51. Natural Selection and Altruism on The Tube – Part 2: Tube Prisoners Dilemma
A couple of weeks ago I spoke of 'Tube Utopia', the story of Tube-Dove's and Tube-Hawks on the London Underground.
The story borrows shamelessly from natural selection and things like that, and as such it tries to demonstrate three things:
1. Selfless altruism on the tube (and in nature and life in general) will have positive benefits for the giver and the wider environment even though it costs something to do it and there may be no obvious immediate payoff.
e.g. When a Tube-Dove gives up their seat it costs them as an individual, but the environment becomes a warmer, happier, more caring place.
2. Selfless indiscriminate altruism on the tube (and in nature and life in general) as a phenomenon can't survive for very long because it is so vulnerable to abuse from those less selfless and altruistic.
e.g. When a Tube-Hawk takes a seat but never gives one up, they gain something at no cost to themselves. Over the long term Tube-Hawk numbers climb (because it's all gain at no cost) and Tube-Dove number fall (because it's unsustainable to give without getting something back indefinitely).
3. Exclusively selfish behaviour on the tube (and in nature and life in general) as a phenomenon can't survive for very long because it eliminates the possibility of co-operation to deal with problems that can't be solved alone.
e.g. When the Tube Flu hit, the only way to survive was through altruism and co-operation, however all of the individuals with those qualities (Tube-Doves) had been eliminated from the tube by the Tube-Hawk's so the entire population perished.
There's a model of behaviour and co-operation called Prisoner’s Dilemma that is based on the scenario of two prisoners, each of whom have been given the opportunity to betray the other for a crime. If one betrays, and the other stays silent, then the betrayer goes free and the other does the full sentence (many years). If they both stay silent then they both do a very small amount of time (months), and if they both betray then they both do half the full sentence (several years).
I've re-worked the model and applied it to the Tube Utopia scenario. Now 'Tube-Hawk' and 'Tube-Dove' is something you choose to do, rather than something you are. The diagram above shows the options available to two tube travellers Carrie and Virginia on a one hour tube journey.
The striking thing about the model is that if Carrie knows nothing about what Virginia is going to do, her best bet is actually to Hawk it, that way she either gets the seat or at least she gets to sit for half the journey. The same goes for Virginia.
Unfortunately if Virginia and Carrie are clever enough to realise this, it means that they'll always choose to Hawk it and neither of them will ever get to sit for more than 30 minutes.
The situation can change completely though if you run the same scenario, over and over again, and throw in 3 conditions.
1. Carrie and Virginia will recognise each other from previous journeys.
2. Carrie and Virginia have the opportunity to show altruism and/or 'trust' (i.e. Dove) each other.
3.Carrie and Virginia have the opportunity to 'punish' (Hawk) each other for betrayal of previous trust.
Going back to the original Tube Utopia scenario, this makes a massive difference to the outcome. If we swap all of the Tube-Dove's for Tube Dove's who remember and recognise then when a Tube-Hawk tries to invade Utopia they'll find early success leads pretty soon to repeated failure.
This sort of pattern can be found in countless scenarios both in nature and in every sort of human interaction.
In Tube Utopia, the Hawks would be forced to change their behaviour or learn to walk.
By Peter Muriuki