Review of Evolutionary Causation edited by Tobias Uller and Kevin N. Laland
JAG WILLIAMS
Evolutionary Causation, edited by evolutionary biologists Tobias Uller and Kevin Laland, is the most recent contribution within the “Vienna Series in Theoretical Biology”. This series “intends to help fill important gaps in our understanding of some of the major open questions of biology, such as the origin and organization of organismal form, the relationship between development and evolution, and the biological bases of cognition and mind” (vii). In this book, the contributors interrogate the concept of evolutionary causation from the perspective of the newly emergent research program in evolutionary biology called the Extended Evolutionary Synthesis (EES). The Extended Evolutionary Synthesis is a developing tradition within evolutionary biology that argues that evolutionary theories must go beyond gene-centered accounts of evolutionary causation by introducing concepts from evolutionary developmental biology and evolutionary ecology (such as niche construction) into the conceptual frameworks and methodologies of population genetics.
In order to define a concept of evolutionary causation along these lines, Uller and Laland have assembled evolutionary biologists and philosophers of science who (broadly) identify with the tradition of Extended Evolutionary Synthesis to contribute to the fifteen chapters of the collection. These fifteen chapters are divided along three sections: (1) the first two chapters dealing with introduction and methodological remarks, (2) chapters three through eleven with biological reflections, and (3) chapters twelve through fifteen with philosophical reflections. In this book review, for the sake of both brevity and clarity, I will limit my discussion to the standout essays that specifically wrestle with the two primary contrasts between the Extended Evolutionary Systems and the gene-centered conceptualizations of evolutionary causation. Namely, I will isolate and explicate the two central theoretical issues in Evolutionary Causation which are 1) organismal agency and 2) the proximate-ultimate causal distinction. These two theoretical targets both implicitly and explicitly guide the discussions and arguments throughout the collected essays and demonstrate how the relevant conceptual debate on evolutionary causation between gene-centric and Extended Systems Synthesis accounts rests on these two issues.
Organismal agency refers to the ability of living organisms to modify their interactions with their environments in order to re-orient their experiences of the world to satisfy relevant metabolic needs and maintain living conditions. Importantly, as Laland, Odling-Smee, and Feldman write, these modified interactions and changes in experiences of the world “are neither predetermined, nor random” because they are directed by the ingenuity of organisms in their pursuit of metabolic needs (131). Moczek’s fourth chapter on evo devo and Laland, Odling-Smee, and Feldman’s seventh chapter on niche construction theory each articulate the evolutionary significance of organismal agency. Moczek’s developmental systems conceptualization of organismal agency emphasizes developmental plasticity (also known as phenotypic plasticity), which is an organism’s ability to behaviorally respond to existing developmental constraints with innovative behavioral adaptations without requiring an initial genetic mutation to catalyze the novel behavior (i.e. new phenotypes). In this view of evolutionary adaptation, rather than just being caused by the selection of genes over long time-scales, adaptation can also be caused and directed by an organism’s pre-existing self-organizing mechanisms which can re-wire behavioral patterns, stabilize successful behavioral variants, and bias future genetic and phenotypic adaptations towards a particular trajectory. Consequently, evolutionary adaptation does not require novel introductions of modules, pathways, or cell fates because developmental constraints and standing genetic variation can be overcome via organismal agency acting to innovate in response to developmental constraints. An organism has the ability to build new behaviors on an existing stable gene pool. Thus, rather than just being gene-centric, Moczeck argues that organisms as developmental systems exercise organismal agency and this organismal agency is evolutionary significant because it can lead to innovative phenotypic variations without first requiring genetic mutation or natural selection over long time-scales.
In their chapter, Laland, Odling-Smee, and Feldman identify the causal relevance of organismal agency for evolutionary causation by focusing on the concept of niche construction. Niche construction is “the process whereby organisms, through their metabolism, their activities, and their choices, modify their own and each other’s niche”, the niche being “the sum of all natural selection pressures to which the population is exposed” (129). The concept of niche construction has always been a relevant concept in evolutionary biology, even in gene-centric theories, as it is nearly impossible to tell a meaningful story about evolution without weaving together some account of fine-grained organism-environment interactions. Yet, gene-centric accounts of evolutionary causation do not typically count niche construction as a causally significant evolutionary process. The authors of this chapter define niche construction as an aspect of organismal agency that is evolutionarily causally significant because it acts as a force for instituting, reworking, and stabilizing novel phenotypes in a population. These novel introductions of phenotypes emerge from goal-driven and self-regulating organism-environment interactions that lead to “a statistical bias on the direction and mode of selection, and hence on the speed and direction of evolution” (142). One of the clearest examples of niche construction in the animal kingdom (besides humans with our cultural structures) is the beaver who, via the creation of networks of dams in an environment, fundamentally alters and reshapes their individual fitness landscape as well as the fitness landscape of future generations. Beavers exercise organismal agency over their evolutionary trajectory via their propensity to enact physical changes in their environment. Thus, in their essay, Laland, Olding-Smee, and Feldman argue that niche construction is an evolutionarily significant type of organismal agency because it is the process by which organisms create physical and/or social structures and incorporate those structures into their behavioral patterns in a way that fundamentally alters their individual population’s fitness as well as the fitness of future generations.
One of the objections levied against treating organismal agency as evolutionarily significant is that it conflates “proximate” and “ultimate” causes together; a distinction that originates in the work of 20th century biologist Ernst Mayr. Philosopher Karola Stotz’s essay on the proximate-ultimate distinction quotes Mayr who writes, “It is evident that the functional biologist would be concerned with analysis of the proximate causes, while the evolutionary biologist would be concerned with analysis of ultimate causes” (333). Mayr is arguing here that proximate causes are essentially about how individualmechanisms and developmental systems work in whereas ultimate causes are about explanationsof why those mechanisms emerged in the organism at all. Failures to recognize this distinction, according to advocates for gene-centric theories of evolutionary causation, have led to what contemporary gene-centered evolutionary biologists have called the “ontogenetic fallacy: explaining an evolutionary outcome through causes of development” (336). For this very reason, the proximate-ultimate distinction marks the second crucial theoretical issue governing the arguments within Evolutionary Causation.
In addition to the various other contributors in the collection who undermine what they see as the false dichotomy at play in Mayr’s formulation (Duckworth (154) and Walsh (243)), Stotz argues that the proximate-ultimate distinction is unhelpful because ultimate explanations of evolutionary change must be grounded in relevant proximate mechanisms at some point in evolutionary history. That is, ultimate explanations of why certain developmental and/or biological systems operate the way they do must have a relevant causal story referring to proximate mechanisms at some point in the organism’s history. As Stotz writes, “All of natural selection’s underlying conditions — trait variation, inheritance, and differential fitness — can be given a causal-mechanistic account of proximate causes. It is only through their role in the selection process that they are rendered as ultimate causes” (334). Stotz is arguing that natural selection across generations of populations does not actually describe a causal force but a statistical distribution across a long timescale. Thus, the proximate-ultimate distinction does not genuinely define two kinds of causation because statistical distributions across time are not genuine physical forces. Rather than two kinds of causation, proximate mechanisms define how “individual populations change over time because of the way physical processes interact with particular organisms” while ultimate causes are really ultimate explanations that are “strictly speaking not a process or a cause but a statistical distribution” (335). With this proximate-ultimate distinction cashed out according to a difference between proximate physical mechanisms of causality and formalized statistical distributions, we can understand how the proximate-ultimate can be relevant for evolutionary biology without undermining the role of organismal agency in evolution. This is because, whether mechanisms of natural selection or organismal agency, causal forces of evolution depend on being instantiated in proximate mechanisms which can lead to formalized statistical distributions for ultimate explanations. The relevant argument, according to Stotz, just turns back to whether or not organismal agency genuinely indicates significant contributions to evolutionary adaptation; this question, however, relates to issues of organismal agency’s significance in general and not its being a proximate mechanism. The central theoretical disputes to be waged, therefore, seem to rest on the role organismal agency in evolutionary directedness and whether or not the proximate-ultimate distinction excludes developmental bias from being evolutionarily significant.
Overall, the focus on the revision of traditional views of evolutionary causation in this book, while fascinating, may have been more precise if some of its contributors attended to more moderate evolutionary biologists and philosophers working in the area of causation. More specifically, I would have enjoyed more of a nuanced discussion of how Extended Evolutionary Synthesis conceptualizations of evolutionary causation fit in with more nuanced theories of evolution found in the works of neo-Darwinian evolutionary philosophers such as Daniel Dennett and Kim Sterelny who explicitly argue for the ubiquity of natural selection in adaptation, while also agreeing wholeheartedly with phenotypic plasticity and genetic accommodation. The ability of Dennett and Sterelny to accept both a natural selection only view of evolutionary causation, while at the same time accepting developmental plasticity, niche construction, and genetic accommodation would seem to undermine the project of the Extended Evolutionary Synthesis to radically revise evolutionary causation. It is possible that Dennett and Sterelny are not entitled to their acceptance of both positions (natural selection only-causation and Extended Evolution Synthesis concepts) but, without the contributors explicit discussion of these more moderate philosophers, I am left without a convincing answer to whether or not I should accept the more moderate version of evolutionary causation found in Dennett and Sterelny or accept EES’s more radical revision that supplements natural selection with other evolutionary processes of causation. Since accepting conservative revision is always a bit more safe than radical revision (particularly in science), Evolutionary Causation’s lack of discussion about how their view measures against more nuanced versions of neo-Darwinianism is an unfortunate omission.
Despite this criticism, I strongly recommend Evolutionary Causation to anyone interested in the field of evolutionary biology and the philosophy of biology. The contributors to the collection have worked hard to insightfully and systematically indicate the chief breaking points between traditional gene-centric natural selection and the organismal agential accounts of evolution in the Extended Evolutionary Synthesis. Evolutionary Causation has shown that the theoretical competition between different accounts of evolutionary causation is to be waged on the grounds of organismal agency and the relevance of the proximate-ultimate distinction. I recommend this book to any experienced reader of evolutionary biology or the philosophy of biology if they are interested in contemporary issues in evolutionary biology.
Review of Evolutionary Causation: Biological and Philosophical Reflections edited by Tobias Uller and Kevin N. Laland. MIT Press. 2019. 361 pp.
