The famous and distinguished film critic Roger Ebert passed away yesterday, after a heroic battle against throat cancer that left him voiceless but hardly wordless the last seven years of his life. The news about the death of such an influential and heroic man was all over the airwaves, especially in Chicago, his hometown and base.
Listening to the reports of Ebert's passing, I was surprised to learn that he had blogged about evolution. Curious, I did a Google search for "Roger Ebert Evolution" to find out what he said.
The first item to appear was a posting on Jerry Coyne's blog, whyevolutionistrue, "Roger Ebert died." Predictably, after praising Ebert's cinematic and culinary taste, Jerry played the religion card: "Ebert was a semi-vociferous atheist, and showed it a bit in a wonderful profile in Esquire (do read it)..."
Looking at Ebert's own posts, I tried to track down what it was he actually said about evolution and the contentious debates about where biological diversity comes from. My search yielded mixed results.
On the positive side, in Ebert's blog on Darwin and Lincoln's joint 200th birthday (Darwin survives as the fittest, February 11, 2009), he elaborated five major points:
1. Do not confuse the everyday use of the word theory with the rather strict scientific definition of the word.
2. Science has no opinion on the supernatural.
3. The Theory of Evolution does not require that you abandon your religion, or vice versa.
4. Neither the Theory of Evolution nor Intelligent Design knows how or why the universe was started, or how life began
5. Darwin did not say your grandfather was an ape.
Certainly, there is little to argue with there. One might even take the second and third points as a rejection of Jerry's atheist proselytizing.
But Ebert's knowledge of the science, like that of most journalists, was limited to conventional wisdom. In his original critique of a pro-ID film called eXpelled, Ebert combined an astute critique of creationist tactics with an exaggerated statement about Darwin's accomplishment and the fate of Darwinism in the days of molecular genetics and genome sequencing:
Darwin's Theory has been much developed and improved by countless scientists over the years, most dramatically since the discovery of DNA -- which Darwin knew nothing about, but which uncannily supported his theory and revealed the mechanism by which it works. The Theory has been called "the best theory in the history of science.
Before we examine the impact of DNA evidence on its merits, it is fair to say that Darwinism has a number of competitors for "the best theory in the history of science." Certainly Newtonian mechanics, Einstein's relativity and quantum mechanics are reasonable candidates for this high praise.
Interestingly, however, some of these competitors for "the best theory in the history of science" have contradictory underlying assumptions. This mutual incompatibility reflects the fact that every theory in science, even the best, is not an eternal statement of truth about nature. They are all just approximate explanatory schemes, inevitably subject to be overturned by new technologies, new data and new ideas. How could we expect it to be otherwise?
What does the DNA evidence tell us about Darwin's views?
Certainly genome sequencing agrees with the view that organisms share ancestry and have changed over time, the idea encapsulated in the phrase "descent with modification." Through genome sequences, we can look more deeply and more thoroughly at the relationships between all forms of life currently on planet Earth.
But the idea of "descent with modification" did not originate with Charles Darwin. It was articulated decades before Origin of Species by a number of thinkers, including Darwin's own grandfather, Erasmus.
Darwin's proposal for how the process of "modification" operates reflected the gradualist philosophy of his geology professor, Charles Lyell:
"If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down." (Origin of Species, chapter 6)
Darwin, of course, knew nothing about cell organization, genetics, chromosomes, DNA or microbes when he advanced his ideas about evolution. For him, all heredity was vertical and went from parent to offspring.
How could Darwin possibly have anticipated some of the many aspects of major rapid hereditary modification that now loom so large in our thinking about evolutionary variation?
• Symbiogenesis and cell evolution
• Horizontal DNA transfer
• Viral infection and proviral genome incorporation
• Hybridization between species and whole genome duplication
• Chromosome rearrangements
• Mobile genetic elements
• Epigenetic heredity and variation
• Regulatory networks and morphological evolution
Roger Ebert was a wonderful film critic and writer. But like many people expressing certainty about the conventional wisdom in a distant field, he was out of his depth.
Ebert had every right to condemn creationist propaganda in films. But he was not in a position to make declarations about the quality of Darwin's evolutionary theory. "The best theory in the history of science" was far more fragile and challenged by DNA evidence than he could ever have imagined.