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REVOLUTIONS IN SCIENCE Dawkins vs. Gould Survival of the Fittest Kim Sterelny Series editor: Jon Turney ICON BOOKS UK TOTEM BOOKS USA

Text copyright © 2001 Kim Sterelny

The author has asserted his moral rights.

Series editor: Jon Turney

Originating editor: Simon Flynn

No part of this book may be reproduced in any form, or by any
means, without prior permission in writing from the publisher.

Typesetting by Hands Fotoset

Printed and bound in the UK
by Cox & Wyman Ltd., Reading

Acknowledgements

Thanks to Mike Ridge, Matteo Mameli, Darryl Jones, Jochen Brocks, Dan Dennett and Jon Turnev for their thoughts on a draft of this book. Thanks also to the Philosophy Program, Research School of the Social Sciences, Australian National University and the Department of Philosophy, Victoria University of Wellington, whose support made it possible for me to write it.

Dedication

For Peter: Friend and colleague

Suggested Reading

Chapter 1

Good general and impartial introductions to evolutionary theory are not thick on the ground. One very simple introduction based on Darwin himself is Ernst Mayr's One Long Argument (Penguin, 1991). A more technical but still readable treatment is John Maynard Smith's The Theory of Evolution (Cambridge, 1993). Mark Ridley's Evolution (Blackwell, 1996) is widely regarded as a classic. But it is demanding, and Ridley is a former student of Dawkins, so his view of the subject is influenced by Dawkins. Richard Fortey's Life: A Natural History of the First Four Billion Years (Vintage, 1999) is a very enjoyable narrative of evolutionary history.

Gould's review of Dennett appeared in two parts in the New York Review of Books in the issues of 12 June and 26 June (1997); there was a heated exchange of letters in the issue of 9 October. Gould reviewed Dawkins' Climbing Mount Improbable in Evolution (vol. 51, pp. 1020-4, 1997); Dawkins reviewed Gould's Full House in the same issue.

Dawkins develops his views of evolution in The Extended Phenotype (Oxford, 1982). This is much his best book and it is readable, though more demanding than his other works. His ideas are stated more succinctly in The Selfish Gene (Oxford,  {141}  1989, second edition) and developed further in Climbing Mount Improbable (WW. Norton, 1996). Gould has developed his views much more through his articles than in his books. These are published both in the technical literature and in his Natural History column 'This View of Life'. Most of these have come out in his anthologies, but perhaps the best single presentation of his ideas is his Wonderful Life: The Burgess Shale and the Nature of History (WW Norton, 1989).

Chapter 2

The evolutionary transition from the first life-like structures to the first organisms is a hot topic in recent evolutionary theory. John Maynard Smith and Eors Szathmary's The Major Transitions in Evolution (Freeman, 1995) is a modern classic but tough going for the chemistry-challenged. Their Origins of Life: From the Birth of Life to the Origins of Language (Oxford, 1999) is a lot easier going but still somewhat demanding. Leo Buss's The Evolution of Individuality (Princeton, 1987) is a superb treatment of the transition from single-celled to multi-celled life. Robert Michod's Darwinian Dynamics: Evolutionary Transitions in Fitness and Individuality (Princeton, 1999) is an important contribution to these issues, but it is in places quite technical. Stuart Kauffman has developed a view of the origin of life which is closer to a 'cell-first' model than a 'replicator-first' model. His The Origins of Order: Self-Organisation and Selection in Evolution (Oxford University Press, 1993) is brutally difficult, but he returns to these themes much more gently in At Home in the Universe (Oxford University Press, 1995). William Schopf gives a palaeontologist's view of these issues in his: The Cradle of Life: The Discovery of Earth's Earliest Fossils (Princeton University Press, 1999).  {142} 

Chapter 3

Dawkins' The Blind Watchmaker (WW. Norton, 1986) and Climbing Mount Improbable (WW. Norton, 1996) are both superb expositions of cumulative selection and its importance. The model of the evolution of the eye is from Nilson and Pelger, A Pessimistic Estimate of the Time Required for the Eye to Evolve', in Proceedings of the Royal Society, B, (vol. 256, 1994, pp. 53-8).

The idea that the genes in the egg carry the information from which the organism is built turns out to be surprisingly difficult and technical. There is no gentle introduction to this problem. I have had a go at explaining the issues in Chapter 5 of Kim Sterelny and Paul Griffiths' Sex and Death: An Introduction to the Philosophy of Biology (University of Chicago Press, 1999), and there is a further development of debate by John Maynard Smith's The Concept of Information in Biology' in the June 2000 issue of Philosophy of Science.

Elliott Sober presents his sceptical response to gene selection in his The Nature of Selection (MIT Press, 1984) and Philosophy of Biology (Westview, 1993). Gould develops a similar, though simpler, critique in 'Caring Groups and Selfish Genes', one of the papers in The Panda's Thumb (Penguin, 1980). Matt Ridley's Genome (HarperCollins, 2000) is an enjoyable introduction to some of the complexities of the way genes help build bodies; in this case, human bodies. (Matt Ridley is not to be confused with Mark Ridley, a student of Dawkins who also writes on evolution.)

Chapter 4

I know of no good but completely non-technical introduction to outlaw genes. But two good recent reviews are Hurst, Atran and Bengtsson, 'Genetic Conflicts', in Quarterly Review of  {143}  Biology (vol. 71, 1996, pp. 317-64), and Werren and Beuke-boom, 'Sex Determination, Sex Ratios and Genetic Conflict', in Annual Review of Ecology and Systematica (vol. 29,1998, pp. 233-61). On the role of mitochondria in turning off maleness in plants, see Saumitou-Laprade and Cuguen, 'Cytoplasmic Male Sterility in Plants', in Trends in Ecology and Evolution (vol. 9, 1994, pp. 431-5). These papers are written for professional audiences but they are reasonably accessible.

Dawkins himself has written the best work on extended phenotypic effects in genes, in The Extended Phenotype. But the three examples I give can be followed up in Gould, 'The Triumph of the Root-heads', in Natural History (vol. 105,1995, pp. 10-17); Sober and Wilson, Unto Others: The Psychology and Evolution of Altruism (Harvard University Press, 1998) and Werren, 'Genetic Invasion of the Insect Body Snatchers', in Natural History (vol. 103, 1994, pp. 36-8), or, for a more recent but more technical treatment, Bourtzis and O'Neill, 'Wolbachia Infections and Arthropod Reproduction', in Bioscience (vol. 48, 1998, pp. 287-93).

Chapter 5

Lee Dugatkin's Cooperation Amongst Animals: An Evolutionary Perspective (Oxford University Press, 1997) is a good survey of the theory of animal co-operation, tied to plenty of actual examples. His Cheating Monkeys and Citizen Bees: The Nature of Cooperation in Animals and Humans (Free Press, 1999) covers similar material much less technically. G.C. Williams' Adaptation and Natural Selection (Princeton University Press, 1966) is the classic critique of group selective explanations of co-operation. Sober and Wilson's Unto Others (Harvard University Press, 1998) is an important attempt to revive those explanations. John Maynard Smith is responsible  {144}  for applying game theory to the evolution of social behaviour. He develops this theory in Evolution and the Theory of Games (Cambridge University Press, 1982), but this is a technical work. Robert Axelrod's The Evolution of Cooperation (Basic Books, 1984) and Sigmund's Games of Life: Explorations in Ecology, Evolution and Behaviour are thoroughly readable alternatives. The theory of kin selection was developed by William Hamilton. These papers are in his Narrow Roads of Gene Land, vol. 1 (Freeman, 1996), and while the papers themselves are extremely demanding, the central ideas are explained with great clarity in his retrospectives on the papers. Gould's views on species selection are developed in two papers written jointly with Lisa Lloyd. These are: 'Species Selection on Variability' and 'Individuality and Adaptation Across Levels of Selection' both published in Proceedings of the National Academy of Science (vol. 90, 1993, pp. 595-9 and vol. 96, 1999, pp. 11904-9).

Chapter 6

The interaction between developmental mechanisms, variation, and evolution is one of the most active fields in contemporary research. Rudy Raff's The Shape of Life (University of Chicago, 1996) is a superb introduction. It is intended for a professional audience, but it is so well written (and it comes with a glossary) that it is accessible to non-experts. Wallace Arthur's The Origin of Animal Body Plans (Cambridge University Press, 2000) is also an important study of these issues. For an extreme version of the view that the supply of variation is so highly constrained that there is little for selection to do, see Brian Goodwin's How The Leopard Changed Its Spots (Charles Scribner, 1994); Goodwin's views are much more extreme than Gould's on this matter.  {145} 

There is no completely non-technical introduction to the methodological issues involved in testing evolutionary hypotheses, though Griffith and I do our best to keep it simple in Chapter 10 of our Sex and Death (University of Chicago, 1999). The latest on these issues is canvassed in Orzack and Sober's Adaptation and Optimality (Cambridge University Press, 2001). The shot across the bows that began much of this is Gould and Lewontin's 'The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme', in Proceedings of the Royal Society of London, B, (vol. 205, 1978, pp. 581-98).

Chapter 7

As Gould sees it, extrapolationism in biology is a continuation of a cluster of methodological ideas from nineteenth-century geology known as 'uniformitarianism'. Uniformitarian ideas were formulated by Lyall, and taken up by Darwin, and hence have been part of evolutionary biology since its beginning. Gould's Time's Arrow, Time's Cycle (Penguin, 1988) is a fine study of uniformitarianism. Two recent and important papers on extrapolationism are: Gould, A Task for Paleobiology at The Threshold of Majority', in Paleobiology (vol. 21,1995, pp. 1-14), and 'The Necessity and Difficulty of a Hierarchical Theory of Selection', in Anne Magurran and Robert May's Evolution of Biological Diversity (Oxford University Press, 1999). Jonathan Weiner's The Beak of the Finch is a superb exposition of selection and evolution on microevolutionary scales. That study documented season-by-season selection on finches scattered across the Galapagos islands.

Chapter 8

Eldredge's Time Frames: The Rethinking of Darwinian  {146}  Evolution and the Theory of Punctuated Equilibria (Simon and Schuster, 1985) is a good place to begin on punctuated equilibrium, not least because it reprints his and Gould's original article. He updates his take on the debate in Reinventing Darwin (John Wiley, 1995). Gould reappraises the issues as he sees them in his 'Punctuated Equilibrium Comes of Age', in Nature (vol. 366, 1993, pp. 223-7). Robert Carroll surveys the empirical evidence for the punctuated equilibrium pattern in his Pattern and Process in Vertebrate Evolution (Cambridge University Press, 1999). John Thompson, in The Revolutionary Process, (University of Chicago Press, 1994) documents many examples of evolutionary changes in local populations. Elizabeth Vrba develops her 'turnover pulse hypothesis' in Turnover-Pulses, The Red Queen and Related Topics', in the American Journal of Science (vol. 293 A, 1993, pp. 418-52). Mayr's views on speciation are given most succinctly in the relevant section of his two volumes of essays, Evolution and The Diversity of Life (Harvard University Press, 1976) and Towards a New Philosophy of Biology (Harvard University Press, 1988). For a very sceptical view of punctuated equilibrium and its significance, see Daniel Dennett's Darwin's Dangerous Idea (Simon and Schuster, 1995).

Chapter 9

Erwin's The Great Paleozoic Crisis (Columbia University Press, 1993) is a superb overview of the Permian extinction. Archibald's Dinosaur Extinction and the End of An Era (Columbia University Press, 1996) is a judicious discussion of the debate about the most contentious extinction of them all. Evolutionary Paleobiology, a collection edited by Jablonski, Erwin and Lipps (University of Chicago Press, 1996), has many papers relevant to these issues. These three books are  {147}  written for professional audiences, though those by Erwin and Archibald, especially, are clear and well written. Peter Ward has written two enjoyable and non-technical books on mass extinction. They are: On Methuselah's Trail: Living Fossils and the Great Extinctions (Freeman, 1992) and (the rather preachy) The End of Evolution (Bantam, 1994). Ward is sympathetic to Gould's take on these issues. Richard Fortey's Life: A Natural History of the First Four Billion Years (Vintage, 1999) is good on these issues, too. David Raup analyses extinction, and particularly whether mass extinction is a fair game, in his Extinction: Bad Genes or Bad Luck? (Oxford University Press, 1991). Gould writes on mass extinction in all of his Natural History collections. In these, he mostly emphasises the discontinuities in evolutionary history that mass extinction causes. He explores the idea that mass extinction imposes a filter on species, rather than the individuals that make up the species, in A Task for Paleobiology' in Paleobiology (vol. 21, 1995, pp. 1-14) and 'The Necessity and Difficulty of a Hierarchical Theory of Selection' in Magurran and May's Evolution of Biological Diversity (Oxford University Press, 1999).

Chapter 10

Gould makes his case about the Cambrian and its significance in Wonderful Life: The Burgess Shale and the Nature of History (WW. Norton, 1989), and in it he makes a pre-emptive strike against Dawkins' line of criticism. These issues were followed up in a series of specialist articles in Paleobiology: Dan McShea, Arguments, Tests, and the Burgess Shale' (vol. 19, 1993, 399-402); Mark Ridley, Analysis of the Burgess Shale' (vol. 19, 1993, pp. 519-21) to which Gould replies, and especially Gould's The Disparity of the Burgess Shale  {148}  Arthropod Fauna: Why We Must Strive to Quantify Morpho-space' (vol. 17, 1991, pp. 411-23). In these papers, Gould explores an additional way of understanding the contrast between Cambrian and post-Cambrian animal life; the distinction between a fauna with a relatively open and flexible developmental system, and a fauna with a less open, more rigid system.

Mark and Dianne McMenamin argue that selection was important in generating disparity in The Emergence of Animals (Columbia University Press, 1991). They suggest that the Cambrian explosion is a response to the invention of preda-tion. Conway Morris, himself one of those who reinterpreted the Burgess Shale, takes issue with Gould in Crucibles of Creation (Oxford University Press, 1998). Morris argues that the history of life is much less contingent than Gould supposes, and that Gould overstates the weirdness of the Burgess fauna. In a recent review paper, Morris attempts to synthesise molecular data from the clock, and fossil evidence about both the Ediacaran and the Cambrian fauna (Morris thinks some Cambrian fauna have clear Ediacaran ancestors), to give an overview of the Cambrian explosion. See 'The Cambrian Explosion: Slow-fuse or Megatonnage', in Proceedings of the National Academy of Science, vol. 97, 2000, pp. 4426-9). For a good recent introduction to cladistics — the view that leads to Ridley's scepticism about the diversity/disparity distinction — see Henry Gee's In Search of Deep Time: Beyond the Fossil Record to a New History of Life (Free Press, 1999).

Chapter 11

The key text from Gould on these issues is Full House (Harmony Books, 1996), though these themes have been explored in his Natural History essays for years, often using  {149}  baseball as a model system for discussing the importance of changes in variation in a system. Maynard Smith and Szath-mary discuss evolutionary transitions in both Major Transitions in Evolution (Oxford University Press, 1995) and Origins of Life (Oxford University Press, 1999). Dawkins discusses progress both in his review of Full House, in Evolution: 'Human Chauvinism' (vol. 51, 1997, pp. 1015-20), and in 'Progress', an essay in Fox Keller and Lloyd's Key Words in Evolutionary Biology (Harvard University Press, 1992). Daniel Dennett defends the idea that life increases in adaptiveness over time in Darwin's Dangerous Idea (Simon and Schuster, 1995). J.T. Bonner defends the idea that there is a real, selection-driven trend for an increase in complexity over time in The Evolution of Complexity By Means of Natural Selection (Princeton University Press, 1988). Michael Ruse puts all these debates into their historical context in From Monad to Man: The Concept of Progress in Evolutionary Biology (Harvard University Press, 1996).

Chapter 12

Gould's views on the relationship between science and religion are explored in his Rocks of Ages (Ballentine, 1999). Dawkins argues for the idea that scientific knowledge is liberating in his Unweaving The Rainbow (Penguin, 1998). The hunch that human evolution depends as much on memes as on genes is explored most systematically not by Dawkins but by Dennett, in Darwin's Dangerous Idea. The best response to meme theory is Dan Sperber's Explaining Culture (Blackwell, 1996). For a provocative, but in my view seriously mistaken, application of evolutionary thought about humans, see Thorn-hill and Palmer's ,4 Natural History of Rape (MIT Press, 2000). There is much better work available than this, especially that  {150}  which locates human social evolution in its great-ape context. Two good recent examples are Michael Tomasello's The Cultural Origin of Human Cognition (Harvard University Press, 1999) and Chris Boehm's Hierarchy in the Forest: The Evolution of Egalitarian Behavior (Harvard University Press, 1999). Sarah Blaffer Hrdy's Mother Nature: Natural Selection and the Female of the Species (Pantheon Books, 1999) is also in places very speculative. But its account of the action of selection on human sexuality is much more subtle than that of Thornhill and Palmer.

Glossary

adaptation: an adaptation is a characteristic of an organism that exists today because it helped that organism's ancestors survive or reproduce.

adaptive trait: a trait that helps an organism with that trait survive or reproduce.

allele: an alternative version of a gene. Genes are located at particular regions of a chromosome. In a particular population, there may be different versions of a gene at a given location. These alternative versions are the alleles of that gene at that location.

amino acids: the building blocks of proteins. The genetic code specifies amino acids in a system that relates a sequence of three DNA bases to a single amino acid.

arms race: evolutionary interactions, within a species or between two species, in which each player becomes better adapted as a result of interaction with the other player.

biota: the totality of living things in a region or at a time.

chromosome: a long sequence of genes joined together in DNA molecules built around structurally supporting proteins. Chromosomes occur only in eukaryotic organisms. The number of chromosomes varies across species, but all (normal) members of a given species will have the same number.  {152} 

clade: a lineage consisting of all of a group of species and their common ancestor.

diploid cell: a cell that has two versions of each chromosome. If the organism is the result of sexual reproduction, each parent provides one of each pair of chromosomes.

ethology: the evolutionary study of animal behaviour in the wild, rather than its study under unusual, laboratory, conditions.

eukaryotes: organisms built from complex eukaryotic cells. Each cell has a discrete nucleus, together with complex cellular machinery usually including mitochondria and, in plants, chloroplasts. Eukaryotic cells are thought to have arisen from the evolutionary fusion of bacteria-like organisms. Mitochondria and chloroplasts had free-living bacteria as ancestors.

fitness: a measure of the probability that an organism (or a gene, or a group) will reproduce itself. Comparative fitness is of particular evolutionary significance: the evolutionary history of a population will depend on which organisms (or genes, or groups) do better than others.

gamete: the sex cell of an organism (e.g. sperm, ova, pollen). It is haploid, having half the chromosome number typical of the species, and fuses in sexual reproduction with another gamete to restore the full set for the species.

gene: a DNA sequence. The exact definition of a gene remains a matter of controversy, but genes are DNA sequences of some kind. The debate is whether each gene must have an identifiable function, or whether the DNA sequences can be of arbitrary length, and with arbitrary boundaries.

genome: the total collection of genes that an organism carries.

genotype: often used as a synonym for 'genome'. But it is sometimes used to specify the genes an organism has at a specific region (or regions) of a chromosome.

haploid cell: a cell that has only a single set of chromosomes.

heritability: a measure of the probability that an offspring  {153}  will share a trait possessed by its parent (at least in mathematical versions of evolutionary theory). A trait is heritable if a parent's having that trait increases the probability that its offspring will also have it.

macroevolution: a series of evolutionary changes in one or more species lineages; typically large, very long-lasting species lineages.

meiosis: the special form of cell division which generates sex cells, each of which has only half the number of chromosomes typical of cells of that species. This is in contrast to standard (asexual) cell division, whereby daughter cells end up with copies of all the structures in the parent cell.

microevolution: evolutionary changes within a single species. The term is sometimes used to refer to the evolution of one species into its immediate descendant(s).

mitochondrion: a special structure in eukaryote cells that generates energy for the cell, and has its own DNA. This DNA is almost always inherited only through the female line.

monophyletic group: a group that contains: (i) an ancestor species, (ii) only the descendants of that ancestor, and (iii) all the descendants of that ancestor.

mutation: a new DNA sequence that is produced when an error occurs in the copying process of a gene (or another replicator), resulting in a difference between the daughter gene and the template from which it was copied. Mutations are one source of new genetic variation in the population. Most, if they have any effects, have bad ones. So selection has acted to make the copying process very accurate indeed. But organisms have so many genes that even accurate copying still generates appreciable numbers of mutations.

natural selection: the process by which the superior fitness of certain traits causes those traits to increase in frequency in a population.  {154} 

phenotype: an organism's developed morphology, physiology and behaviour. It contrasts with the genotype: the genes that an organism carries.

prokaryotes: single-celled organisms, such as bacteria, without a nucleus or mitochondria. Prokaryotes are the simplest and oldest forms of life.

protein: a very large molecule made up of chains of amino acids folded in extraordinarily complex ways.

replicator: a structure that causes copies of itself to be made, and that, in combination with others, sometimes constructs a vehicle of selection. It is Dawkins' unit of heredity and selection.

species: there is no uncontroversial definition of a species. The most usual definition is the 'biological species concept' which defines a species as an interbreeding population of organisms. But there are many problems in making this notion precise. Moreover, using this definition, no asexual organisms form species.

species sorting: any pattern in species survival or extinction counts as species sorting, whatever the cause of that pattern. If, for example, for whatever reason, species with small population sizes are at a greater risk in mass extinction events, that would count as species sorting.

vehicle: a structure built by gene combinations in development. A vehicle mediates the reproduction of the genes responsible for its production. The clearest examples of vehicles are individual organisms, but there may be others, including groups of organisms.

Appendix: Geological Time Scale

BP = years before present

mya = millions of years ago

All figures are approximate.