https://www.huffpost.com/entry/replace-the-modern-sythes_b_5284211***********
Suzan Mazur: In recent years the modern synthesis has been declared extended by major evolutionary thinkers (e.g., "the Altenberg 16" and others), as well as dead by major evolutionary thinkers, the late Lynn Margulis and Francisco Ayala among them. Ditto for the public discourse on the Internet. My understanding is that you are now calling for the modern synthesis to be replaced.
Denis Noble: I would say that it needs replacing. Yes.
The reasons I think we're talking about replacement rather than extension are several. The first is that the exclusion of any form of acquired characteristics being inherited was a central feature of the modern synthesis. In other words, to exclude any form of inheritance that was non-Mendelian, that was Lamarckian-like, was an essential part of the modern synthesis. What we are now discovering is that there are mechanisms by which some acquired characteristics can be inherited, and inherited robustly.
my argument for saying this is a matter of replacement rather than extension is simply that it was a direct intention of those who formulated the modern synthesis to exclude the inheritance of acquired characteristics. That would be my first and perhaps the main reason for saying we're talking about replacement rather than extension.
The second reason is a much more conceptual issue. I think that as a gene-centric view of evolution, the modern synthesis has got causality in biology wrong. Genes, after all, if they're defined as DNA sequences, are purely passive. DNA on its own does absolutely nothing until activated by the rest of the system through transcription factors, markers of one kind or another, interactions with the proteins. So on its own, DNA is not a cause in an active sense. I think it is better described as a passive data base which is used by the organism to enable it to make the proteins that it requires.
The third is an experimental reason. The experimental evidence now exists for various forms and various mechanisms by which an acquired characteristic can be transmitted.
Suzan Mazur: Margulis added that "people are always more loyal to their tribal group than to any abstract notion of truth. Scientists especially tend to be loyal to the tribe instead of the truth."
Would you comment?
Denis Noble: I would certainly go along with the view that gradual mutation followed by selection has not, as a matter of fact, been demonstrated to be necessarily a cause of speciation.
Suzan Mazur: University of Chicago microbiologist Jim Shapiro, whose work you cite, told me in our 2012 interview that he no longer uses the word "gene," saying: [
I]t's misleading. There was a time when we were studying the rules of Mendelian heredity when it could be useful, but that time was almost a hundred years ago now. The way I like to think of cells and genomes is that there are no "units"; there are just systems all the way down.What is the status now of the gene in your view?
Denis Noble: My argument is very simple. Wilhelm Johannsen in 1909 introduced the definition of "gene." He was the first person to use that word, although he was introducing a concept that existed ever since Mendel. What he was actually referring to was a phenotype trait, not a piece of DNA. He didn't know about DNA in those days. We now define a gene, when we attempt to define it, as a particular sequence with "start" and "stop" codons, etc., in a strip of DNA. My point is that the first definition of a gene -- Johansen's definition as a trait, as an inheritable phenotype -- was necessarily the cause of a phenotype, because that's how it was defined. It was, if you like, a catch-all definition of a gene. Anything that contributed to that particular trait -- inheritable, according to Mendelian laws -- would be the gene, whether it is a piece of DNA or some other aspect of the functioning of the cell. That we define "gene" as a sequence of DNA becomes an empirical question, not a conceptual necessity. It becomes an empirical question whether that particular strip of DNA has a function within the phenotype.
So I go further than Jim. Not only is it difficult, as he says in his book, to now define what a gene is; one should be thinking more of networks of interactions than single and fatalistic genes at the DNA level. It's also true that the concept of a gene has changed in a very subtle way, and in a way that makes a big difference to how the concept of a gene should be used in evolutionary biology.
Suzan Mazur: There's also natural selection, which became a catch-all term. As Richard Lewontin has pointed out, it was intended as a metaphor not to be taken literally by generations of scientists.
It seems natural selection is used as a catch-all for a failure to identify what the mechanisms are.
Denis Noble: I think that's right. In principle, Darwin didn't refer to any mechanisms.
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