1. Predator/Prey Simulation for Investigating Emergent Behavior Jay Shaffstall

2. Introduction Overview of emergent behavior Evolution & emergent behavior Predator/Prey simulation Outcomes

3. Emergent Behavior An emergent behavior is a behavior that is not programmed into the system. An emergent behavior evolves over time from more primitive behaviors. The classic example: ant colony

4. Emergent Behavior The ant colony looks like it is strongly organized…each ant does a job to keep the colony healthy. In reality, each ant is responding to local rules. Each ant decides what to do next based on what is in its immediate area. An ant has no concept of the colony.

5. Emergent Behavior So emergent behavior is behavior that arises from the interaction of a lot of local behaviors. Another example is how cities seemingly organize into neighborhoods, even though each individual is making decisions based on what is best for them.

6. Evolution & Emergent Behavior Evolution allows a population to adapt to its environment over time. Environmental pressure Characteristics Natural selection Evolution is the process of a species adapting to environmental changes Does nothing for the individual

7. Evolution & Emergent Behavior Over time, individuals may start to cooperate in local ways. This local cooperation leads to emergent behavior, in which widely separated individuals appear to be working toward the same purpose

8. Predator/Prey Simulation A predator/prey simulation provides a simple environment in which evolution can happen There are three types of organisms in the simulation Plants Prey Predators

9. Predator/Prey Simulation Each organism has its own genetic structure. One gene for the prey, for example, might control how far the prey can move in one action Each organism also has rules for how it interacts with its local environment

10. Predator/Prey Simulation Each organism can breed to produce more organisms. The organisms that live long enough to breed are considered to be “fit”, and pass on their genetic characteristics to their children. Over time, the children become more and more “fit”

11. Predator/Prey Simulation Stages of development Environment Invasive plants Crippled prey Nice predators No more lemmings A complete simulation

12. Predator/Prey Simulation Goals of the simulation: Provide an environment in which evolution could take place for predators and prey See what emergent behaviors come out of the local behaviors

13. Outcomes The first non-testing run of the simulation took about 15 hours, and generated around 10 gigabytes of data. Let’s look at a sample of the displays. This sample is from the 8 th step of the simulation.

16. Outcomes That was from the 8 th step, where we still have the initial random distribution of animals and plants. Let’s look at a display from the 5600 th step, about 15 hours later.

18. Outcomes But what happened between those steps? Did evolution take place? Let’s look at a population graph for that run.

20. Outcomes Clearly, evolution did not take place. So, when the program doesn’t work like you expected, you find out why. The big question is why didn’t the prey population increase when the plant population increased? Consider this zoomed in part of the 5600 th step.

22. Outcomes The failure of prey to reproduce is the key problem with the simulation as it is written. Because of that, we do not see evolution Without evolution, we don’t see emergent behavior

23. Conclusion I set out to write a simulation to investigate emergent behavior Much bigger project than I thought, but also a lot of fun I recommend future students to look at projects dealing with emergent behavior

24. Conclusion To learn from my mistakes: Capstone paper available at http://cs.franklin.edu/~shaffsta/paper.zip