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?To this, Francis responds:
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.This is similar to what Jerry Coyne wrote (paraphrased) that even if we didn't have a fossil record, evolution would still be true, based on the genomic revolution that has occurred in the last fifteen years. The fact that we have the fossil record, which backs up the genomic evidence is just another nail in the coffin.
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.
Francis Collins finishes by writing: There’s lots of stuff we [his fellow geneticists] 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.Yup. Read the whole thing as well as the first post.