Prisoner’s Dilemma and Evolutionary Biology
This article from Quanta Magazine describes the disconnect that seems to appear when discussing the optimal strategy of the Prisoner’s Dilemma and the idea of cooperation that appears in biology. In particular, they cited the example of Vervet monkeys. Vervet monkeys are known for screaming when they spot a predator. This not only alerts the monkeys nearby of an incoming predator but also has a drawback in that it alerts the predator to the screaming monkey’s location. Evolutionary biology claims that if predators were to pick out all the screaming monkeys, natural selection would ensure that Vervet monkeys no longer are able to scream. However, their continued ability and use of screaming to alert others about predators show that they would prefer to work cooperatively, which is a direct contradiction to what we learned regarding Game Theory and acting selfishly.
In class, we talked about the Prisoner’s Dilemma, where the optimal strategy was to act selfishly each time. Looking in terms of Nash Equilibria, it appears that it would be better for Vervet monkeys to act selfishly by not screaming, thus maximizing his benefit. The reason that this does not happen in real life is that the Prisoner’s Dilemma and its corresponding Nash Equilibrium only applies to a single instance. When done over multiple instances and applied to survival, the optimal strategy changes. It is in the monkey’s best interest over the course of years to alert its neighbors and for them to do the same. It also looked into how cooperation played out. The article found that over time, people who cooperated tended to continue to cooperate, while people who refused to cooperate with each other tended to be worse off overall (an aspect that is in sync with Nash Equilibrium). This shows that while there is an incentive to act selfishly, acting selfishly leads to everyone acting selfishly, leading to a worse outcome overall and explains why cooperation exists despite the appearance of an optimal strategy to act selfishly. This could also be applied to other real world situations, such as nuclear warfare.
https://www.quantamagazine.org/game-theory-explains-how-cooperation-evolved-20150212/