Flocking seems like a complex behavior that should require careful collaboration between all the birds involved, but Craig Reynolds demonstrated back in 1986 that simulated birds, or boids, would realistically flock if they just followed three basic steering behaviors:
- Separation: steer to avoid crowding local flockmates.
- Alignment: steer towards the average heading of local flockmates.
- Cohesion: steer to move toward the average position of local flockmates.
He went on to demonstrate all sorts of Steering Behaviors For Autonomous Characters, including pursuit and evasion — but not pack-hunting.
Now C. Muro et al. have demonstrated that the sophisticated teamwork of a wolf pack also stems from simple rules:
We have produced computational simulations of multi-agent systems in which wolf agents chase prey agents. We show that two simple decentralized rules controlling the movement of each wolf are enough to reproduce the main features of the wolf-pack hunting behavior: tracking the prey, carrying out the pursuit, and encircling the prey until it stops moving.
The rules are (1) move towards the prey until a minimum safe distance to the prey is reached, and (2) when close enough to the prey, move away from the other wolves that are close to the safe distance to the prey.
The hunting agents are autonomous, interchangeable and indistinguishable; the only information each agent needs is the position of the other agents. Our results suggest that wolf-pack hunting is an emergent collective behavior which does not necessarily rely on the presence of effective communication between the individuals participating in the hunt, and that no hierarchy is needed in the group to achieve the task properly.