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The nature of human altruism
TL;DR: Current gene-based evolutionary theories cannot explain important patterns of human altruism, pointing towards the importance of both theories of cultural evolution as well as gene–culture co-evolution.
Abstract: Some of the most fundamental questions concerning our evolutionary origins, our social relations, and the organization of society are centred around issues of altruism and selfishness. Experimental evidence indicates that human altruism is a powerful force and is unique in the animal world. However, there is much individual heterogeneity and the interaction between altruists and selfish individuals is vital to human cooperation. Depending on the environment, a minority of altruists can force a majority of selfish individuals to cooperate or, conversely, a few egoists can induce a large number of altruists to defect. Current gene-based evolutionary theories cannot explain important patterns of human altruism, pointing towards the importance of both theories of cultural evolution as well as gene–culture co-evolution.
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TL;DR: Five mechanisms for the evolution of cooperation are discussed: kin selection, direct reciprocity, indirect reciprocities, network reciprocation, group selection, and group selection.
Abstract: Cooperation is needed for evolution to construct new levels of organization. Genomes, cells, multicellular organisms, social insects, and human society are all based on cooperation. Cooperation means that selfish replicators forgo some of their reproductive potential to help one another. But natural selection implies competition and therefore opposes cooperation unless a specific mechanism is at work. Here I discuss five mechanisms for the evolution of cooperation: kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. For each mechanism, a simple rule is derived that specifies whether natural selection can lead to cooperation.
4,899 citations
TL;DR: A large-scale analysis of tweets reveals that false rumors spread further and faster than the truth, and false news was more novel than true news, which suggests that people were more likely to share novel information.
Abstract: We investigated the differential diffusion of all of the verified true and false news stories distributed on Twitter from 2006 to 2017. The data comprise ~126,000 stories tweeted by ~3 million people more than 4.5 million times. We classified news as true or false using information from six independent fact-checking organizations that exhibited 95 to 98% agreement on the classifications. Falsehood diffused significantly farther, faster, deeper, and more broadly than the truth in all categories of information, and the effects were more pronounced for false political news than for false news about terrorism, natural disasters, science, urban legends, or financial information. We found that false news was more novel than true news, which suggests that people were more likely to share novel information. Whereas false stories inspired fear, disgust, and surprise in replies, true stories inspired anticipation, sadness, joy, and trust. Contrary to conventional wisdom, robots accelerated the spread of true and false news at the same rate, implying that false news spreads more than the truth because humans, not robots, are more likely to spread it.
4,241 citations
TL;DR: The major theme of the review is in what sense and how the graph structure of interactions can modify and enrich the picture of long term behavioral patterns emerging in evolutionary games.
2,548 citations
Cites background from "The nature of human altruism"
...As for the first, it seems at least possible that the evolutionary advantages of cooperative behavior have exerted a selective pressure to make humans hardwired for cooperation (Fehr and Fischbacher, 2003)....
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...common knowledge; etc. As for the first, it seems at least possible that the evolutionary advantages of cooperative behavior have exerted a selective pressure to make humans hardwired for cooperation (Fehr and Fischbacher, 2003). This would imply a genetic predisposition for the player’s utility function to take into account the well-being of the co-player too. The pure “monetary” payoff is not the ultimate utility to conside...
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TL;DR: The evolution of cooperation by indirect reciprocity leads to reputation building, morality judgement and complex social interactions with ever-increasing cognitive demands.
Abstract: Natural selection is conventionally assumed to favour the strong and selfish who maximize their own resources at the expense of others. But many biological systems, and especially human societies, are organized around altruistic, cooperative interactions. How can natural selection promote unselfish behaviour? Various mechanisms have been proposed, and a rich analysis of indirect reciprocity has recently emerged: I help you and somebody else helps me. The evolution of cooperation by indirect reciprocity leads to reputation building, morality judgement and complex social interactions with ever-increasing cognitive demands.
2,064 citations
TL;DR: A surprisingly simple rule is described that is a good approximation for all graphs that are analysed, including cycles, spatial lattices, random regular graphs, random graphs and scale-free networks: natural selection favours cooperation if the benefit of the altruistic act, b, exceeds the average number of neighbours, k, which means b/c > k.
Abstract: The evolution and maintenance of cooperative behaviour take some explaining. Cooperative groups can be undermined by ‘cheaters’ who selfishly exploit common resources, and a large body of theory predicts that cheats will usually displace cooperators. But a possible explanation of why cheats don't always prosper emerges from competition experiments between strains of yeast that act as cooperators and cheaters, competing for glucose and utilizing it either efficiently or ‘selfishly’. The results show that both strategies can coexist, because both are associated with costs and benefits. There is a cost to cheating; in this instance the production of fewer offspring than the opposition. A graphic — really — demonstration that natural selection can favour cooperation comes in a study by Ohtsuki et al. of the evolutionary dynamics of structured ‘virtual’ populations formed of points on a graph. Cooperation is favoured if the benefit of the altruistic act divided by the cost exceeds the average number of neighbours. So cooperation can evolve as a consequence of this ‘social viscosity’ even in the absence of reputation effects or strategic complexity. Natural selection generally favours cooperation if the benefit of the altruistic act divided by the cost exceeds the average number of neighbours, indicating that cooperation can evolve as a consequence of ‘social viscosity’, even in the absence of reputation effects or strategic complexity. A fundamental aspect of all biological systems is cooperation. Cooperative interactions are required for many levels of biological organization ranging from single cells to groups of animals1,2,3,4. Human society is based to a large extent on mechanisms that promote cooperation5,6,7. It is well known that in unstructured populations, natural selection favours defectors over cooperators. There is much current interest, however, in studying evolutionary games in structured populations and on graphs8,9,10,11,12,13,14,15,16,17. These efforts recognize the fact that who-meets-whom is not random, but determined by spatial relationships or social networks18,19,20,21,22,23,24. Here we describe a surprisingly simple rule that is a good approximation for all graphs that we have analysed, including cycles, spatial lattices, random regular graphs, random graphs and scale-free networks25,26: natural selection favours cooperation, if the benefit of the altruistic act, b, divided by the cost, c, exceeds the average number of neighbours, k, which means b/c > k. In this case, cooperation can evolve as a consequence of ‘social viscosity’ even in the absence of reputation effects or strategic complexity.
1,942 citations
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TL;DR: In this paper, a model is presented to account for the natural selection of what is termed reciprocally altruistic behavior, and the model shows how selection can operate against the cheater (non-reciprocator) in the system.
Abstract: A model is presented to account for the natural selection of what is termed reciprocally altruistic behavior. The model shows how selection can operate against the cheater (non-reciprocator) in the system. Three instances of altruistic behavior are discussed, the evolution of which the model can explain: (1) behavior involved in cleaning symbioses; (2) warning cries in birds; and (3) human reciprocal altruism. Regarding human reciprocal altruism, it is shown that the details of the psychological system that regulates this altruism can be explained by the model. Specifically, friendship, dislike, moralistic aggression, gratitude, sympathy, trust, suspicion, trustworthiness, aspects of guilt, and some forms of dishonesty and hypocrisy can be explained as important adaptations to regulate the altruistic system. Each individual human is seen as possessing altruistic and cheating tendencies, the expression of which is sensitive to developmental variables that were selected to set the tendencies at a balance ap...
9,318 citations
"The nature of human altruism" refers background in this paper
...Among animals, fitness-reducing acts that confer fitness benefits on other individuals are largely restricted to kin groups; despite several decades of research, evidence for reciprocal altruism in pair-wise repeated encounter...
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TL;DR: This article showed that if a fraction of the people exhibit inequality aversion, stable cooperation is maintained although punishment is costly for those who punish, and they also showed that when they are given the opportunity to punish free riders, stable cooperations are maintained.
Abstract: There is strong evidence that people exploit their bargaining power in competitive markets but not in bilateral bargaining situations. There is also strong evidence that people exploit free-riding opportunities in voluntary cooperation games. Yet, when they are given the opportunity to punish free riders, stable cooperation is maintained although punishment is costly for those who punish. This paper asks whether there is a simple common principle that can explain this puzzling evidence. We show that if a fraction of the people exhibits inequality aversion the puzzles can be resolved.
6,919 citations
TL;DR: The authors demonstrate that people are motivated by both their pecuniary payoff and their relative payoff standing, and demonstrate that a simple model, constructed on the premise that people were motivated by either their payoff or their relative standing, organizes a large and seemingly disparate set of laboratory observations as one consistent pattern, which explains observations from games where equity is thought to be a factor, such as ultimatum and dictator, games where reciprocity is played a role and games where competitive behavior is observed.
Abstract: We demonstrate that a simple model, constructed on the premise that people are motivated by both their pecuniary payoff and their relative payoff standing, organizes a large and seemingly disparate set of laboratory observations as one consistent pattern The model is incomplete information but nevertheless posed entirely in terms of directly observable variables The model explains observations from games where equity is thought to be a factor, such as ultimatum and dictator, games where reciprocity is thought to play a role, such as the prisoner's dilemma and gift exchange, and games where competitive behavior is observed, such as Bertrand markets (JEL C78, C90, D63, D64, H41)
5,391 citations
TL;DR: In this article, the authors designed an experiment to study trust and reciprocity in an investment setting and found that observed decisions suggest that reciprocity exists as a basic element of human behavior and that this is accounted for in the trust extended to an anonymous counterpart.
5,033 citations
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TL;DR: In this article, it is shown that every mutual-max or mutual-min Nash equilibrium is a fairness equilibrium, and that if payoffs are small, fairness equilibria are roughly the set of mutualmax and mutualmin outcomes; if payoff are large, fairness equilibrium are roughly a set of Nash equilibra.
Abstract: People like to help those who are helping them and to hurt those who are hurting them. Outcomes rejecting such motivations are called fairness equilibria. Outcomes are mutual-max when each person maximizes the other's material payoffs, and mutual-min when each person minimizes the other's payoffs. It is shown that every mutual-max or mutual-min Nash equilibrium is a fairness equilibrium. If payoffs are small, fairness equilibria are roughly the set of mutual-max and mutual-min outcomes; if payoffs are large, fairness equilibria are roughly the set of Nash equilibria. Several economic examples are considered and possible welfare implications of fairness are explored. Copyright 1993 by American Economic Association.
4,981 citations