Reciprocal Altruism Simulator

互惠利他主义模拟器

Evolution of Cooperation

English
中文

Population Evolution

0
Generation
0
Current Round
Rounds per Match
10
Population Size
100
Mutation Rate
2%
Generations
10
Simulation Speed
50%
Player 2
Cooperate Defect
Player 1 Cooperate 3,3 0,5
Defect 5,0 1,1

Select Strategies to Include

Prisoner's Dilemma
Reciprocal Altruism
Connection to "The Selfish Gene"

The Prisoner's Dilemma

The Prisoner's Dilemma is a classic game theory scenario that illustrates why two rational individuals might not cooperate, even when it would be in their best interests to do so. In this scenario, two prisoners are separated and offered a deal:

  • If both remain silent (cooperate with each other), they each get a short sentence (3 points each)
  • If one betrays the other (defects) while the other remains silent, the betrayer goes free (5 points) and the silent one gets a long sentence (0 points)
  • If both betray each other (both defect), they both get medium sentences (1 point each)

The rational choice for a single interaction is to defect, since defecting gives a better outcome regardless of what the other player does. This leads to the paradoxical result where both players defect and get 1 point each, when they could have each received 3 points by cooperating.

However, when the game is repeated over multiple rounds with the same players (an iterated Prisoner's Dilemma), cooperation can emerge as a successful strategy. This provides a model for understanding how reciprocal altruism might evolve in nature.

Reciprocal Altruism in Evolution

Reciprocal altruism is a form of altruism where an organism acts in a way that temporarily reduces its fitness while increasing another organism's fitness, with the expectation that the other organism will act in a similar manner at a later time. Unlike kin selection, reciprocal altruism can evolve between unrelated individuals.

For reciprocal altruism to evolve, several conditions must be met:

  • Individuals must interact repeatedly
  • They must be able to recognize each other
  • They must be able to remember past interactions
  • The cost of helping must be less than the expected future benefit of being helped

Examples in nature include:

  • Vampire bats share blood meals with hungry bats who have failed to feed, with the expectation that they will receive the same treatment when they need it
  • Cleaner fish remove parasites from larger predatory fish who could easily eat them, but don't because the service is valuable
  • Warning calls among some species may be based on reciprocity rather than just kin selection

This simulation demonstrates how cooperative strategies can evolve and persist in a population, even when defection might seem advantageous in the short term.

Reciprocal Altruism in "The Selfish Gene"

In "The Selfish Gene," Dawkins discusses reciprocal altruism in Chapter 10, "You Scratch My Back, I'll Ride on Yours." He explains how apparently altruistic behaviors between unrelated individuals can evolve through the mechanism of reciprocity.

Dawkins draws heavily on Robert Axelrod's work on the iterated Prisoner's Dilemma, which demonstrated that a simple strategy called "Tit for Tat" (cooperate first, then do whatever your opponent did in the previous round) can be remarkably successful in repeated interactions.

This connects to the central thesis of "The Selfish Gene" in an interesting way. Even though genes are "selfish" in that they promote their own replication, this doesn't mean the organisms they build will behave selfishly in all contexts. When reciprocal altruism is beneficial for gene propagation, genes will program organisms to engage in cooperative behaviors.

Dawkins writes:

"A gene for reciprocal altruism can be favored in evolution by natural selection, even though it is not a gene for kin altruism, so long as the individuals who reciprocate are able to recognize each other and to refuse to continue the relationship if it is being abused."

This simulator demonstrates how strategies for cooperation can evolve and stabilize in a population, showing how "selfish genes" can lead to cooperative behaviors when the conditions are right.

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