>Again we have this "it must be evolution" argument!,:-) No one denies
>that changes to genes can produce changes to forms. If you could add,
>subtract, mutliply and divide fruit-fllies genes enough you could
>presumably make any living thing?
Yes. That is what evolution is all about! But you should ask yourself why
is it that these changes produce forms which are reminescent of the fly's
evolutionary ancestors. If the changes were random changes in morphology due
to scrambling the genes, why don't the morphologies change in a RANDOM
fashion. Why don't mammalian, reptilian ar avian morphologies result from
this type of genetic knockout experiment? Why only the ancestor forms?
Stephen wrote:
>
>You call this a "small genetic change". A single-step change that
>these scientists have done with intelligent planning and execution, is
>an argument for special creation, not naturalistic evolution.
>
By this reasoning you have disallowed every experiment from supporting
anything other than special creation. Every experiment requires planning and
intelligence and so falls under your restriction. The experiments I performed
to measure the speed of light as a physics student required intelligence and
planning (although I got my worst physics grade on that lab- shows my
intelligence!). Do all experiments, even experiments which measure the speed
of light argue for special creation? If the answer is yes, I want to talk to
my congressman to get him to quit spending money on all the experiments which
can do nothing but support special creation. I would tell him we have enough
experimental support for special creation now!
Experiments are carefully planned so that they can isolate certain
variables. The scientist says,"If I can remove only this one gene, what are
the effects?" That is why the planning and intelligence are required. The
scientist needs to be sure that the only thing he does to those flies is to
knockout the one gene and not others. If you can prove that the only change
you made in the animals genome is the removal of one gene, then you can
figure out what the gene does by looking at the result. Special creation is
not even involved in the propositional logic that went into the experiment.
Nowhere did the scientist say, "If I can remove one gene from this fly, I
can prove that God created this stupid fly. How does the removal of one gene
prove God created the fly? I fail to see how this follows. Thus your
assumption that this careful planning is nothing more than an acceptance of
an argument which has been told to christians so often that lots of people
believe it now. It is, as the philosphers say, a non sequitur.
Stephen wrote:
>The question is, did the "small genetic change" you have referred to,
>actually happen in nature, and did it happen by purely naturalistic
>processes? When? Where? How?<
I believe that these changes did occur in nature. Can I prove it like a
mathematical theorem? No. But then I can't prove that George Washington
existened if I must hold to that standard.
Did it happen naturalistically? I honestly can't answer that. God has not
told us those types of details. I can not know that it happened by your
definition of naturalism any more than you can be sure that it didn't. God
has not told us in his Scripture that he personally added these segments of
DNA onto the genome of the onychophorans. Thus you should be a little less
definitive that God could not have used a set of laws He designed to
accomplish the purposes He wanted.
God might have personally added these DNA segments. I can not be
positive that he didn't. But I do not know how to tell the difference
between that and Him using the natural laws He instituted. In either case,
GOD IS INVOLVED IN THE FORMATION OF THE ANIMALS AND IT CAN NOT POSSIBLY BE
CALLED NATURALISTIC! Anything God does is by definition THEISTIC! The
question is what did he do?
Stephen wrote:
>None of this is new. Gould discusses it in "Hen's Teeth and Horse's
Toes", under the heading "Helpful Monsters". It is interesting that
he does not claim this is necessarily how evolution occurred:<<
He then quotes Gould on page 194.
Au contraire. Gould does suggest that this is how evolution occurred. But it
is not in quite the fashion that Goldschmidt envisioned. On page 195 Gould
notes that homeotic genese prove that very little of the genetic material is
really involved in laying out the body plan. Gould then notes that the
homeotic genes are hierarchical. and on page 196 he wrote:
"If embryology is a hierarchical system with surprizingly few master switches
at high levels, then we might draw an evolutionary message after all. If
genetic programs were beanbags of independent genes,each responsible for
building a single part of the body, then evolution would have to occur slowly
and sequentially as thousands of parts achieved their independent
modifications. But genetic programs are hierarchies of master switches, and
small genetic changes that happen to affect the switches, might engender
cascading effects throughout the body. Homeotic mutants teach us that small
genetic changes can affect the switches and produce remarkable changes in an
adult fly. Major evolutionary transitions may be instigated (although not
finished all at once as hopeful monster enthusiasts argue) by small genetic
changes that translate into fundamentally altered bodies. If classicla
Darwinian gradualism is now under attack in evolutionary circles, the
hierarchical structure of genetic programs forms a powerful argument for the
critics."Stephen J. Gould, Helpful Monsters," _Hen's Teeth and Horse's Toes_,
1984, Penguin,p196
To me the greatest problem Christianity has in the area of origin science is
that we are always behind the curve. We never seem to be able to anticipate
what the Naturalists are about to spring on us. All our arguments about
gradualism and how mutations affecting evolution occur are about to be
overthrown (if theyhaven't already been) by new discoveries. Creationists
still argune from the "beanbag view" of genetics.
The new view of evolution is seen in the following. Scott Gilbert wrote:
"Thus when we say that the contemporary one-toed horse evolved from a
five-toed ancestor, we are saying that hereditable changes occurred in the
differentiation of limb mesoderm into chondrocytes during embryogenesis in
the horse lineage. In this perspective, evolution is the result of
hereditary changes affecting development. This is the case whether the
mutation is one that changes the reptilian embryo into a bird or one that
changes the color of Drosophila eyes." Scott F. Gilbert, Developmental
Biologuy (Sunderland: Sinauer Assoc. Inc., 1991), p. 841
Mutations which affect the early part of development can have a much larger
effect. But what impresses me is that these experiments are revealing that
the way a reptile was transformed into a bird is being slowing revealed. A
hereditable change in the way the tibia and fibia develop produced the bird's
leg. While to my knowledge the exact genetic switches have not been found
the following illustrates the pathway.
Stephen Gould wrote:
"In 1959, the French embryologist Armand Hampe reported some experiments on
the development of leg bones in chick embryos. In ancestral reptiles, the
tibia and fibula (the bones between your kneecap and ankle) are equal in
length; the ankle region below includes a series of small bones. In
Archaeopteryx, the first bird, tibia and fibula are still equal in length,
but the ankle bones below have been reduced to two, one articulating
[joining-grm] with the tibia, the other with the fibula. In most modern
birds, however, the fibula has been reduced to a splint. It never reaches
the ankle region, while the two ankle bones are 'engulfed' by the rapidly
growing tibia and fuse with it. Thus, modern birds develop a single
structure (the tibia with ankle bones fused to it and the rudimentary fibula
at its side), articulating with the bones of the foot below.
"Hampe reasoned that the fibula might well maintain its capacity for
attaining full ancestral length, but that competition for material by the
rapidly growing tibia might deprive it of opportunity to express this
potential. He therefore performed three types of experiments, all directed
toward giving the fibula some relief from its imperialistic and normally
victorious neighboring bone."Stephen J. Gould, "Hen's Teeth and Horses Toes",
"Hen's Teeth and Horse's Toes", 1984, Penguin, p184
(His three experiments did not prove special creation)
I will now quote Gilbert about this experiment,
"Correlated progression has also been shown experimentally. Repeating
earlier experiments of Hampe (1959), Gerd Muller (1989) inserted barriers of
gold foil into the prechondrogenic hindlimb buds of a 3.5 day chick embryo.
This barrier separated the regions of tibia formation and fibula formation.
The results of these experiments are twofold. First, the tibia is shortened
and the fibula bows and retains its connection to the fibulare. Such
relationships between the tibia and fibula are not usually seen in birds, but
they are characteristic of reptiles. Second, the musculature of the hindlimb
undergoes parallel changes with the bones. Three of the muscles that attach
to these bones now show characteristic reptilian patterns of insertion. It
seems, therefore, that experimental manipulations that alter the development
of one part of the mesodermal limb-forming field also alter the development
of other mesodermal components as well."Scott F. Gilbert, Developmental
Biologuy (Sunderland: Sinauer Assoc. Inc., 1991), p. 846
If these changes have nothing to do with evolution, why are the changes only
in the direction of reptiles? Why do none of these alterations give a
characteristic mammalian pattern?
One final item. The fact that you can very simply transform a bird leg into
a reptile leg with a simple alteration of the flow of material, reveals the
reason why all those transitions in the fossil record are never going to be
found. Nature, biological nature, does not work in the fashion which would
produce thousands and millions of intermediate forms. As the homeotic
mutations which control one or another region of the developing embryo during
a transformation, took over, one part of the body would shift tothe new form
while another part would be left looking like the ancestor species. This is
why the fossil record of the major transitions yield creatures with features
looking in both directions. Like Ambulocetus with his mesonychid toes and
cetacean skull.. The developing view of embryology fits like a glove with
the nature of the fossil record and we Christians in our zeal to avoid
evolution at all costs are still arguing "beanbag" genetics. Worse, we teach
our children outmoded views of genetics , inadequate pictures of the fossil
record and an erroneous description of geology. Then send them to college
ripe for the picking by the first naturalist or atheist they encounter who
corrects the mis-information we gave them! Of course, we then blame it on
those bad professors.
glenn