Rock Paper Scissors Ecosystem
A simple 3-way ecology. Hit flag to restart.
Rocks, papers, & scissors are randomly scattered at the start, but soon we see swirling clusters of rocks overtake scissors, and paper overtake rock.
Rocks beats scissors if 3 or more rocks are next to scissors. Same idea with paper and scissors. Dynamic balance and co-existence usually result, with spiral patterns and oscillations. There’s no single, top-dog super-predator.
Here’s a game version.
Pack Attack
Use 3 coin types or chips of 3 colors on a grid, to get a feel for the rules and dynamics.
To protect herself against Scissors, Paper wants to avoid attacking a certain rock (shown with red arrow).Paper player can use a sand dollar to shield a Paper against attack.
Scissors has the fewest pieces. But by not attacking a particular Paper (green arrow), Scissors lets Paper eliminate Rock packs, using an “enemy of my enemy is my friend” effect to win.
Skilled players can use this “enemy of my enemy is my friend” effect to their advantage. This effect exists in ecosystems.
The game is a balanced ecosystem model that you can learn to “tip” in your favor. The game dynamics of balancing, tipping and the “enemy of my enemy” effect are seen in competing bacteria, lizards, and many other ecosystems.
The rules are simple (click for rules movie) but yield complex system dynamics, such as rebounds, resilience, and a surprising “survival of the weakest” effect that sometimes occurs in nature.
Survival of the Weakest
Hit flag to restart.
Shows 3 species of E. coli bacteria in an ecosystem.
Use sliders to weaken one of the species.
What happens? Try another species.
If all 3 species are equally strong, they coexist in a dynamic equilibrium, as in the 3 species of E. coli studied. But, weaken one species significantly, and something counter-intuitive happens.
Despite the simple game rules, complex dynamics emerge, like survival of the weakest. You can use those dynamics to your strategic advantage in our board game version.
To read more about the dynamics that can result, see our paper on “Resilience, tipping, and hydra effects.”
Awesome Global Patterns
The rules of neighbor interaction are simple. Yet, swirling global patterns emerge.
Those global patterns are easiest to see with computer models. Here is the basic model in Python. and here it is in NetLogo. The most user friendly versions here in our Scratch studio.
Here’s a variation in NetLogo that uses minimal code (and bird-like tiles for fun). After you click on the models and play with it, you can scroll down to “NetLogo code.” There you will see code like the following:
The above code is a simpler variation on the dynamic where each piece interacts with just one random neighbor. Contrast that with the NetLogo model using Little Tip rules where any piece is vulnerable to invasion if next to three or more neighbors.
Click Ecosystem Studio for more of our related Scratch models.
You can personalize the game with your own drawings or photos. Below is an example of a personalized version in Scratch
