on a blade of grass. Just one blade of grass out of millions? What was the chance of that? It must have been very well aimed!
Natural selection - at least for bacteria - is the equivalent of trillions of golfers shooting trillions of balls at more blades of grass than there are stars in the universe. And as long as one hits, it works.
quote:
And just to add to that, on the basis of Lenski's results to date, there's no indication that these changes are on the way to building a new *complex* system.
And why would you expect to see that after only twenty years?
Think of the scale again. There are some thousands of major metabolic pathways. They probably took two billion years for bacteria to evolve them. (As I said before there are a handful that evolved in plants or animals but most come from bacteria) The whole world is, as I said, vastly bigger than the experiment. So if the experiment was capable of evolving new metabolic machinery at the same rate as real life (& it won't be because its so much simpler) how likely is it that you would see one in a mere twenty years?
quote:
Obviously the whole science of evolution won't be re-written on the basis of this experiment, but it's throwing up challenges to our understanding of evolutionary theory to which we need to give proper consideration.
It makes the kind of evolution we see in the world around us seem even easier and more likely than we used to think it was.
Think of the scale!
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Ken
L’amor che move il sole e l’altre stelle.
Posts: 39579 | From: London | Registered: Mar 2002
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Ramarius
Shipmate
# 16551
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Posted
@Croeses. The difference between micro and macro evolution is noghing to do witn size. Micro evolution refers to changes signin existing structures. This is what Darwin observed, and what Lenski is observing. Macro evolution refers to large-scale innovation, the coming into existence of new organs, structures, body-plans, of qualitatively new genetic material; for example, the evolution of multicellular from single cell structures - it thus involves a marked increase in complexity.
You've misunderstood Behe's point on multiple adaptions but I'll come back to that since it raises a wider issue. Your last point completely misunderstands the issue. It's precisely because it's a controlled environment with variables removed that makes Lenski's experiments unlike nature. You simply wouldn't get this very precise environment in a natural context. It's not that the bacteria are behaving differently because someone is watching, more that without the scientists they would never get the chance to have fun in this playground in the first place.
Posts: 950 | From: Virtually anywhere | Registered: Jul 2011
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Ramarius
Shipmate
# 16551
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Posted
quote:
Originally posted by Ramarius:
@Croeses. The difference between micro and macro evolution is noghing to do with size. Micro evolution refers to changes within existing structures. This is what Darwin observed, and what Lenski is observing. Macro evolution refers to large-scale innovation, the coming into existence of new organs, structures, body-plans, of qualitatively new genetic material; for example, the evolution of multicellular from single cell structures - it thus involves a marked increase in complexity.
You've misunderstood Behe's point on multiple adaptions but I'll come back to that since it raises a wider issue. Your last point completely misunderstands the issue. It's precisely because it's a controlled environment with variables removed that makes Lenski's experiments unlike nature. You simply wouldn't get this very precise environment in a natural context. It's not that the bacteria are behaving differently because someone is watching, more that without the scientists they would never get the chance to have fun in this playground in the first place.
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Posts: 950 | From: Virtually anywhere | Registered: Jul 2011
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Rex Monday
None but a blockhead
# 2569
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Posted
quote:
Micro evolution refers to changes within existing structures. This is what Darwin observed, and what Lenski is observing. Macro evolution refers to large-scale innovation, the coming into existence of new organs, structures, body-plans, of qualitatively new genetic material; for example, the evolution of multicellular from single cell structures - it thus involves a marked increase in complexity.
I don't think this makes sense. 'Large scale innovation' in biology is always a collection of small changes. Do you have a specific example in mind of a large-scale change that couldn't be the result of incremental smaller ones? (it may save everyone some time, if you're tempted to use something from Behe, if you google for the rebuttals first.)
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I am largely against organised religion, which is why I am so fond of the C of E.
Posts: 514 | From: Gin Lane | Registered: Mar 2002
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Ramarius
Shipmate
# 16551
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Posted
quote:
Originally posted by Rex Monday:
quote:
Micro evolution refers to changes within existing structures. This is what Darwin observed, and what Lenski is observing. Macro evolution refers to large-scale innovation, the coming into existence of new organs, structures, body-plans, of qualitatively new genetic material; for example, the evolution of multicellular from single cell structures - it thus involves a marked increase in complexity.
I don't think this makes sense. 'Large scale innovation' in biology is always a collection of small changes. Do you have a specific example in mind of a large-scale change that couldn't be the result of incremental smaller ones? (it may save everyone some time, if you're tempted to use something from Behe, if you google for the rebuttals first.)
It's a standard
definition. The idea that macroevolution is the result of multiple small steps is the Neo-Darwinian view, but there are others. See the article, particularly the views of Gould and others who suggest that you don't need a continuous succession of small steps to get a macroevolutionary change.
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Louise
Shipmate
# 30
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Posted
Hi Ramarius,
You do realise what source you're linking to for your definition?
quote:
This encyclopedia transcends the metaphysical assumptions of both the Enlightenment and Modern Encyclopedias. The originator of this project is Sun Myung Moon. Thus, scholarly content carries and projects values tied to human purpose, the design of creation found in the world's great religions and spiritual traditions, as well as that which is clearly revealed through science and in the lives and work of people of conscience.
I would be wary of using a Unification Church-sponsored encyclopaedia, which seems from its blurb to assume intelligent design as a starting point, for discussion of anything connected to evolutionary science.
It pays to read the small print on these things!
cheers,
Louise
[ 01. April 2012, 14:26: Message edited by: Louise ]
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Now you need never click a Daily Mail link again! Kittenblock replaces Mail links with calming pics of tea and kittens! http://www.teaandkittens.co.uk/ Click under 'other stuff' to find it.
Posts: 6918 | From: Scotland | Registered: May 2001
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Rex Monday
None but a blockhead
# 2569
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Posted
quote:
It's a standard definition
It's not a scientific definition, though.
Do you have an example in mind?
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I am largely against organised religion, which is why I am so fond of the C of E.
Posts: 514 | From: Gin Lane | Registered: Mar 2002
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Ramarius
Shipmate
# 16551
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Posted
quote:
Originally posted by Louise:
Hi Ramarius,
You do realise what source you're linking to for your definition?
quote:
This encyclopedia transcends the metaphysical assumptions of both the Enlightenment and Modern Encyclopedias. The originator of this project is Sun Myung Moon. Thus, scholarly content carries and projects values tied to human purpose, the design of creation found in the world's great religions and spiritual traditions, as well as that which is clearly revealed through science and in the lives and work of people of conscience.
I would be wary of using a Unification Church-sponsored encyclopaedia, which seems from its blurb to assume intelligent design as a starting point, for discussion of anything connected to evolutionary science.
It pays to read the small print on these things!
cheers,
Louise
Well I'm not prejudiced as to sources - it was written clearly enough and didn't appear to show any particular bias. If you want a more formal expression of the definition, you can always go here
Posts: 950 | From: Virtually anywhere | Registered: Jul 2011
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Net Spinster
Shipmate
# 16058
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Posted
quote:
Originally posted by Ramarius:
Well I'm not prejudiced as to sources - it was written clearly enough and didn't appear to show any particular bias. If you want a more formal expression of the definition, you can always go here
And that is a source that can be edited by anyone. However talk.origins does have an extended discussion of the terms.
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spinner of webs
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Ramarius
Shipmate
# 16551
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Posted
quote:
Originally posted by Net Spinster:
quote:
Originally posted by Ramarius:
Well I'm not prejudiced as to sources - it was written clearly enough and didn't appear to show any particular bias. If you want a more formal expression of the definition, you can always go here
And that is a source that can be edited by anyone. However talk.origins does have an extended discussion of the terms.
Very helpful link NS
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Dafyd
Shipmate
# 5549
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Posted
quote:
Originally posted by Ramarius:
See the article, particularly the views of Gould and others who suggest that you don't need a continuous succession of small steps to get a macroevolutionary change.
AIUI the article is misrepresenting Gould in that case. Gould does believe that in general you need a continuous succession of small steps. He just thinks that under the right circumstances you can get a lot of small steps cropping up in a short(*) timescale.
(*) For an appropriate value of short. In this context, short is over tens of thousands of years.
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we remain, thanks to original sin, much in love with talking about, rather than with, one another. Rowan Williams
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Louise
Shipmate
# 30
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Posted
quote:
it was written clearly enough and didn't appear to show any particular bias.
Unless you're an expert, you've no way of telling whether a source which states that it has an agenda like that is giving a full or accurate picture or not. If you are an expert, then surely you can do better in terms of linking to sources in good standing in your field?
L.
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Now you need never click a Daily Mail link again! Kittenblock replaces Mail links with calming pics of tea and kittens! http://www.teaandkittens.co.uk/ Click under 'other stuff' to find it.
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Dafyd
Shipmate
# 5549
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Posted
quote:
Originally posted by Ramarius:
The difference between micro and macro evolution is noghing to do witn size. Micro evolution refers to changes signin existing structures. This is what Darwin observed, and what Lenski is observing. Macro evolution refers to large-scale innovation, the coming into existence of new organs, structures, body-plans, of qualitatively new genetic material; for example, the evolution of multicellular from single cell structures - it thus involves a marked increase in complexity.
You're assuming the development of the ability to metabolise a new compound is qualitatively less complex than growing a new organ. I'm not at all sure that's true.
Organs like a heart or lungs seem to me fairly simple to develop from pre-existing structures. On the other hand, evolving the ability to metabolise a new compound without interfering with any of the other metabolic pathways that happen within the cell seems to me rather difficult. It's a bit like moving one square on an especially fiendish Rubik's cube without ever getting any side less than half full of one colour.
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we remain, thanks to original sin, much in love with talking about, rather than with, one another. Rowan Williams
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Ramarius
Shipmate
# 16551
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Posted
quote:
Originally posted by Dafyd:
quote:
Originally posted by Ramarius:
See the article, particularly the views of Gould and others who suggest that you don't need a continuous succession of small steps to get a macroevolutionary change.
AIUI the article is misrepresenting Gould in that case. Gould does believe that in general you need a continuous succession of small steps. He just thinks that under the right circumstances you can get a lot of small steps cropping up in a short(*) timescale.
(*) For an appropriate value of short. In this context, short is over tens of thousands of years.
I'm still trying to make sense of all this Dafyd . Do you have a reference where I can see what Gould has to say for himself? I'm struggling to find somewhere that discusses these issues by accurately representing alternate views without a polemic overlay (other than relying on the good offices of shipmates who will also have other interests.
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Ramarius
Shipmate
# 16551
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Posted
quote:
Originally posted by Louise:
quote:
it was written clearly enough and didn't appear to show any particular bias.
Unless you're an expert, you've no way of telling whether a source which states that it has an agenda like that is giving a full or accurate picture or not. If you are an expert, then surely you can do better in terms of linking to sources in good standing in your field?
L.
Fair comment Louise. Part of what I'm hoping to get from this discussion is an idea of where, as a non-expert, I can find info that is both authoritative and comprehensible. Part of the problem with the micro/macro definitions is the inconsistent way they are used by scientists ![[Frown]](frown.gif) . So how about the following definition from the following source:
''Macroevolution is at least evolution at or above the level of speciation, but it remains an open debate among scientists whether or not it is solely the end product of microevolutionary processes or there is some other set of processes that causes higher level trends and patterns."
http://www.talkorigins.org/faqs/macroevolution.html
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Palimpsest
Shipmate
# 16772
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Posted
quote:
Originally posted by Ramarius:
[I'm still trying to make sense of all this Dafyd . Do you have a reference where I can see what Gould has to say for himself? I'm struggling to find somewhere that discusses these issues by accurately representing alternate views without a polemic overlay (other than relying on the good offices of shipmates who will also have other interests.
A chaoter of his major last writing on evolution that deals with Puncuated Equilibrium has been published as a separate book.
Punctuated Equilibrium
One review says it's fairly opaque
to the layman but includes a useful appendix.
quote:
But all is not lost. Gould includes a 63-page Appendix that is very readable by the layman. The Appendix deals with the controversies aroused by punctuated equilibrium in the broader media and academic communities outside palaeontology. The "hijacking" of punctuated equilibrium by creationists to debunk Darwin is well-covered and very interesting. Thankfully, Gould explains where creationist views are ignorant, wrong or dishonest - often all three.
I haven't read it but it is probably an accurate summary of what he was saying.
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ken
Ship's Roundhead
# 2460
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Posted
quote:
Originally posted by Ramarius:
Do you have a reference where I can see what Gould has to say for himself?
The obvious place is Gould's big book, The Structure of Evolutionary Theory. I have a copy. Its interesting, and like most of Gould's books its well-written if a bit anecdotal and rambling at times (makes a nice change from some over-formal science writing) Its huge, and expensive, and I'd be lying if I said it was an easy read, or that I've read and fully understood every point in it. I am, however, reasonably confident in saying that it doesn't challenge, and wasn't intended to challenge, the broad consensus of neo-Darwinian synthesis. Its a critique of many details of the consensus, and an attempt to promote a new view of it, but the basic ideas are the same.
Academic arguments are often expressed in surprisingly strong language. And polemical books - and this is a polemical book - are likely to focus on the points of disagreement rather than the landscape of agreement. Just as with group selection and cladism and the "selfish gene" this is not something that YECcies and IDiots can take much support from.
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Ken
L’amor che move il sole e l’altre stelle.
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mousethief
Ship's Thieving Rodent
# 953
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Posted
quote:
Originally posted by Crœsos:
quote:
Originally posted by mousethief:
Can one of you help me? I'm having (don't ask why) something of a debate with a creationist over on Facepalm, and he made the statement that "scientists are abandoning evolution and big bang cosmology in droves." What on earth is he talking about? Is this some new wrinkle in the creationist bullshit? Some article that some absurd creationist journal published? Where does this come from?
Actually it's very old creationist bullshit. I can't say what's kicked off the recent spate of "evolution is on its last legs" that you've come across, but creationists have been predicting the imminent collapse of Darwinian evolution (and before that, geology) for literally centuries now.
Any . . . minute . . . now!
When I asked for a credible source that said scientists were abandoning evolution in droves, and mentioned in passing that I doubted very much that Scientific American would miss such an exodus (he had said all the science mags were about 10 years behind the times), I was greeted with silence. Oh well. Not somebody I even know anyway.
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This is the last sig I'll ever write for you...
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Soror Magna
Shipmate
# 9881
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Posted
Ramarius' latest posts have reminded me of the need to have some understanding of basic scientific concepts underlying physics, chemistry, biology, etc. in order to discuss these topics properly. It doesn't matter so much with evolution, but there are lots of other important scientific isssues that have more direct impact e.g. it has become apparent that quite a few people have no clue how birth control pills work. ![[Eek!]](eek.gif) It would be nice if people were making choices based on something more than book reviews, second-hand analyses, letters to the editor, websites selling supplements and all the other less-than-reliable sources out there. A high-school or undergraduate text can provide the basics. Furthermore, there are lots of issues where the "alternate" view is simply horseshit, and no, the issue is not accurately represented by presenting both points of view. Fire, air, earth and water are not a credible alternate view of the periodic table. OliviaG
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"You come with me to room 1013 over at the hospital, I'll show you America. Terminal, crazy and mean." -- Tony Kushner, "Angels in America"
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Ramarius
Shipmate
# 16551
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Posted
quote:
Originally posted by ken:
quote:
Originally posted by Ramarius:
Do you have a reference where I can see what Gould has to say for himself?
The obvious place is Gould's big book, The Structure of Evolutionary Theory. I have a copy. Its interesting, and like most of Gould's books its well-written if a bit anecdotal and rambling at times (makes a nice change from some over-formal science writing) Its huge, and expensive, and I'd be lying if I said it was an easy read, or that I've read and fully understood every point in it. I am, however, reasonably confident in saying that it doesn't challenge, and wasn't intended to challenge, the broad consensus of neo-Darwinian synthesis. Its a critique of many details of the consensus, and an attempt to promote a new view of it, but the basic ideas are the same.
Thanks for this Ken. I had a look on Amazon - goes beyond my current book budget
I'll work with Dafyd's definition for the time being and question the source for anyone who tries to tell me different.
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Rex Monday
None but a blockhead
# 2569
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Posted
quote:
Originally posted by OliviaG:
Ramarius' latest posts have reminded me of the need to have some understanding of basic scientific concepts underlying physics, chemistry, biology, etc. in order to discuss these topics properly...
It is frustrating when you get those who say "I know the science of X is wrong" and then follow it up with an admission that they don't understand what that science is saying - worse yet, that they don't want to understand it. I've never worked out how to make any progress in those kinds of discussions.
(whether any's made in any other kind of discussion is perhaps moot...)
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I am largely against organised religion, which is why I am so fond of the C of E.
Posts: 514 | From: Gin Lane | Registered: Mar 2002
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Crœsos
Shipmate
# 238
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Posted
quote:
Originally posted by Ramarius:
@Croeses. The difference between micro and macro evolution is noghing to do witn size. Micro evolution refers to changes signin existing structures. This is what Darwin observed, and what Lenski is observing. Macro evolution refers to large-scale innovation, the coming into existence of new organs, structures, body-plans, of qualitatively new genetic material; for example, the evolution of multicellular from single cell structures - it thus involves a marked increase in complexity.
Once again, single-celled organisms don't have "organs" or "body plans" in the ordinary sense. At any rate, it could be argued that membrane permeability is bacterial biology and that the Cit+ trait is somewhat akin to developing a wing out of an ordinary limb. Under your definition that would also count as "micro-evolution" I guess, since it doesn't involve a new organ, just the adaptation of an existing one.
quote:
Originally posted by Ramarius:
You've misunderstood Behe's point on multiple adaptions but I'll come back to that since it raises a wider issue. Your last point completely misunderstands the issue. It's precisely because it's a controlled environment with variables removed that makes Lenski's experiments unlike nature. You simply wouldn't get this very precise environment in a natural context. It's not that the bacteria are behaving differently because someone is watching, more that without the scientists they would never get the chance to have fun in this playground in the first place.
I've got to call "bullshit" on this one. There are plenty of other examples of such adaptations occurring outside controlled laboratory conditions, including cases where the resulting adaptation was both unintentional and undesired. There's no consistent reason in this context to distinguish between an artificially-produced selective environment and a naturally occuring one. The only difference in the lab is the ability to exclude extraneous factors.
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Humani nil a me alienum puto
Posts: 10706 | From: Sardis, Lydia | Registered: May 2001
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Justinian
Shipmate
# 5357
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Posted
quote:
Originally posted by Ramarius:
You've misunderstood Behe's point on multiple adaptions but I'll come back to that since it raises a wider issue.
At this point introducing you to your source would be a good idea. Michael Behe has admitted under oath (at Kitzmiller vs Dover Area School District) that "there are no peer reviewed articles by anyone advocating for intelligent design supported by pertinent experiments or calculations which provide detailed rigorous accounts of how intelligent design of any biological system occurred". In order to class Intelligent Design as science he needed to redefine science such that Astrology is classed as a science.
And claiming that your book has been peer reviewed when you have to admit under oath that it hasn't isn't the act of an honest man.
(As for Behe on maths, his own maths make multiple mutations inevitable).
quote:
Your last point completely misunderstands the issue. It's precisely because it's a controlled environment with variables removed that makes Lenski's experiments unlike nature. You simply wouldn't get this very precise environment in a natural context. It's not that the bacteria are behaving differently because someone is watching, more that without the scientists they would never get the chance to have fun in this playground in the first place.
Except as Creosus has pointed out, we've seen such happen in nature. He pointed out two - MRSA and nylon eating bacteria. The real world is a huge playground and there are far more niches to occupy when conditions are uncontrolled.
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My real name consists of just four letters, but in billions of combinations.
Eudaimonaic Laughter - my blog.
Posts: 3926 | From: The Sea Coast of Bohemia | Registered: Dec 2003
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ken
Ship's Roundhead
# 2460
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Posted
quote:
Originally posted by Crœsos:
Once again, single-celled organisms don't have "organs" or "body plans" in the ordinary sense.
Well, bacteria don't. There are plenty of single-celled eukaryotes that have quite complex body plans. But your point is of course correct and important.
quote:
At any rate, it could be argued that membrane permeability is bacterial biology and that the Cit+ trait is somewhat akin to developing a wing out of an ordinary limb. Under your definition that would also count as "micro-evolution" I guess, since it doesn't involve a new organ, just the adaptation of an existing one.
Not even as big as that. Just a small change. But the real point is surely that the population of bacteria is so large, and so varied, and has been around for so much time, that its more or less inevitable that loads of small changes accumulate to make large changes. As large as you want.
There is no real distinction between "micro" and "macro" evolution for bacteria. One is just the other repeated a lot.
quote:
Originally posted by Justinian:
The real world is a huge playground and there are far more niches to occupy when conditions are uncontrolled.
Yep. Exactly!
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Ken
L’amor che move il sole e l’altre stelle.
Posts: 39579 | From: London | Registered: Mar 2002
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Ramarius
Shipmate
# 16551
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Posted
I think we might be talking to crossed purposes here. Just to be clear, I'm not an ID advocate - I haven't looked into ID (although there's an interesting discussion on it upthread).
The question I'm puzzling over with respect to adaptations is the degree of difficulty that needs to be overcome for an adaptation to occur. In our current bio system there are a massive number if factors that can contribute to stimulate adaptations. Ken gave the figures upthread
A scientific experiment replicates a much simpler environment in which fewer factors can come into play, and the scientist can decide which ones he wants to introduce and exclude. So my point on that is that it's a misnomer to describe Lenski's work as evolution re-run. Clearly it's not. Let's learn what we can from it without over-egging its significance.
What I've found helpful in the discussion is getting clearer on how Gould resolved his problems in understanding the fossil record (that's much clearer thanks especially to Daffyd) and the fascinating question raised by Conway Morris as to whether there are (in effect) a limited range of adaptations that can occur irrespective of the number of potential factors available.
I'll do a bit more research and come back with some more questions. Basically, there's a range of issues being discussed in evolutionary biology and I'm trying to make sense of them. So unlike in Purg (where I generally have a view to defend) this forray into Dead Horse territory is purely exploratory.
[ 11. April 2012, 20:20: Message edited by: Ramarius ]
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Posts: 950 | From: Virtually anywhere | Registered: Jul 2011
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Alan Cresswell
Mad Scientist 先生
# 31
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Posted
quote:
Originally posted by Ramarius:
A scientific experiment replicates a much simpler environment in which fewer factors can come into play, and the scientist can decide which ones he wants to introduce and exclude. So my point on that is that it's a misnomer to describe Lenski's work as evolution re-run. Clearly it's not. Let's learn what we can from it without over-egging its significance.
You are right in that the experiment doesn't re-run Evolution. It re-runs evolutionary pathways within tightly controlled conditions. That sort of model is the bread and butter of science. It gives this physicist hope that biologists might be scientists after all. Scientists design experiments and models to learn as much as possible about systems.
Whether or not it's possible to properly understand a complex system such as an ecosystem by systematically investigating components in semi-isolation is an interesting philosophical question. My feeling is it's possible to gain understanding, but if you only think of the system at the level of individual components you fail to understand properly - you fail to see the wood for the trees; we need to understand both the trees and the entire wood (which includes a whole lot more than just trees).
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Don't cling to a mistake just because you spent a lot of time making it.
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Louise
Shipmate
# 30
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Posted
Bump.There's a very detailed discussion on the evolution of the eye which kicks off towards the foot of p.9. Here
[ 23. September 2012, 03:36: Message edited by: Louise ]
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Now you need never click a Daily Mail link again! Kittenblock replaces Mail links with calming pics of tea and kittens! http://www.teaandkittens.co.uk/ Click under 'other stuff' to find it.
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Hawk
Semi-social raptor
# 14289
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Posted
On the Non-Right-Wing Creationism thread, there was a conversational tangent about the irreducability of the eye which I was about to reply to when I noticed the hosts were ordering it to be redirected here. In case Mark Betts wants to continue the conversation on this thread, here is my reply:
quote:
Originally posted by Mark Betts:
quote:
Originally posted by Curiosity killed ...:
To be helpful, here's a preview article from Scientific American explaining how scientists have been working on evolution of the eye and why it's a problem. They have been using embryo research across a range of species and DNA studies.
quote:
From the article:
The results indicate that our kind of eye—the type common across vertebrates—took shape in less than 100 million years, evolving from a simple light sensor for circadian (daily) and seasonal rhythms around 600 million years ago to an optically and neurologically sophisticated organ by 500 million years ago.
Can you really not see it? "This evolved from that, then something else evolved..."
Do you really believe that this finally "puts the nail in the coffin" of the irreducable complexity argument? It doesn't even touch on irreducable complexity!
So far you have been shown summaries of the theory of eye evolution, since the usual first argument that Creationists use is that it is theoretically impossible that the eye could have evolved, even if the theory of evolution was correct, since the theory cannot explain the irreducible complexity of the eye. The counter-argument scientists use is to prove that theoretically, it is perfectly possible for the eye to evolve, and explain the steps that woud be necessary for this.
Yet this isn't enough for some creationists, they then change the goalposts to say that, okay the theory explains how an eye could have evolved, but you haven't proved that it did evolve. And therefore the explanation is just speculation (or faith) and thus quot et demonstrandum and nee-na nee-na (with appropriate gestures).
So, here is one article arguing the case for the evidence that supports the theory of eye evolution. And here is a longer (but still quite brief) scientific summary of the larger quantity of evidence doing the same.
From the second article:
quote:
...all the observations are entirely consistent with predictions of [Darwin's] theory, as well as the computer modeling predictions indicating evolution of an eye by small increments in less than one million years. Rather than “intelligent design,” the structure of the oldest preserved fossil evidence for the vertebrate eye and brain shows the legacy of an ancestral segmented animal in the derivation and arrangement of nerves and muscles controlling eye movement, subdivision of the braincase, and other features. Despite the complexity, the organisation of the brain and eye ... illustrated here demonstrate a unique morphology, intermediate between living jawless and jawed vertebrates...Like ... many other vertebrate fossils elucidated since Darwin’s time, these are examples of the transitional forms that he predicted — they show combinations of characters that have never been observed together in living species.
Now I admit, this isn't a real-time youtube video documenting the millions of years of evolution directly. So it won't convince you at all. But you have to admit, it's certainly more than just someone saying, 'this happened, then this happened'. This is someone saying, 'the evidence shows us that at Time A this was happening, then at Time B it had changed to this, and at Time C, it had further changed to this. Therefore this matches the predictions our theory made that the eye at Time A changed over generations into the eye at Time C'.
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“We are to find God in what we know, not in what we don't know." Dietrich Bonhoeffer
See my blog for 'interesting' thoughts
Posts: 1739 | From: Oxford, UK | Registered: Nov 2008
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Crœsos
Shipmate
# 238
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Posted
quote:
Originally posted by Hawk:
So far you have been shown summaries of the theory of eye evolution, since the usual first argument that Creationists use is that it is theoretically impossible that the eye could have evolved, even if the theory of evolution was correct, since the theory cannot explain the irreducible complexity of the eye. The counter-argument scientists use is to prove that theoretically, it is perfectly possible for the eye to evolve, and explain the steps that woud be necessary for this.
And, of course, it's important to note that while it is complicated, the human eye is not irreducibly complex.
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Humani nil a me alienum puto
Posts: 10706 | From: Sardis, Lydia | Registered: May 2001
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Alan Cresswell
Mad Scientist 先生
# 31
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Posted
quote:
Originally posted by Crœsos:
quote:
Originally posted by Hawk:
So far you have been shown summaries of the theory of eye evolution, since the usual first argument that Creationists use is that it is theoretically impossible that the eye could have evolved, even if the theory of evolution was correct, since the theory cannot explain the irreducible complexity of the eye. The counter-argument scientists use is to prove that theoretically, it is perfectly possible for the eye to evolve, and explain the steps that woud be necessary for this.
And, of course, it's important to note that while it is complicated, the human eye is not irreducibly complex.
I would add that there are an awful lot of things that are complicated. But, none of them, not one little thing, has been shown to be irreducibly complex. Plenty of things ID proponents have proposed as irreducibly complex, of course, but none that have stood up to someone with a wee bit of knowledge in the field coming along and showing how that mechanism could have arisen from several other mechanisms wiithout out the need for an external agency poking around.
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Don't cling to a mistake just because you spent a lot of time making it.
Posts: 32413 | From: East Kilbride (Scotland) or 福島 | Registered: May 2001
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lilBuddha
Shipmate
# 14333
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Posted
quote:
Originally posted by Alan Cresswell:
but none that have stood up to someone with a wee bit of knowledge in the field
But this is the problem then, yeah? All the combined knowledge of the ages cannot match the power of willful ignorance.
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I put on my rockin' shoes in the morning
Hallellou, hallellou
Posts: 17627 | From: the round earth's imagined corners | Registered: Dec 2008
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Rex Monday
None but a blockhead
# 2569
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Posted
Speaking as someone who's recently lost a lot of my eyesight because of a fundamental design flaw in the eye - the optic nerve connects to the front of the retina, rather than the back - I'm unimpressed by anyone holding the system up as an example of something that had to have been designed.
Whoever did it was either unaware of the octopus eye, which has the optic nerve connection behind the retina, or knocked it off as version 2.0.
R
(The problem is: the optic nerve has to come through a hole in the back of the eye and through the retina. If that hole is too small, as mine is, the blood supply in the optic nerve can get cut off and bad things happen.)
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I am largely against organised religion, which is why I am so fond of the C of E.
Posts: 514 | From: Gin Lane | Registered: Mar 2002
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Penny S
Shipmate
# 14768
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Posted
And I have to look forward to macular degeneration in the right eye and cataract in the left. It's not a very well designed tool, the eye, is it?
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Jamat
Shipmate
# 11621
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Posted
quote:
Originally posted by Penny S:
And I have to look forward to macular degeneration in the right eye and cataract in the left. It's not a very well designed tool, the eye, is it?
Yes I wear glasses too. The problem is sin. Sin corrupts health, weakens the gene pool,causes aging. Design on the other hand withstands it rather well. I wear glasses but I can still see. How clever of Evolution to not design our bodies so as to appear it did.
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Brenda Clough
Shipmate
# 18061
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Posted
Gosh, we could start our own thread. I too have macular degeneration and loss of sight in my left eye. My retinologist was able to save most (but not all) of the sight in that eye with intraocular injections. These were fully as fearful as you are imagining.
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Science fiction and fantasy writer with a Patreon page
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