The spontaneous organization of collective activities in animal groups and societies has attracted a considerable amount of attention over the last decade. This kind of coordination often permits group-living species to achieve collective tasks that are far beyond single individuals’ capabilities. In particular, a key benefit lies in the integration of partial knowledge of the environment at the collective level. In this contribution, we discuss various self-organization phenomena in animal swarms and human crowds from the point of view of information exchange among individuals. In particular, we provide a general description of collective dynamics across species and introduce a classification of these dynamics not only with respect to the way information is transferred among individuals but also with regard to the knowledge processing at the collective level. Finally, we highlight the fact that the individual’s ability to learn from past experiences can have a feedback effect on the collective dynamics, as experienced with the development of behavioral conventions in pedestrian crowds.
The discussion of various cases highlighted that individuals exchange information by means of direct or indirect interactions. This local exchange of information is then integrated at the collective level by means of feedback loops to produce adapted collective responses to various kinds of problems. Swarms and crowds consequently manage to take advantage of their numbers to cope with their complex environment and achieve sorting tasks, optimize their activities, or reach consensual decisions. Furthermore, through learning processes, individuals can develop behavioral specificities that may have additional effects on the collective dynamics. In human societies, for example, the emergence of behavioral conventions can induce a common behavioral bias in the population that enhances in turn the self-organized dynamics.