This is the second in a six part discussion between BioLogos vice-president Karl Giberson and founder Francis Collins, co-authors of The Language of Science and Faith: Straight Answers to Genuine Questions (note: Francis Collins' work on this project was completed prior to his appointment as director of the National Institutes of Health). The conversation first appeared as "Evolution, the Bible, and the Book of Nature" in Books and Culture and took place during a conference at Azusa Pacific University in 2008.
Karl Giberson: One of the things I appreciate a lot about Darrel Falk, who I think is a courageous voice in this conversation, is that he will come out and say that common ancestry is simply a fact. And that if you’re not willing to concede that the genetic evidence points to common ancestry than you’re essentially denying the field of biology the possibility of having facts at all. That’s the strong language that he uses.
Would you say that common ancestry and evolution in general is at that level? How compelling is the evidence at this point?
Francis Collins: The evidence is overwhelming. And it is becoming more and more robust down to the details almost by the day, especially because we have this ability now to use the study of DNA as a digital record of the way Darwin’s theory has played out over the course of long periods of time.
Darwin could hardly have imagined that there would turn out to be such strong proof of his theory because he didn’t know about DNA - but we have that information. I would say we are as solid in claiming the truth of evolution as we are in claiming the truth of the germ theory. It is so profoundly well-documented in multiple different perspectives, all of which give you a consistent view with enormous explanatory power that make it the central core of biology. Trying to do biology without evolution would be like trying to do physics without mathematics
KG: But are not some of these comparisons cheating a bit? Isn’t it cheating when people like Dawkins compare the theory of evolution to, say, the theory of relativity? I don’t think this is a good comparison. To me, it seems like evolution is this gigantic, complicated tapestry of interwoven bits of explanatory power. Ernst Mayr talked about the five separate theories that come to together in evolution. But this big tapestry of evolution is filled with holes. It still hangs together, of course, but it does have holes. For example, evolution requires the invocation of common ancestors that we don’t have any fossil record for; we don’t really know anything about them, other than indirect DNA inferences. A layperson is understandably skeptical when they are told that there’s this tree of life going back to a common ancestor and all these animals are on the tree but we have no direct evidence for most of them and we have to infer them hypothetically. How do you respond to this large number of missing pieces in the puzzle? Does that bother you at all?
FC: I know it bothers people who are not really convinced yet about the consistency of the whole theory but it doesn’t bother me at all. Is the absence of a fossil representation of an organism really all that troubling when you realize that what you’re asking for in that case—fossilization— is extremely unlikely to have happened? Now we can actually go back and predict pretty much to the base pair what was the genome sequence of the common mammalian ancestor.
We have done that for big stretches of the genome to show how you can computationally assemble that information. And it’s breathtaking that you can actually look now at the DNA sequence, which is a fossil record of its own, of an organism that we’re all descended from. And so are all the other mammals because we have enough evidence from today that we are able to look back through history to see what that must have looked like.
Maybe because I’m a geneticist and I’m particularly interested in genomes, but that is more interesting to me than having a fossil record of that individual common ancestor because the genome is much more detailed and gives you a richness of information about that organism. And we can do that. So that fills in a lot of the holes. Again, evolution may seem from the outside to have a lot of complexities and components and, certainly, lots of details—some of which we haven’t worked out—and for anybody to say there are no arguments would be a total mistake. There’s lots of stuff we don’t agree upon. But we do agree upon descent from a common ancestor, gradual change over a long period of time, and natural selection operating to produce the diversity of living species. There is no question that those are correct. Those are three cardinal pillars of Darwin’s theory that have been under-girded by data coming from multiple directions and they are not going to go away. Evolution is not a theory that is going to be discarded next week or next year or a hundred or a thousand years from now. It is true.