Re: new method of evolutionary change

David Campbell (bivalve@mailserv0.isis.unc.edu)
Thu, 17 Dec 1998 14:26:02 -0400

[snipped various old parts]
>> However, there are
>>a few points in animal evolution where the amount of DNA has about doubled
>>and the number of copies of certain genes has increased.
>Could you name one of those points and how we are aware of a "point in
>animal evolution"

One point is around the transition from invertebrates to vertebrates. I do
not remember what organisms have been checked. At least many invertebrates
and vertebrates have been checked, and the vertebrates have consistently
much more DNA and more hox genes. I think lancelets (also known as
amphioxus, Branchiostoma I believe is the main modern genus) have similar
amounts of DNA to other invertebrates. They are the closest living
relatives of vertebrates. Assuming that the animals (or at least the
chordates) are all descended from a common ancestor, at some point the
extra DNA must have appeared. All vertebrates have it and it seems no
invertebrates have it, it must have occured in a common ancestor of all
modern vertebrates. By supplying extra DNA to work with, the mutation
could have been the impetus for the evolution and diversification of
vertebrates. I think American Scientist had a good article on this
recently, but could be mistaken about the journal.

>>More frequently, there are many gene families that appear to have arisen by
>>unequal crossing over or other duplication of a small part of the genome.
>>A particular example involving color vision in monkeys has been
>>well-studied. Normally, this species is colorblind. A simple mutation
>>changes the type of color blindness. If a normal and a mutant breed, the
>>offspring will have both genes and color vision. Unequal crossing over can
>>then put the two on the same chromosome, so that full color vision (by
>>primate standards) is now coded by two genes rather than different versions
>>of the same gene.
>These colorblind mutations are natural or engineered?

I think they occur naturally. I am reasonably certain that the mutation
was not artificially induced, though it may have been found in captive
rather than wild animals.

>>I think God directly controls everything. For example, He is no less
>>involved if I let go of a rock in midair and it falls to the floor than if
>>it were to remain hovering without support. The vast majority of the time,
>>He follows certain patterns in how He runs nature. These patterns are what
>>we try to describe as natural laws. Miracles are when He does not follow
>>these patterns because of some more important factor, such as revelation of
>>His nature to humans. I do not see any particular evidence that He did not
>>stick with patterns in the process of creeating life. The evidence neither
>>requires nor rules out miracles in the process, but He seems to use them
>>only when necessary, and I do not believe that they were needed for
>>physical creation, except at some point in the very beginning when creation
>>was started. I do not know enough physics to guess at what point this
>>beginning would have been.
>Here I am struggling. What do you mean by "directly controls everything.
>Like if God were to blink it would all be up for grabs in the natural law
>scene? Seems like God's goodness and other concepts get a bit strange if
>God's will actively holds bullets on their course. What about the brain of
>man? How could freedom exist? Have I missed something? On the other hand if
>God sets it up and lets it go then some of what you describe like "unequal
>crossing over" and even mutation begin to sound less like a creative act
>and more like accidents. Any guidance here?

My inclination is rather Calvinistic, so I am not too bothered with
limiting freedom. Any Arminians wish to take a stab at an explanation?
God's blinking, if it were not contrary to His nature, would eliminate the
universe, including the natural laws.

I hope this clarifies my previous message.

David C.