Cognitive Biology: Surprising Model Organisms for Cognitive Science

Cognitive Biology: Surprising Model Organisms for Cognitive Science William Bechtel (bechtel@ucsd.edu) Department of Philosophy and Center for Chronobiology, University of California, San Diego La Jolla, CA, 92093-0119 USA Abstract per, I provide examples of what has been learned about cog- nitive mechanisms from bacteria and invertebrates. There is not space to examine research on plants here, but for illumi- nating discussion illustrating the potential of plant research to inform cognitive science, see Garzon and Keijzer (2011). Cognitive biology refers to investigations of cognitive pro- cesses in a wide range of model organisms from bacteria to plants and animals. Although this research has generally been beyond the scope of mainstream cognitive science, I argue that cognitive science would benefit from integrating investi- gations into model organisms and focus on what can be learned from surprising model organisms—bacteria and in- vertebrates. Evolution is a highly conserved process, and the mechanisms developed in our common ancestors with these species provide the foundation for many of our cognitive ac- tivities. Since these organisms lack some of the complications that have evolved in us, research on them can help reveal key features of our cognitive mechanisms. The Advantages of Using Model Organisms There are a number of reasons biologists choose to investi- gate model organisms (Ankeny & Leonelli, 2011). For most model organisms there are well developed breeding pro- grams that have generated stable lineages with greatly re- duced genetic variability, enabling researchers to perform replicable investigations on the mechanisms that generate the phenomenon of interest. Moreover, the research com- munity that has coalesced around model organisms has of- ten developed and calibrated a host of investigative tools that researchers can employ. But the reason that is most relevant to the investigation of cognitive traits is that mech- anisms in model organisms typically are simpler variants of ones found in the target organisms, allowing researchers to discover the basic components of the mechanism. Evolution often proceeds through duplication of genes and the subse- quent specialization of the duplicates. This can result in a more complex mechanism in subsequent organisms in which it is difficult to make interventions that reveal the key components of the mechanism underlying the phenomena. While the advantages of using model organisms may seem most obvious in the study of the genes and neural sys- tems, my focus is on how it can contribute to understanding the mechanisms of cognition. The investigation of genes and neural circuits can itself contribute to understanding cognitive mechanisms, as these serve as their components. In understanding cognition, though, the focus is on the in- formation processing operations these components perform. And in fact neurobiologists studying individual cells and small circuits are increasingly employing cognitive vocabu- lary to describe these information-processing mechanisms. In turning to model organisms to study cognition, there are two divergent strategies—focus on organisms phyloge- netically closest to humans or on the simplest organisms in which versions or components of the cognitive operations can be found. Each has its advantages. Close phylogenetic neighbors (primates or mammals) perform cognitive activi- ties that are in many cases very similar to those of humans, reducing the number of modifications or additions of opera- tions needed to realize the human cognitive capacities. In- vestigating organisms more reflective of our more ancient ancestors, on the other hand, provides insights into the basic cognitive operations that evolution made available for build- ing other cognitive systems. Keywords: Cognitive biology; model organisms; perception; decision making; memory and learning; sleep Introduction Biologists routinely conduct research on other species cho- sen to facilitate particularly productive investigation of the mechanisms operative in the species of primary interest, often humans. Often research focuses on organisms for which the last common ancestor occurred very early in phy- logeny but that nonetheless exhibit a version of the phe- nomenon of interest. In contrast, most research in main- stream cognitive science investigates the target organism, humans. Comparative psychologists have extended cogni- tive approaches to other organisms, especially primates and other vertebrates. While there are important exceptions, this research has tended to draw upon cognitive science to in- form studies of these other organisms, and has had limited impact on cognitive science itself. I follow the lead of Lyon (2006) in highlighting the potential for influence in the other direction—invoking research on other organisms to inform cognitive science. Instead of focusing on our phylogenet- ically closer relatives, as valuable as that is, I turn to organ- isms for which the last common ancestor is much more an- cient—bacteria and invertebrates. My contention is that cognitive science has much to gain by following the lead of biologists in incorporating research on cognitive processes in our most distant relatives into mainstream research and theorizing. In particular, understanding the mechanisms from which our more elaborate cognitive mechanisms evolved can provide distinctive insight into the core princi- ples employed in the mechanisms operative in us. In the next section I explore what cognitive science can hope to gain from incorporating research on model organ- isms, emphasizing that the goal is not to show that the mod- els exhibit exactly the same cognitive traits as the targets, but that they are informative about the mechanisms opera- tive in the target system. Then, in the remainder of the pa-