Abstract
Can evolutionary theory be properly characterised as a “theory of forces,” like Newtonian mechanics? One common criticism to this claim concerns the possibility to conceive genetic drift as a causal process endowed by a specific magnitude and direction. In this chapter, we aim to offer an original response to this criticism by pointing out a connection between the notion of force and the notion of explanatory depth, as depicted in Hitchcock and Woodward’s manipulationist account of causal explanation. In a nutshell, our argument is that since force-explanations can be consistently reframed as deep explanations and vice versa and the notion of drift can be characterised in manipulationist terms as constitutively intervening in evolutionary deep explanations, then drift-explanations can be consistently reframed as force-explanations, and drift can be properly considered as a force of evolution. Insofar as similar considerations may be extended also to other evolutionary factors – chiefly selection – our analysis offers an important support to the claim that evolutionary theory is a theory of forces.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Notes
- 1.
Shapiro and Sober (2007) are nominally committed to the force analogy. Yet, besides their manipulationist argument for considering drift as a cause, they do not provide any further strong reason to conceive it, in addition, as a force.
- 2.
Dobzhansky and Pavlovsky separated 20 replicate populations of Drosophila in 2 groups of 10 populations each. The first group was composed by large populations while the second by very small populations (10 males and 10 females). Dobzhansky and Pavlovsky aimed to track two allelic types that, initially, were present in each population with a ratio of exactly 50:50. By reducing the size of the second group of populations they intended to simulate a founder effect (which is usually considered as a common cause of drift). After a certain number of generations, they let all the populations grow to the same size. Finally, they let selection act freely and after a number of generations necessary to reach the equilibrium, they recounted type frequencies in each population. The result was that while in large populations the degree of variance between frequencies at equilibrium was small, in small populations it was far greater.
- 3.
Of course, also purifying selection is an eliminative process. Stephens is rather contrasting eliminative forces with forces generating variation (e.g., mutation).
- 4.
Henceforth, except if otherwise specified, we shall use the word “force” to refer to component forces, and not to net forces. As a matter of fact, we take the expression “net force” to denote a theoretical representation of the combinatorial effects of interacting forces (as represented in the consequence laws of a theory of forces) while only the component forces are causally efficient.
- 5.
Blanchard et al. (2018) think that stability should be better characterised as denoting two distinct explanatory virtues, that is, breadth and guidance. We do not need to enter into such details here.
- 6.
Quite clearly, the criteria for explanatory depth here adopted are not metric, i.e., they do not allow arranging distinct explanations of a given phenomenon on a univocal scale ranging from the shallowest to the deepest. Rather, they have to be interpreted, more modestly, as comparative criteria. This does not mean, as we shall see in the next sections, that they cannot be useful as analytic tools.
- 7.
In the last section we noticed – regarding our hypothetical generalisations concerning plant height – that some background conditions are ineliminable. This is possibly true also of generalisations dealing with more fundamental features of the physical world, but we shall not discuss this issue here.
- 8.
Even though also mutation might be considered as a stochastic process, in traditional population genetic models it is commonly conceived as a deterministic one (see, for instance, Hartl and Clark 2007).
- 9.
Effective population size can be conceptualized in a variety of ways. When it is estimated that human effective population size is around 10.000 individuals (Yu et al. 2004) even though current census size is over 7 billion, reference is to the genetic variability in sampled genes. The reason for this discrepancy – already highlighted by Wright (Ohta 2012, p. 2) – is that a bottleneck in the history of the lineage drastically reduces effective population size. Another, more general and less refined, conceptualisation of effective population size merely draws on the difference between potential and actual reproducers. While both ways of conceptualising effective population size are legitimate (indeed there are many more, see note 11), the vernacular conceptualisation is sufficient to ground our argument.
- 10.
This is not to say that the size of a population cannot play a causal role in evolutionary dynamics but just that it is not because of the causal role that population size plays that drift can be considered as a force.
- 11.
There exist at least three ways in population genetics to conceptualise effective size: besides variance effective population size, they are inbreeding effective population size and eigenvalue effective population size. Although they have different functions within population modelling, they all represent the number of actual reproducers in contrast with the number of potential reproducers denoted by census population (see note 9).
References
Beatty, J. (1984). Chance and natural selection. Philosophy of Science, 51, 183–211.
Beatty, J. (1992). Random Drift. In E. K. Keller & E. A. Lloyd (Eds.), Keywords in evolutionary biology (pp. 273–381). Cambridge, MA: Harvard University Press.
Blanchard, T., Vasilyeva, N., & Lombrozo, T. (2018). Stability, breadth and guidance. Philosophical Studies, 175, 2263–2283.
Brandon, R. N. (2006). The principle of drift: Biology’s first law. Journal of Philosophy, 103, 319–335.
Brandon, R. N. (2010). A non-newtonian model of evolution: The ZFEL view. Philosophy of Science, 77, 702–715.
Caponi, G. (2014). Leyes sin causas y causas sin ley en la explicación biológica. Bogotá: Universidad Nacional de Colombia.
Charlesworth, B. (2009). Effective population size and patterns of molecular evolution and variation. Nature Reviews, Genetics, 10, 195–205.
Dobzhansky, T. (1937). Genetics and the origin of species. New York: Columbia University Press.
Dobzhansky, T., & Pavlovsky, O. (1957). An experimental study of interaction between genetic drift and natural selection. Evolution, 11, 311–319.
Dowe, P. (2000). Physical causation. Cambridge, NY: Cambridge University Press.
Endler, J. A. (1986). Natural selection in the wild. Princeton: Princeton University Press.
Filler, J. (2009). Newtonian forces and evolutionary biology: A problem and solution for extending the force interpretation. Philosophy of Science, 76, 774–783.
Fisher, R. A. (1921). Review of the relative value of the processes causing evolution. The Eugenics Review, 13, 467–470.
Fisher, R. A., & Ford, E. B. (1947). The spread of a gene in natural conditions in a colony of the moth Panaxia Dominula. Heredity, 1, 143–174.
Futuyma, D. J. (2005). Evolution. Sunderland: Sinauer.
Gildenhuys, P. (2009). An explication of the causal dimension of drift. British Journal for the Philosophy of Science, 60, 521–555.
Gillespie, J. H. (2004). Population genetics: A concise guide. Baltimore: John Hopkins University Press.
Hartl, D. L., & Clark, A. G. (2007). Principles of population genetics (4th ed.). Sunderland: Sinauer.
Hitchcock, C., & Velasco, J. D. (2014). Evolutionary and Newtonian forces. Ergo, 1.
Hitchcock, C., & Woodward, J. (2003). Explanatory generalisations, part II: Plumbing explanatory depth. Noûs, 37, 181–199.
Hodge, J. (1987). Biology and philosophy (including ideology): A study of Fisher and Wright. In S. Sarkar (Ed.), The founders of evolutionary genetics (pp. 231–285). Dordrecht: Springer.
Jammer, M. (1956). Concepts of force: A study in the foundations of dynamics. New York: Dover.
Kitcher, P. (1989). Explanatory unification and the causal structure of the world. In P. Kitcher & W. C. Salmon (Eds.), Scientific explanation (pp. 410–505). Minneapolis: University of Minnesota Press.
Lewis, D. K. (1986). Philosophical papers (Vol. 1). Oxford: Oxford University Press.
Luque, V. (2016). Drift and evolutionary forces. Theoria: Revista de Teoría, Historia y Fundamentos de la Ciencia, 31, 397–410.
Matthen, M., & Ariew, A. (2002). Two ways of thinking about fitness and natural selection. Journal of Philosophy, 99, 55–83.
Millstein, R. L. (2002). Are random drift and selection conceptually distinct? Biology and Philosophy, 17, 33–53.
Millstein, R. L. (2005). Selection vs drift: A response to Brandon’s reply. Biology and Philosophy, 20, 171–175.
Millstein, R. L. (2006). Natural selection as a population-level causal process. The British Journal for the Philosophy of Science, 57, 627–653.
Ohta, T. (2012). Drift: theoretical aspects. In Encyclopedia of Life Sciences. Chichester: John Wiley & Sons, Ltd. http://www.els.ne0; https://doi.org/10.1002/9780470015902.a0001772.pub3. (last accessed 05/09/2018).
Pence, C. H. (2016). Is genetic drift a force? Synthese, 194, 1967–1988.
Plutynski, A. (2007). Drift: A historical and conceptual overview. Biological Theory, 2, 156–167.
Reisman, K., & Forber, P. (2005). Manipulation and the causes of evolution. Philosophy of Science, 72, 1113–1123.
Rice, S. H. (2004). Evolutionary theory: Mathematical and conceptual foundations. Sunderland: Sinauer.
Roffé, A. (2017). Genetic drift as a directional factor: Biasing effects and a priori predictions. Biology and Philosophy, 32, 535–558.
Salmon, W. (1986). Scientific explanation and the causal structure of the world. Princeton: Princeton University Press.
Shapiro, L., & Sober, E. (2007). Epiphenomenalism – The Dos and the Don’ts. In G. Wolters & P. Machamer (Eds.), Thinking about causes: From Greek philosophy to modern physics (pp. 235–264). Pittsburgh: University of Pittsburgh Press.
Sklar, L. (2013). Philosophy and the foundations of dynamics. Cambridge, UK: Cambridge University Press.
Sober, E. (1984). The nature of selection. Cambridge, MA: The MIT Press.
Stephens, C. (2004). Selection, drift, and the “forces” of evolution. Philosophy of Science, 71, 550–570.
Stephens, C. (2010). Forces and causes in evolutionary theory. Philosophy of Science, 77, 716–727.
Stoltzfus, A., & McCandlish, D. M. (2017). Mutational biases influence parallel adaptation. Molecular Biology and Evolution, 34, 2163–2172.
Walsh, D. M., Lewens, T., & Ariew, A. (2002). The trials of life: Natural selection and random drift. Philosophy of Science, 60, 195–220.
Weslake, B. (2010). Explanatory depth. Philosophy of Science, 77, 273–294.
Woodward, J. (2003). Making things happen. Oxford: Oxford University Press.
Woodward, J. (2006). Sensitive and insensitive causation. Philosophical Review, 115, 1–50.
Woodward, J. (2010). Causation in biology: Stability, specificity and the choice of levels of explanation. Biology and Philosophy, 25, 287–318.
Woodward, J. (2016). Unificationism, explanatory internalism, and autonomy. In M. Couch & J. Pfeifer (Eds.), The philosophy of Philip Kitcher (pp. 121–146). Oxford: Oxford University Press.
Woodward, J., & Hitchcock, C. (2003). Explanatory generalizations, part I: A counterfactual approach. Nôus, 37, 1–24.
Wright, S. (1932). Evolution in Mendelian populations. Genetics, 16, 97–159.
Ylikoski, P., & Kuorikoski, J. (2010). Dissecting explanatory power. Philosophical Studies, 148, 201–219.
Yu, N., Jensen-Seaman, M. I., Chemnick, L., Ryder, O., & Li, W. H. (2004). Nucleotide diversity in gorillas. Genetics, 166, 1375–1383.
Acknowledgments
We would like to thank Victor Luque, Elliott Sober, Luciana Zaterka and two anonymous reviewers for useful comments. We acknowledge the financial support of the Fondo Nacional de Desarrollo Científico y Tecnológico de Chile (Grant N° 1171017 FONDECYT REGULAR). Lorenzo Baravalle acknowledges the financial support of the Fundação de Amparo à Pesquisa do Estado de São Paulo, FAPESP (Grant N° 2017/24766-3), the Conselho Nacional de Desenvolvimento Científico e Tecnológico do Brasil, CNPq (Grant N° 402619/2016-1) and the Fundação para a Ciência e a Tecnologia de Portugal, FCT (Contract N° DL57/2016/CP1479/CT0064). Davide Vecchi acknowledges the financial support of the Fundação para a Ciência e a Tecnologia, FCT (Contract N° DL57/2016/CP1479/CT0072; Grant N. UID/FIL/00678/2019; BIODECON R&D Project grant PTDC/IVC- HFC/1817/2014).
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2020 Springer Nature Switzerland AG
About this chapter
Cite this chapter
Baravalle, L., Vecchi, D. (2020). Drift as a Force of Evolution: A Manipulationist Account. In: Baravalle, L., Zaterka, L. (eds) Life and Evolution. History, Philosophy and Theory of the Life Sciences, vol 26. Springer, Cham. https://doi.org/10.1007/978-3-030-39589-6_9
Download citation
DOI: https://doi.org/10.1007/978-3-030-39589-6_9
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-030-39588-9
Online ISBN: 978-3-030-39589-6
eBook Packages: Religion and PhilosophyPhilosophy and Religion (R0)