IDCs Accept Common Descent? News to Me

A philosophical look at evolution and creation by a newly-minted history Ph.D., Leslie Tomory, is titled The Shock and Awe of Creation. Tomory is in the theistic evolution camp, and argues on philosophical grounds that antievolution is a bad thing, while affirming that faith and science can co-exist.

That’s fine by me. But here is one of the issues that diminished my enjoyment of the piece.

Young earth creationists are the first and crudest variant of this reaction, but they are by no means the only one. The Intelligent Design (ID) movement accepts common descent to varying degrees, but rejects the established mechanisms of evolutionary change. The arguments of ID proponents are structured in the way I have outlined. Reacting to evolutionism, they have chosen to go on the attack against natural selection and genetic drift. They recognize that common descent is evident and they accept it.

Uh, no. There is one major “intelligent design” advocate, Michael Behe, who is on record saying that he has no particular reason to disagree with common descent, which is a rather different proposition from saying that he accepts common descent, much less that he feels that it is evident. Within the “intelligent design” movement, acceptance of common descent ranges from a (quite common) nil of the young-earth creationists in the movement to the grudging acquiescence of Mike Behe. Wherever one finds “intelligent design” material that addresses common descent, it uniformly seeks to make common descent seem less “evident” to the reader. Common descent is still quite plainly a target of “intelligent design” advocates, but it is also clear that they recognize they have a fine line to walk if they want to appear to be at all reasonable to the rest of the world. Have a look at “Of Pandas and People” and “Explore Evolution” sometime. When they talk to a “safe” audience, though, the stops often come off.

Another issue in the essay:

The final concept contained within the notion of evolution is the pace of evolutionary change. Although gradualism was dominant in Darwin’s thinking, the second half of the 19th century witnessed the rise of other opinions regarding the pace of evolutionary change, the most important of which was mutation theory’s large jumps. The rediscovery of genetics, with its emphasis on clearly distinct expression of genes, gave further impetus to mutation theory’s jumps. This changed, however, with the forging by Theodosius Dobzhansky among many others, of the modern or neo-Darwinian synthesis in the 1930s. This united Darwinian mechanisms with Medelian genetics and the study of population dynamics. Gradualism was once again the dominant opinion, although it was somewhat modified in the 1970s.

It was at this point when Niles Eldredge and Stephen Jay Gould put forward their theory of punctuated equilibrium, which argued that evolution proceeds by bursts, followed by long periods of stasis. Their arguments were based on observations of the fossil record which seems to indicate that on the whole, evolution proceeds in this uneven way. The bursts should not, however, be understood as occurring in a few generations. Rather, these bursts are only rapid when considered on geological time scales spanning millions of years, and speciation events occur over thousands of generations, making punctuated equilibrium a form of gradualism.

While Tomory eventually finishes by saying that punctuated equilibrium turns out to be a form of gradualism, he fails to elucidate the terminological problem at basis here. Gradualism of the sort that Darwin espoused wasn’t about constancy of rate, but rather the rather banal fact that it is populations that evolve, and its antithesis is saltationism, where new species are instantiated and founded by single organisms. Gould and Eldredge did rail against “gradualism”, but if you read the original papers carefully every such instance is best understood as shorthand for their slightly longer novel phrase of “phyletic gradualism”, a very specific and delimited concept of anagenetic speciation with constant rates of change in traits associated with the speciation event. I’m not sure that it is at all accurate to say that “gradualism” was modified in the 1970s. Gould and Eldredge elicited a lot of reactions that assumed that they were advocating saltationism, and they had, it seems, quite a bit of fun in tweaking people’s noses over the fact that they were doing no such thing. All in all, most of the brouhaha over punctuated equilibria appears, in retrospect, to have the form of an extended academic practical joke, as the rhetoric and phrasing of the original proposal appears to be gauged to elicit exactly the sort of mistakes in response as did follow. This does nothing to lessen the positive aspects of punctuated equilibria in making clear the importance of allopatric speciation on the patterns seen in the fossil record, but it does illustrate that there is more happening in the scientific literature than just straightforward explication of research findings.

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Wesley R. Elsberry

Falconer. Interdisciplinary researcher: biology and computer science. Photographer. Husband. Christian. Activist.