English: Video sequence portraying a representative of the evolved swarming behaviour (evolution no. 4). Polarization and momentum are very low throughout the entire simulation run and the evolved behaviour can be classified as swarming behaviour. Note that the local density is higher than in the case of evolutions with no predator present (see S1 Video). Prey agents learned to stay inside the borders of the living area, and to avoid each other (prevent collisions). They learned also to group (by circling each other in an unordered fashion) and react to predator attacks (see frames 3700–3800 and 4600–5000). Note that soon after the disturbances induced by the predator attacks the swarming behaviour re-stabilizes.