Tinbergen’s Missing Question: What is Animal Behavior Good For?

Nikolaas Tinbergen proposed four questions to guide the study of animal behavior: mechanism, development, function, and evolution. A fifth question, however, never made the list: what is it good for? The question is not hypothetical. It arrives at dinner parties, public events, and family reunions alike. For years I gave the standard answer: fundamental knowledge and the long-term dividends of curiosity-driven research. But that never seemed to satisfy my interlocutors, so I, and a few of my collaborators, decided to do something about it instead. This talk documents two attempts. First, army ants build elaborate living structures from nothing but their own bodies; by characterizing the growth dynamics of these living architectures, we identified the decentralized rules underlying their self-assembly. These rules directly inspired the creation of Kastor, a startup developing modular, self-assembling conveyor tiles for construction sites. The second attempt draws on a rather different organism. Physarum polycephalum, a slime mold with no brain, no nervous system, and no obvious computational abilities, achieves seemingly complex adaptive behaviors through a single mechanochemical mechanism; we used that mechanism as the blueprint for RAPID, a demand-responsive public transit algorithm, in which buses dynamically reroute through a cooperative process. Animal behavior, as it turns out, might be good for something. Whether this settles Tinbergen's missing question, I leave to the audience. But I suspect it will come up again at my family's Christmas dinner.