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

by dhw, Monday, September 07, 2020, 14:38 (1537 days ago) @ David Turell

dhw: 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.

DAVID: Your bolded proposal ignores the point of the article. It is now accepted that new mutations (new genes) are most always deleterious or if effective lead to minor alterations of no major consequence to furthering evolution. If read carefully, the article is in full support of Behe.

dhw: We are not talking about deleterious mutations but about gene loss. I challenged your statement that “advances ALWAYS result from loss of genes”. Look at the title: “By Losing Genes, Life Often Evolved More Complexity”. Often, not always.

By Losing Genes, Life Often Evolved More Complexity
Recent major surveys show that reductions in genomic complexity — including the loss of key genes — have successfully shaped the evolution of life throughout history.
https://www.quantamagazine.org/by-losing-genes-life-often-evolved-more-complexity-20200...

Here are some quotes from the article:

But in reality, the majority of gene losses during evolution are likely to be neutral, with no fitness consequences for the organism…

The reason is that evolutionary gene losses often occur after some change in the environment or behaviors makes a gene less necessary. If a key nutrient or vitamin suddenly becomes more available, for example, the biosynthetic pathways for making it may become dispensable, and mutations or other genetic accidents may make those pathways disappear. Losses can also occur after a chance gene duplication, when the superfluous copy degenerates, since selection no longer preserves it.

Of course, the risk of evolving by jettisoning genes is that even if a gene is dispensable in particular environmental conditions, it might be needed again millions of years later, Jedd says. What then? It turns out that yeasts, at least, can sometimes get genes back.

dhw: Please note the emphasis on the influence of the environment, the necessity or otherwise of the gene (he uses the term "dispensable"), and the role played by selection. There is nothing in the article about innovation. It deals with adaptation [although as I keep repeating, it is sometimes very difficult to draw a line between adaptation and innovation]. Under the photo of the author, we read: "Cristian Cañestro, a professor of genetics, microbiology and statistics at the University of Barcelona, has argued for years that gene loss can be an adaptive evolutionary force."

There is absolutely nothing in this article that contradicts my proposal bolded above.

David: The crutch of your leaning upon the word 'often' is refuted if you read the entire article with all of the studied cited. All implying loss of genes results in advances in form. I view 'often' as a hedge by the author about how current direction research is taking away from Darwin theory. A step most writers take hesitantly in today's resistance to leaving Darwin.

I read the entire article, which you claimed supported your argument that advances always result from loss of genes and which, as you can see, did no such thing. Of course I haven’t read all the studies cited – I can only comment on what you offer, and if you choose to ignore the quotes, that’s up to you. We are not discussing how right/wrong Darwin is/was/.

DAVID: The use of the word 'complexity' implies more than some adaptive modification. This article is couched in Darwin-protective terminology, but it supports, if carefully, the Behe direct attack. And please keep in mind, I have no 'hatred' of Darwin. He did the best he could. It is his current brain-dead researchers I abhor.

The use of ‘complexity’ is not the same as ‘innovation’, which is crucial to speciation in the broad sense (as opposed to variations within species, which some people also regard as speciation). I don’t see any hidden meaning in the quotes, which quite explicitly emphasize the role of the environment, and the fact that under certain conditions genes become dispensable and are therefore discarded, in keeping with the theory of natural selection. I find this completely logical. Perhaps now, forgetting about Darwin and using my own terminology, you would tell me why my own proposal bolded above is not feasible.