This “clique” solution has some problems. First, a single mutant can’t form a clique. OK, but maybe the mutant is interacting with nearby individuals, some of whom also share the mutation? That works if the nearby partners are relatives, but the difficulty there is that kin selection would already be favouring co-operation with neighbours, so how does TFT get an advantage? You can juggle with the pay-offs and the “shadow of the future” probability to try and get this to work (i.e. find a set of parameters where co-operation with neighbours via kin selection is not favoured, whereas TFT is), but it all looks a bit shaky.
Andreas Griger below suggests that the TFT mutants preferentially interact with each other rather than the TFT-n (or DefectBots) around them. This is another solution, though it adds to the overhead/complexity of a successful invader. However, it does lead to a nice testable prediction: species which practice reciprocation with non-relatives will also practice partner selection.
The point about adaptation executors not being fitness maximizers was also brought up by Unnamed below though see my response. The general issue is that citing the link is not an all-purpose excuse for maladaptation (what Richard Dawkins once referred to as the “evolution has bungled again” explanation). In particular you might want to see a paper by Fehr and Henrich Is Strong Reciprocity a maladaptation? which looks at the maladaptation hypothesis in detail and shows that it just doesn’t fit the evidence. Definitely worth a read if you have time.
This “clique” solution has some problems. First, a single mutant can’t form a clique. OK, but maybe the mutant is interacting with nearby individuals, some of whom also share the mutation? That works if the nearby partners are relatives, but the difficulty there is that kin selection would already be favouring co-operation with neighbours, so how does TFT get an advantage? You can juggle with the pay-offs and the “shadow of the future” probability to try and get this to work (i.e. find a set of parameters where co-operation with neighbours via kin selection is not favoured, whereas TFT is), but it all looks a bit shaky.
Andreas Griger below suggests that the TFT mutants preferentially interact with each other rather than the TFT-n (or DefectBots) around them. This is another solution, though it adds to the overhead/complexity of a successful invader. However, it does lead to a nice testable prediction: species which practice reciprocation with non-relatives will also practice partner selection.
The point about adaptation executors not being fitness maximizers was also brought up by Unnamed below though see my response. The general issue is that citing the link is not an all-purpose excuse for maladaptation (what Richard Dawkins once referred to as the “evolution has bungled again” explanation). In particular you might want to see a paper by Fehr and Henrich Is Strong Reciprocity a maladaptation? which looks at the maladaptation hypothesis in detail and shows that it just doesn’t fit the evidence. Definitely worth a read if you have time.