Date: Fri Jun 18 1993 04:22:00
From: Dr Pepper
To: Eddie Johnston
Subj: Intro to Evolution
A Quick Description of the Theory of Evolution for Creationists
First we have to distinguish between the theory of evolution, and
the fact of evolution. I'll start with the fact.
Well you've probably heard the phrase "A change in allele
frequencies over time" but that's a little complex. So i'll stick
with Darwin's phrase "Descent with Modification", which is still an
Descent with modification means that as one observes a population
over time, one sees change over generations. The amount of change
can vary, but in general, the more time, the more change.
We can observe this happening today by direct observation, over
relatively short periods of time. And we can observe it happening in
the past through the fossil record, over relatively long periods of
So as you can see, to say that "evolution happens" is pretty much on
a par with saying "gravity happens". The theory has to do with
So now i will state the theory. Again, i will use an old and
DIFFERENTIAL REPRODUCTIVE SUCCESS
which means that within a given population, different individuals
will, under the same conditions, have different chances to
reproduce, and thus pass on their particular genetic makeups. And
since genetic makeups are always changing, there are always
differences. It doesn't matter how the differences arise, nor the
nature of the circumstances that affect reproductive success. As
long as both exist, evolution will happen.
As you can see, my statements above contained no unfounded
assertions, no statements against any other theory, nor was it just
a list of predictions. However, it is a basis from which we can go
on and make predictions.
One important prediction is that for any given physical feature, (to
the extent the data is available), we can take a horizontal slice,
that is in one time period examine different species that have that
trait, and find a range of variants of it. The beaks of Darwin's
finches are a classic example of this.
Or we can take a vertical slice, that is look at a given trait in
through time, and see a sequence of change. Further we can see
development, that is to say, if a given trait has a given use we can
go back and find in the lineage of the creature that has that trait,
an earlier creature that has a less developed version of it, where
"less developed" is used in the sense of the later use, not in the
sense of it being *totally* useless before then.
A fine example of this is the development of the mammalian inner ear
from the reptilian jawbone. A faq is available on this.
Another, somewhat trivial prediction is the phylogenic tree itself.
Now of course, you have heard that there are a number of different
theories, plural, of evolution. Yes there are. And all of them are
perfectly compatible with "Descent with modification". These
theories are intended to fine tune the above and explain the
details. This is analogous to the way quantum physics explains
electron orbitals without repudiating the idea that electrons are
bound to the atomic nucleus by the attraction of opposite charges.