The evolution of physical computation in animal collectives

Iain D. Couzin

Max Planck Institute for Ornithology, Germany

Understanding how social influence shapes biological processes is a central challenge in contemporary science, essential for achieving progress in a variety of fields ranging from the organization and evolution of coordinated collective action among cells, or animals, to the dynamics of information exchange in human societies. Using an integrated experimental and theoretical approach, I will address how, and why, animals exhibit highly coordinated collective behavior. I will demonstrate new imaging technology that allows us to reconstruct (automatically) the dynamic, time-varying networks that correspond to the visual cues employed by organisms when making movement decisions. Sensory networks are shown to provide a much more accurate representation of how social influence propagates in groups, and their analysis allows us to identify, for any instant in time, the most socially influential individuals within groups, and to predict the magnitude of complex behavioral cascades before they actually occur. I will also investigate the coupling between spatial and information dynamics in groups and reveal that emergent problem solving is the predominant mechanism by which mobile groups sense, and respond to, complex environmental gradients. Evolutionary modeling demonstrates that such ‘physical computation’ readily evolves within populations of selfish organisms and that, counter to the prevailing view, mixing in populations enhances the evolution of cooperative traits. Finally, I will reveal the critical role that uninformed, or unbiased, individuals play in effecting fast and democratic consensus decision-making in collectives, and will test these predictions with experiments involving schooling fish and wild baboons.