30 September 2007

Sympathy for the Devil's Chaplain (Part I)

Well, I guess I should start with some contrition. I have gotten cheap laughs referring to Richard Dawkins as an idiot, such that students of mine have twice referred to him simply as 'The Idiot,' knowing they'd be perfectly well understood. The context of this classroom slander is his infamous conflation of Christian belief and natural theology, an obnoxious habit for which he has been amply excoriated (e.g., by Michael Ruse and Alister McGrath). Years ago, when I first read his 1995 Scientific American piece "God's Utility Function," I was astonished by the banality of the argument, and for years thereafter I had him pegged as the anti-Phillip Johnson, the yin to scores of creationist yangs. After all, when Dawkins talks about religion, he tends to make an ass of himself. (Some of his friends can see this, and they note it ruefully. I'm not sure what's going on with those who rise to his defense.)

Now, I'm not at all sorry about observing that the Professor with the Overlong Title frequently makes atheists look like ignorant thugs. But the whole 'idiot' thing... well, here's the problem. I've recently read some of Dawkins' other work, the stuff that made him famous enough to be able to publish swill like The God Delusion on something other than, say, a blog. :-) And this work is just flat brilliant -- I mean over-the-top fantastic -- and now I'm feeling a little sheepish about suggesting that Dawkins is a simpleton. So, I have two aims in these next two posts: 1) in the current post, to reflect on (and strongly recommend) the book that Dawkins himself identifies as his best work; and 2) in the next article, to give the Professor with the Overlong Title credit for at least some of his many claims that are fully correct -- claims that are, in some cases, proof texts cited repeatedly by Christian critics.

So: let's see if you can guess which of these Dawkins masterpieces has been identified by the author as his best (or at least his most important):
  • The Blind Watchmaker
  • The Selfish Gene
  • The God Delusion
...time's up! Well, if you picked any one of the above, you're wrong! Nyaahahahaha! (Unfair! Unfair! Unf--ooof!)

Uh, seriously, here is an excerpt from the preface of the Oxford Paperback Edition of The Extended Phenotype:
I suppose most scientists -- most authors -- have one piece of work of which they would say: It doesn't matter if you never read anything else of mine, please at least read this. For me, it is The Extended Phenotype. In particular, the last four chapters constitute the best candidate for the title 'innovative' that I have to offer.
That preface was written in 1989, after The Blind Watchmaker, but admittedly before The God Delusion. Perhaps the Devil's Chaplain doesn't think his most recent work is an embarrassing joke, but plenty of his fellow evolutionists/scholars/atheists do, and so I'm willing to bet that Dawkins hasn't changed his mind about The Extended Phenotype. (None of his other works from 1990 on seem to come close, but I'll gladly accept nominations from those who feel otherwise.)

Originally published in 1982, The Extended Phenotype has three main sections:
  1. An introductory section in which Dawkins answers criticisms and objections to the "gene's-eye view" of life that he first put forth in The Selfish Gene;
  2. A longer middle section in which he advances arguments for the primacy of the "genetic replicator" as the so-called unit of selection; and
  3. The final four chapters, "the heart of the book," in which Dawkins describes the concept of the extended phenotype, nicely summarized in the 1989 edition's subtitle: "The long reach of the gene."
I won't review the whole book here. Instead, I'll offer some highlights from those three sections.

Section 1: Dealing with objections to the gene's-eye view of selection

I'm a huge fan of Stephen Jay Gould. I once got to talk to him on a call-in radio program in Boston. (The Connection, then with Christopher Lydon. Maybe you heard me...the show was national. The topic was evolution for some reason, and it was Opening Day 1998 or 1999.) And Gould was, as you might know, one of Dawkins' most bitter rivals. I still count Gould as one of my favorite authors (he was, among other things, the pre-web incarnation of the ultimate blogger), but his well-intentioned vendetta against "genetic determinism" sometimes led to oversimplification. And one of his main beefs with Dawkins' ideas was this one: that too strong an emphasis on genes as targets of evolutionary selection can lead to a sort of biological Calvinism:
If we are programmed to be what we are, then these traits are ineluctable. We may, at best, channel them, but we cannot change them either by will, education, or culture.
-- from Ever Since Darwin, quoted in The Extended Phenotype, p. 10
This is, in fact, a typical objection to any sort of "determinism," and who could disagree? Gould is talking about genes here, but I think the problem can crop up at almost any level of natural explanation. Christians (or worse, Calvinists like me) love to worry about this sort of thing, since we are understandably preoccupied with moral agency.

Dawkins deftly answers the challenge by first attacking the idea that genes are any more "deterministic" than other influences. He notes at the outset that biological "determinism" (read: causation) is a statistical -- not absolute -- matter.

For example, the claim that "smoking causes cancer" is understood by most to mean this: smoking increases one's risk of getting lung cancer. A genetic influence, Dawkins argues, should be viewed in exactly the same way. So, if you know that a certain adult has a Y chromosome, then you might bet that this person would be larger or stronger than a certain adult without Y chromosomes, and you would be unwise to bet the other way. And yet you wouldn't be utterly flummoxed when you learned that sometimes your bet was wrong.

Then he explodes the myth that genetic influences are any less modifiable than are other influences on a person's traits:
People seem to have little difficulty in accepting the modifiability of 'environmental' effects on human development. If a child has had bad teaching in mathematics, it is accepted that the resulting deficiency can be remedied by extra good teaching the following year. But any suggestion that the child's mathematical deficiency might have a genetic origin is likely to be greeted with something approaching despair: if it is in the genes 'it is written', it is 'determined' and nothing can be done about it; you might as well give up attempting to teach the child mathematics. This is pernicious rubbish on an almost astrological scale. Genetic causes and environmental causes are in principle no different from each other. Some influences of both types may be hard to reverse; others may be easy to reverse. [...] The important point is that there is no general reason for expecting genetic influences to be any more irreversible than environmental ones.
-- The Extended Phenotype, page 13
Dawkins then offers two ideas regarding how and why genes acquired "their sinister, juggernaut-like reputation." This one is worthy of serious reflection: genetic inheritance, which is famously inflexible and inexorable, is easily confused with the expression of genetic characteristics in an individual person (or other organism), which is maddeningly variable. Adding to the confusion, surely, is the fact that most people are aware that learning and achievement don't change one's genes (this is the heresy of Lamarckianism), and this knowledge probably makes it difficult to understand that the expression of those genes, and their influence on a person's life, has much to do with learning and achievement.

There's so much more, just in that second chapter, that is worthy of consideration (musings about variation in human intelligence, careful discussion of the meaning of adaptation, explanation of the importance of differences as the focus of adaptive evolution), but you have other blogs to read. Seriously, if you've read The God Delusion, you'll be astonished to learn that the same guy wrote Chapter 2 of The Extended Phenotype. At least that's how I felt.

Section 2: Genetic replicators as the "units of selection"

I hope you can tell that some of the ideas in The Selfish Gene were controversial in their time; the first section of The Extended Phenotype deals with objections of a serious nature (i.e., not creationist objections). The complaints about determinism and adaptationism, however, are not as central to Dawkins' thesis as are objections like this one, again from Stephen Jay Gould:
No matter how much power Dawkins wishes to assign to genes, there is one thing that he cannot give them -- direct visibility to natural selection. Selection simply cannot see genes and pick among them directly. It must use bodies as an intermediary. A gene is a bit of DNA hidden within a cell. Selection views bodies.

It [selection] accepts or rejects entire organisms because suites of parts, interacting in complex ways, confer advantages. The image of individual genes, plotting the course of their own survival, bears little relationship to developmental genetics as we understand it.
-- The Panda's Thumb, pages 90-91
Now, at first blush I found Gould's objection quite compelling. In fact, if you know a little about developmental biology, or especially if you know a lot about developmental biology, you might be cheering out loud. As before, it sure seems like he has a good point. But here's what Dawkins writes at the end of Chapter 6 ("Organisms, Groups, and Memes: Replicators or Vehicles?"):
Of course genes are not directly visible to selection. Obviously they are selected by virtue of their phenotypic effects, and certainly they can only be said to have phenotypic effects in concert with hundreds of other genes. But it is the thesis of this book that we should not be trapped into assuming that these phenotypic effects are best regarded as being neatly wrapped up in discrete bodies (or other discrete vehicles). The doctrine of the extended phenotype is that the phenotypic effect of a gene (genetic replicator) is best seen as an effect on the world at large, and only incidentally upon the individual organism -- or any other vehicle -- in which it happens to sit.
-- The Extended Phenotype, page 117 (italics in original)
Now I hope you can see what the book is about. It's about establishing the gene as the unit of selection, by showing that only the reference point of the gene is ultimately helpful in understanding selection -- because genes can exert influences outside of the organism in which they exist. Even before I toss you a few of Dawkins' examples, see if you agree with me that Gould's objection is already in serious trouble.

Chapter 4, "Arms Races and Manipulation," is a feast for anyone who thinks biology is interesting. Dawkins notes that organisms have much to gain by manipulating other organisms. Just think: you're a bug or a bird, competing with other bugs and birds for resources and opportunities, and you find out that you could have someone else gather your food, build your house, raise your kids. Selfish, even evil, but...smart. Could such behaviors arise through evolution? In other words, can such manipulation be evolutionarily stable? Wouldn't the organisms getting ripped off fight back, evolutionarily speaking? What, after all, could be more evolutionarily insane than spending your life as a slave, feeding someone else's offspring? Dawkins explains why manipulation can be, and is, evolutionarily stable, and even commonplace.

The basic idea is illustrated by the moral of one of Aesop's fables: the rabbit runs faster than the fox, because the rabbit is running for his life, but the fox is only running for his dinner. Manipulation is predicted to lead to an evolutionary "arms race," because the manipulated species will "fight back," but the outcome can be stable if there are large asymmetries in costs and benefits. In other words, if species A has a lot to gain from the manipulation of members of species B, but members of species B have little to lose by being exposed to this risk, species A can "get away with" the manipulation of members of species B. The turning point of Chapter 4 is here:
If the individual manipulator has more to lose by failing to manipulate than the individual victim has to lose by failing to resist manipulation, we should expect to see successful manipulation in nature. We should expect to see animals working in the interests of other animals' genes.
-- The Extended Phenotype, page 67
And what are the best examples? So-called brood parasites, the cuckoo being the classic example. Cuckoos lay their eggs in other birds' (warblers') nests, and the victims slavishly feed the baby cuckoo, even after it kicks their own babies out of the nest, growing far bigger than its "adoptive parents." Some ant species use mysterious chemical signals to fool entire colonies of ants of another species into raising the raider's kids. Other species are slavers, carrying off babies of other species and "forcing" them to work for the advancement of their own colony. These are fascinating, weird stories, and there are cooler and weirder tales in Chapter 12, "Host Phenotypes of Parasite Genes." These accounts overwhelmingly make the point: individual organisms sometimes work to advance the replication of genes in someone else's body. Focusing on genetic replicators provides explanatory power, and whimpering about "determinism" or swatting "plotting genes" strawmen just doesn't get it done.

Chapter 7, "Selfish Wasp or Selfish Strategy?" is interesting to me, because in reading it I became aware, for the first time, that Richard Dawkins used to be a pretty good scientist. This probably sounds obnoxious, and it's really not meant to be an insult. Dawkins is a fantastic science writer, but it's not accurate, in my view, to call him a scientist. He's not what I would call a "practicing scientist" -- he hasn't contributed to the primary research literature in decades. And when he did, he worked as an ethologist (one who studies behavior) and not strictly as an evolutionary biologist. I surely don't mean to suggest that he's not right about evolution (see the next post). I just happen to think that actually doing science can keep one honest in ways that Richard Dawkins (and some others I can think of) clearly needs.

Well, in that chapter Dawkins uses his own research to illustrate precisely why a gene's-eye view of selection can be helpful "on the ground" in formulating and testing hypotheses. It's wonderfully interesting -- and, to me, just a little sad -- to read.

Section 3: The doctrine of the extended phenotype

This final section contains some riveting scientific writing. Chapter 11, "The Genetical Evolution of Animal Artefacts," serves an obvious purpose in Dawkins' quest to liberate the analysis of genetic effects from the confines of the bodies in which the genes are found, by pointing out that the effects of some genes are clearly manifested outside of that body. Dawkins notes that the causal connections between genes and their phenotypic expression are often utterly byzantine, and no one is surprised by that. So, "further extensions of the concept of phenotype should not overstretch our credulity." What follows is a tour de force of scientific persuasion. If a spider's hairy exterior is genetically influenced, via some poorly-understood interplay of genes, development and environment, then mightn't the spider's web be similarly influenced, similarly under the control of genes and, therefore, similarly acted upon by natural selection?
By whatever embryological routes the genes may work in detail, the small extra step from behaviour to web is not any more difficult to conceive of than the many causal steps which preceded the behavioural effect, and which lie buried in the labyrinth of neuroembryology.
-- The Extended Phenotype, page 199
The point, again, is this: genes don't have to act on bodies per se. They act on the "world at large." And more specifically, genetic effects which are the subjects of natural selection need not be exerted within the body that hosts the genes in question. The phenotype, which is the output of evolutionary interest, is not tied to the organism itself.

The final chapter, "Rediscovering the Organism," seeks an explanation for why organisms are a good vehicle for genetic replicators. It might seem like a weird question, but given the centrality of genetic replicators and their phenotypes as objects of selection, it's a fair one. Organisms occupy a prominent place in the order of biological creation. Why?

One idea that Dawkins explores is the role of cyclical development in the evolution of complex (multicellular) organisms. He maintains that such prodigies of creation are only possible in the context of a "complex developmental sequence." Specifically, he proposes a definition of an organism as:
...the unit which is initiated by a new act of reproduction via a single-celled developmental 'bottleneck.'
-- The Extended Phenotype, page 258 (italics in original)
According to Dawkins, the doctrine of the extended phenotype leads to this explanation for the utility of organisms and their developmental trajectories:
An organism is the physical unit associated with one single life cycle. Replicators that gang up in multicellular organisms achieve a regularly recycling life history, and complex adaptations to aid their preservation, as they progress through evolutionary time.
-- The Extended Phenotype, page 258
In other words, the regular re-start associated with developmental life cycles creates the opportunity for evolutionary adaptation. Interesting ideas for fans of evo-devo like me.

Okay, so I hope I at least got you to see the brilliance of Dawkins' thinking, at least as it stood in 1982. He birthed interesting new ideas, and handled his critics with grace that is undetectable in his current screeds. He's not an idiot, or at least he wasn't one back then.

But one more thing. The idea of selfish replicators has been linked (correctly) with the existence of "junk DNA," especially since animal genomes are nearly overrun with seemingly parasitic elements that look exactly like "selfish genes." (Dawkins would call them "outlaws;" see page 163.) Referring to plasmids and other DNA fragments that insert themselves into host genomes, Dawkins writes:
It is impossible to imagine a more intimate parasite. 'Selfish DNA' itself is not more intimate, and indeed we may never know how many of our genes, whether 'junk' or 'useful', originated as inserted plasmids. It seems to follow from the thesis of this book that there is no important distinction between our 'own' genes and parasitic or symbiotic insertion sequences. Whether they conflict or cooperate will depend not on their historical origins but on the circumstances from which they stand to gain now.
-- The Extended Phenotype, page 226
Compare that reflection on "junk DNA" (or the longer discussion in Chapter 9, "Selfish DNA, Jumping Genes, and a Lamarckian Scare") to the simplistic claims of anti-evolutionists who think that finding "functions" for "junk DNA" is somehow a problem for evolutionary theory. It's not, and I'll take that up sometime soon. But first, part II of my contrition for the Idiot Episode.


RBH said...

Thanks for that. I read The Extended Phenotype in the early 1980s, shortly after it came out, and it is indeed his best scientific book. His best expository book -- popularization -- was The Ancestor's Tale, in my opinion.

John Farrell said...

I loved the Blind Watchmaker and later grimaced through God Delusion; so I'm going to add Phenotype to my wish list at Amazon.

Excellent post.