Survival of the fittest theory: Darwinism's limits by Fodor & Piattelli-Palmarini
(via Jerry Coyne's blog)
Yet another case of New Scientist realising that controversy sells, and so does crappy science journalism. I wouldn't call it anti-science, just horrible misinformed and poorly thought out. But that is not about to stop me from unleashing the mother of all rants. Just because I can. I have a midterm tomorrow, a horribly busy week ahead, and am sort of stressed and grumpy, so what better time is there to rip someone's article to shreds?
Now, I must say, as someone who's rather annoyed by the hyper-adaptationist tones both within and outside biological evolution, I must partly sympathise with some of their argument. But they take it too far, and seriously miss the freaking point. Also, there's a fine line between provocative revolutionaries and drama queens, and they crossed it ages ago.
Let's go!
Much of the vast neo-Darwinian literature is distressingly uncritical. The possibility that anything is seriously amiss with Darwin's account of evolution is hardly considered.Because we have better things to do than worry about what some guy got wrong 150 years ago?
The methodological scepticism that characterises most areas of scientific discourse seems strikingly absent when Darwinism is the topic.'Darwinism' is a topic? For the love of FSM, can somebody PLEASE enlighten me on what the fuck IS 'Darwinism'? In all my admittedly still short biological training, I have not once come across such a field. I've scoured evolutionary biology far and wide in search of 'Darwinism', and failed to find it. I know of molecular evolutionary biol, I know of population genetics, I know of cell evolution and genomic evolution and ecological evolution, evolutionary psych, evolutionary linguistics, evolutionary you-name-it... but not once have I c0me across this obscure discipline called Darwinism. Seriously, what am I doing wrong? How can I miss something so well-known by the general public and various outsiders?
OH FOR FUCK'S SAKE EVOLUTION DOES NOT EQUAL DARWINISM!!! I'm not even gonna rebutt that paragraph... *headdesk*
But we don't think it is true. A variety of different considerations suggesting that it is not are mounting up.Ok, I'm ready. This better be good!
Given a certain amount of conceptual and mathematical tinkering, it follows that, all else again being equal, the fitness of the species's phenotype will generally increase over time, and that the phenotypes of each generation will resemble the phenotype of its recent ancestors more than they resemble the phenotypes of its remote ancestors.Huh? "Species's phenotype"? I'm definitely no population geneticist (and suck at it), but something seems off about that phrase. Phenotype is something an individual has, not a species! Ok, let's assume they meant the species' average phenotype -- still sounds shaky but meh -- they're trying to say the overall fitness with regards to that trait would gradually increase over time? Well, sure, maybe. That's not really the crux of whatever they call 'Darwinism', since survival is much more important than improvement. 'Improvement' isn't actually necessary, but rather a byproduct of survival. "Survival of the good enough".
And as for the last part, phenotypes resembling those of recent ancestors more so than remote ones...isn't that like, basic inheritance, not selection? What the hell does that have to do with anything?
Skinner's theory, though once fashionable, is now widely agreed to be unsustainable, largely because Skinner very much overestimated the contribution that the structure of a creature's environment plays in determining what it learns, and correspondingly very much underestimated the contribution of the internal or "endogenous" variables - including, in particular, innate cognitive structure.Oh. So that's where we're going! Skinner's behaviourism became unfashionable in cognitive science and psychology (rightly so, but only because it was extreme -- elements of it may still be quite valid!), and since natural selection is an environmental explanation, it ignores inner developmental constraints and self-organising features. Apparently, Fodor and Piattelli-Palmarini think they're being revolutionary.
Stuart Kauffman beat them to it AGES ago. Thing is, he's a real biologist, and has plenty of modeling and real evidence backing his claims. He's does seem a bit loud about his argument, but
I happen to have Kauffman's The Origins of Order: Self organisation and selection in evolution sitting on my desk, for no good reason. (had to prepare a small talk on neutral evolution a while ago, but didn't quite swallow enough of Kauffman's rather terrifying math for it to be of any use at the time...)
First of all, what Kauffman attacks is what he calls the Neo-Darwinian Synthesis (Kauffman 1993 p10), which is the 'marriage' of what was at that time a Darwinian view of evolution, and Mendelian genetics into a new form of evolutionary biology. This was happening around the 60's, when it actually became feasible to talk about the stuff of biological inheritance -- DNA, genes, etc. Prior to that, evolutionary biology was mostly environment-oriented, mainly because that's all they had to work with. Perhaps that's what Fodor and Piattelli-Palmarini call 'Darwinism'?
A while later was Kimura's Neutral Theory, which while being quite accepted today apparently caused an uproar back in the day (1970's). This theory showed how some evolutionary change can happen independently of selection, by being selectively neutral. Later on we get Ohta's Nearly Neutral Theory (reviewed in Zuckerdandl 1996 J Mol Evol), where even slightly deleterious mutations can be tolerated, since selection would act much more strongly on greatly deleterious mutations rather than the slightly bad ones.
A common fallacy is to assume selection acts immediately and absolutely -- that any slightly bad change will automatically be removed. First off, selection takes time, and sure, if you randomly mutate a population and leave it static indefinitely, selection will eventually weed out all deleterious traits, even the very nearly neutral ones. But environments are messy and too turbulent to justify modelling selection as acting indefinitely. Secondly, selection follows a bit of a probability curve -- the strongly deleterious traits are much more likely to be erradicated within a certain unit of time, but that does NOT mean they necessarily will be! In summary, selection is not black-and-white, and plenty of neutral processes lurk in the background.
Even most selectionists would agree that selection is not a black-and-white thing, and that it works in conjunction with other processes. Our disagreement is how much emphasis to place on natural selection, not whether or not it exists!
Back to Kauffman. He states four issues he has with modern (as of 1993) Neo-Darwinian Synthesis (p10):
- Selection as the sole source of order in organisms. I agree there is a little too much emphasis on selection being the source of order -- self-organisation doesn't suddenly stop once selection comes into play! But most biologists recognise that, I think.
- The concept of a linear "genetic program". (the genome as a computer) He argues for a 'parallel distributed regulatory network', which is generally how developmental biologists view development today. In fact, networks are quite the hype these days...
- The tendency to see organisms as "ad hoc contraptions cobbled together by evolution." In other words, organisms being viewed as pure historical accidents. He argues that various changes have different probabilities, and that a likelihood model is more suitable than 'pure randomness'.
- The concept of developmental constraints in evolution. What Kauffman alludes to is this notion that if selective pressures would favour a certain trait, the organism would eventually develop it. Nowadays, with the rise of evo-devo and a slightly better understanding for how development actually works, everyone recognises developmental constraints!
Note that nowhere in there does Kauffman claim that natural selection is 'dead' or 'useless' -- instead, he argues that other processes are not to be ignored. Fodor and Piattelli-Palmarini, on the other hand, are little more than ignorant drama queens.
Speaking of drama queens, back to their article.
Over the aeons of evolutionary time, the interaction of these multiple constraints has produced many viable phenotypes, all compatible with survival and reproduction. Crucially, however, the evolutionary process in such cases is not driven by a struggle for survival and/or for reproduction. Pigs don't have wings, but that's not because winged pigs once lost out to wingless ones. And it's not because the pigs that lacked wings were more fertile than the pigs that had them. There never were any winged pigs because there's no place on pigs for the wings to go. This isn't environmental filtering, it's just physiological and developmental mechanics.And...? You've just shocked the entire evolutionary biology community! Fuck!
And then there is this in March 2009 from molecular biologist Eugene Koonin, writing in Nucleic Acids Research (vol 37, p 1011): "Evolutionary-genomic studies show that natural selection is only one of the forces that shape genome evolution and is not quantitatively dominant, whereas non-adaptive processes are much more prominent than previously suspected." There's quite a lot of this sort of thing around these days, and we confidently predict a lot more in the near future.More SHOCK! OH NOES, NATURAL SELECTION IS DEAD!!! Perhaps instead of criticising us, your should instead focus your energy on criticising your own discipline and your own misinterpretations of evolutionary theory? Just sayin'.
We should stress that every such case (and we argue in our book that free-riding is ubiquitous) is a counter-example to natural selection. Free-riding shows that the general claim that phenotypic traits are selected for their effects on fitness isn't true.Free-riding as a counter-example to natural selection? Huh? Followed by a complete non-sequitur. My, Jerry Fodor must have gone senile...
The most that natural selection can actually claim is that some phenotypic traits are selected for their effects on fitness; the rest are selected for... well, some other reason entirely, or perhaps for no reason at all.Doesn't selection by definition act on fitness? If the other traits have nothing to do with fitness, then, by definition, they are not 'selected for'. Why can't we just say 'evolved'?
It's a main claim of our book that, when phenotypic traits are endogenously linked, there is no way that selection can distinguish among them: selection for one selects the others, regardless of their effects on fitness.Ooooh, you discovered pleiotropy? Congratulations! =D Although the selection part is still muddled up a bit. But yeah, byproduct of selection do happen, quite frequently too. That doesn't mean there is no fitness involved!
Natural selection has shown insidious imperialistic tendencies. The offering of post-hoc explanations of phenotypic traits by reference to their hypothetical effects on fitness in their hypothetical environments of selection has spread from evolutionary theory to a host of other traditional disciplines: philosophy, psychology, anthropology, sociology, and even to aesthetics and theology.Actually, despite the drama queen -esque language ("insidious imperialistic tendencies" -- what the fuck?), I must kind of agree. Instead of applying evolutionary theory outside biology, the scholars instead just took natural selection, which is but a part of the overall theory. I have issues with that too. But this isn't so much a fault of evolutionary biologists (communication -- sure, but perhaps not so much the field itself) -- but rather the unwillingness of some rash humanities scholars to actually comprehend evolutionary theory prior to shoving it everywhere possible. Natural selection is a powerful concept that does deserve application outside biology, but in conjunction with other parallel processes!
Accordingly, if natural selection disappears from biology, its offshoots in other fields seem likely to disappear as well. This is an outcome much to be desired since, more often than not, these offshoots have proved to be not just post hoc but ad hoc, crude, reductionist, scientistic rather than scientific, shamelessly self-congratulatory, and so wanting in detail that they are bound to accommodate the data, however that data may turn out.HEY LOOK, WE'RE DRAMA QUEENS! WHEEEEE! Behold our powaz of teh rhetorik! MWAHAHA! But seriously, the very ideo of natural selection disappearing from biology...just...how? Dear FSM, how is that even supposed to be conceived? Any finite system is bound to have selection, just because you will eventually end up with limited resources, and subsequent competition for said limited resources, which will favour entities that are more stable and efficient at procuring said limited resources. If you agree that biological systems are finite (which they ultimately are, to any sane person), then it must follow that there will be competition and selection! It's inherent in the system!
Of course, natural selection is just one process, and that I'll agree with them on (although I seriously doubt that they really understand what they're talking about), and it may perhaps in some cases even not play a major role in order/change in complexity/evolution overall, but it's still there, lurking in the background, and directing evolution when the situation is right.
So it really does matter whether natural selection is true.How can it be untrue!? I don't get it -- they mean, there is no selection happening, AT ALL? So I guess competition in the business world also goes by some other model, that has nothing to do with natural selection, despite the concept actually originating there? Like...that sentence...makes no sense, actually. They could've asked "whether natural selection is significant in [situation X]" or "whether natural selection is a prominent force" or anything along those lines, but debating its truth value? Huh?
I guess I'm just too scientistically reductionist to comprehend such lofty topics. Oh well.
(I would've typically been more polite about stuff like this, but Jerry Fodor really pisses me off on some other topics too. Don't. Get. Me. Started.)
It sounds like these people have "natural selection" confused with "panadaptationism". If you replace the one with the other in any of their work, it starts to make sense. Not particularly new sense, but still.
ReplyDeleteSince you asked, the usual definition of "Darwinism" is equivalent to that of panadaptationism, for reasons that escape me completely. Darwin was quite explicit -- emphatic, even -- that natural selection was not the only force behind what he called descent with modification and what we call evolution.
That explains these authors' displeasure with "Darwinism", but not their misunderstanding of the concept of natural selection. The broad sweeping statements about "the vast neo-Darwinian literature" are merely indicative of them not being familiar with that literature. Yes, there are panadaptationists still out there, but disagreeing with them is hardly revolutionary.
This article is but further evidence that people mysteriously manage to get published in spite of not understanding their subject. I can only take comfort in this being popular-science literature, rather than something actually representative of the field -- although the downside to that is that this ignorant tripe might convince the laity that its authors are on to something.
In short: feh.
This entire 'adaptationism' vs. 'neutralism' thing has been a useless tempest-in-a-teapot discussion for years. For the most part, the panadaptationists don't exist, and neither do the non-adaptationists. Actual real scientists often disagree on the specifics of how much selection vs. drift/contingency/etc. played a role in the evolution of any particular trait, but the far edges of that spectrum are straw men.
ReplyDelete...In most cases. Because every once in a while you'll get a real wacko who'll come along and argue that some complex, intangible trait (like 'racism' or 'the sense of a square deal') was specifically selected for this or that purpose. Such arguments should draw the wolves. But otherwise, the people who come off as being firmly selectionist or driftist are much more in the middle than they come off.