hpb etc.

Dispatches from the Seminar: FTNS

Last Monday (29 January), my HPB seminar met to talk about Fisher's "Fundamental Theorem of Natural Selection." (Go here for the reading list.)

It's well known that Fisher's own statement of the FTNS, whether he made it in the 1930 or 1958 edition of The Genetical Theory of Natural Selection or in the 1941 paper, "Average Excess and Average Effect of a Gene Substitution", is virtually impenetrable. And so the immediate question to ask in a seminar is "What does the FTNS say?" The second question, and perhaps the more interesting one, is, "What's fundamental about the FTNS?"

The Price-Ewens interpretation is widely acknowledged to be the one that captures what Fisher wanted to say with the theorem (Ewens 1989, Price 1972). At the same time, probably the clearest statement of the theorem in words is Edwards' (1994). Edwards accepts the Price-Ewens derivation of the theorem, as he should it seems, but he words the theorem in a way that captures what Price and Ewens accomplished in more "Fisherian" terms. He says (Edwards 1994, p. 450):

The rate of increase in the mean fitness of any organism at any time ascribable to natural selection acting through changes in gene frequencies is exactly equal to its genic variance in fitness at that time.

Compare this to Fisher's 1958 (p. 37) version of the theorem:

The rate of increase in fitness of any organism at any time is equal to its genetic variance in fitness at that time.

Edwards (1994, pp. 450-451) explains his statement of the FTNS as follows:

This [the statement of the theorem above] is as close as I can get to Fisher's wording whilst following the interpretation of Price and Ewens. "Genic" has replaced "genetic" [to capture that Fisher means 'additive genetic variance'] and 'mean fitness' has replaced 'fitness of any organism'; these are uncontroversial rewordings. ... I have added 'ascribable to natural selection acting through changes in gene frequencies' from Fisher's own words: 'ascribable to natural selection' is from his 1941 explanation of the Theorem and '[due to all] changes in gene frequencies' is from the sentence preceding his statement of the theorem [in 1930 and 1958] modified as suggested by Price. Price and Ewens repeatedly emphasize that Fisher thought  of the immediate effect of natural selection as being only through the changes in gene frequencies. For the sake of minimizing the changes I have kept Fisher's word 'organism', though it would not now be the first choice; in fact Fisher himself replaced it by 'species' in the Summary at the end of Chapter II of The Genetical Theory. 'Population' might now be the preferred word.

So let's say, then, that the FTNS states the following:

The rate of increase in the mean fitness of any population at any time ascribable to natural selection acting through changes in gene frequencies is exactly equal to its genic variance in fitness at that time.

Let's also be clear about the theorem's assumptions: no mutation, fixed fitness values, no fertility differences, no random effects, no geographical structure, one sex only, and all the other usual assumptions except that there is no restriction on the mating structure (Ewens 1989,p. 167-168).

With all that said, Fisher's FTNS is true and exact (Edwards 1994, Ewens 1989, Price 1972). It seems to me that this is all quite uncontroversial and barely worth mentioning except for background to the more important question of the theorem's biological "fundamentality."

Out of Fisher's Genetical Theory, the papers by Edwards, Ewens, Price and a new philosophical paper by Plutynski (2006), who agrees with the Price-Ewens derivation of the theorem, our seminar listed several candidate answers to the question:

Fisher (1958, pp. 37-39)

For Fisher, the theorem makes a "deep" biological claim about the nature of selection, that is, that the partial change in mean fitness is due to single-locus gene frequency changes. Fisher also thought that the theorem's biological depth and more generally its scope afforded a comparison to the Second Law of Thermodynamics.

Price (1972, pp. 139-140)

Price thinks the main importance of the theorem for biology is its scope (it requires only statistical smoothing through large N and on assumptions of no meiotic and gametic selection). Price also thinks that the theorem is the best anyone had said (at least by 1972) about natural selection. At the same time, Price thinks the theorem isn't as important, biologically, as Fisher thought, due to what he (and others) consider(s) to be the defect of treating non-additive gene effects as "environment." He further thinks that the theorem is defective because it appears to treat mean population fitness as always increasing but generally close to zero.

Ewens (1989, p. 179)

Ewens agrees with Price's assessment of the biological importance of the theorem. He's a bit clearer, however: Ewens doesn't see any justification for singling out the partial change in mean fitness Fisher does as isolating natural selection from the total change in mean fitness. After all, all of the terms of the FTNS, mean fitness, average excess, and average effect all depend on gene frequency and all change with changes in gene frequency.

Edwards (1994, p. 469-470)

Edwards says "Fisher's Fundamental Theorem of Natural Selection is important for three reasons. (p. 469)" First, the theorem directly influenced Wright's construction of the adaptive topography. Second, he agrees, mostly, with Fisher's assessment of the theorem and thinks we can't have expected more out Fisher than he gave (contra Price and Ewens). Third, it's extendable.

Plutynski (2006, p. 75)

According to Plutynski, Fisher regarded his theorem as "so very fundamental" because it was "a culmination of Fisher's lifelong project to vindicate Darwinism and unify the biometrical gradualist model of evolution and Mendelism in a rigorous mathematical theorem analogous to the physical sciences."

My own view about these five candidate answers to the "fundamentality" question is this: Price and Ewens are right. And I think we've all known this for a long time. Their assessment just follows from the math (see especially Ewens 1989, p. 171). If Fisher had captured what he thought he did with the theorem, then I think the FTNS would be fundamental in evolutionary genetics in the same way that the Hardy-Weinberg Equilibrium Principle is --you can't do population genetics without it.

Fisher is incorrect about the "depth" of the theorem for precisely the reasons Price and Ewens give about the lack of justification for singling out the partial change in mean fitness as isolating natural selection from the total change in mean fitness. This means that Edward's third reason for the importance of the theorem is mistaken. I'm certain Edwards' first reason is wrong, that is, that Wright didn't get the idea of the adaptive topography from Fisher. This is easy to see just by reading Provine's (1986) biography. And I'm not terribly confident about the substance of Edwards' third reason, although it's more a question that will be answered by history (but see Frank and Slatkin 1992 and Lessard and Castilloux 1995 for extensions of the theorem to clutch size and to fertility selection respectively).

I admit I'm not sure I understand Plutynski's claim. (Neither did the seminar participants.) Actually, I think there are lots of problems with the paper. But focusing just on Plutynski's claim about the importance of the theorem, one wonders what she means when she asks, "Why did Fisher regard his theorem as so very 'fundamental'?" (2006, p. 75). Actually, I don't know if any answer to that question is much more than historical/philosophical speculation about what was going on in Fisher's head at the time. Anyway, it's not the right "fundamentality" question to ask. But I can't see in the paper where Plutynski clearly answers the question about the theorem's biological "fundamentality." She does agree with the Price-Ewens derivation of the theorem, but it's not clear she agrees with their assessment of its importance.

Ultimately, there's not much new historically or philosophically to say about Fisher's FTNS specifically. The more interesting question concerns the place of the theorem in Fisher's larger argument for neo-Darwinism. And, actually, this is where Plutynski's paper is quite relevant. I don't think focusing on the theorem as she does, though, is the right way to answer it. But what Plutynski does say about the structure of Fisher's argument strikes me as backwards. She gets it right when she says that the theorem culminates Fisher's neo-Darwinian argument, but that's small beer --the theorem came pretty much last in the effort, so of course it does. It's the details of Fisher's argument Plutynski gets wrong. This is a major research topic of mine at the moment, and you'll see some of it on this blog in due time. For now, see here and here; there are glimmers.

References

Edwards, A. W. F. (1994), "The Fundamental Theorem of Natural Selection", Biological Reviews of the Cambridge Philosophical Society 69: 443-474.

Ewens, W. (1989), "An Interpretation and Proof of the Fundamental Theorem of Natural Selection", Theoretical Population Biology 36: 167-180.

Fisher, R. A. (1930, 1958, 1999), The Genetical Theory of Natural Selection. Oxford: Oxford University Press.

Fisher, R. A. (1941), "Average Excess and Average Effect of a Gene Substitution", Annals of Eugenics 11: 53-63.

Frank, S. and M. Slatkin (1992), "Fisher's Fundamental Theorem of Natural Selection", TREE 7: 92-95.

Lessard, S. and A.-M. Castilloux (1995), "The Fundamental Theorem of Natural Selection in Ewens' Sense: Case of Fertility Selection. Genetics 141: 733-742.

Plutynski, A. (2006), "What was Fisher's Fundamental Theorem of Natural Selection and What was it For?", Studies in History and Philosophy of Biological and Biomedical Science 37: 59-82.

Price, G. (1972), "Fisher 'Fundamental Theorem' Made Clear", Annals of Human Genetics 36: 129-140.

Provine, W. (1986), Sewall Wright and Evolutionary Biology. Chicago: University of Chicago Press.

My HPB Seminar

My history and philosophy of biology seminar had its first meeting on Monday (8 January). I mentioned a post or so ago that I would post the reading list; you'll find it below, sans some of the citation information. Here's the syllabus. (Anyone who wants cites can email me.)

The seminar follows the arc of Mike Dietrich's, "From Mendel to Molecules" paper in Fox and Wolf's Evolutionary Genetics: Concepts and Case Studies. Incidentally, that anthology is just excellent. I don't think there's a paper not worth reading in the bunch. (If only philosophers of biology would pick it up!) Razib, over at Gene Expression, has been working through the book.

At any rate, as I say, my seminar follows the arc of Dietrich's paper. Dietrich's brief history of evolutionary genetics is of its core controversies, starting with early critiques of Darwin's pangenesis all the way to controversies over the molecular clock. My course structures the history in the same way, but I don't cover as much ground. Actually, I can't cover that much ground in what for me will be an abbreviated quarter --only 8 meetings. (And I doubt I could do much better in 10.)

We started out yesterday with Dietrich's paper as background and I gave an overview of the topics we're going to focus on. There's a general theme of the rise and fall (?) of panselectionism. But there are more specific issues in the conceptual foundations of evolutionary genetics and the nature of scientific controversy. Our next meeting, a sort of two-in-one since we won't meet on MLK Day, covers the origins of population genetics and a sketch of the evolutionary synthesis --or at least the synthesis of Mendelian genetics and Darwinian natural selection. We'll have read:

• Provine 2001, The Origins of Theoretical Population Genetics
• Fisher 1922, "On the Dominance Ratio"
• Fisher 1930a, "The Distribution of Gene Ratios for Rare Mutations"
• Wright 1931, "Evolution in Mendelian Populations"
• Haldane 1932, The Causes of Evolution, Appendix
• Provine 1986, Sewall Wright and Evolutionary Biology, chapter 8 (on Wright, Fisher, and evolution)
• Hodge 1992, "A Study of Fisher and Wright"
• Gould 1983, "The Hardening of the Modern Synthesis"

I realize that's a huge amount of reading, including an entire book. But, in fact, I edited the list down. And, again, it's a two-in-one meeting.

Once we get the back story down, we'll launch into portions of the controversy between Fisher and Wright (see my own views here, here, and here), starting out with Fisher's Fundamental Theorem of Natural Selection:

• Fisher 1930b, The Genetical Theory of Natural Selection, chapter 2 (on the theorem)
• Price 1972, "Fisher's 'Fundamental Theorem' Made Clear"
• Ewens 1989, "An Interpretation and Proof of the Fundamental Theorem...."
• Edwards 1994, "The Fundamental Theorem of Natural Selection"
• Plutynski 2006, "What was Fisher's Fundamental Theorem...?"

I think I have a new way of reconstructing Fisher's construction of his theorem. So I'll no doubt have a lot to say about Plutynski's historical and philosophical view, and perhaps Price's, Ewens', and Edwards' views as well. After the FTNS, we look at Wright's adaptive landscape:

• Wright 1932, "The Roles of Mutation...."
• Provine 1986, Sewall Wright and Evolutionary Biology, chapter 9 (Wright's SBT)
• Wright 1988, "Surfaces of Selective Value Revisited"
• Ruse 1996, "Are Pictures Really Necessary?"
• Skipper 2004a "The Heuristic Role of … the Adaptive Landscape"
• Pigliucci and Kaplan 2006, Making Sense of Evolution, chapter 8 (on adaptive landscapes)

In addition to looking at Fisher's and Wright's disagreements with regard to their general theories, we'll also look at the problems endemic to each view and, on the landscape stuff, we'll worry a little about the role of diagrams in producing scientific knowledge.

Of course, this is really the tip of the iceberg in a discussion of Fisher's and Wright's theoretical disagreements. But time is a problem. And so we'll proceed to look at two key empirical debates, over the Panaxia dominula and Cepaea nemoralis:

• Provine 1986, Sewall Wright and Evolutionary Biology, chapter 12 (1940-1955)
• Turner 1987, "Random Genetic Drift...."
• Skipper forthcoming, "Revisiting the R. A. Fisher-Sewall Wright Controversy"
• Beatty 1987a, "Dobzhansky and Drift...."
• Millstein forthcoming, "Concepts of Drift and Selection...."

I'm not just interested in the debates over the roles of selection and drift in these cases, but also in the concepts of drift in particular and changes in methodology between the moth work and the snail work.

Finally, we get to the debates between Coyne, Barton, and Turelli and Wade and Goodnight over Wright's SBT, capping off our long if not truncated study of the Fisher-Wright Controversy.

• Coyne, Barton, and Turelli 1997, "A Critique of Sewall Wright's SBT"
• Wade and Goodnight 1998, "Evolution in Metapopulations...."
• Skipper 2002, "The Persistence of the R. A. Fisher-Sewall Wright Controversy"
• Skipper 2004b, "Calibration of Laboratory Models in Population Genetics"
• Plutynski 2005, "Parsimony in the Fisher-Wright Debate"

Of course we'll focus on the specific issues that occupied Coyne and Wade. But I also want to look at the role of parsimony in these specific disagreements. I've talked about this before, here. I haven't changed my mind.

Then we leave Fisher and Wright and move forward to the Classical-Balance Controversy and the "Electrophoretic Revolution":

• Muller 1950, "Our Load of Mutations"
• Dobzhansky 1955, "A Review of Some Fundamental Concepts...."
• Beatty 1987b, "Weighing the Risks...."
• Lewontin 1974, The Genetic Basis of Evolutionary Change, chapter 5 (paradox of variation)
• Gillespie 1991, The Causes of Molecular Evolution, chapter 1 (protein evolution)
• Skipper forthcoming, "Stochastic Evolutionary Dynamics: Drift vs. Draft"

In this part of the course I'm really looking at the nature of selection and explanations of genetic variation. So, the emphasis will largely be on Lewontin's discussion of the Classical and Balance positions and Maynard Smith and Haigh's hitchhiking response and then later Gillespie's new approach in the guise of genetic draft. Lots and lots of selection here folks.

In our last meeting, we'll look at the neutral theory and its role not only in Lewontin's discussion but its place in evolutionary genetics more broadly.

• Dietrich 1994, "Origins of the Neutral Theory"
• Kimura 1968, "Evolutionary Rate at the Molecular Level"
• King and Jukes 1969, "Non-Darwinian Evolution"
• Dietrich 1998, "Paradox and Persuasion"
• Dietrich and Skipper forthcoming, "Manipulating Underdetermination...."

The cornerstone piece is really Dietrich's "Origins of the Neutral Theory." I say just go get it and read it. In addition to exploring the neutral theory's origins, we'll look at the controversy between Takahata and Gillespie over the nature of the molecular clock. More selection, obviously, but also biological theory assessment in situations of underdetermination.

I know I've left a huge amount off my reading list. In part, I did that because I want my students to discover some things on their own. (This is supposed to be a learning experience after all.) But I also had to consider how much heavy reading I could expect a group of mostly philosophy of science students could take in a single week. And I'm sure I'm asking too much. (I always ask too much, so don't suggest I stop, because I won't.)

I'm excited about the seminar. Not only is it the sort of seminar I've wanted to run since I got this job at UC (sorry, Razib), but the timing is terrific: I'm working on Fisher during the spring, and I think a book reflecting the topics of the seminar is falling into place.

We meet next on 22 January. If something interesting happens or if I just have something worth blogging about, I'll do so.

HPB Seminar Redux I

Two folks have chimed in for a depth seminar on chance in evolution. It dawned on me that I could, to frame such a seminar, organize it around a symposium I was part of at the 2004 meeting of the Philosophy of Science Association in Austin, TX. The symposium was called, "Four Case Studies of Chance in Evolution." (The papers will come out in a supplement to Philosophy of Science, although I wonder if that will happen before the 2006 meeting in November. If not, woe unto those responsible.)  Here's a top view of how the seminar would look on this approach.

Part I: Darwin's studies of variation in orchids

The first paper in the "Case Studies" symposium was John Beatty's, "Chance Variation: Darwin on Orchids." Beatty explores how Darwin thought chance variation affected evolutionary outcomes. And like Beatty, we'd focus on Darwin's (1862), On the Various Contrivances by which British and Foreign Orchids are Fertilised by Insects.

Part II: Cavalli-Sforza's studies of human blood group distribution

My colleague here at UC, Bob Richardson, did the second paper in "Case Studies," on the Parma Valley studies of blood group distribution by Cavalli-Sforza (and his collaborators). This is really a case of genetic drift in action, and is taken to be quite a beautiful one. Consequently, in the seminar, we'd look at the definitive treatment of the case, i.e., Cavalli-Sforza, Moroni, and Zei's (2004), Consanguinity, Inbreeding, and Genetic Drift in Italy (MPB-39).

Part III: Kimura, Gillespie, Takahata and others on neutrality and molecular evolution

There seems only one person in history and philosophy of biology doing much work, in print at least, on molecular evolution: Mike Dietrich. His paper from "Case Studies" explores three perspectives on neutral molecular evolution: (1) as a model early on, (2) as a testable model in population genetics, and (3) as an explanation of the molecular clock. There's lots to read here, but presumably we'd focus on works referenced below by King and Jukes, Kimura (also with Ohta), Gillespie, and Takahata. This is all hard stuff.

Part IV: Gillespie on genetic draft

My paper in "Case Studies" looked at Gillespie's recent work on genetic draft and its relationship to genetic drift as a process that reduces heterozygosity in populations. While this stuff is painfully difficult to get through, there's not much of it. Obviously, we'd read the relevant set of papers by Gillespie, all of which are referenced below (from 2000-2004). I've talked about draft in relation to "Lewontin's paradox" before and I'd like to do more. My paper is available here.

This hypothetical, top-level view sets up the the aspects of chance in evolution we'd look at. From the point of view of these case studies, we'd then explore some of the recent philosophical literature on chance in evolution with the aim of exploring the implications of the biology on the philosophy. For the most part, the philosophical literature is devoid of real biological examples. On occasion, there will be some simple cases of drift, but often even those are cooked. So the key will be to infuse the philosophical work with the biological work and find the truth. There are several issues here, including the proper interpretation of chance in evolution, the determinism/indeterminism problem, and conceptually distinguishing drift.

I have to think a bit more about how to make the intersection of the biology with the philosophy. The papers from the symposium, and in particular Roberta Millstein's commentary (available here), do some of that. So, in my next post on this seminar, I'll try to organize some philosophical readings. Clearly, the first set of papers are those from the symposium, i.e., Beatty (in press), Dietrich (in press), Richardson (in press), Skipper (in press), and Millstein's commentary (in press).

Notice that even without the philosophy, this is way too much to do in 10 weeks! (I long for the semester system.) But the graduate students who know me, know I'm not much deterred by too much reading. In all seriousness, however, I'll have to pare this way down, probably by eliminating one or more of the case studies. The question is, how to pare down?

References (aka Partial Reading List):

Beatty, J. (in press), "Chance Variation: Darwin on Orchids", Philosophy of Science.

Darwin, C. (1862), On the Various Contrivances By Which British and Foregin Orchids are Fertilised by Insects and on the Good Effects of Intercrossing. London: John Murray.

Cavalli-Sforza, L.,  Moroni, A., and Zei, G. (2004), Consanguinity, Inbreeding, and Genetic Drift in Italy (MPB-39). Princeton: Princeton University Press.

Dietrich, M. (in press), "Three Perspectives on Neutrality and Drift in Molecular Evolution", Philosophy of Science.

Gillespie, John (1978) "A General Model to Account for Enzyme Variation in Natural Populations. V. The SAS-CFF Model," Theoretical Population Biology 14: 1-45.

Gillespie, John (1984a) "The Molecular Clock May Be an Episodic Clock," Proceedings of the National Academy of Sciences 81: 8009-8013.

Gillespie, John (1984b) "Molecular Evolution Over the Mutational Landscape," Evolution 38: 1116-1129.

Gillespie, John (1984c) "The Status of the Neutral Theory," Science 224: 732-733.      

Gillespie, John (1986a) "Natural Selection and the Molecular Clock," Molecular Biology and Evolution 3: 136-155.

Gillespie, John (1986b) "Variability of Evolutionary Rates of DNA," Genetics 113: 1077-1091.

Gillespie, John (1987) "Molecular Evolution and the Neutral Allele Theory," Oxford Surveys of Evolutionary Biology 4:10-37.

Gillespie, John and Langley, Charles (1979) "Are Evolutionary Rates Really Variable?," Journal of Molecular Evolution 13: 27-34.

Gillespie, John (2000a), "Genetic Drift in an Infinite Population: The Pseudohitchhiking Model", Genetics 155: 909-919.

Gillespie, John (2000b), "The Neutral Theory in an Infinite Population", Gene 261: 11-18.

Gillespie, John (2001), "Is the Population Size of a Species Relevant to its Evolution?", Evolution 55: 2161-2169.

Gillespie, John (2004), Population Genetics: A Concise Guide. 2nd edition. Baltimore: Johns Hopkins University Press.

Kimura, M. (1968) "Evolutionary Rate at the Molecular Level," Nature 217: 624-626.

Kimura, M. (1969) "The Rate of Molecular Evolution Considered from the Standpoint of Population Genetics," Proceedings of the National Academy of Sciences 63: 1181-1188.

Kimura, M. (1979) "The Neutral Theory of Molecular Evolution", Scientific American 241: 98-127.

Kimura, M. (1983) The Neutral Theory of Molecular Evolution. Cambridge: Cambridge University Press.

Kimura, M. (1987) "Molecular Evolutionary Clock and the Neutral Theory," Journal of Molecular Evolution 26: 24-33.

King, Jack and Thomas Jukes (1969) "Non-Darwinian Evolution," Science 164: 788-798.

Millstein, R. (in press), "Discussion of 'Four Case Studies on Chance in Evolution': Philosophical Themes and Questions, Philosophy of Science.

Ohta, Tomoko (1977) "Extension to the Neutral Mutation Random Drift Hypothesis," Molecular Evolution and Polymorphism. Motoo Kimura, ed. Mishima, Japan: National Institute of Genetics Publications.

Ohta, T. and Kimura, M. (1971) "On the Constancy of the Evolutionary Rate of Cistrons," Journal of Molecular Evolution 1: 18-25.

Richardson, R. (in press), "Chance and the Patterns of Drift: A Natural Experiment", Philosophy of Science.

Skipper, Jr., R. A. (in press), "Stochastic Evolutionary Dynamics: Drift vs. Draft", Philosophy of Science.

Takahata, Naoyuki (1987) "On the Overdispersed Molecular Clock," Genetics 116: 169-179.

Takahata, Naoyuki (1988) "More on the Episodic Clock," Genetics 118: 387-388.

HPB Seminar

During 2006-2007, I'm offering a graduate seminar in the history and philosophy of biology. I've not given the seminar too much thought up to now. But I'm beginning to wonder what the plan of the seminar will be. I have two very general structures in mind: a breadth seminar or a depth seminar.

If I decide to run a breadth seminar, then the plan could be to do the canonical problems in philosophy of biology. These problems include adaptationism, the interpretation of fitness (and of evolutionary theory more generally), units of selection, the species problem, the developmentalist challenge, reduction of Mendelian to molecular genetics, and biological function. I can't say I'm excited to work through these canonical issues. But anyone who wants to do philosophy of biology needs to go through them. Consequently, I feel obligated to do a breadth seminar on these problems.

But what about a depth seminar? Here, I might take a more historical track. I might, for instance, focus on the origins of theoretical population genetics, some key controversies in evolutionary genetics such as the Fisher-Wright controversy, the classical-balance controversy, and so on. I could, of course, take a more strictly philosophical track and work through a hot topic in philosophy of biology. If I were to do that, I might do the developmentalist challenge, or the role of chance in evolution, or something along those lines. The idea would be to critically read everything (or almost everything) on the topic.

There are constraints, naturally. We're on the quarter system at UC, so I've got only 10 weeks; we meet once a week for about three hours. I can't demand any background in the life sciences, so I will either have to teach it myself or run a breadth seminar that emphasizes philosophy (which I'd prefer not to do). (Now, I've got no qualms about assigning vast quantities of reading. But I have to make each reading count, regardless of whether I do a breadth or depth seminar.)

I'd be grateful for feedback from visitors, historians, philosophers, or biologists, about what sort of seminar they'd be most interested in. In particular, I'd love to hear what hpb-types think are the most important papers or books to read in the field, and what biologists think philosophers absolutely must know if we're to be taken seriously. I have my views. But I don't want to muddy the waters to begin.