Model Organisms are Not (Theoretical) Models

Abstract

Many biological investigations are organized around a small group of species, often referred to as ‘model organisms’, such as the fruit fly Drosophila melanogaster. The terms ‘model’ and ‘modelling’ also occur in biology in association with mathematical and mechanistic theorizing, as in the Lotka–Volterra model of predator-prey dynamics. What is the relation between theoretical models and model organisms? Are these models in the same sense? We offer an account on which the two practices are shown to have different epistemic characters. Theoretical modelling is grounded in explicit and known analogies between model and target. By contrast, inferences from model organisms are empirical extrapolations. Often such extrapolation is based on shared ancestry, sometimes in conjunction with other empirical information. One implication is that such inferences are unique to biology, whereas theoretical models are common across many disciplines. We close by discussing the diversity of uses to which model organisms are put, suggesting how these relate to our overall account. 1 Introduction 2 Volterra and Theoretical Modelling 3 Drosophila as a Model Organism 4 Generalizing from Work on Model Organisms 5 Phylogenetic Inference and Model Organisms 6 Further Roles of Model Organisms 6.1 Preparative experimentation 6.2 Model organisms as paradigms 6.3 Model organisms as theoretical models 6.4 Inspiration for engineers 6.5 Anchoring a research community 7 Conclusion