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Kansas Teach-In on "Science, Teaching and the Search for Origins"
14-15 April 2000
The University of Kansas

Keynote Address
"Finding Darwin's God: The New Battle Over Evolution"

Kenneth R. Miller
Professor of Biology, Brown University

Events around the united states, including the well-known actions of the Kansas Board of Education in 1999, have once again made evolution a contentious issue for public education. There are many ways to respond to the opponents of evolution, but tonight I will address what I regard as the best, most appropriate, and over the long run, the most effective strategy to preserve the integrity of scientific teaching. It is to treat "scientific" creationism as though it were a scientific idea.

I suggest this not because I am in favor of conferring the mantle of scientific legitimacy on the opponents of evolution. Quite the contrary. By taking their various statements as "scientific" proposals, we can subject them to the same degree of scrutiny and analysis as we do any scientific idea. When this is done, as we will see tonight, these ideas collapse upon inspection.

Three lines of attack
In recent years 3 principal lines of attack have emerged against evolution:

1. Young Earth Creationists, who insist that the world is a recent creation (less than 10,000 years) and that all organisms that have ever lived originated in an essentially simultaneous creation event.
2. Intelligent Design theorists, including University of California lawyer Phillip Johnson, who maintain that evolutionary science carries with it an implicit set of materialist assumptions that render it inherently anti-theistic. These individuals also make the substantive scientific charge that the mechanisms propose for evolution are incapable of producing the changes in organisms over time that Darwin's theory demands, and therefore the mechanism of evolution does not work.
3. Advocates of Biochemical Design, including Michael Behe of Lehigh University, who maintain that Darwinian mechanisms are incapable of explaining the biochemical complexity of the living cell (Ironically, Behe endorses evolution as an explanation for the fossil record and states that the evidence for common descent of many organisms, including humans and the great apes, is convincing.)

I propose that we examine each of these anti-evolution positions, and see whether or not they will stand the test of scientific analysis.

Did species originate simultaneously?
No. and the evidence they did not is overwhelming. members of the general public often underestimate just how extensive our current fossil collections are, how detailed individual fossils can be, and how remarkably they document many episodes in the history of life. More importantly, fossils appear in sequences that show a pattern that has been recognized for more than two centuries. Darwin called this pattern "Descent with Modification."

The figure to the left (from biology by miller & levine, 5th edition, © 2000, prentice hall, new york) illustrates what i mean by this. this highly-simplified drawing shows some of the fossils documenting the evolution of the modern camel from ancestral forms that existed in much earlier geologic ages. the ability to trace such lineages, time and time again, backwards in time shows that the connection between past and present is genuine, and that an evolutionary description of earth history fits the facts of the geologic record.

To be sure, in recent years paleontologists have begun to emphasize that the pattern of change is more complex than a simple lineage might suggest.

 

 

The diagram at right (biology by miller & levine, 5th edition, © 2000, prentice hall, new york) illustrates a more detailed view of the nature history of the modern horse, Equus. Over the last 30 or 40 million years, no fewer than 20 different genera of horses have come and gone, branching into repeated patterns of appearance and extinction. Opponents of evolution have only two ways to explain away such facts of natural history. The first is to suggest that the record is genuine, but that new species, as they appear, are the products of "intelligent design." This suggestion seems interesting until we consider what it implies about a "designer."

It would mean, for an example, that the designer created four or five species many millions of years ago, all somewhat similar. All of those species became extinct. He then created a few more species, each only slightly different from those that had preceded them. They went extinct, too, and then he repeated the process again and again and again until he finally designed the modern horse less than 2 million years ago. Curiously, two things characterize this "designer's" work. First ? lack of competence. More than 99% of the creatures he has designed have become extinct, and nearly all of them went to extinction in only a few million years. Second ? a determination to mimic what we now call "evolution." Every time the designer produces a new species to replace one of his failed creations, the new species looks like a slight-modified version of the one that had just died out. In other words, the designer was determined to create in a way that would imply descent with modification. Such a designer would be both deceptive and incompetent, hardly an "answer" that creationists could present as a genuine scientific theory.

Al alternative approach, one favored by creationists such as Duane Gish, Henry Morris, and Ken Ham, is to claim that the entire geologic record is an illusion. In this scenario, they suggest that a single world-wide flood churned up all of the earth's inhabitants, and deposited them in a sequence of buried fossils that today we "misinterpret" as the geologic ages that document evolution.

This explanation, also known as "flood geology," fails the test of scientific analysis so completely it is almost comic. It predicts, for example, that bottom-dwelling sessile creatures such as sea urchins should be found at the bottom of the geologic column, since they would be among the very first organisms to be buried in the sediment at the bottom of such a flood. However, sea urchins are not found there, nor are any complex marine organisms. Sea urchins do not appear until the early Paleozoic, for the very simply reason that they had not yet evolved. In fact, the distribution of sea urchin fossils in the fossil record is the exact opposite of that predicted by flood geology.

 

Does the fossil record document the origin of new species?
Yes. in those rare cases when the fossil record is complete enough, paleontologists have been able to study the emergence of new species in patterns that are remarkably close to those outlined by Darwin in the single sketch of speciation he included in On the Origin of Species. One striking example (shown during the lecture in a slide taken from: Thomas M. Cronin and Cynthia E. Schneider (1990) "Climatic influences on species: Evidence from the fossil record," Trends in Evolutionary Biology and Ecology, 5: 275-279.) is the evolution of two diatom species, Rhizosolenia praebergonii and Rhizosolenia bergonii, from a single ancestral species.

Are there more examples? And are there examples that concern organisms in which most of us would express a greater interest than diatoms? Once again, the answer to both questions is "yes."

Shown at the right is the fossil record of an organism plotted in a way that shows the splitting of a single lineage into two during the past 3 million years.

The record shows no obvious gap, documents a split that occurred about 2 million years ago (ending with the extinction of one of the lines shortly thereafter).

What are these organisms whose fossil record shows the transition to a new species so clearly?

They are us. These data show the increase in the size of the cranium from the roughly 400 cubic centimeter size of our pre-human ancestors, the split between our genus, Homo, and Australopithecus, and also illustrates just how complete the human fossil record has become.

These data were taken from a summary of fossil specimen cranial volumes reported in a 1998 paper in Science magazine by Faulk (see original figure and reference at right).

Figure from D. Faulk (1998) Science 280: 1714.

Can we be certain that the human fossil record documents a genuine transition from non-Human to Human species?

For the most part, yes. i believe one of the best ways to demonstrate this is to take the word of the creationists themselves. they have generally tried to counter the extensive nature of the human fossil record by claiming that specimens fall unambiguously into one of two categories: either ape-like or human-like. therefore, there are no transitional forms documenting a genuine evolutionary transformation.

However, the creationists themselves disagree as to whether or not specific fossil specimens are more ape-like or human-like. jim foley, in his excellent monograph ("fossil hominids") at the talk.origins web site (http://www.talkorigins.org) has pointed this out in graphic fashion, as shown below. as you will note, this chart shown how the same 6 fossil specimens have been classified in 5 different ways by various creationist writers in 10 different publications. what this means, of course, is that the claim that these pre-human fossils can be easily sorted into two distinct groups (ape-like or human-like) is not true. rather, the fact that creationists themselves disagree as to whether specific specimens are more ape-like or human like shows just how "transitional" these specimens truly are.

References for this chart:

• Baker S.: Bone of contention: is evolution true?, Evangelical Press, 1976
• Bowden M.: Ape-men: fact or fallacy? Bromley,Kent:Sovereign, 1981. Ed. 2
• Gish D.T.: Evolution: the fossils say no, San Diego:Creation-Life Publishers, 1979. Ed. 3 (this is the third edition of a book first published in 1972 and is somewhat out of date)
• Gish D.T.: Evolution: the challenge of the fossil record, El Cajon, CA:Creation-Life Publishers, 1985.
• Lubenow M.L.: Bones of contention: a creationist assessment of human fossils, Grand Rapids,MI:Baker Books, 1992.
• Mehlert A.W. : Australopithecus and Homo habilis - pre-human ancestors? Creation Ex Nihilo Technical Journal, 10.2, 219-40, 1996.
• Menton D.N.: The scientific evidence for the origin of man, 1988. (a creationist essay)
• Taylor P.S.: The illustrated origins answer book, Mesa,Arizona:Eden Productions, 1992. Ed. 4
• Taylor P.S.:Who's who and what's what in the world of "missing" links?, 1996
• Taylor P.S. and Van Bebber M.: Who's who and what's what in the world of "missing" links?, 1995 (an earlier version of Taylor 1996