Abstract:

Collective motion, ubiquitous in  nature,  has  traditionally  been  explained  by  ‘self-propelled particle’  models  from  theoretical  physics.  Here we show,  via  field,  lab  and  virtual  reality experimentation, that classical models of collective behavior cannot account for how collective motion emerges in marching desert locusts (whose swarms impact the livelihood of millions). In contrast with previous assumptions, locusts do not explicitly align with neighbors. While individuals respond to moving dot stimuli via the optomotor response, this innate behavior does not mediate social response to neighbors. By contrast, locust behavior, across scales, can be explained by a ring attractor - a cognitive framework - that explicitly considers the sensorial representation of (direction to, as opposed to direction of) neighbors. This challenges long-held beliefs about how order can emerge from disorder in animal collectives.