Altruism in Animals: A best response?
We have examined the Prisoner’s Dilemma in Game Theory where we found that prisoners often confess when they should cooperate with each other and stay silent. When we think about this logic in terms of animal behavior, we might wonder how cooperation could ever arise in animals. However, the difference between the prisoner’s scenario and animal behavior is the idea of “tit-for-tat”. (1) In animals, it is likely that cooperation will evolve since they are likely to interact multiple times with each other. If the prisoners were to also encounter each other, they would eventually learn that cooperating is the better choice to make.
One interesting example of game theory in action is altruism in animals. Altruism is a different type of interaction since it involves increasing the fitness of the other animal at the expense of one’s own fitness. In the prisoner’s dilemma case, this would be equivalent to a scenario when the prisoners would cooperate, and one would agree to take the blame and the other would stay silent. This strategy seems to be evolutionarily unstable and one may question how natural selection could even work to select such behavior. However, altruism is prevalent in nature since animals that are altruistic will likely receive help when they are in need as well.
Vampire bats, for example, need to feed every 1.5 days and it is normal for females to share the blood they collect with weak males. Although this is an example of altruism, the females may also be cooperating with the males for selfish reasons. In the case when they are weak and need help, the males may be able to reciprocate the favor. (2) Other animals, such as dolphins and elephants show altruism to their mates. Squirrels, for example, relay warning signals when a predator is nearby. However, this altruistic behavior puts them at risk of being eaten.
One important point that studies have shown is that animals usually show altruistic behaviors to the same members in the group. (2) For example, male chimpanzees form close bonds that allow them to be altruistic to their group members. However, altruism to strangers is not typically observed in nature. This goes back to the prisoner’s dilemma logic. Although it makes sense that in a repeated prisoners dilemma game that the two players would learn to cooperate, this is only because they both encounter each other multiple times. The “tit-for-tat” tactic will work if you will see this patient over again. With strangers, there is no evolutionary benefit to being altruistic since you will be unlikely to see the stranger again and they will be unlikely to perform the same altruistic behavior to you.
- http://www.nature.com/scitable/knowledge/library/game-theory-evolutionary-stable-strategies-and-the-25953132
- http://www.theguardian.com/science/2015/jan/26/rationing-ravens-merciful-monkeys-can-animals-be-altruistic