Evolution: a different view with loss of traits; not Behe (Introduction)

by David Turell , Sunday, September 13, 2020, 18:49 (1320 days ago) @ dhw

DAVID: And what is found is disappearance of DNA. If loss of DNA results in beneficial adaptation within a species, it is easy to make a stretch, as you do in so many of our debates, to suggest that might be the way new species appear. Behe's book makes quite a case for it. At least accept that point.

dhw: I am happy to accept the point that loss of DNA accompanies adaptation, and to accept the “stretch”. I’m not convinced that loss of genes causes adaptation, let alone speciation, but I'd need to study all the arguments for and against before forming any opinion. A “stretch” and “might be” and “quite a case” are all welcome modifications of your earlier authoritative statements. Meanwhile, you rejected my proposal on the grounds that there were no new genes. You have withdrawn that objection, so once more, please tell me why you still reject my proposal.

DAVID: You are struggling with the concept presented by Behe. He starts his book by presenting the polar bear who is closely related to the grizzly and the black bears, and evolved away by degrading two key genes. The field is changing. Time will tell you to support Behe or not.

dhw: I would not regard differences between bears as proof that speciation in the broad sense (e.g. bears versus cats) is always caused by loss of genes. These bears live in different environments, which suggests to me adaptation, with a loss of genes that would not be needed for their environment. But if your interpretation of Behe’s theory is correct, and he says all speciation results from loss of genes, yes, let’s see whether time and science support him.

The bears are just one example. I can't repeat the entire book here. I gave one example of many.

dhw: Meanwhile, I have asked you repeatedly why you have rejected my proposal, having withdrawn your original objection that there were no new genes. Here it is again, to refresh your memory:

I suggest that the process is on-going, with a constant acquisition of new genes (or new functions for old genes) and loss of unwanted genes. Natural selection merely decides which genes are necessary and which are not.[…]

New mutations occur by chance under Darwinian science. That is where you are starting. Have you forgotten that only a few new mutations are helpful, many are deleterious and the majority are neutral? Human DNA in everyone studied is filled with neutral mutations. I view evolution as over and Behe's probable explanation of speciation as a very cogent avenue for a new theory of speciation. But, yes, adaptation goes on either by deletion or gene modification.