Extant Variation
Post of the Month: December 1998
by Adam Noel Harris

We often see (well, more often as late, at least) creationist claims that mutation cannot lead to increases in "information," which is usually a term that means something that is "common sense" to the creationist.

What I want to know is what creationists think is the origin of variation - at both the allele and morphological levels - in extant populations.

Not all humans look alike. In fact, most humans are distinguishable from each other, and this is generally accepted to have much to do with genetic differences (twins can be distinguished by those who are familiar with them and remind us that not all variation is based in genetics). Other organisms can be observed to have genetically based variation as well, although it is often harder to observe for those who haven't studied it (don't all those penguins look pretty much the same? ;) ).

Furthermore, it is generally accepted by evolutionists and creationists alike that extant domestic dog breeds are descended from wolf ancestors. We can thus see that there was probably a great deal of allelic variation in the ancestral population(s), and artificial selection and inbreeding have translated this variation into remarkable visible differences in morphology.

The problem then exists, where did this variation come from, and (less often discussed here but just as important) how is this variation maintained. Population genetics has shown that variation has a tendency to decrease over time as a result of drift and selection. The maintenance of heterozygosity in a population is explained by invoking mutation as a continual source of new variation. In the evolutionary explanation, "initial variation" is somewhat nonsensical, since there was probably never a clear time in which wolves, for example, came into being. "Initial variation" can be said to be the result of mutation in ancestral populations. It's mutation all the way down, so to speak.

How do Young Earth Creationists explain the origin and maintenance of variation within populations? If they believe in a global flood, then by what mechanism has variation come about since the Noah's Ark bottleneck?

How do Old Earth Creationists explain the origin and maintenance of variation? Presumably a great amount of variation could have been part of the creation event. But how has this variation been maintained? Are population genetics models way off, and if not, how do new variants arise in nature as old variants are removed by drift? If new variants do not arise or are limited in their scope, how long could wolves have been present on the earth prior to the beginning of breeding of domestic dogs for the variation needed to make chihuahuas and Saint Bernards to still be present? Are modern wolf populations likely inadequate to produce a similar range in dog variation as is seen today? If new variants are proposed to arise, do any of these variants represent increases in "information?"

Finally, how do anti-Darwinian evolutionists explain the origin and maintenance of variation? If Darwinian mechanisms are not sufficient to counteract the continual loss of variation in an ancestral wolf population by providing new "information" (which has since enabled the breeding of a wide variety of domestic dogs), what mechanisms might be invoked as a source for this new information? Are these likely to be the same mechanisms which anti-Darwinists invoke to explain larger changes in evolutionary history (e.g. dino to bird), or might a different set of mechanisms account for such micro-maintence vs. macro-change?

-Adam --

Opinions expressed are not necessarily those of Stanford University.
PGP Fingerprint = C0 65 A2 BD 8A 67 B3 19  F9 8B C1 4C 8E F2 EA 0E

First posted 21 December 1998

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