Darwin hoped we'd discover evolutionary precursors to the animals of the Cambrian explosion, when the number of new species took a giant leap. Since then, paleontologists have uncovered many ancient fossils - even exquisitely preserved soft-bodied creatures from the Precambrian - but no credible ancestors to the Cambrian forms.
Should students learn about such weaknesses in modern evolutionary theory? Some insist the weaknesses are trivial because Darwinism is the cornerstone of modern experimental biology. Actually, it isn't, and high school biology students would be better served if they understood that.
Students could begin by reading a comment by Darwinist A.S. Wilkins, editor of the journal BioEssays: "While the great majority of biologists would probably agree with Theodosius Dobzhansky's dictum that 'nothing in biology makes sense except in the light of evolution,' most can conduct their work quite happily without particular reference to evolutionary ideas. Evolution would appear to be the indispensable unifying idea and, at the same time, a highly superfluous one."
My research with antibiotics during World War II received no guidance from insights provided by Darwinian evolution. Nor did Alexander Fleming's earlier discovery of bacterial inhibition by penicillin. Recently, I asked more than 70 eminent researchers if they would have done their work differently if they'd thought Darwin was wrong. All said no.
I examined the great biodiscoveries of the 20th century - the double helix, the mapping of genomes, the characterization of the ribosome, research on medications and drug reactions, improvements in food production and sanitation, new surgeries.
I even queried biologists in areas where you'd expect Darwinian theory to most benefit research, as in the emergence of antibiotic and pesticide resistance (antibiotic resistance was first recognized in the clinic, from fatal relapses among tuberculosis patients). Darwin's theory provided no discernible guidance. Instead, it was brought in, after the breakthroughs, as an interesting narrative gloss.
This, too, is its function in the many academic papers in experimental biology I considered. All this confirmed my suspicion: modern experimental biology gains its strength from new instruments and methodologies, not from historical biology.
When I suggested this disconnect publicly, I was vigorously challenged. One person noted my use of Wilkins and charged me with quote-mining.
The proof? Wilkins' subsequent passage: "Yet, the marginality of evolutionary biology may be changing. More and more issues in biology, from diverse questions about human nature to the vulnerability of ecosystems, are increasingly seen as reflecting evolutionary events. A spate of popular books on evolution testifies to the development."
Actually, the passage illustrates my point. The work mentioned there is not experimental biology but rather an attempt to explain already authenticated phenomena in Darwinian terms, things like human nature.
What's more, Darwinian explanations for such things are often too flexible: Natural selection makes humans selfish and aggressive - except when it makes them altruistic and peaceable. Or natural selection produces men who eagerly spread their seed - except when it produces men who are faithful protectors and providers. When an explanation is so supple it can explain any behavior, it's difficult to test it experimentally, much less use it as a catalyst for scientific discovery.
Darwinian evolution - whatever its other virtues - isn't the cause for breakthroughs in experimental biology. This becomes especially clear when we compare it with frameworks like the atomic model, which opened up structural chemistry and led to the synthesis of many new molecules of practical benefit.
What should be taught in high school biology classes? Focus on the variety of living organisms in our biocosm and on two questions: How do those organisms function so admirably over their lifetime, and how do they interact with one another?
For students aspiring to benefit society through experimental biology, Darwinism is simply beside the point.
Philip S. Skell is a member of the National Academy of Sciences and Evan Pugh Professor of Chemistry, emeritus, at Penn State University.