On Wed, 11 Dec 96 21:45:59 -0800, Tuyen Nguyen wrote:
TN>In reading the transcript of the debate between Dr. Johnson and
>Dr. Provine in 1994 at Cornell Univ, Dr. Provine seems to
>emphasize the theme of common descent and the ability of artificial
>selection to produce new species (like the size of the dog). What
>are the answers to these questions? I am sure of the importance of
>these issues. Can you illuminate on these issues?
Thanks for reminding me of this Tuyen. (And welcome to the Reflector
if you've only joined recently). Here is what Johnson said:
"...Francis Crick...co-discoverer of DNA, and a passionately
atheistic materialist and neo-Darwinist...strongly recommends a book
by Richard Dawkins called The Blind Watchmaker, which presents the
modern argument for the Darwinian mechanism of mutation and
selection. Here is what Crick says:
`...Dawkins gives a nice argument to show how far the process of
evolution can go in the time available to it. He points out that
man, by selection, has produced an enormous amount of types of dogs
such as Pekingese, bulldogs, and so on, in the space of only a few
thousand years. Here man is the important factor in the environment,
and it is his peculiar tastes that have produced, by selective
breeding, not by design, the freaks of nature we see preserved all
around us as domestic dogs. Yet the time required to do this on an
evolutionary scale of hundreds of millions of years is
extraordinarily short, so we should not be surprised at the ever
greater variety of creatures that natural selection has produced on
this much larger timescale.'
Now that's typical Darwinian reasoning. Selective breeding proves
that small-scale change can lead to macro-change, i.e., to new forms
of life and new complex organs. All that's needed is enough time.
Yet a child should be able to see that the example is quite beside
the point. It's quite beside the point because selective breeding is
a purposeful process in which a human breeder pursues a distant goal
with skill and persistence. Yet the crucial claim of Darwinian
evolution is that unguided processes can do the work of creation.
The analogy fails because the processes being described are
fundamentally different. Moreover, as is well known, even with all
the power of human intelligence and purpose, breeders are able to
produce change only within boundaries. Even those dogs are all
members of a single biological species. Dogs don't get bigger and
bigger indefinitely -- as big as elephants or whales -- much less
change into elephants or whales, and the reason is not that there is
not enough time. Rather, the genetic variability gives out."
(Johnson P.E., "Darwinism: Science or Naturalistic Philosophy?",
Exerpts of a debate between William B. Provine and Phillip E. Johnson
at Stanford University, April 30, 1994)
Provine responded:
"Let's look at Phil on artificial and natural selection. He just
told you that artificial selection has definite limits on the amount
of variation of even the most highly skilled breeders can achieve.
Dogs do not change into elephants because dogs do not have the
genetic capacity for that degree of change, and they stop getting
bigger when the limit is reached. I suppose the limit is reached
now. Well, let's see...Let's see how far artificial selection can
go. Breeders do, in fact, run out of heritable variations from time
to time, but recombination and mutation mean that the limits that
Phil claims simply don't exist. Let's look at some of the evidence
for this, from long continued selection experiments. The oil and
protein content of corn have been going up since the turn of the
century. No limits have been reached: both protein and oil are
still going right ahead. What about chickens? I grew up on a
chicken farm. Chickens are getting more and more diverse. They are
laying more and more eggs now than when I was a kid. The ratio of
fat content to lean in hogs, coat colors in fancy mice -- just go to
an animal or plant breeding book, and you'll find lots of examples.
Take the example of dogs. We can get Chihuahuas and St. Bernards
out of wild wolves in just a few thousand years. But Phil wants us
to believe that we can't go any farther. Sure, we can go farther
than that. We can make dogs the size of rats and buffalo. It
wouldn't even take a few million years. I suspect it would only take
a few tens of thousands of years. Not only that, they would be what
we call "species" -- different species indeed. Where did Phil get
the information that artificial selection just comes to an end, that
there are limits to the size to which dogs can be selected to be? I
don't know how he knows what the limits are. Animal and plant
breeders certainly have not found them."
(Provine W.B., "Darwinism: Science or Naturalistic Philosophy?",
Exerpts of a debate between William B. Provine and Phillip E. Johnson
at Stanford University, April 30, 1994)
I was amazed at Provine's arguments when I first read them about a
year ago, and I am still amazed at them. They are just wishful
thinking and at best half-truths. However, the fact that Provine is
a Neo-Darwinist heavyweight, make his arguments important, because
they presumably represent the state-of-the-art Neo-Darwinist
explanation. Let's examine them one by one:
1. "Breeders do, in fact, run out of heritable variations from time
to time, but recombination and mutation mean that the limits that
Phil claims simply don't exist."
Here Provine concedes Johnson's main point, namely that "Breeders do,
in fact, run out of heritable variations...". His additional "from
time to time" is a misleading qualification. They run out
*full-stop", as even Dawkins admits:
"Animal and plant species are usually immediately amenable to
selective breeding, and breeders detect no evidence of any intrinsic,
anti-evolution forces. If anything, selective breeders experience
difficulty after a number of generations of successful selective
breeding. This is because after some generations of selective
breeding the available genetic variation runs out, and we have to
wait for new mutations." (Dawkins R., "The Blind Watchmaker",
Penguin: London, 1991, p247)
This last "and we have to wait for new mutations", BTW is what Johnson
calls "the crucial weakness" of the whole Neo-Darwinist theory of
macroevolution:
"In fact, I would say that the crucial weakness, the weakness of
weakness (there are so many weaknesses, I hate to pick one out as
my favorite), but I think the one to keep your eye on, is the claim that
nature supplies helpful mutations in quantity, just when they're
needed, so this process of micromutation and selection can go on in
all of the thousands and millions of species around the world
throughout a long period of time and produce those long-term
effects. There is no evidence of that. Observed mutations are almost
always, or nearly always, harmful, and so that they come in the kinds
of quantities that the theory requires is purely wishful. That is why I
say in my book that creation by Darwinist evolution is as invisible as
creation by God." (Johnson P.E., "What is Darwinism and Why Does
it Matter?", tape 1 of 1, Access Research Network: Colorado Springs
CO, 1991)
Maynard Smith also agrees there is a limit to "genetic variability":
"...artificial selection experiments are a poor model of evolution.
In experimental populations, changes occur at a rate many orders of
magnitude greater than the rates characteristic of evolution...but
they continue only for a time, and cease when all the available
genetic variability has been fixed. No further progress can be made
until new variability has been generated by mutation. In evolution
there must in the long run be a balance between the fixation of
genetic variation by selection and the generation of new variation by
mutation." (Smith J.M., "The Theory of Evolution", Cambridge
University Press: Cambridge UK, Canto Edition, 1993, p164)
Note this important point. If the right mutations, to the right
organ/body part (actually only the germ-cells that will build that
organ/body part), in the right anima/plant, in the right order,
at the right time, don't come along, then evolution (according to the
Neo-Darwinist model) just doesn't happen.
But as Ambrose, emeritus Professor of Cell Biology at the University
of London points out, it needs at least five favourable mutations to
make any new structure, and the probability of these coming together
at the same time in the one animal/plant, is effectively zero:
"The frequency with which a single non-harmful mutation is known to
occur is about 1 in 1000. The probability that two favourable
mutations would occur is 1 in 10^3 X 10^3, 1 in a million. Studies
of Drosophila have revealed that large numbers of genes are involved
in the formation of the separate structural elements. There may be
30-40 involved in a single wing structure. It is most unlikely that
fewer than five genes could ever be involved in the formation of even
the simplest new structure, previously unknown in the organism. The
probability now becomes one in one thousand million million. We
already know that mutations in living cells appear once in ten
million to once in one hundred thousand million. It is evident that
the probability of five favourable mutations occurring within a
single life cycle of an organism is effectively zero." (Ambrose
E.J., "The Nature and Origin of the Biological World", Wiley: New
York, 1982, p120, in Bird W.R., "The Origin of Species Revisited",
Regency: Nashville TN, 1991, Vol. I, p88)
Ambrose says that the same problem occurs for the five favourable
mutations in a population - they must all be brought together at the
same time in one individual organism if they are to generate a new
structure, and unless there is some selective advantage to them
*before* they form the new structure (and how could there be?), the
probability they would come together in the one organism is likewise
"extremely small":
"Let us consider the alternative possibility that the five mutations
occur spontaneously within a large population of interbreeding
organisms. They will have to be brought together eventually in a
single organism, if they are to generate the structure at a new level
of complexity, favourable for natural selection. According to our
definition, each of the genes we are considering is due to a mutation
which will give rise to a hitherto unknown structure of additional
complexity once it meets the other four genes in a single fertilized
egg cell. It would indeed be surprising if any [one alone] of these
mutations could, at the same time, modulate an existing structure in
a manner which would be selected favourably by natural selection. It
is only when the five genes find themselves together that a selective
advantage will emerge. They are more likely to be present
independently within the population, as so-called neutral genes....
In the absence of a selective advantage, the probability of the five
genes coming together simultaneously within a single organism, will
be extremely small." (Ambrose , 1982, pp120-121, in Bird, 1991,
Vol. I, p88).
But the biggest problem, according to Ambrose, is that for a
cluster of five genes to fit in to the existing tightly integrated
genetic system, is "impossible to explain these events in terms of
random mutation alone":
"The difficulties in explaining the origin of increased complexity as
a result of bringing a 'cluster' of genes together within the nuclei
of a single organism in terms of probabilities, fade into
insignificance when we recognise that there must be a close
integration of functions between the individual genes of the cluster,
which must also be integrated into the development of the entire
organism The improbability increases at an enormous rate as the
number of genes increases from one to five.... The problem of
bringing together the five mutated genes we are considering, within a
single nucleus, and for them to 'fit' immediately into this vast
complex of interacting units, is indeed difficult. When it is
remembered that they must give some selective advantage, or else
become scattered once more within the population at large, due to
interbreeding, it seems impossible to explain these events in terms
of random mutation alone." (Ambrose, 1982, pp123-124, in Bird, Vol.
I, pp86-87).
Ambrose, although he is not a theist, was forced to conclude that
the bringing together of favourable mutations to make a new
structure and making them fit into an existing interacting genetic
system, required "creative intelligence":
"We conclude therefore that recent hypotheses about the origin of
species fall to the ground, unless it is accepted that an intensive
input of new information is introduced at the time of isolation of
the new breeding pair. This can be explained in terms of the
operation of creative intelligence.... It looks as though the
advances in molecular, cellular, and developmental biology, which
have been made in recent years and are summarised in this book, have
brought us to the stage where a creative view of the origin of life
and species no longer needs to be defended against evolutionary
arguments." (Ambrose, 1982, p143, in Bird, Vol. II, p201).
2. "Let's look at some of the evidence for this, from long continued
selection experiments."
While it is true that modern intensive selective breeding has
improved the yield of most agricultural products, a large part of
this was due to better management, not genetics:
"In most Western countries there was a pronounced improvement in many
economically important traits of farm animals after World War II. In
the United States, for example, the average yield of milk from
milk-recorded cows increased from 4,275 kilograms in 1955 to 5,538
kilograms in 1967. This represents an increase of 29.5%, or 2.27%
per year. For the Swedish red and white breed the average milk yield
increased from 4,297 kilograms in 1960 to 5,032 kilograms in 1969-
i.e., by 17.1%, or 1.71% per year. It has been estimated that the
genetic improvement of this breed during the same period corresponded
to about 1% per year, or more than half the actual rise in milk
yield." (Johansson I., "Animal Breeding", Encyclopaedia Britannica,
1984, 1:907).
However, after an initial rapid increase, a plateau was reached as
genetic limits were approached:
"It seems probable that the major part of the genetic improvement in
this instance was due to a more efficient progeny-testing and
selection program that had been started among the tested bulls in the
mid-1950s. Similarly, in Danish pig-testing stations, the average
daily gain in live weight increased from 678 to 697 grams from 1955
to 1962, the length of carcasses increased from 93.8 to 95.9
centimetres, and the backfat thickness decreased from 3.26 to 2.80
centimetres. The modern broiler chick is an example of the success
obtained by crosses between breeds that have been specialized for
different lines of production without close inbreeding. When there
is a considerable amount of hereditary variation, it is possible to
change a breeding population quite considerably in about 5-10
generations of intense selection. Sooner or later, however, the
response to selection decreases, and ultimately a selection limit is
reached. This may be due to an exhaustion of the genetic variation
or, more likely, to a disturbed gene balance..." (Johansson,
Encyclopaedia Britannica, 1984, 1:907)
a. "The oil and protein content of corn have been going up since the
turn of the century. No limits have been reached: both protein and
oil are still going right ahead."
This is only partly true. Lester & Bohlin point out that for corn
indeed "No limits have been reached":
"Selection for over fifty generations in corn brought about large
changes in oil and protein content. From a starting point of 10.9
percent, protein content could be brought as low as 4.9 percent and
as high as 19.4 percent. Oil content starting at 4.7 percent was
raised to 15.4 percent and lowered to 1.0 percent. Even after these
fifty generations, it was evident that there was still variation
present. A limit or plateau had not yet been reached." (Lester L.P.
& Bohlin R.G., "The Natural Limits to Biological Change", 1989, p78)
But, it is *not* true that "both protein and oil are still going
right ahead". Lester & Bohlin point out that the rate of increase
in corn oil and protein is falling off:
"Oil and protein production in corn showing extensive variation
because of the probable involvement of many genes never reached a
limit. However, it seems that a limit would have been reached if the
experiment had continued: the amount of change per generation was
definitely leveling off..." (Lester & Bohlin, 1989, p96)
This was also the experience of sugar beet breeders:
"...Beginning in 1800, plant breeders sought to increase the sugar
content of the sugar beet. They were successful. After seventy-five
years of selective breeding, they were able to increase the sugar
content from 6 percent to 17 percent. But no further progress could
be made." (Lester & Bohlin, 1989, p95)
b. "What about chickens? I grew up on a chicken farm. Chickens are
getting more and more diverse. They are laying more and more eggs
now than when I was a kid."
This another half-truth. Chickens have indeed become
"more...diverse" due to modern selective breeding techniques:
"Chicken breeding is an outstanding example of the application of
basic genetic principles of inbreeding, line-breeding, and
crossbreeding, as well as of intensive mass selection to effect
faster and cheaper gains in broilers and maximum egg production for
the egg-laying strains. Maximum use of heterosis, or hybrid vigour,
through incrosses and crossbreeding has been made....Rapid and
efficient weight gains, and high quality, plump, meaty carcasses have
been achieved...Among the world's agricultural industries, meat
chicken breeding in the U.S. is one of the most advanced. It is
presently considered the model for other animal industries, the
broiler industry leading the way in advanced agricultural technology
and efficiency. Intensive nutritional research and application,
highly improved breeding stock, intelligent management, and
scientific disease control have gone into the effort to give a modern
broiler of uniformly high quality produced at ever-lower cost....A
modern broiler chick gains over 43 times its initial weight in an
eight-week period...." (Garrigus W.P., "Livestock and Poultry
Farming", Encyclopaedia Britannica", 1984, 10:1286)
But they are *not* "getting *more and more* diverse". After an
initial increase in diversity limits have been reached as genetic
variability ran out:
"...all the examples of artificial selection can be interpreted as
demonstrating the opposite of the point to be made. Rather than
showing that limitless change is possible, the overriding observation
is that there are limits to change. Many varieties of chickens have
been produced from the wild jungle fowl. But breeders have been
unable to create any new varieties because all the genes in the wild
jungle fowl have been sorted out into the existing varieties- there
is strictly limited variation...." (Lester & Bohlin, 1989, p95)
Similarly, chickens are indeed "laying more...eggs now than when"
Prof. Provine "was a kid":
"The average egg production of a white leghorn flock was increased
from 125.6 eggs per hen per year in 1933 to 249.6 eggs per year by
1965, a 100 percent increase in thirty-two years..." (Lester &
Bohlin, 1989, p78)
"...Annual egg production per hen has increased from 104 to 218 since
1910." (Garrigus, Encyclopaedia Britannica, 1984, 10:1286)
But they are *not* "laying *more and more* eggs now" than they were
then:
"...Egg production was sharply increased but eventually leveled off."
(Lester & Bohlin, 1989, p96)
3. "Take the example of dogs. We can get Chihuahuas and St.
Bernards out of wild wolves in just a few thousand years."
a. "But Phil wants us to believe that we can't go any farther. Sure,
we can go farther than that. We can make dogs the size of rats and
buffalo. It wouldn't even take a few million years. I suspect it
would only take a few tens of thousands of years."
This is a good (or bad) example of Neo-Darwinist extrapolation beyond
the empirical evidence. While "dogs the size of rats" may be
possible (eg. the chihuahua) the claim that " We can make dogs the
size of...buffalo" even "in a few tens of thousands of years" is
without any foundation whatsoever. The fact is that after thousands
of years of breeding, the range of dogs by body weight is between
1-70 kg (2-150 lbs):
"One of the outstandingly variable characteristics of dogs is body
weight, ranging from as little as 0.9 kilograms (two pounds) in dwarf
breeds such as the chihuahua, to 68 kilograms (150 pounds) in some of
the large breeds such as the mastiff and St. Bernard. (Johansson
I., "Animal Breeding", Encyclopaedia Britannica, 1984, 5:935)
There is no way of breeders getting very much bigger dogs (certainly
not the size of a buffalo), because breeding from two large varieties
of dogs risks genetic defects due to inbreeding:
"It is well known that inbred populations exhibit certain traits that
are not found in normal outbred populations. This is because
breeding among closely related individuals increases the probability
of matching up recessive alleles. In normal outbreeding populations,
these recessive alleles, often deleterious, are masked by normal
dominant alleles. Inbreeding in laboratory populations is
consistently used to uncover unusual recessive traits that a
population carries in its gene pool but rarely expresses..."
(Lester & Bohlin, 1989, p78)
while breeding with smaller varieties of dogs leads to a reduction in
size:
"Offspring from crosses between large and small breeds tend to be
intermediate in size, and the trait is affected by large numbers of
genes...It is very likely that more than one combination of genes
will produce a desirable trait in a dog; therefore, two excellent
dogs bred together may produce somewhat inferior offspring, and vice
versa." (Johansson, Encyclopaedia Britannica, 1984, 5:935)
However, the freaks of nature that breeders have managed to produce
by decidedly *un*-natural selection, would die out in the wild.
"At the same time there is in most pure breeds a large number of
undesirable recessive traits of form and behaviour that crop out in
certain matings. Many of these are preserved and may be spread
throughout a breed if, for instance, a champion male carrying an
undesirable recessive trait is widely bred to numerous females.
Furthermore, many of the traits desired by dog fanciers, such as the
bulldog head, which would be a defect in a wild animal and promptly
"selected out" in nature, are perpetuated by man through special care
and attention." (Johansson, Encyclopaedia Britannica, 1984, 5:935)
b. "Not only that, they would be what we call "species" -- different
species indeed."
It may be that dog breeders will one day produce a new species:
"Whether selection has ever accomplished speciation (i.e. the
production of a new species) is not the point. A biological species
is simply a group capable of interbreeding. Success in dividing a
fruitfly population into two or more separate populations that cannot
interbreed would not constitute evidence that a similar process could
in time produce a fruitfly from a bacterium. If breeders one day did
succeed in producing a group of dogs that can reproduce with each
other but not with other dogs, they would still have made only the
tiniest step towards proving Darwinism's important claims." (Johnson
P.E., "Darwin on Trial", 1993, pp19-20)
But this only highlights the fact that they haven't done it yet.
c. "Where did Phil get the information that artificial selection just
comes to an end, that there are limits to the size to which dogs can
be selected to be? I don't know how he knows what the limits are.
Animal and plant breeders certainly have not found them."
Another misleading statement. Of course it is technically true that
no one knows "what the limits are" and that "Animal and plant
breeders certainly have not found them". In the nature of the case,
it is always possible that a slighly bigger dog could be bred, but
the universal experience of "Animal and plant breeders" is that there
*are* limits and we are approaching them because of the slow-down in
the rate of change. Macbeth says:
{"When the experience of breeders is in question, it is prudent to
consult competent breeders. Luther Burbank who, though no
theoretician, was the most competent breeder of all time, looked at
this problem. He eloquently endorsed the limited charter:
`There is a law...of the Reversion to the Average. I know from
my experience that I can develop a plum half an inch long or one 2
1/2 inches long, with every possible length in between, but I am
willing to admit that it is hopeless to try to get a plum the size of
a small pea, or one as big as a grapefruit. I have daisies on my
farms little larger than my fingernail and some that measure six
inches across, but I have none as big as a sunflower, and never
expect to have. I have roses that bloom pretty steadily for six
months in the year, but I have none that will bloom twelve, and I
will not have. In short, there are limits to the development
possible, and these limits follow a law. But what law, and why? It
is the law that I have referred to above. Experiments carried on
extensively have given us scientific proof of what we had already
guessed by observation; namely, that plants and animals all tend to
revert, in successive generations, toward a given mean or average.
Men grow to be seven feet tall, and over, but never to ten; there are
dwarfs not higher than 24 inches, but none that you can carry in your
hand.... In short, there is undoubtedly a pull toward the mean which
keeps all living things within some more or less fixed limitations 21
(Burbank L., in Hall W., ed., "Partner of Nature", Appleton-Century,
1939, pp98-99).
(Macbeth N., "Darwin Retried: An Appeal to Reason", 1978 (reprint),
Garnstone Press, London, p36)
Lester and Bohlin conclude:
"The force of Darwin's argument for the importance of natural
selection stemmed from his analogy to artificial selection in
domesticated plants and animals. The analogy, however breaks down on
two counts. First, in artificial selection, there is a preconceived
desired goal. A particular trait is designated for increase or
decrease. This is true selection. In natural populations, this is
not so....natural selection is a passive phenomenon. There is no
selector. No desired goal or sense of progress is possible. Natural
selection operates on random mutations that do not anticipate a
determined end result. Many have assigned a more powerful ability to
natural selection than to artificial selection. This appears
entirely out of order and unrealistic....A rule that all breeders
recognize, is that there are fixed limits to the amount of change
that can be produced. It is of course unequivocal that there is
extensive variation in nature...However, chickens- don't produce
cylindrical eggs. We can't produce a plum the size of a pea or a
grapefruit. There are limits to how far we can go. An alternate
explanation is that mutations may possibly narrow or broaden the
limits, but they never break them. Some people grow as tall as seven
feet, and some grow no taller than three; but none are over twelve
feet or under two. Artificial selection, then, is not the best
analogy for natural selection. The two have little in common.
Artificial selection demonstrates well the large amounts of genetic
variation in nature, but it offers little in aiding our understanding
of natural selection." (Leste & Bohlin, 1989, p96)
God bless.
Steve
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