Addressing Darwin\'s Dilemma: \"Eternal Ephemera\" by Niles Eldredge

Books

SARAH BEVINS

Sarah Bevins (sarah.n.bevins@aphis. usda.gov) is a research biologist with the US Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center in Fort Collins, Colorado.

doi:10.1093/biosci/biv113

ADDRESSING DARWIN’S DILEMMA Eternal Ephemera: Adaptation and the Origin of Species from the Nineteenth Century through Punctuated Equilibria and Beyond. Niles Eldredge. Columbia University Press, 2015. 416 pp., illus. $35.00. (ISBN 0231153163 cloth).

P

hilosopher of biology Elliott Sober (1993) once quipped that Charles Darwin’s seminal text should have been titled On the Unreality of Species as Demonstrated by Natural Selection (p. 143). With typical insight, Sober explained a tension apparent http://bioscience.oxfordjournals.org

in Darwin’s work: that the theory intended to explain the emergence of new species was supported by an argument implying that species are mere illusions. This tension is the subject of Eternal Ephemera, the latest book by Niles Eldredge.

Eternal Ephemera consists of one long argument. In this, the work resembles Darwin’s Origin of Species (1859), itself a clear source of inspiration and frustration for Eldredge. The frustration stems from the point made above: Darwin’s argument for evolution by natural selection undermines belief in the objective reality of species even though observational evidence implies otherwise. Eldredge defines his alternative “taxic” perspective as one in which “species are real, with explicable births, histories, and deaths” (p. 161). He finds agreement in Michael Ghiselin’s (1974) individuality thesis, tracing that idea back to Giambattista Brocchi’s analogy between the lifespans of organisms and those of species. In arguing for his perspective, Eldredge returns to the tension found in Darwin (1859). Belief in the discrete reality of species is both intuitive and parsimonious, but theorists in the twentieth century seemed content to follow Darwin in denying that belief. In the first half of his text, Eldredge elaborates the conceptual background of Darwin’s theory, closing that narrative with Darwin’s succumbing to the “transformational”—that is, antirealist—perspective of species. The second half lays out the modern conceptual tools, developed in the last six decades

of evolutionary theorizing, for correcting Darwin’s mistake. The book’s structure calls to mind Stephen Jay Gould’s The Structure of Evolutionary Theory (2002). Eldredge’s work here extends many of his late colleague’s considerations. The reader’s response to Gould (2002) should therefore serve as a fair litmus test for reception of this new text. For my own part, I endorse Eldredge’s thesis as a valuable antidote to species antirealism. The supporting narrative is useful in showing not only how Darwin (1859) would eventually beget the gene-centric view popularized by Richard Dawkins but also how the history of the field might have unfolded differently. As Eldredge puts it, Darwin made a choice that we need not make now. The Beagle voyage yielded both fossil evidence that implied species’ stability over time and collections that implied the variability of species over geographic space. Darwin chose to accept the collections as data and the fossil evidence as misleading. Modern evolutionary research shows that species are real actors on a macroevolutionary stage, just as organisms are players on a microevolutionary one. The analogy between individuality at different scales was available to Darwin through Brocchi’s work; Darwin could have chosen differently. So can we. Eldredge’s narrative makes this point clear: Antirealism is not a necessary consequence of natural selection. Theorists who study the “species problem” tend to endorse Ghiselin’s version of the individuality thesis (Ereshefsky 2010). Most should therefore be sympathetic with Eldredge’s view. Nevertheless, Eldredge’s references to the species-problem literature are minimal. Perhaps this is because biologists regularly concede the species problem as a philosophical issue, but Eldredge agrees that his argument is conceptual, citing the straightforwardly philosophical works of Bunge (1977), Hull (1976, 1978, 1980), and Grene (1958, 1987). More attention paid to work already done on the species problem could provide a strong independent basis of support.

November 2015 / Vol. 65 No. 11 • BioScience 1101

Downloaded from http://bioscience.oxfordjournals.org/ by guest on March 22, 2016

not themselves the focus but rather serve to highlight the great amount of uncertainty and conflicting ideas that exist among scientists, even when health policy is often presented to the public as an absolute. A discussion of uncertainty in science also makes a useful appearance. This book exists in a zone in which it may be too general for disease researchers but lacking sufficient background for nonspecialists. This, combined with the somewhat muddled organization, may be off-putting for some, but the author brings to light some very important issues associated with disease outbreaks that are worthy of discussion, and she offers a unique perspective on pandemic responses. Those with a particular interest in medical anthropology would likely enjoy this perspective.

Books it leaves unaddressed the possibility that Darwin conceived of species as classes that are nevertheless real— that is, as natural kinds. Following Winsor (2009), I have argued that such a view would render the principle of divergence consistent with the rest of Darwin’s oeuvre (Finkelman 2013). Without addressing that third possibility, Eldredge’s narrative is insufficient to show that Darwin’s choice was either mistaken or consequently fateful. This objection should not undermine Eldredge’s conclusion. He gives other good reasons to accept the taxic perspective. That perspective remains a necessary prerequisite for paleontology, which is, in turn, the best tool for recognizing large-scale patterns in evolutionary history. The transformational perspective follows from the belief that microevolutionary processes can explain all evolutionary patterns, but the extrapolationist view seems increasingly insufficient. These points—both of which have been elaborated in the theoretical literature (Kitcher 1984, Grene 1987, Okasha 2006, Pigliucci and Müller 2010)—would be enough to support the taxic perspective without commitment to the text’s overarching historical narrative. Whatever its faults, Eldredge’s narrative has significant heuristic value. His text also makes other valuable additions. To wit: The broader dissemination of Brocchi’s thinking should be helpful to biologists and philosophers alike as they probe the conceptual limits of the individuality thesis. Eldredge’s clear presentation style ensures that the text is accessible to researchers in a variety of fields, as is appropriate for a work that crosses disciplinary boundaries among the life sciences, history, and philosophy. It is perhaps ironic that Eldredge’s presentation makes this, a work about the importance of classification, so difficult to classify. It is a text about empirical sciences with a conceptual thesis, developed in isolation from literature about the concept, given a presentation structured

1102 BioScience • November 2015 / Vol. 65 No. 11

around history. To quote Eldredge’s colleague David Kohn, “We all are, or think we are, Darwinians” (1985). Perhaps the best inference to draw from the present work is that we all have roles to play in defending that mutual affinity. References cited

Bunge M. 1977. Ontology 1: The Furniture of the World. Treatise on Basic Philosophy, vol. 3. Reidel. Darwin C. 1859. The Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. Murray. Ereshefsky M. 2010. Species. In Zalta EN, ed. The Stanford Encyclopedia of Philosophy, Spring 2010 ed. (22 July 2015; http://plato.stanford. edu/archives/spr2010/entries/species) Finkelman L. 2013. Systematics and the Selection of Species. City University of New York. Ghiselin MT. 1974. A radical solution to the species problem. Systematic Biology 234: 536–544. Gould SJ. 2002. The Structure of Evolutionary Theory. Harvard University Press. Grene M. 1958. Two evolutionary theories. British Journal for the Philosophy of Science 9: 110–127, 185–193. ———. 1987. Hierarchies in biology. American Scientist 75: 504–510. Hull DL. 1965. The effect of essentialism on taxonomy: Two thousand years of stasis. British Journal for the Philosophy of Science 15: 314–326. ———. 1976. Are species really individuals? Systematic Biology 252: 174–191. ———. 1978. A matter of individuality. Philosophy of Science 45: 335–360. ———. 1980. Individuality and selection. Annual Review of Ecology and Systematics 11: 311–332. Kitcher P. 1984. Species. Philosophy of Science 51: 308–333. Kohn D, Kottler MJ. 1985. The Darwinian Heritage. Princeton University Press. Okasha S. 2006. Evolution and the Levels of Selection. Clarendon Press. Pigliucci M, Müller GB. 2010. Evolution: The Extended Synthesis. MIT Press. Sober E. 1993. Philosophy of Biology. Westview Press. Winsor MP. 2009. Taxonomy was the foundation of Darwin’s evolution. Taxon 58: 1–7.

LEONARD FINKELMAN

Leonard Finkelman is affiliated with the Department of Philosophy at Linfield College, in McMinnville, OR. doi:10.1093/biosci/biv128

http://bioscience.oxfordjournals.org

Downloaded from http://bioscience.oxfordjournals.org/ by guest on March 22, 2016

Indeed, whereas theorists are largely in agreement with Eldredge’s conclusions, some will find fault with his supporting narrative. According to that narrative, Darwin faced a dilemma: Observation suggests that species are real things, but the logic of natural selection implies that species are illusory. Eldredge presents this dilemma as a choice between the taxic perspective— that species are real, spatiotemporally bounded individuals—and the transformational perspective—that species are classes of organisms that lack objective reality. Eldredge omits a third option. Most of the species-problem literature denies the possibility that species are natural kinds—that is, real, objectively delineable classes of organisms—on the strength of Hull’s arguments (1965). It is unclear what Darwin thought on that matter. Gould (2002) argued that Darwin lacked the conceptual framework for drawing a distinction between kinds and individuals but nevertheless expressed commitment to the idea that species are objectively real classes of organisms. Winsor (2009) also argued that Darwin did not reject a view of species as natural kinds. Proponents of the natural-kind perspective remain in the ideological minority, but a growing number now argue that the view is consistent with Darwinian theory (Ereshefsky 2010). Eldredge argues that Darwin made a fateful and mistaken choice of the transformational perspective over the taxic one, citing as evidence Darwin’s principle of divergence. The principle is an early form of species-level selection, suggesting that more-specialized species drive less-specialized intermediate groups to extinction. According to Eldredge, this principle is a clear example of taxic reasoning: It requires that species are real and objectively distinguished from one another. Eldredge also argues that it is an unusual point of inconsistency with the rest of Darwin’s theory, in which species are normally considered as classes. This is presented as evidence for Darwin’s transformational commitment. But