Saturday, October 30, 2010

Answers in Genesis, not in Apes (Part 2)

The current issue of Acts & Facts (the journal of the Institute for Creation Research) has an article by Randy J. Guliuzza, MD, titled "Similar Features Demonstrate Common Design."  Although superficially similar in theme to the AiG article by the Viets, Guliuzza goes into considerably more depth in his argument.  He starts by noting that evolutionary theory deals in "function," not "purpose;" it explains a bird's wing or bat's wing in terms of mutations selected for their ability to aid in gliding or flying, not for a Creator's purpose in creating a flying animal.  This doesn't, really, offer much of an explanation of why, e.g. a bat's wing, a whale's flipper, and a human arm have such detailed correspondences in their skeletal structure, or why there are such differences in the way the tetrapod forelimb is modified into a wing in pterosaurs, birds, and bats.  Guliuzza mocks evolutionists for refusing to acknowledge "purpose," but he doesn't really offer any "purpose" for such a pattern of similarities and differences in living things.

Rather, he goes on to offer a series of not-terribly-coherent attacks on evolutionary theory and methodology.  He argues, e.g. that to properly understand homologous structures, we must:

  • Stop looking to the extrinsic environment coupled to natural selection to explain the origin and primary source of adaptive capability, and start looking to the built in diversifying reproductive power of organisms. Environments do not select organisms for habitation. Rather, organisms occupy environments when they generate traits that fit.
  • Drop the evolutionarily-tainted belief that answers to what causes adaptive change can be reduced to one or several components (e.g., DNA) of organisms—a fallacy basic to assertions of bit-by-bit origins from individual parts—and begin treating the entire organism as the minimum component necessary to reproduce, adapt, and fill environments.
  • Embrace the search for purpose as a guide for biological research to encourage the broadest array of questions and testing of all possible explanations.
Now, the first of these points seems weirdly wrong: organisms often occupy environments to which they are only indifferently fit.  The Italian wall lizards that evolved cecal valves in their guts on Pod Mrcaru didn't occupy the island because they were already ideally fitted to it: they did so because they could survive, and over time their descendants became better able to survive on a new diet in a new environment.   The same principle is seen in bacterial cultures that evolve traits ranging from antibiotic resistance to the ability to digest nylon.  The environment is not the "primary source of adaptive capability;" it is the source of selective pressures on the capacity of organisms to reproduce and mutate.

Obviously, entire organisms reproduce.  Indeed, quite a bit of evolutionary theory deals with the constraints on evolution imposed by the fact that isolated bits can't evolve by themselves: whether a given change is beneficial or not depends not only on that change, but on how it affects other parts of the organism, from the energy costs of building it to the effects on the development of other organs or structures (one species of blind cave fish, for example, seems to have its vestigial eyes selected for not directly, but as a side effect of selection for a larger jaw; as the jaw grows larger in embryonic development, it leads to shrinking of the eye -- which implies that the larger jaw wouldn't be beneficial if the fish needed to see, even if it made feeding easier).  But "begin treating the organism as a whole" doesn't give much guidance in explaining how adaption -- even the sorts and degrees of adaptions accepted by creationists -- occur.

And as noted, the "search for purpose" doesn't do much to account the question the article is supposed to be addressing: why, e.g. detailed similarities exist between structures that serve vastly different functions, whether the forelimbs of moles and bats, or the GULO gene in moles and the GULO pseudogene in old world anthropoids.   Guliuzza wants to argue that living "kinds" were created with the in-built ability to evolve so far and no further, but offers neither a real mechanism nor a basis for built-in limits that would prevent, e.g. humans and macaques from sharing a common ancestor.  Guliuzza argues that:
Any explanation must explain these observations: diversity within, and similar features between, kinds of organisms; and stasis, meaning a fossil and its living counterpart show remarkably little change.3 Biological life is fundamentally discontinuous, meaning organisms fit only one phylum, class, and order. Common descent explanations generally clash with these observations.
Note that "stasis," as commonly used by paleontologists, means that a fossil species does not show microevolutionary change across its geological duration.  It doesn't mean that sequences of species don't exist that demonstrate significant change over time (and Guliuzza has already conceded microevolutionary change, and probably accepts, as other ICR writers do, speciation within "kinds").  Note also that species fitting into only one phylum, class, order, etc. is in fact a prediction of branching descent with modification: nothing in creationism prevents, e.g. something like centaurs that nest in multiple different places in the nested hierarchy simultaneously: a "creation model" is compatible with, e.g. bats with feathers or birds with mammary glands in a way that evolution is not.

Guliuzza goes on to make a rather strange argument, possibly having changed trains of thought halfway to his demonstration.  He notes that gene regulatory networks that accomplish similar ends often use very different sequences of regulators, and hence are regarded as having evolved convergently.  He then goes on to mock the fact that although evolutionists explain homology (detailed similarity in structure beyond that needed to account for similarity of function) in terms of common ancestry, they do not explain analogy (lack of similarity beyond that needed to account for similarity in function) this way: an obvious contradiction, by his lights.

Frankly, his entire article, despite bursts of erudition, is a mess.

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