BIO150Y: Evolution of Cooperation Evolutionary Game

Expt. 3: Can Tit for Tat invade a population of cheaters?

Your Objective

Conduct simulations of a population which initially consists of a small number of TFT individuals (N=6) and a large number of cheats (N = 20) to see if TFT can persist.

Suggested Methods

  • Conduct replicates.
  • You can download a worksheet (as a PDF file) which contains data tables to record your results.
  • Based on your results, answer the quiz questions below.


  • Each coloured graph line tracks the number of players for each strategy through the 20 generations that the experiment takes.
  • Point+click on Reset to set up each new replicate experiment.


Based on your results, answer the following questions:

Can a small number of TFT invade a population of cheats (ALLD)?

If TFT never actually scores more points than ALLD in an encounter, why does it predominate in a mixed population?

"Do animals use Tit for Tat?"

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