Evolution of cooperation by reciprocation within structured demes

Joshi, N. V. (1987) Evolution of cooperation by reciprocation within structured demes Journal of Genetics, 66 (1). pp. 69-84. ISSN 0022-1333

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Official URL: http://www.ias.ac.in/jarch/jgenet/66/69.pdf

Related URL: http://dx.doi.org/10.1007/BF02934456


The iterative two-person Prisoners' Dilemma game has been generalised to the N-person case. The evolution of cooperation is explored by matching the Tit For Tat (TFT) strategy (Axelrod and Hamilton 1981) against the selfish strategy. Extension of TFT to N-person situations yields a graded set of strategies from the softest TFT, which continues cooperation even if only one of the opponents reciprocates it, to the hardest, which would do so only when all the remaining opponents cooperate. The hardest TFT can go to fixation against the selfish strategy provided it crosses a threshold frequency pc. All the other TFT are invadable by the selfish (D) or the pure defector strategy, while none can invade D. Yet, provided a threshold pc is crossed, they can coexist stably with D. As N, the size of the group increases, the threshold pc also increases, indicating that the evolution of cooperation is more difficult for larger groups. Under certain conditions, only the soft TFT can coexist stably against the selfish strategy D, while the harder ones cannot. An interesting possibility of a complete takeover of the selfish population by successive invasions by harder and harder TFT strategies is also presented.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Evolution of Cooperation; Group Selection; Reciprocation; Game Theory; Tit For Tat
ID Code:60616
Deposited On:20 Jun 2012 06:42
Last Modified:18 May 2016 10:39

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