Re: EvolutionVsDevelopment

Glenn Morton (
Tue, 21 Jan 1997 20:22:46

Bob Dehaan defined 3 meanings of evolution and then wrote:

>I arrange the three meanings in the form of a target face, with natural
>selection being the bull's eye; the first ring, descent with modification;
>the second ring, change through time. The farther one moves out from the
>bull's eye the further they are removed from objective, empirical data; and
>the more flexibility one has in fitting the theory to many different
>situations. I believe that the first meaning contains the guts of the theory
>of evolution. It supplies the mechanism that second and third meanings need.
> It is to them as Christ is to Christianity. Remove Christ and you have cut
>the heart out of Christianity. Remove natural selection from evolution and
>you have taken the indispensable causal mechanism from the second and third
>meanings of evolution.
>As I read your post on limits to change, I conclude that by evolution you
>mean *change through time*.

I would object here. My post was specifically aimed at showing that there is
NO limit to change via mutation. As such, I did not feel the need to raise
the natural selection issue in that context.

While you include mutations in your two posts, I
>find nothing about *selection*, the second indispensable step in natural
>selection. Do you agree? Or have I missed something?

If you remember my very simplifed diagram of a phase space where each location
represents a unique sequence of DNA. I had a "." for genomes which allowed a
living system and a "*" for those that didn't. If a mutation gave a fertilized
egg a genome represented by a "*"; it dies. That is the highest penalty
natural selection can wreak on a being. However, I didn't make explicit how
natural selection works in relation to the sequence space. Consider the
situation below. (I will use "-" instead of a '.' because of the way the
archive treats these characters)


If species with genomes near A finds itself in an environment where a genome B
is better able to survive, then there would be a gradient from left to right
in which it is more likely that a mutation which moves the genome from A
towards be will survive than one which moves in the opposite direction.
Eventually the genome will follow a path through phase space marked by the
path "p". During the evolution from A to B some offspring will be still born
because they have mutations which put them into one of the "*" locations.
Mathematically, for those who are of that bent, in sequence space a selective
advantage for a human is a 3.5 billion dimensional Markov probability vector.

If the selective advantage reverses, then an animal at B would move to A.

>Let's get on to some specifics. I asked whether a the first mutation toward
>a leg would not be detrimental. Your answer was: "If the prey were faster
>than a fin could move the predator, the mutation would have been
> advantageous
>not detrimental." I doubt that. I'd guess the probability is pretty low
>that an incipient leg could move a fish faster than fins and a tail. You
>must have seen yourself how fast a fish can move, even in shallow water.
> The *Eusthenopteron*, a crossopterygian fish looks as graceful, streamlined,
and fast swimming as any modern fish, yet is considered a lobe-fin fish that
had evolved in the direction of land-living amphibians. (Colbert and Morales,
>*Evolution of the Invertbrates* 1991, p. 67). I don't doubt the transition
>to land animals occurred. I merely challenge the evolutionary explanation
>that relies on the land-based food, and the need to move faster to catch
>hypothetical land-based food or other food as the incentive. I believe that
>the genetic developmental programs were already present in the germ line of
>crossopterygian fish and when the programs were expressed they drove the fish
>to eventually become amphibians, thus actualizing their ability to catch
>terrestrial and some kinds of aquatic food.
I would say two things. First, the addition of front paws, provides an extra
joint,(at the wrist) which can add extra impulse to motion that can not be
provided by the elbow alone. Bind your ankle so it can not move and see how
high you can jump by motion at your knees alone. Let your ankle move and you
can jump much higher. The extra joint makes a lot of difference.

Secondly and more importantly, if you believe that the genomic program for
feet was already included in the genome of the panderichthys, then this would
imply that every other genome in the descendants of the panderichthys was also
included in that genome. Carried to its logical conclusion, if Panderichthys
gave rise to amphibians and amphibians to reptiles and repitles to mammals
this would mean that the entire genetic developmental code for all living land
animals were included in panderichthys. Obviously I don't know how big the
genome of Panderichthys was, but that would seem to be excessive.

>I resist efforts of evolutionary authors to co-opt development, or to make
>development a secondary process to evolution. I gave a number of
>characteristics that demarcate it from evolution. Here they are again.
> Development is end-directed and purposive, internally driven, autonomous
>from the environment, hierarchically organized, has a seamless genetic
>connection with phyletic lineage, form of an organism appears before its
>function or behavior. It is a naturalistic process. Principles of
>development apply to large groups of animals over geologic time as well as to
>individuals, in the developmental framework. Form precedes function in
>development. Referring to the last statement you said "So why isn't this
>evolution? That is exactly what evolutionists think happened. The
>evolutionist thinks that the form came first in the legs then the use came
>later." Not so, as I noted above. The point I want to make is that the
>characteristics of development set it apart from evolution.

I agree that God designed living systems and thus life is purposive. If I am
understanding you correctly, I would not be able to tell the difference
between what you propose and evolution at least as far as the fossil record is
concerned. You do make a different prediction that the developmental programs
for lots of animals are contained in their genomes. This would imply that a
few mutations might be able to change a swan into a kitty cat or frog. Or
maybe more correctly, a panderichthys into a frog or kitty cat. Is this not
similar to what Goldschmidt suggested? I am not being critical here, just
trying to see what your theory entails.

>Natural selection, on the other hand, does not foresee the future, is
>purposeless, unplanned, undesigned, originates in random mutations and is
>guided by an opportunistic environment. These are avowed views of many
>evolutionary authors, including Darwin, Simpson, Futuyma to say nothing of
>Dawkins, Dennett, and others. Those characteristics make evolution a very
>unsatisfactory paradigm to me.

Are you denying that natural selection operates? Is not the development of
immunity by disease causing bacteria a result of natural selection?

>It seems to me you have accepted the evolutionary paradigm, and added the
>purposive activity of God to it, thereby avoiding the negative aspects of
>natural selection in its strict Darwinian form. Concluding your diagram in
>your Limits to Change post, you wrote "Is this a purposiveless view of
>nature? Does this view destroy God's control? Of course, not. God
> designed
>the phase spaces and in doing so, God was essentially laying down a nearly
>undetectable railroad track which would lead from one animal to the next,
> not
>according to an unplanned sequence of events but according to His
>foreknowledge. In other words, God rigged the roulette wheel, BY DESIGN."
> The question is, what is the "nearly undectable railroad track"? If it is
>not an evolutionary "unplanned sequence of events" what is it? I claim that
>the "nearly undectable railroad track" consists of developmental programs
>operating in the germ line of the lineage unfolding over geologic time.
> Development is the biological instrument of God's foreknowledge. The
>characteristics of development make it an ideal causal agency for God's
>purposive activities in the history of life on earth.

I find your view quite interesting and I have many questions for it.

Has the unfolding ceased? If it hasn't can we experimentally turn an animal
into what it will become?

When Panderichthys changed into Acanthostega, did the organism lose the
genetic program for panderichthys development?

Is the region of the genome containing the future developmental programs
immune from mutation? If not, how was the development program for an animal
20 million years in the future preserved? If it is immune, why? Is there
experimental evidence for such a region?

How do you explain the fact that all vertebrates arrive at the pharyngula
stage of embryonic development by different developmental pathways. (See
Gilbert, Developmental Biology, 3rd ed.1991 p. 840 figure 11.? He shows that
the blastula and gastrula stages are quite different in salamander, chick and


Foundation,Fall and Flood