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Tuesday, May 02, 2017

Debating philosophers: The Modern Synthesis

I'm discussing a paper by Lu and Bourrat (2017) [Debating philosophers: The Lu and Bourrat paper]. They begin by describing current evolutionary theory, known (to them) as the Modern Synthesis. The paper is about challenges to current evolutionary theory from those who advocate an extended evolutionary synthesis or from those who would replace, rather than extend, current evolutionary theory. It is reasonable to begin with a description of the theory that's being challenged.

Here's what Lu & Bourrat say,

By the 1940s, the marriage between Darwinian theory of evolution (Darwin 1859) and Mendelian genetics (Correns [1900]; Tschermak [1900]; de Vries [1900]; Mendel [1865]) was integrated into a general consensus known as the Modern Synthesis (MS). This synthesis provided theoretical foundations for a quantitative understanding of evolution. It has been regarded as a paradigm for evolutionary theory over the last sixty years. The original MS has been extended in at least three regards. First, since the 1950s, classical population genetics has been generalized to quantitative genetics for continuous traits (Falconer and Mackay [1996], p. 100). Although the former focuses on allele frequencies and genotypes, whereas the latter by its nature begins from the phenotype, the mathematical models of the two can be formally connected (Wade [2006]). Therefore, we will regard both disciplines as formal evolutionary theory in this paper. Second, formal evolutionary theory is now better suited to account for the evolution of microorganisms and plants, which used to be the glaring omission of classical population genetics (Ayala et al. [2000]). Third, progress made in various biological sub-fields has extended evolutionary theory in many respects. The discovery of DNA structure in 1953 (Watson and Crick [1953]), for instance, prompted the development of molecular genetics and stimulated the discussion of gene selectionism. Also, the integration of development and evolution resulted in the new research field of evolutionary developmental biology (Goodman and Coughlin [2000]). In spite of these three extensions, current evolutionary theory is still remarkably reliant on the tenets of the MS.
I don't think I've ever heard of those three extensions before—at least not in the way they are described here. The problem with this description is that the really important modification of the classical Modern Synthesis is completely ignored. I'm referring, of course, to Neutral Theory and the increased emphasis on random genetic drift. This has led to all kinds of developments that are completely foreign to the original tenets of the classic Modern Synthesis. It's rather silly to refer to current evolutionary theory without mentioning these changes.

It's impossible to imagine how proponents of the old Modern Synthesis could possibly understand concepts such as the drift-barrier hypothesis [Learning about modern evolutionary theory: the drift-barrier hypothesis] or constructive neutral evolution [Constructive Neutral Evolution (CNE)] or junk DNA. How could they have understood sequence comparisons and molecular clocks without incorporating Neutral Theory and random genetic drift?

Lu & Bourrat have fallen into the same trap as those who promote an extended evolutionary synthesis. They are describing a strawman version of evolutionary theory that hasn't represented the current view for over 40 years [Kevin Laland's new view of evolution] [More calls to extend the defunct Modern Synthesis] [Rethinking evolutionary theory].

I'm reminded of a comment by Arlin Stoltzfus [Arlin Stoltzfus explains evolutionary theory] who said,
Every scientist with a PhD knows that it takes years of study to be an expert-- you not only have to ingest hundreds of books and papers, you have to digest this information, sifting it and evaluating it, and converting it into knowledge and judgment. Yet evolutionists all think they are automatic experts on the topic of "the Modern Synthesis" or "the history of evolutionary thought" without doing original research on it, or reading hundreds of secondary sources.
Understanding current evolutionary theory is hard. I urge philosophers (and others) to work harder at the task. They could begin by reading a modern evolutionary biology textbook and then read the primary literature written by experts in evolutionary theory and modern population genetics.

What they can't do is rely on the secondary literature written by opponents of the old classical Modern Synthesis. If you are going to write a paper on challenges to the Modern Synthesis then you'd better do your homework or you are going to look rather foolish.

There are many scientists who don't understand evolution (e.g. ENCODE researchers). They have no excuse. If they are going to write about evolution in their papers then they'd better get it right. However, philosophers of science who write about evolutionary theory are in a somewhat different category since they portray themselves as experts in the subject. It is, after all, their specialty. When they publish a philosophical paper about evolution one holds them to a very high standard. They don't often meet that standard and that's surprising.

Lu, Q., and Bourrat, P. (2017) The evolutionary gene and the extended evolutionary synthesis. The British Journal for the Philosophy of Science, (advanced article) April 20, 2017. [doi: 10.1093/bjps/axw035] [PhilSci Archive]


Joe Felsenstein said...

I didn't realize that the Modern Synthesis originally did not take quantitative characters into account. I always thought that Fisher, Wright, and Haldane, whose work was the original foundation of the modern synthesis, had something to do with the theory of quantitative genetics.

Similarly for plants.

Someone is relying too much on secondary sources for their history.

Larry Moran said...

See, you learn something new every day from philosophers. :-)

Robert Byers said...

Did Watson/Crick DNA "discovery" stimulate the discussion of gene selectionism??
I see no relation between REAL TIME gene structures and how they were selected, if they were, in biology change.
In fact it seems close again to the selfish gene concept!

A creationist would say dNA helped in no way evolutionism . it only allowed a furtherance of a line of reasoning of connecting genes together based on likeness. Yet DNA does not show any common descent. Any more then fossils do.
Its funny yet more science paper researchers are said to not understand evolution!!
I think it is true that it really is a complicated subject .
In fact creationists would say Darwin made it too simple about what is very complicated.
Biology is more glorious in its elements then physics subjects. Physics wrongly gets a higher grade for being complicated and so its thinkers get more acclaim.

pierrick Bourrat said...

I did not realize that when someone writes "First, since the 1950s, classical POPULATION GENETICS has been generalized to quantitative genetics for continuous traits (Falconer and Mackay [1996], p. 100)" means that they refer to the MODERN SYNTHESIS. I always thought they were refering to POPULATION GENETICS. Someone has read a lot of primary sources but I hope they did so in a much more careful way than that.

I see that I learn something every day from *some* biologists. ;-)

Anonymous said...


You missed the entire paragraph before your (out of context) quote.


P.S. Read(properly) & learn (from biologists)!

judmarc said...

They could begin by reading a modern evolutionary biology textbook and then read the primary literature written by experts in evolutionary theory and modern population genetics.

This is something I've been thinking of lately. Gerard t'Hooft, a Nobel Prize winner, was kind enough to list on his web site various suggested readings to develop some knowledge in some developments in physics. While being an autodidact lacks advantages provided by learning with experts and peers, did you have any suggestions for books that might help interested amateurs who want to make a start?

Paul griffiths said...

It is very depressing how much of this discussion and commentary focuses on the low standards of 'amateurs' and 'autodidacts' and 'philosophers'. This is an argument from authority. It is also a bit silly, as both these authors have biology degrees, and one has published a number of articles in behavioral ecology in their previous career as a scientist. I say that just to neutralise the argument from authority. Now let's focus on the substance!

christine janis said...

There's a difference in an argument *from* authority and an argument *with* authority

Anonymous said...

I was drawn here by the linking of philosophy with science. I was a bit surprised to get the impression that only recently was the emphasis put on quantitative analysis but on re-reading I realise you're not saying that. But you got a comment from Joe Felsenstein! Wow! I'd have been pretty pleased if he'd commented on my blog! How cool just to flick him off with an implication that he's just another philosopher :-S . Actually I'm pretty certain he'll go down in history as a bioinformaticist.

"How could they have understood sequence comparisons and molecular clocks without incorporating Neutral Theory and random genetic drift?"
Many evolutionists I know don't understand genetic clocks amongst other things.

"Yet evolutionists all think they are automatic experts on..."
Many evolutionists think they're experts in things they aren't.

"However, philosophers of science who write about evolutionary theory are in a somewhat different category since they portray themselves as experts in the subject."
Experts in philosophy of science or evolutionary theory? Few scientists have adequate expertise in philosophy of science.

Faizal Ali said...

It's always risky to make comments about a blog you have just joined. If you had first looked thru the archives,, you would have seen that Joe Felsenstein has a long and distinguished history of commenting on this blog, and that Larry Moran is quite well aware of who he is. With that context, perhaps you will now be able to properly understand Larry's response. (The smiley at the end is a hint.)

Faizal Ali said...

Oh, in addition: A quick look thru the archives would also reveal that Larry is very prone to criticizing his fellow evolutionists for not understanding basic concepts e.g. neutral theory. In fact, he does that in this very article. Somehow, you seem to have overlooked this.

Anyway, welcome to Sandwalk!

Anonymous said...

Ah - Right!

Thanks Lutesuite :-) . I don't look through the archives of every blog I comment on but these ones I expect to check out in due course! Cheers.

Eric said...

"The value today of philosophy to physics seems to me to be something like the value of early nation-states to their peoples. It is only a small exaggeration to say that, until the introduction of the post office, the chief service of nation-states was to protect their peoples from other nation-states. The insights of philosophers have occasionally benefited physicists, but generally in a negative fashion—by protecting them from the preconceptions of other philosophers."--Steven Weinberg, "Dreams of a Final Theory"

I would replace "physics" with "biology", and leave the rest of the Weinberg quote alone.