Fettisdagskorrespondens

(Bakgrund: Huruvida vi ska förkasta "gene's-eye"-perspektivet; rama in hötorgskonst med fläskfiléer; hjärnkok; julkorrespondens; skriket från vänster; Frågan på vilken människolivet är ett svar.)

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Dear professor Samir Okasha,

I finally read your book Evolution and the levels of selection. It contained a lot of the answers to questions I have struggled with for years, so I am happy that I ran across it. Thank you!

I have a few questions though, if you do have the time to answer [...]

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Dear [Antropofagi],

Thanks for your kind comments about my book. Apologies for the delay in replying. My replies to your queries are below.

First, on meta-debate:

1. Have you ever seen the "anti-group selection-lobby" (Pinker, Yudkowsky et al) respond to the content of your book? They seem to have made a good job of making thoughts about levels of selection taboo, and contributed greatly to the initial confusion that your book partially dissolved for me. I got the feeling that there was something there, that I wasn't allowed to pursue, if you know what I mean.

I haven't seen reviews by Pinker or other members of this lobby. I have generally tried to stay away from this debate, as it generates more heat than light. I think that both sides tend of overstate their case, both Pinker and the pro-group selectionists like DS Wilson. The truth lies somewhere in between.

On the more philosophical/metaphysical side:

2. Why is it that evolution on the "price equation level" (selection of genotypes) at all map on to the gene-frequency-view? With all the aspects of evo-devo, the fourth law of behavioural genetics, etcetera, why would we "see" evolution at all on our level of emergence? Why is it's signal visible to us? (I'm not sure how to phrase this question, but my hope is that you'll catch my drift.)

Well, I don't think that all evolutionary changes necessarily map onto changes in gene-frequency (which some authors make into a definitional truth); but most do. That is, if we define evolution as "change in frequency of different types in a population", and "type" is required to be heritable, then in practice this means that most of the time, if not always, evolution will involve gene-frequency change.

However, that is very different from saying that all evolutionary changes are best studied by studying gene frequency change - a reductionist view that I don't necessarily endorse.

3. Is there downward causation? Does selection occur on the fenotype-level at all, and how do you think about that?

Well, downward causation is a complex and much-debate issue. But I would say that selection does definitely occur at the phenotype level - in the sense that it is because of their phenotypic differences that organisms exhibit differences in survival / reproduction, and hence the population evolves.

Or should the good reductionist just assume that everything is a representation of the underlying facts of the "lowest" ontological level? Is that what constitutes the "book-keeping critique", that gene frequencies only track the "output" of evolution, while the interesting causal stuff happens when fenotypes are selected at the macro level? (You of course cover some perspectives of this in your book, but I feel as if I am still missing some crucial pieces of understanding here.)

We might be able to represent the outcome of evolution at the "lowest" level, but that doesn't mean that the causal process is taking place at that level. This is the point of the book-keeping critique, and I think it is basically right.

4. Why should the molecular biological level be considered a fundamental level in a reductionist ontology? Why should the genotype-level be more valid than the fenotype-level, when the real reductionist should want to reduce all the way down to the true base level of quarks or quantum amplitudes or what ever? Why does the molecular biology-level seem so inherently "stabil" in this context? (I mean, why does it show predictable patterns... I immagine that the quark-level should be less intelligible.)

Well, certainly the gene isn't the lowest level in the biological hierarchy - after all, genes contain smaller parts such as nucloetides. Eventually, if we keep going in disaggregating entities, we will arrive at entities that aren't biological at all, but rather chemical or physical.

It is only in the context of evolutionary biology that it's sensible to treat the gene as the lowest level - but even there, there is a tricky question about why this is. (cf R Dawkins' discussion about the "selfish nucleotide" theory).

5. You write the following:

The gene'seye approach has often been described as 'reductionist', both by its detractors and supporters [...] But in what sense? [...] It is true that molecular biologists frequently give 'bottom up' explanations from a genic basis, for example, when they explain cellular differentiation by reference to which genes in the cell are being transcribed. But the molecular biologist's 'gene' is not the same as the 'gene' of the gene's-eye theorist [...] The former refers to a length of DNA that codes for a protein, the latter for a lenght of DNA that survives meiosis intact. So although the research programme of molecular biology is reductionistic, in the part-whole sense, this has no bearing on the gene's-eye approach to evolution.

This blew my mind a little bit. Is it correct to revise my understanding so that genes are not at all a more fundamental layer of reality? That what is selected for or against is not what constitutes a kind of base layer in this context, i.e. molecular biology? Does this mean that there is nothing to the reductionist claim, or should we just be a little bit more careful with our ideal, Scala natura-type of ontological hierarchies?

Well, the point I am making in this passage isn't original - it is a familiar point, emphasized by Dawkins himself and many subsequent philosophers of biology - that "gene" means different things in different contexts. What a molecular biologist calls a gene isn't the same as what a classical population geneticist calls a gene.

6. Do I make my self guilty of some kind of fallacy when I at all consider genes to be somewhat more fundamental than fenotypes? It strikes me (and maybe you argue that in the book somewhere, I don't remember) that a body is made up of muscles etc. that are made up of cells etc. that are made up of organelles that are made up of ... molecules, atoms, subatomic particles, etcetera. The genes does not seem to be any kind of actual building block or level of fine-granuilty in this layering. They appear to code for structures from the sideline at one particular level, so to speak. To use a tired analogy, more of a blueprint than building blocks.

I agree that genes are not the building blocks in this sense. But the importance of genes is that they are passed on, more or less intact as discrete units, from one (organismic) generation to another. This is why they are the focus of evolutionary analysis.

Ok, this was leanghty but my confusion is still boiling and I fear that I might even lack the understanding to understand what I don't understand.

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Have a good one, despite the pandemic, and thank's again for a wonderful book [...]

Best regards, [Antropofagi]

[B]est wishes

Samir