Ch. 9: Searching for Quality

[Chris OConnor]

Ch. 9: Searching for Quality

Please use this thread to discuss the above listed chapter of "Darwin's Dangerous Idea: Evolution and the Meanings of Life" by Daniel Dennett.

[Harry Marks]

My main reactions here are to his oblique criticisms of Gould and Lewontin. Several issues.
First, he does not go into the character of their objection. I have not read Gould and Lewontin, but I find it objectionable in quasi-academic discourse to conclude, as he does at the end of the chapter, that they have looked for an intellectual skyhook, without ever going through an explanation that motivates this. In my other reading of Gould, he sets out a fairly clear case for believing that contingency can play a role as great as adaptation in determining particulars of a species' genotype. Dennett in fact agrees with every proposition Gould has made in the abstract, about what might happen, and is very vague about his criticism of the application of this in practice.

[Likewise, Gould has pretty much agreed with the points made about adaptation, including that biologists have no better approach to offer. He seems to simply lay down a marker that contingency needs to be kept in mind as an alternative. One of Dennett's examples from Dawkins, a hyper-adaptationist if there ever was one, makes this point. The flatfish with the suboptimal strategy probably was working with the contingency of a "hidden constraint" and Dawkins seems comfortable with that even though Dennett only gives it a free pass in Dawkins' hand.]

So he should have explained the role of contingency, and perhaps given a sense of the connection to Gould's "Punctuated Equilibrium" reading of the fossil record. If, as Gould suggested (too strongly, in "Wonderful Life") much of the variation we observe in nature is due to a proliferation of species after the board has been cleared, so to speak, by a mass extinction, with some of the experiments succeeding and many failing, then the accidents of asteroid impacts and mega-volcanism may have set many of the parameters for which life succeeded and which failed. Suppose, for example, that the dinosaurs had been wiped out before the proto-mammals evolved. We might have an environment in which only lizards survived, and anything remotely like a mammal was eaten by the bird-branch of reptilia before it could experience whatever advantage it had over dinosaurs.

Gould believed that the record we have, with hundreds of millions of years dominated by dinosaurs, reflects the general case: what has succeeded continues to succeed, and so the genotypes are fairly stable over time, at least to the extent we can look at the fossil record to see.

Instead, Dennett chose to start out complaining about "some readers' interpretations" of Gould and Lewontin, and then reach some pretty negative conclusions about the work itself without explaining.

Second, his invocation of a Turing machine for the use of the Game of Life to find an optimal chess strategy struck me as an egregious abuse of "infinity." It may be true, in some abstract sense, that you can use such a totally unsuited mechanism to solve a real problem, but that is about as helpful as setting the million monkeys typing in order to hammer out a work of Shakespeare. You would die and your descendants to the thousandth generation be rotting in their graves long before any of you could locate the Shakespeare in any of that randomness.

Third, I rather liked the game theory role and the examples given. Cooperation is a big issue in economics, as well as political science, and it is useful to think about how its role is played in the "mindless" setting of genetic competition. If only to highlight the potential for minds to find the win-win that genetics cannot seem to do.

[Harry Marks]

So, when I sat down to read Ch. 10, I realized that the conclusion I objected to in Ch. 9 was in the paragraph where he gives a preview of the upcoming chapter. I will respond under Ch. 10's discussion, where I think my comments belong.

[geo]

. . . Dennett chose to start out complaining about "some readers' interpretations" of Gould and Lewontin, and then reach some pretty negative conclusions about the work itself without explaining.

I'm finally getting back into this book and will have to agree with Harry here on several points.

In this chapter, Dennett makes a convincing case why an adaptionist approach is crucial to evolutionary science. For example, we would suppose that color vision emerged in evolution, not merely to "delight men's eyes" but to provide some kind of advantage, either in survival or sexual selection or both. Using an adaptionist approach, scientists can come up with a "Just So" story to explain this adaptation, and either the evidence will bear it out or it won't. According to Dennett, this kind of reverse engineering has been shown to predict areas of research in evolution with stunning success.

This quote from Martin Daly, a Professor of Psychology at McMaster University, is useful, I think.

Adaptionism, the paradigm that views organisms as complex adaptive machines whose parts have adaptive functions subsidiary to the fitness-promoting function of the whole, is today about as basic to biology as the atomic theory is to chemistry. And about as controversial. Explicitly, adaptionist approaches are ascendant in the sciences of ecology, ethology, and evolution because they have proven essential to discovery . . .

For some reason, Dennett focuses a lot of attention to the “massively misread classic” paper by Stephen Jay Gould and Richard Lewontin, The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptionist Programme. Phew!

Dennett himself spends a lot of time explaining the limitations of adaptionist thinking. You can come up with a “Just So” explanation for just about anything, but it remains a “Just So” story until the evidence bears it out. (The “Panglossian reference in the title of Gould’s paper is a reference to Voltaire’s satire, Candide. Dr. Pangloss is the one who claims that this world is the best of possible worlds and then goes on to rationalize all the evils of the world like disease and death.)

So, on one hand, Dennett describes the paper as a “classic” but then proceeds to attack it and Gould for being anti-adaptionist. Indeed, this attack almost becomes the focus of this chapter. And, as Harry says, he provides absolutely no context for this attack. It’s as if he himself as suddenly become one of those misreading the paper. He points to this passage from Gould’s and Lewontin’s paper:

. . . The eskimo face, once depicted as "cold engineered" (Coon, et al., 1950), becomes an adaptation to generate and withstand large masticatory forces (Shea, 1977). We do not attack these newer interpretations; they may all be right. We do wonder, though, whether the failure of one adaptive explanation should always simply inspire a search for another of the same general form, rather than a consideration of alternatives to the proposition that each part is "for" some specific purpose.

It seems to me that Gould and Lewontin are only suggesting that we keep an open mind and to keep looking for other possible adaptive explanations. We have all seen time and again how the real world turns out to be more complex than we had previously imagined. And many biological adaptations have multiple purposes or even change from one use to another over time. This is where the famous reference to spandrels in architecture comes in. But Dennett cites this specific passage and says this:

What particularly infuriates Gould and Lewontin, as the passage about the Eskimo face suggests, is the blithe confidence with which adaptionists go about their reverse engineering, always sure that sooner or later they will find the reason why things are as they are, even if it so far eludes them.

You may be scratching your head now, wondering how Dennett could possibly interpret this passage in this way. It seems to me that Dennett is creating a straw man just so that he can attack something. Indeed, take a look at the entire paragraph from Gould’s and Lewontin’s paper:

If one adaptive argument fails, try another. Zig-zag commissures of clams and brachiopods, once widely regarded as devices for strengthening the shell, become sieves for restricting particles above a given size (Rudwick, 1964). A suite of external structures (horns, antlers, tusks) once viewed as weapons against predators, become symbols of intra-specific competition among males (Davitashvili, 1961). The eskimo face, once depicted as "cold engineered" (Coon, et al., 1950), becomes an adaptation to generate and withstand large masticatory forces (Shea, 1977). We do not attack these newer interpretations; they may all be right. We do wonder, though, whether the failure of one adaptive explanation should always simply inspire a search for another of the same general form, rather than a consideration of alternatives to the proposition that each part is "for" some specific purpose.

So Dennett veers from a thorough, well-reasoned, and truly fascinating argument for adaptionism to this sometimes shrill and poorly argued rant against Gould and Lewontin. Maybe he was trying to inject a little controversy into the book, but he fails to show that Gould is anti adaptionist at all. And I’m not willing to take his word for it.

This discussion of Gould's and Lewontin's paper was a minor detour and overall this was a very interesting chapter. I especially like Dennett’s analogy of the chess player who makes a move and realizes that he will be able to check mate in two moves. “How brilliant—and I almost thought of it!”

Dennett: “. . . this retrospective endorsement of brilliance is the way Mother Nature herself always operates. Adaptionists should hardly be faulted for being unable to predict the brilliant moves that Mother Nature herself was oblivious of until she’d stumbled upon them.”