Reflectorites
On Thu, 16 Mar 2000 17:07:08 -0000, Richard Wein wrote:
[continued]
[...]
>>RW>With regard to your specific question about the creative power of random
>>>mutation and natural selection, the most impressive demonstration of this
>>>that I've seen is Nilsson and Pelger's computer simulation of the
>>evolution of an eye.
>SJ>...But there is however an immediately problem. If random mutation and
>>*positive* natural selection is as pervasive in nature as it would have to
>>be if Neo-Darwinism is true, why is there a need to rely for one's best
>>evidence of it on a computer *simulation*? Why not just go out and
>>document it directly from nature?
RW>I think that's rather obvious. Evolution in nature of a major structure like
>the eye takes hundreds of thousands of years.
I did not say that Richard had to watch it happen! If the eye evolved by
step-by-step random mutation and natural selection, as Nilsson & Pelger's
simulation purports to show, then it should easily be able to be documented
in nature. Where is that documentation in the *real* world?
>SJ>There are a number of other problems with the biological realism of
>>Nilsson and Pelger's eye simulation, in their paper (Nilsson D.E. & Pelger
>>S., "A pessimistic estimate of the time required for an eye to evolve",
>>Proceedings of the Royal Society B, 1994, v.256, pp.53-58) which I may
>>deal with in a future post, time permitting. But the major problem that is
>>immediately evident is that it is a self-evident truism and therefore
>>scientifically uninteresting.
RW>I assume the "self-evident truism" that you're referring is the fact that
>complex structures can be created by an algorithmic process of random
>variation and cumulative undirected selection.
No. I was referring to the fact that to reverse engineer the eye unto
1829 steps, as Nilsson D.E. & Pelger did, and then to run it through a
computer algorithm which re-assembled those 1829 steps back into the eye
again, is "a self-evident truism and therefore scientifically
uninteresting".
The problem is that all these computer simulations of what purports to
be evolution by random mutation and natural selection are *designed*
unrealistically to *never fail*:
"Yet the simulation not only succeeds in accomplishing its task, but it
does so very rapidly and consistently It never fails, NEVER. The
computer simulations use many unrealistic assumptions that favor
evolution. First, the simulations assume away everything that could
prevent evolution. They do not allow extinction, which normally would
terminate all further evolution. They do not allow error catastrophe,
which normally would cause a degradation away from any target
sequence-no matter how severe the selection. They do not allow
canyons and hills in the fitness terrain, which normally would prevent
evolution. In short, they assume naive natural selection -that evolution
is upward, ever upward. Having artificially disallowed all possible
failure modes, it is not surprising the evolution simulations work.
(ReMine W.J., "The Biotic Message," 1993, p232)
If the program didn't work the first time (and no programs ever do),
the programmer would redesign the program until it did what it was
designed to do, show how random mutation and natural selection can
build complex designs easily and quickly:
"How fast will the evolution happen? Here the simulations use
additional assumptions to artificially increase the speed. Dawkins'
simulation gives many unrealistic advantages to evolution:
* The simulation disallows recessive mutations, ordinary epistasis,
polygenic and pleiotropic effects-which would normally increase
the cost of substitution and slow down evolution.
* The simulation assumes perfect selection (s=1), which is not
typical of nature. Evolutionists ordinarily acknowledge that the
typical beneficial mutation has less than a one percent advantage
(s<0.01).
* The simulation assumes extreme truncation selection, which is
not like nature.48 Nature has no means to count mutations, rank
the population by the count, and keep only the highest ranking
individual. Truncation selection gives an unrealistic advantage to
evolution by substantially lowering the cost of mutation.
* The simulation disallows any costs due to random death,
balancing selection, heterosis, or segregation.
* The simulation assumes a high probability of beneficial mutation.
It assumes that a mutation has one chance in 27 of being so
beneficial that the rest of the population is completely wiped out.
This high rate of beneficial mutation reduces the cost of harmful
mutation and increases the speed of evolution
* Dawkins did not say in his book, but his simulation must have
assumed a high reproduction rate (N=100 or higher) This is higher
than real species can produce For a sexual species to accomplish
this, the females must give at least 200 progeny each.
* Dawkins did not say, but he must have chosen the mutation rate
to optimize the speed of evolution. If he had chosen a low mutation
rate, (such as 10^-8 as in humans) then the simulation would
require roughly 50 million generations. On the other hand, if he had
chosen too high a mutation rate, then it would cause error
catastrophe and the target phrase would never be reached.
Dawkins picked the mutation rate that produced the fastest
evolution.
Dawkins' readers got the impression he casually threw the
computer simulation together and speedy evolution just happened
automatically. In reality, Dawkins carefully designed his simulation
to favor rapid evolution. One could hardly design a simple, easily
understood simulation that is faster. His computer simulation aids
the illusion that evolution is simple in concept, inevitable, and fast."
(ReMine W.J., "The Biotic Message," 1993, p.233)
RW>I think the phrase "self-evident truism" may be overstating the case, but I
>would agree that it's hardly a surprising result. Isn't it amazing, then,
>that so many anti-evolutionists refuse to accept it?
By "self-evident truism" I was referring to Nilsson & Pelger's
simulation.
And I note Richard's attempt to use words, ie. "*refuse* to accept it"
(my emphasis) to make out that those who are unconvinced that
Nilsson & Pelger's simulation is a realistic model of what happened
in the real word, are being unreasonable.
But it is not only "anti-evolutionists" who are not convinced by it.
The well-known anthropologist Jeffrey Schwartz, in his book
"Sudden Origins" does not accept it either:
"More recently, the sociobiologist and promoter of the notion of
"selfish genes," Richard Dawkins, has championed a proposal that
estimated how many generations it would take to go from having
no eye almost to having the kind of eye that vertebrates and
octopuses have.
The scenario that Dawkins embraced had been formulated by two
biologists, Dan Nilsson and Susanne Pelger. They began with their
hypothetical eye being already in a formative stage that consisted
of a patch of light-receptive cells at the skin's surface that was
sandwiched between a transparent protective layer of cells above
and a layer of darkly pigmented cells below By way of
mathematical modeling, Nilsson and Pelger calculated,
conservatively, that it would take only 400,000 generations for this
non-eye region of skin to be transformed into an organ of sight.
Even when only a 1 percent change per generation is invoked over
what is really a relatively short period of geologic time, Nilsson and
Pelger predicted that selection would be able to cause the skin to
invaginate, bringing the presumptive retinal layer down with it, and
then to fill with fluid of a very low refractive index Still no functional
eye, but then a lens begins to emerge and eventually it achieves a
refractive index sufficient to provide sight. The maximum number of
tiny steps required to go from the flat to the invaginated structure
was estimated at 1,033. It took only 529 more steps to make a lens
and put the eye into its final, semi-flattened shape.
Absent from this simulation was consideration of the origin of the
patch of layered cells in the right place, the development of a
variable iris and controlled focusing, the creation of the nervous
optic chiasma that is the region in which the optic nerves cross
over, and the innervation of the eyeballs by the optic nerves, which
constitute one of the twelve pairs of primary nerves that emanate
from the brain itself. Curiously lacking, as well, was any discussion
by Dawkins of the selection pressure that would have set the
process in motion and of the selective advantage members of more
than 399,000 generations of their species would have enjoyed as
they served as conduits for this ever-invaginating, liquid-filled pair
of pockets in their head region. But, once the process had taken off
on this trajectory, there was, as Dawkins saw it, no turning back.
For, in his view of evolution, "[u]nlike human designers, natural
selection can't go downhill, not even if there is a tempting higher
hill on the other side of the valley." It is, however, one thing to
model how such changes might have occurred seamlessly and
gradually, and another to have a basis for doing so.
(Schwartz J.H., "Sudden Origins: Fossils, Genes, and the
Emergence of Species," John Wiley & Sons: New York NY, 1999,
pp.361-362)
RW>That the pessimistic estimate of the time required for an eye to evolve
>turned out to be fairly low (less than half a million years) is certainly
>not a self-evident truism, but an interesting discovery.
It would only be "an interesting discovery" if it faithfully modelled
biological reality. Where is the evidence from the *real* world that the
vertebrate camera eye evolved by random mutation and natural selection in
"less than half a million years"?
>SJ>That is, given that the existing vertebrate camera eye is: a) comprised of
>>three layers of cells; and b) optimal for sensing light; then it follows
>>deductively that one can, at least *in theory*, reverse engineer it on a
>>computer by breaking it down into a series of small stages such that are
>>each lower stage is slightly less optimal for light-sensing than the next
>>higher one in the series, and stopping the series when the model starts to
>>break down (ie. when one has to explain where the three layers of cells
>>came from). Then one simply re-runs the program in reverse, and hey-
>>presto, the camera eye that one started with, arises of *necessity*!
RW>What does this mean? How can you run a computer program in reverse?
I meant to run the *steps* in reverse.
>SJ>But whether this exercise in *virtual* reality bears any more than a
>>superficial resemblance to the *real* world of biology is another matter
>>entirely.
RW>True, but you only asked me for evidence of the power of random mutation and
>natural selection. That's what I gave you.
What Richard gave was a computer *simulation* of random mutation and
natural selection". No one denies that one can program a computer to
appear to *simulate* random mutation and natural selection. Dawkins had
already done this with his METHINKS IT IS LIKE A WEASEL program.
But few biologists were impressed.
What Richard needs to do is provide "evidence of the power of random mutation
and natural selection" to build the *real* vertebrate camera eye (not a grossly
oversimplified model of it), in the *real* world of biology.
>SJ>That is probably why this `evidence' has never, AFAIK, been taken up and
>>published by leading scientific journals, like NATURE and SCIENCE, but
>>has remained buried in a relatively obscure like the "Proceedings of the
>>Royal Society", and is only used by Darwinist propagandisers like
>>Dawkins.
RW>Well, I'm not familiar with the Proceedings so I don't know whether they're
>obscure, but I rather doubt it. And I assume that articles in it are
>peer-reviewed (correct me if I'm wrong).The Royal Society is a prestigious
>organization, our nearest equivalent to your National Academy of Sciences.
>If a paper has already been published there, why should some other journal
>republish it?
I am interested that Richard regards this simulation by Nilsson and Pelger
as his best "evidence of the power of random mutation and natural
selection" yet he has apparently not even read the article?
And if Nilsson and Pelger's simulation was among the best evidence for
the creative power of random mutation and natural selection, one would
expect that at least one of the leading journals like SCIENCE or
NATURE (or even a lesser one like New Scientist or Scientific
American) would have republished it. That does not seem to have
been the case?
[continued]
Steve
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"There are a number of problems with hypothetical schemes capable of
producing rapid, large, coherent changes in phenotypes. Equally large
immediate changes in the genotype might be needed, and any large change
in genotype or phenotype must surely be sufficiently disruptive to be lethal.
And where would a large change in a phenotype or genotype come from?
Moreover, suppose an oddity were to be produced, how would a
population be established and maintained?" (Thomson K.S., "The Meanings
of Evolution," American Scientist, Vol. 70, September-October 1982,
pp.529-531, p.530)
Stephen E. Jones | sejones@iinet.net.au | http://www.iinet.net.au/~sejones
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