Papers by Pierrick Bourrat
Journal of Cognition and Culture
The question of whether cultural transmission is faithful has attracted significant debate over t... more The question of whether cultural transmission is faithful has attracted significant debate over the last 30 years. The degree of fidelity with which an object is transmitted depends on 1) the features chosen to be relevant, and 2) the quantity of details given about those features. Once these choices have been made, an object is described at a particular grain. In the absence of conventions between different researchers and across different fields about which grain to use, transmission fidelity cannot be evaluated because it is relative to the choice of grain. In biology, because a genotype-to-phenotype mapping exists and transmission occurs from genotype to genotype, a privileged grain of description exists that circumvents this ‘grain problem.’ In contrast, in cultural evolution, the genotype–phenotype distinction cannot be drawn, rendering claims about fidelity dependent upon researchers’ choices. Thus, due to a lack of unified conventions, claims about fidelity transmission are ...
Biological Theory
This article proposes two conditions to assess whether an entity at a level of description is a u... more This article proposes two conditions to assess whether an entity at a level of description is a unit of selection qua interactor. These two conditions make it possible to (1) distinguish biologically relevant entities from arbitrary ones and (2) distinguish units that can potentially enter a selection process from those that have already done so. I show that the classical approaches used in the literature on units and levels of selection do not fare well with respect to either or both of these desiderata.
Previous work has shown how a minimal ecological structure consisting of patchily distributed res... more Previous work has shown how a minimal ecological structure consisting of patchily distributed resources and recurrent dispersal between patches can scaffold Darwinian properties onto collections of cells. When the timescale of dispersal is long compared with the time to consume resources, patches evolve such that their size increases, but at the expense of cells whose growth rate decreases within patches. This creates the conditions that initiate evolutionary transitions in individuality. A key assumption of this scaffolding is that a bottleneck is created during dispersal, so patches are founded by single cells. The bottleneck decreases competition within patches and hence creates a strong hereditary link at the level of patches. Here we construct a fully stochastic model of nested Darwinian populations and investigate how larger bottlenecks affect the evolutionary dynamics at both cell and collective levels. It is shown that, up to a point, larger bottlenecks simply slow the dynam...
The Evolution of Multicellularity
BJPS Review of Books, 2021
The British Journal for the Philosophy of Science, 2022
The hierarchy of life is the result of a succession of evolutionary transitions in individuality ... more The hierarchy of life is the result of a succession of evolutionary transitions in individuality (ETIs). During an ETI, individuals at a particular level of organization interact in such a way as to produce larger-level entities that become individuals in their own right. These new individuals are defined by their capacity to exhibit Darwinian properties of variation, differences in fitness, and heredity. One difficulty in accounting for ETIs is articulating how these properties are acquired at a higher level from the lower ones. Collaborators and I recently proposed the 'ecological scaffolding' model in which imposing an ecological scaffold (that is, a structure in the environment) on lower-level entities initiates an ETI. Here, I present a new model that extends this work. Within this new model, I propose a mechanism of scaffold endogenization, demonstrating that collectives can become resilient to the ecological scaffold being removed. This type of resilience is not observed in the ecological scaffolding model. However, classically, a biological individual would be regarded as an entity capable of withstanding environmental changes. Thus, the new model proposed here represents a step towards a more complete explanation for ETIs.
European Journal for Philosophy of Science, 2021
Studies in History and Philosophy of Science, 2022
Despite being widely used in both biology and psychology as if it were a single notion, heritabil... more Despite being widely used in both biology and psychology as if it were a single notion, heritability is not a unified concept. This is also true in evolutionary theory, in which the word 'heritability' has at least two technical definitions that only partly overlap. These yield two approaches to heritability: the 'variance approach' and the 'regression approach.' In this paper, I aim to unify these two approaches. After presenting them, I argue that a general notion of heritability ought to satisfy two desiderata-'general applicability' and 'separability of the causes of resemblance.' I argue that neither the variance nor the regression approach satisfies these two desiderata concomitantly. From there, I develop a general definition of heritability that relies on the distinction between intrinsic and extrinsic properties. I show that this general definition satisfies the two desiderata. I then illustrate the potential usefulness of this general definition in the context of microbiome research.
Notre Dame philosophical reviews, 2017
Biology & Philosophy
Showing that the arithmetic mean number of offspring for a trait type often fails to be a predict... more Showing that the arithmetic mean number of offspring for a trait type often fails to be a predictive measure of fitness was a welcome correction to the philosophical literature on fitness. While the higher mathematical moments (variance, skew, kurtosis, etc.) of a probability-weighted offspring distribution can influence fitness measurement in distinct ways, the geometric mean number of offspring is commonly singled out as the most appropriate measure. For it is well-suited to a compounding (multiplicative) process and is sensitive to variance in offspring number. The geometric mean thus proves to be a predictively efficacious measure of fitness in examples featuring discrete generations and within- or between-generation variance in offspring output. Unfortunately, this advance has subsequently led some to conclude that the arithmetic mean is never (or at best infrequently) a good measure of fitness and that the geometric mean should accordingly be the default measure of fitness. We...
Entropy
Invariance is one of several dimensions of causal relationships within the interventionist accoun... more Invariance is one of several dimensions of causal relationships within the interventionist account. The more invariant a relationship between two variables, the more the relationship should be considered paradigmatically causal. In this paper, I propose two formal measures to estimate invariance, illustrated by a simple example. I then discuss the notion of invariance for causal relationships between non-nominal (i.e., ordinal and quantitative) variables, for which Information theory, and hence the formalism proposed here, is not well suited. Finally, I propose how invariance could be qualified for such variables.
The selected effects or ‘etiological’ theory of Proper function is a naturalistic and realist acc... more The selected effects or ‘etiological’ theory of Proper function is a naturalistic and realist account of biological teleology. It is used to analyse normativity in philosophy of language, philosophy of mind, philosophy of medicine and elsewhere. The theory has been developed with a simple and intuitive view of natural selection. Traits are selected because of their positive effects on the fitness of the organisms that have them. These ‘selected effects’ are the Proper functions of the traits. Proponents argue that this analysis of biological teleology has the unique advantage that the selected effect function of a trait is also a causal explanation of the trait: the trait exists because it performs this function. We show, however, that selected effect functions as currently defined explain the existence of traits only under highly restrictive assumptions about evolutionary dynamics. In many common scenarios in which traits evolve by natural selection, selected effect functions do no...
The British Journal for the Philosophy of Science, 2021
Mismatch is a prominent concept in evolutionary medicine and a number of philosophers have publis... more Mismatch is a prominent concept in evolutionary medicine and a number of philosophers have published analyses of this concept. The word 'mismatch' has been used in a diversity of ways across a range of sciences, leading these authors to regard it as a vague concept in need of philosophical clarification. Here, in contrast, we concentrate on the use of mismatch in modelling and experimentation in evolutionary medicine. This reveals a rigorous theory of mismatch within which the term 'mismatch' is indeed used in several ways, not because it is ill-defined but because different forms of mismatch are distinguished within the theory. Contemporary evolutionary medicine has unified the idea of 'evolutionary mismatch', derived from the older idea of 'adaptive lag' in evolution, with ideas about mismatch in development and physiology derived from the Developmental Origins of Health and Disease (DOHaD) paradigm. A number of publications in evolutionary medicine have tried to make this theoretical framework explicit. We build on these to present the theory in as simple and general a form as possible. We introduce terminology, largely drawn from the existing literature, to distinguish the different forms of mismatch. This integrative theory of mismatch captures how organisms track environments across space and time on multiple scales in order to maintain an adaptive match to the environment, and how failures of adaptive tracking lead to disease. Mismatch is a productive organising concept within this theory which helps researchers articulate how physiology, development and evolution interact with one another and with environmental change to explain health outcomes.
Encyclopedia of Evolutionary Psychological Science, 2021
There is a tension between, on the one hand, the view that natural selection produces adaptations... more There is a tension between, on the one hand, the view that natural selection produces adaptations, and on the other hand, the theoretical results showing that the links between natural selection are weakened in different evolutionary scenarios such as situations of (negative) frequency-dependent selection or more generally in situations where fitnesses are not constant. If these results are taken at face value, in the absence of alternative explanations to natural selection for adaptation, the existence of most complex biological structures appear as mysterious. In this paper, I provide an analysis of this problem. I show that the theoretical framework establishing only weak links between natural selection and adaptation refers to what I call 'local populations.' In contrast, I argue that assessing such links should be regarded from the perspective of 'global populations,' that is populations of local populations which, in some cases, can be constituted of more than ...
Following from my criticisms of Calcott’s analysis on the permissive/instructive distinction, I r... more Following from my criticisms of Calcott’s analysis on the permissive/instructive distinction, I rebut his claims that 1) he clarifies my measure one-to-one specificity; 2) for all intents and purposes of his analysis his notion of precision is different from my measure of one- to-one specificity; 3) Waddington box is a better and different model than the extension of Woodward’s radio I propose.
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Papers by Pierrick Bourrat
selection which is pervasively invoked in biology and other ‘evolutionary’ domains. Although
what constitutes the process of natural selection appears to be very intuitive (natural selection
results from entities exhibiting differences in fitness in a population), this conceals a number of
theoretical ambiguities and difficulties. Some of these have been pointed out numerous times;
others have hardly been noticed. One aim of this work is to unpack these difficulties and
ambiguities; another is to provide new solutions and clarifications to them using a range of
philosophical and conceptual tools. The result is a concept of natural selection stripped down
from its biological specificities.
I start by revisiting the entangled debates over whether natural selection is a cause of evolutionary
change as opposed to a mere statistical effect of other causes, at what level this putative cause
operates and whether it can be distinguished from drift. Borrowing tools from the causal
modelling literature, I argue that natural selection is best conceived as a causal process resulting
from individual level differences in a population. I then move to the question of whether the
process of natural selection requires perfect transmission of types. I show that this question is
ambiguous and can find different answers. From there, I distinguish the process of natural
selection from some of its possible products, namely, evolution by natural selection and complex
adaptation. I argue that reproduction and inheritance are conceptually distinct from natural
selection, and using individual-based models, I demonstrate that they can be conceived as
evolutionary products of it. This ultimately leads me to generalise the concepts of heritability and
fitness used in the formal equations of evolutionary change. Finally, I argue that concepts of
fitness and natural selection crucially depend on the grains of description at and temporal scales
over which evolutionary explanations are given. These considerations reveal that the metaphysical
status of the process of natural selection is problematic and why neglecting them can lead to
flawed arguments in the levels of selection debate.