Sunday, December 27, 2009

Richard Lenski on the Fact of Evolution: A Teaching Moment

Evolutionist Richard Lenski explains that evolution is both a fact and a theory. Lenski's reasoning is typical of evolutionary thinking and therefore useful in understanding this genre of thought. Lenski begins by defining evolution as biological change over time. Since such change is not controversial, it follows that evolution is a fact:


Readers who first encounter such passages in the evolution literature may be surprised. Is this not a radical broadening of the very definition of evolution? How can mere change over time, which even the Genesis account calls for, be counted as evolution? This may seem to be a concession. Have evolutionists dropped the claim that strictly naturalistic explanations are sufficient to account for the origin of species?

No, evolutionists have made no such concession. It is typical to find in the evolution genre apparent logical disconnects such as this. In his article, Lenski explains evolution as the usual unguided biological variation coupled with natural selection (along with dozens of other occasional mechanisms, as needed).

So how should the reader understand and interpret the apparent disconnect. How can Lenski define evolution as mere change over time, but then swap back to the traditional understanding of evolution as strict naturalism? Is this an equivocation—a cheap ploy to prove evolution while bypassing its massive scientific problems?

No, this is not an equivocation. To understand the evolution genre one must understand the history of thought behind it. Even evolutionists are often not completely aware of this history, but the equating of evolution with mere change over time is shorthand for a centuries old metaphysical claim that underwrites evolution. The claim is that if God created the species they would be fixed. Indeed, divine creation would produce a static, unchanging world.

This thinking is often associated with the great eighteenth century Swedish botanist Carl Von Linne, or Linnaeus. At one time he advocated the fixity of species concept and later was troubled when he discovered hybrids—species that are produced by the crossing of two related species.

Linnaeus softened his doctrine of fixity of species, but this was inconsequential. His system with its conception of species became deeply rooted, and the nineteenth century began with the notion of species as immutable still strongly in place. This notion was increasingly being challenged but it was nonetheless a major obstacle for Darwin to overcome.

It was therefore highly significant when Darwin became persuaded that related populations of birds he saw at the Galapagos were actually different species. If there was the slightest foundation for this idea, Darwin had anticipated in a famous notebook entry, it "would undermine the stability of species."

Today's readers often fail to understand the significance. After all, what can be so important about some different birds on some islands? Certainly the birds did not suddenly reveal to Darwin how fishes could change to amphibians, or how amphibians could change to reptiles, or how reptiles could change to mammals. Rather, the revelation was that the idea of divine creation was suddenly becoming untenable. The crucible for Darwin was not an abundance of positive evidence for evolution but rather negative evidence against creation.




The pre-Darwinian metaphysic was that species were fixed and essentialistic. Evidence for small-scale change argued against the old view and in so doing became an important proof text for evolution.

This is the story between the lines when evolutionists casually associate their theory with change over time. It is shorthand for a long-held tradition in the history of thought. If there is change, then divine creation is false, and if creation is false then evolution, in one form or another, is true.

Metaphysical claims such as these mandate evolution. They underwrite the fact of evolution. The rest is just research problems on how evolution occurred—the theory of evolution. As Lenski explains, evolution is both fact and theory. Religion drives science, and it matters.


  1. Here's one of those unanswerable hypothetical questions. Is the easy identification of transmutationism with strict physicalism an accident of history, a consequence of the fact that (probably) the most consistently and clearly physicalist of all the long-nineteenth-century transmutationists happened to be the one whose theory made the breakthrough into mainstream scientific acceptance? Or was the physicalism of Darwin's theory itself an indispensable requirement for its success (in C19), so that guys like St. Hilaire or Richard Owen (or Lamarck or maybe even Wallace) never really stood a chance?

  2. indispensable requirement for its success (in C19)

    'success' meaning mainstream scientific acceptance here, rather than say fruitfulness or predictive value or even broad social impact.

  3. Here's an interesting older article that has been around since 2002 dealing with the supposed evolutionary wonder of Richard Lenski's E-coli experiment.

    It's a paper entitled:

    "Parallel changes in gene expression after 20,000 generations of evolution in Escherichiacoli"

    Here is an example of two isolated populations changing their gene expression in the exact same 59 locations by chance.

    Steven J. Gould once said that "Since the mechanism of evolution is random mutation, if life on earth started all over again it could never follow the same path twice."

    Hmmmmmmmmm ??? This looks like a case for "Scientific Method" in action. Repeatable testing of real science, rather than theory, shows a the probability of a directed adaptation in two different lines of E.coli.

  4. Eocene:


    Thanks for passing that along. It looks like a good piece of work with interesting findings, but I don't suspect it has much implications for evolution (in spite of Lenski's erroneous claims, as explained in the above post).

    In two evolving populations, they found 59 genes with significant yet similar expression level change. The DNA mutations, on the other hand, were not at all identical.

    It is not known how many different sets of mutations can effect these expression level changes, but from a quick scan of the paper I have no reason to doubt that undirected mutations could do the job.