[asa] Dr. Herbert, mitochondrial genetic variation and creationism

I’ve been reflecting on Hebert’s interview statement about the data
being more in line with ‘creationism’ than neo-Darwinian theory. While I
suspect it was largely tongue-in-cheek (as will be parts of my letter
here), I think perhaps it also reflects his lack of familiarity with
creation theories. Those familiar with various popular creation theories
would note that the mitochondrial data presents a problem for such
theories as well. I have a hard time blaming Dr. Hebert for his lack of
familiarity with creation theories: First, they aren’t taught in any
detail in most undergraduate or graduate courses, nor do the vast
majority of scientific journals have sections devoted to creation
research. Second, which creation theory to consider? Practically every
culture has a separate explanation for the creation of the world and its
flora & fauna. These can differ greatly and so it is important to
specify a particular ‘model’ when discussing creation. (Aside: Most
creation explanations completely ignore the dominant biological groups
on the planet, microbes, with the notable exception of yeasts that
employed in the production of fermented beverages and leavened bread).
So, one can also question which creation theory Dr. Hebert had in mind
when he made his brief statement.

In any case, I’d like to start with a review of some of the more
predominant creation models found in North America (and excepting those
of its aboriginal people). The first is Young-Earth Creationism and it
is based on a particular interpretation of the Old Testament. In this
model, species or ‘kinds’ were separately created relatively recently,
roughly between 6K to 100K years ago. Also in this model, at some point
in the past, many land animals faced an extreme and simultaneous
population constriction because of a global flood. While the
mitochondrial genetic diversity data for humans exhibits a population
bottleneck within this possible time frame, many other animals do not.
And while Dr. Hebert notes that mitochondrial sequence diversity seems
constrained relative to that of nuclear DNA, how YEC creationists might
reconcile these disparate observations remains a problem. YEC models
predict a simultaneous, recent bottleneck where nothing widespread is
actually found, even with the observations with mitochondria.

Another popular model is Old Earth Creationism and this can be split
into two dominant camps: Creation of kinds from which individual species
might later emerge by ‘natural’ means vs. common descent with a mixture
of natural and ‘interruptive’ mechanisms (by ‘interruptive’, I refer to
the notion that some steps in evolution require direct intervention to
alter the normal, regular course of events. e.g. ‘miracles’, or
manipulation of biological material in a lab by researchers). Those like
Dr. Behe favor the latter.

In any case, the observations for mitochondrial data do not match what
one might expect for both OEC models. With the separate creation of
kinds, one would not necessarily expect variety to map a pattern of
nested hierarchy across kinds, unless one posits that kinds refer to
eukaryotes, archaebacteria and eubacteria (even that is sketchy), in
which case subsequent evolution should proceed by natural means
(one-time creation of kinds model) or a combination of natural means and
‘design’ (pace Behe). Why mitochondrial gene sequence diversity should
be narrower than nuclear gene sequence diversity remains a problem in
either case. Mutation is a perpetually present mechanism that acts to
increase genetic diversity and mutations will always happen in both
nuclear and mitochondrial genomes. Presumably, there are other
mechanisms that affect genetic diversity differentially across nuclear
and mitochondrial DNA, but OEC models neither predict nor explain the
discrepancy.

There is a way out for the OEC models: Recall that ID/OEC models
encompass both natural and ID/divine mechanisms. In this scheme,
evolutionary theory and natural, regular mechanisms are a subset of the
influences over the development of life. Now, while there may be no good
explanation for the mitochondrial data based on the “ID/divine-side” of
mechanisms, it is possible that natural mechanisms like selective sweeps
and ‘hitchhiking’ can account for the apparent discrepancy. This is
useful because it suggests that it might be possible to reduce the
problem to a form that modern science is particularly best equipped to
investigate.

Anyway, to sum my thoughts: I believe the Dr. Hebert is actually wrong
when he mentioned that the mitochondrial data better fit creation models
than evolutionary or neo-Darwinian ones. I suggest the data actually
remains a significant problem for popular creation models as well. It is
not a case of ‘score one for the creation side’ but a discovery of a
problem for *both* evolutionists and creationists to address. Never
forget there is another, more common and well-stocked ‘bin’ in which to
sort observed phenomena: It’s labeled, ‘To be determined.’

Regards,
T. Ikeda

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Received on Sun Aug 23 13:47:16 2009