…[W]e would like to have some reason for believing that…evolution had actually resulted in only one outcome: one mechanism of inheritance in sexual organisms, one mechanism of development on eukaryotes, one foraging strategy in herbivores. But why would we expect evolutionary outcomes to be so constrained?
–John Beatty (1994, 52) Theoretical Pluralism in Biology
Abstract
What is the relationship between evolutionary contingency and diversity? The evolutionary contingency thesis emphasizes dependency relations and chance as the hallmarks of evolution. While contingency can be destructive of, for example, the fragile and complex dynamics in an ecosystem, I will mainly focus on the productive or causal aspect of contingency for a particular sort of diversity. There are many sorts of diversities: Gould is most famous for his diversity-to-decimation model, which includes disparate body plans distinguishing different phyla. However, structural diversity construed more broadly spans scales, such as organization in and among cells, structural arrangements and biomechanics on various scales, and even the profile of ancestor-descendent relationships or community structure of interactions within ecosystems. By focusing on stochastic processes in contingent evolution, I argue that contingency causes structural diversity. Specifically, I focus on the plurality of structural types of cells, genetic codes, and phyla diversity as case studies.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Notes
Another way to think about process-based approaches versus primarily modal approaches to evolutionary contingency is this: ‘thin’ accounts of contingency appeal primarily to modal properties of evolutionary trajectories, whereas ‘thicker’ accounts include more specific causal details about the processes responsible for those modal properties.
There has been controversy over reclassification of Burgess Shale fauna (Brysse 2008). Changes in taxonomic methodology and the adoption of stem group concepts concerning Burgess creatures’ relationships with modern organisms has challenged the range of Cambrian diversity. Brysse understands this shift as a methodological artifact not necessarily forged by new data.
The line between modal versus process-based approaches may not be as clear cut as presented here, though it serves as a heuristic to navigate the contingency literature landscape.
I am very much indebted to Derek Turner and Joyce Havstad for articulating the dilemma to follow through in order to consider contingency as causal.
O. johnstoni as a necessary condition for G. Camelopardalis does not mean “if O. johnstoni occurs, then G. camelopardalis necessarily occurs.” In other words, to recognize the dependence of G. camelopardalis on O. johnstoni is to acknowledge prior needed (yet individually insufficient) conditions of a particular path leading to a particular outcome. Identifying necessary and sufficient conditions can be used to make sense of the historical dependency relation between species, but Desjardins has showed how such path dependent relationships can come in degrees of sensitivity too.
Currie (2018, 204) analyzes positive and negative historicity in terms of our evidential access to the past and how it can be used for historical reconstruction. Currie draws from Wimsatt’s work on generative entrenchment where dependencies accumulate and become necessary for future contingencies.
It has been pointed out to me that if absences can be causes (e.g., not locking my door is a causal factor in my house being robbed), then why can’t insufficiency as a lack of causal power itself be a causal factor? I’ll leave the controversy over the causal power of absences and Tyler Goldschmidt’s paper to the Daily Nous!
See Gould and Lewontin (1979) for a critique of adaptationism.
Schank and Wimsatt (1986, p. 52) explore an experiment by Stuart Kauffman on gene control networks, which they argue showed significant limitations on the power of selection with changes in properties of the networks better explained by intrinsic constraints rather than selection.
Stochastically-produced outcomes are not truly random in a way that circumvents rational explanation. Instead, such outcomes are “chance events from the viewpoint of function” (Noble 2013, p. 1236). It is better to think of stochastic processes as merely unbiased to the environment, rather than occurring purely without reason or pattern. This means that coherent explanations of diversity are still possible even when they draw from the role of chance.
Does contingency just amount to any other evolutionary force other than natural selection on my account? McConwell and Currie (2017, pp. 250–251) argue that natural selection can be a source of contingent evolution too: evolutionary outcomes can be sensitive to initial conditions such as a traits heritability for example. At the very least natural selection can be a source for historical contingency, but my emphasis on chance drives the contrast between processes under the banner of contingency and natural selection.
Convergences are also cited in support of evolutionary inevitability or predictability of outcomes (Morris 2003).
A reviewer for this paper raised concerns about the implication that functional analyses make evolution appear more constrained, and so they requested that something akin to that claim should be defended.
Stop signals halt translation into proteins.
Elzanowksi and Ostell’s list of genetic codes can be found at: https://www.ncbi.nlm.nih.gov/Taxonomy/Utils/wprintgc.cgi?mode=c.
Dendrites are short branching extensions of nerve cells, but there are dendritic cells that are part of mammalian immune systems named for their tree-like or dendritic shapes.
One reviewer suggested that even though cell type diversity is realized through multiple pathways (and I suggested the contingent evolution of those pathways be explored), this could be an example of a different type of convergent evolution. Perhaps the idea is that while one can distinguish between structural types based on contingent features and mechanisms, one might also distinguish between different functional types based on their prior histories (e.g. convergent evolution, parallelism).
Cell-type classification might call for philosophical analogues of various species concepts: Vickaryous and Hall (2006, p. 426) hope for unique cell markers to demonstrate unambiguous identity of cells, but despair about identity complications, such as how some cells can come to share features with recently encountered cells, and how identification is often up to the investigator.
Levin et al (2016) argue that phyla can be distinguished by mid-developmental transitions, which serves as an example of how structural typing can include fine-grained patterns and not just abstract anatomical descriptions.
A reviewer asks why I have not addressed simple cases: “Darwin would have said that structural variation within pigeons was due to the chance processes of accidental mutations. This process would help to increase variability in the population, and this is how we (sometimes) model mutation in population genetics, as introducing variation…there is an obvious case in which contingency causes diversity.” I avoid those cases because my aim is not to discuss accidental mutations as merely introducing variation for selectionist frameworks of evolution. My aim is to show how contingency, by causing structural diversity, results in pluralism. We sometimes find a plurality of x in the biological domain (kinds of heredity, for example), however, I aim to provide an explanation for that pluralism by appeal to evolutionary contingency as an explanatory framework.
Brysse (2008, p. 299) argues that changes in taxonomic methodology and the advent of stem group concepts that fit the “weird wonders” from the Burgess Shale with modern phyla, change the model of history to a less diverse base. Evolutionary systematics concerning similarity produces more phyla diversity compared to cladistics, which produces less.
Bausman (2016, pp. 8, 224) explores neutral theory—a theory of patterns of kinds of species in an ecological community. The primary process is ecological drift: demographic stochasticity or random birth and death similar to the MBL model that explains evolutionary patterns stochastically and without selection. He discusses how species can maintain an equilibrium despite speciation and extinction (as a product of drift), as analogous to how the water level in your sink is explained by the inflow rate from the faucet and the outflow rate of the drain. Solving how species number remains constant is like “solving the sink problem when the water level is constant” (21).
References
Arendt D, Musser JM, Baker CVH, Bergman A, Cepko C, Erwin DH, Pavlicev M, Schlosser G, Widder S, Laubichler MD, Wagner GP (2016) The origin and evolution of cell types. Nat Rev Genet 17(12):744–757
Babonis LS, Martindale MQ (2017) Phylogenetic evidence for the modular evolution of metazoan signalling pathways. Philos Trans R Soc B Biol Sci 372:20150477
Bausman WC (2016) Neutral theory, biased world. Dissertation. University of Minnesota
Beatty J (1980) What’s Wrong with the Received View of Evolutionary Theory ? In: PSA: proceedings of the biennial meeting of the philosophy of science association, vol 1980, no 2, pp 397–426
Beatty J (1992) Random drift. In: Keller E, Lloyd L (eds) Keywords in evolutionary biology. Harvard University Press, Cambridge
Beatty J (1994) Theoretical pluralism in biology, including systematics. In: Grande L, Rieppel O (eds) Interpreting the hierarchy of nature: from systematic patterns to evolutionary process theories. Academic Press, San Diego, pp 33–60
Beatty J (2006) Replaying life’s tape. J Philos 103:336–362
Beatty J (1995) The evolutionary contingency thesis. In: Wolters G, Lennox JG (eds) Concepts, theories, and rationality in the biological sciences, the second Pittsburgh-Konstanz colloquium in the philosophy of science, University of Pittsburgh Press, Pittsburgh
Ben-Menahem Y (1997) Historical Contingency. Ratio: An Internation J Anal Philos 10(2):99–107
Brigandt I (2007) Typology now: homology and developmental constraints explain evolvability. Biol Philos 22:709–725
Brigandt I (2017) Typology and natural kinds in evo-devo. In: de la Rosa LN, Müller G (eds) Evolutionary developmental biology: a reference guide. Springer, Cham
Brigandt I (2015) From developmental constraint to evolvability: how concepts figure in explanation and disciplinary identity. In: Love AC (ed) Conceptual change in biology: scientific and philosophical perspectives on evolution and development, Springer, Dordrecht, pp 305–325
Briggs DEG, Fortey RA (2005) Wonderful strife: systematics, stem groups, and the phylogenetic signal of the cambrian radiation. Paleobiology 31(2):94–112
Brysse K (2008) From weird wonders to stem lineages: the second reclassification of the Burgess Shale fauna. Stud Hist Philos Biol Biomed Sci 39:298–313
Cavalier-Smith T (2017) Origin of animal multicellularity: precursors, causes, consequences—the choanoflagellate/sponge transition, neurogenesis, and the Cambrian explosion. Philos Trans R Soc B Biol Sci 372:20150476
Cornish-Bowden A, Pereto J, Cardenas ML (2014) Biochemistry and evolutionary biology: two disciplines that need each other. J Biosci 39:13–27
Cresswell M, Mares E, Rini A (2016) Logical modalities from aristotle to carnap: the story of necessity. Cambridge University Press, Cambridge
Crick FH (1968) The origin of the genetic code. J Mol Biol 38(6):357–379
Currie A (2018) Rock, Bone, and Ruin: an optimist’s guide to the historical sciences. MIT Press, Cambridge
da Costa C, Galembeck E (2016) The evolution of the Krebs cycle: a promising subject fork meaningful learning of biochemistry. Biochem Mol Bio Educ 44(3):288–296
Darlington CD (1939/1958) The evolution of genetic systems. Basic Books, New York
Desjardins E (2011) Reflections on path dependence and irreversibility: lessons from evolutionary biology. Philos Sci 78(5):724–738
Doneley R (2016) The clinical examination. In: Samour J (ed) Avian medicine, 3rd edn. Elsevier, Amsterdam, pp 49–72
Elzanowski A, Jim O (2019) The genetic codes. National center of biotechnology information. https://www.ncbi.nlm.nih.gov/Taxonomy/Utils/wprintgc.cgi
Erwin DH (2016) Wonderful life revisited: chance and contingency in the Ediacaran–Cambrian radiation. In: Ramsey G, Spence C (eds) Chance in evolution. University of Chicago Press, Chicago, pp 277–298
Foote M (1993) Discordance and concordance between morphological and taxonomic diversity. Paleobiology 19:185–204
Garcia-Algarra J, Pastor JM, Iriondo JM, Galeano J (2017) Ranking of critical species to preserve the functionality of mutualistic networks using the k-core decomposition. PeerJ 5:e3321
Gould SJ (1989) Wonderful Life. W.W. Norton and Company, New York
Gould SJ (1991) The disparity of the Burgess Shale Athropod Fauna and the limits of cladistics analysis: why we must strive to quantify morphospace. Paleobiology 17(4):411–423
Gould SJ (1993) How to analyze the burgess shale disparity: a reply to Ridley. Paleobiology 19:52223
Gould SJ (2002) The structure of evolutionary theory. The President and Fellows of Harvard College, Cambridge
Gould SJ, Lewontin RC (1979) The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme. Proc R Soc Lond Ser B Contain Pap Biol Character R Soc G B 205(1161):581–598
Hull D (1987) Geneological actors in ecological roles roles. Biol Philos 2:168–184
Jordano P (2016) Chasing Ecological Interactions. PLoS Biol 14(9):e1002559
Jukes TH, Osawa S (1990) The genetic code in mitochondria and chloroplasts. Experientia 46(11–12):1117–26
King HM, Shubin NH, Coates MI, Hale ME (2011) Behavioural evidence for the evolution of walking and bounding before terrestiality in sarcopterygian fishes. PNAS 108(52):21146–21151
Kubyshkin V, Acevedo-Rocha CG, Budisa N (2018) On universal Coding events in protein biogenesis. Biosystems 164:16–25
Levin M, Anavy L, Cole AG, Winter E, Mostov N, Khair S et al (2016) The mid-developmental transition and the evolution of body plans. Nature 531:637–641
Love AC (2009) Typology reconfigured: from the metaphysics of essentialism to the epistemology of representation. Acta Biotheor 57:51–75
Maclaurin J, Sterelny K (2008) What is biodiversity?. The University of Chicago Press, Chicago
Magurran AE (1988) Ecological diversity and its measurement. Springer, Dordrecht
Martin WF, Garg S, Zimorski V (2015) Endosymbiotic theories for eukaryotic origin. Philos Trans R Soc B Biol Sci 370:20140330
McConwell AK (2017) Contingency and individuality: a plurality of evolutionary individuality types. Philos Sci 84(5):1104–1116
McConwell AK, Currie A (2017) Gouldian arguments and sources of contingency. Biol Philos 32(2):243–261
Millstein R (2006) Discussion of “four case studies on chance in evolution”: philosophical themes and questions. Philos Sci 73(5):678–687
Morris SC (2003) Life’s solution: inevitable humans in a lonely universe. Cambridge University Press, Cambridge
Mougi A, Kondoh M (2012) Diversity of interaction types and ecological community stability. Science 337:349–351
Mukai T, Hayashi A, Iraha F, Sato A, Ohtake K, Yokoyama S, Sakamoto K (2010) Codon reassignment in the Escherichia coli genetic code. Nucleic Acids Res 38(22):8188–8195
Noble D (2013) Physiology is rocking the foundations of evolutionary biology. Exp Physiol 98(8):1235–1243
Penumaka A (2011) The cambrian explosion and the origins of diversity. Harvard Sci Rev 44–47
Pigluicci Massimo (2008) Is evolvability evolvable? Nat Rev Genet 9:75–82
Powell R, Mariscal C (2015) Convergent evolution as natural experiment: the tape of life reconsidered. Interface Focus 5:20150040
Ridley M (1993) Analysis of the burgess shale. Paleobiology 19(4):519–521
Schank JC, Wimsatt WC (1986) Generative entrenchment and evolution. In: PSA proceedings of the biennial meeting of the philosophy of science association, vol 1986, pp 33–60
Soyer OS, Bonhoeffer S (2006) Evolution of complexity in signalling pathways. PNAS 103(44):16337–16342
Turner Derek (2011) Gould’s replay revisited. Biol Philos 26:65–79. https://doi.org/10.1007/s10539-010-9228-0
Turner D (2015) Historical contingency and the explanation of evolutionary trends. In: Malaterre C, Braillard P-A (eds) Biological explanation: an enquiry into the diversity of explanatory patterns in the life sciences. Springer, New York, pp 73–90. https://doi.org/10.1007/978-94-017-9822-8
Vickaryous MK, Hall BK (2006) Human cell type diversity, evolution, development, and classification with special reference to cells derived from the neural crest. Biol Rev 81:425–455
Wills MA, Briggs DEG, Fortey RA (1994) Disparity as an evolutionary index: a comparison of Cambrian and recent arthropods. Paleobiology 20(2):93–130
Winkler MW, Shoa G, Tran ST, Xie Y, Thomasy S, Raghunathan VK, Murphy C, Brown DJ, Jester JV (2015) A comparative study of vertebrate corneal structure: the evolution of a refractive lens. Invest Ophthalmol Vis Sci 56(4):2764–2772
Acknowledgements
Special thanks to Derek Turner and Joyce Havstad for providing challenges to contingency’s causality. They helped to shape a significant portion of this paper. Thanks to Will Bausman for the use of his wonderful sink metaphor, to Celso Neto for comments on previous versions, to the two reviewers whose comments significantly improved the manuscript, and to Marc Ereshefsky and Adrian Currie for their continued guidance on this project overall. Finally, I’m indebted to Ken Waters and everyone in Calgary’s research group From Biological Practice to Scientific Metaphysics for conversations about causation, as well as to Alan Love for his feedback on the very early stages of this work, and everyone at the Philosophy of Paleobiology workshop where these ideas were discussed. And of course, the funding from the John Templeton Foundation was much appreciated during my time at the University of Calgary where a significant portion of this paper was developed, as well as the funding through the Patrick Suppes Center for The History and Philosophy of Science at Stanford University where the paper was finalized.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
McConwell, A.K. Contingency’s causality and structural diversity. Biol Philos 34, 26 (2019). https://doi.org/10.1007/s10539-019-9679-x
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s10539-019-9679-x