October 11, 2007
Why Pigs Don’t Have Wings
Jerry Fodor in the London Review of Books:
We have just seen the last of a terrible century with, quite possibly, worse to come. Why is it so hard for us to be good? Why is it so hard for us to be happy?
One thing, at least, has been pretty widely agreed: we can’t expect much help from science. Science is about facts, not norms; it might tell us how we are, but it couldn’t tell us what is wrong with how we are. There couldn’t be a science of the human condition. Thus the received view ever since Hume taught that ought doesn’t come from is. Of late, however, this Humean axiom has come under attack, and a new consensus appears to be emerging: Sachs was right to be worried; we are all a little crazy, and for reasons that Darwin’s theory of evolution is alleged to reveal. What’s wrong with us is that the kind of mind we have wasn’t evolved to cope with the kind of world that we live in. Our kind of mind was selected to solve the sorts of problems that confronted our hunter-gatherer forebears thirty thousand years or so ago; problems that arise for small populations trying to make a living and to reproduce in an ecology of scarce resources. But, arguably, that kind of mind doesn’t work very well in third millennium Lower Manhattan, where there’s population to spare and a Starbucks on every block, but survival depends on dodging the traffic, finding a reliable investment broker and not having more children than you can afford to send to university. It’s not that our problems are harder than our ancestors’ were; by what measure, after all? It’s rather that the mental equipment we’ve inherited from them isn’t appropriate to what we’re trying to do with it. No wonder it’s driving us nuts.
More here. [Thanks to Jonathan Kramnick.]
Posted by Abbas Raza at 05:37 PM | Permalink
Comments
Arches don't select for spandrels or vice versa, arches and spandrels are a package that are selected. If traits are packaged, it's meaningless to say that one of the in-package traits (arches) was selected instead of another (spandrels). If spandrels are coextensive with arches, then architectural selection would select for the "arches and spandrels" package. Since tameness is part of a package and we select for the package, we get the side-effects of the package (such as fur color differences, and other neoteny).
He said: "why domesticated animals tend to have floppy ears. They just do". There is a deterministic cause. In the same way that buildings structure with arches get spandrels from geometry, animals bred for neoteny get other young-animal features like floppy ears due to natural selection acting on young animals. It is genetically advantageous for young animals to have a set of physiological features, and we've selected for them in adults. It's not "just because".
It's conceivable that in some other branch of creatures (not mammals), selecting for tameness would include a different (perhaps opposite) set of free-rider features, like stiffer ears. So what? No geneticist has ever claimed that genetic features are independent of each other, and that every trait has been independently selected for!
However, almost every trait (except for random, genetically-neutral mutations) is part of a genetic *package* that has undergone selection. Even if it has no effect on selection (eg. a spandrel), it's part of a package that has.
He says "Nor can I believe that living like a hunter-gatherer would make me happier". This argument is ridiculous, because being selected for a trait doesn't mean that you enjoy the trait! It's conceivable that depression could be selected for (if not in our world, in some other).
Furthermore, does he honestly not understand what "selection for" means? It's which animals have offspring, and that falls out from natural deterministic laws (physics, etc). This is easy first-year biology. It's not individual traits that are selected for, it's individuals. Individuals carry some of their traits in their genes.
Natural selection is, in fact, very similar to breeding because the evolutionary environment for selectively-bred animals is the breeder's care and judgement (instead of the savannah or jungle) - the mechanics of their genetic adaptation are identical. The term "environment" includes all the phenotypes of any animal that's interacted with, including the breeder, and the animal in question (which he seems to call "channeling"). And regarding winged pigs - does he believe adaptationism implies the claim that every possible animals needs to exist? Channeling is not mutually exclusive with natural selection. Either he's making claims that go over my head, or this whole article is ridiculous and flawed.
Posted by: - | Nov 3, 2007 4:01:46 PM
Hyphen,
When someone says that something has gone over his head, I have to wonder where that head is. Is it possible that you were ducking? Fodor's comments didn't seem particularly obscure to me, nor do you seem particularly dim.
Whether or not it is made explicit, the adaptationist perspective does imply that traits can be considered individually. Otherwise, how would we separate the wheat of selected traits from the chaff of "free riders?" In the case of domesticated animals, we know what was selected for, because we were there, and it was done purposefully. We know we weren't particularly interested in color patches in fur, or floppy ears, but rather in docility, companionability, and obedience.
In the case of natural selection though, we can only guess. The effects are visible to us but the causes are lost to time. Looking at a (biologically) historical equivalent of floppy ears, we can't with certainty determine whether or not it was advantageous in itself, or a free rider, in a package with some other selected trait. We can imagine how the trait might have conferred a survival benefit, and we may often imagine correctly, but true certainty would require a greater data set of environmental variables than we can possibly know.
What Fodor is calling "channeling" is a well-established factor of development that Waddington dubbed "canalization." It refers to the degree to which an organism will resist environmental influence, and it is described by precise cellular processes. In other words it is an anti-adaptationist mechanism. Without the innate robustness and persistence of phenotypes over time, life would simply be too unstable. What is perhaps more remarkable than how much life has changed in 4 billion years, is how much it has resisted change. Natural selection alone does not account for the means by which this resistence is possible.
Fodor's point is that to attribute every phenotypic trait to an environmental influence is to consider organisms as entirely pliable. What we know about molecular biology does not permit this consideration. The palatte of what can be selected for is restricted by the preservational forces (or mechanisms, if you prefer) in the cell. The old notion of genes (or gene "packages") being exposed naked on the proving ground of their environment, by which they are ruthlessly tried and tested, is not supported by the last 40 or 50 years of study into epigenetic factors such as chromatin, various enzymes, and so-called "regulatory genes." Stable organisms, and stable species, strike a balance between constancy and adaptability.
In addition to epigenetics, there is also the growing field of biological self-organization, which examines the extent to which the form, or order, of living things is "built in," in the same sense that every snowflake develops into a 6-tined crystal. We already know that lipids will form into a bilayer, under the right conditions, or that proteins will fold into complex 3D configuration, of their own accord (or in accordance with as-yet unarticulated laws). No gene controls these forms of organization. This means that organisms are not mere blank slates for nature to write on. Some things are never going to happen, just like no magnet is ever going to have 2 north poles, and no snowflake is going to be dodecahedral. This is what Fodor is after with his Pigs on the Wing discussion.
A modern scientific understanding of evolution must attend to the innate morphology of living things, as much as to to the external factors which influence their development. I believe a major block to this understanding is undue attachment to the old myth of "the struggle for existence," under which much contemporary biology continues to labor. There is struggle in life, to be sure, but there is also extraordinary providence. (Small "p").
Posted by: C. Schoen | Nov 6, 2007 12:08:56 PM
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