 | This article may be too technical for most readers to understand.(April 2015) |
Reciprocity in evolutionary biology refers to mechanisms whereby the evolution of cooperative or altruistic behaviour may be favoured by the probability of future mutual interactions. A corollary is how a desire for revenge can harm the collective and therefore be naturally deselected.
Three types of reciprocity have been studied extensively:
Direct reciprocity was proposed by Robert Trivers as a mechanism for the evolution of cooperation. [1] If there are repeated encounters between the same two players in an evolutionary game in which each of them can choose either to "cooperate" or "defect", then a strategy of mutual cooperation may be favoured even if it pays each player, in the short term, to defect when the other cooperates. Direct reciprocity can lead to the evolution of cooperation only if the probability, w, of another encounter between the same two individuals exceeds the cost-to-benefit ratio of the altruistic act: [2] w > c / b
"In the standard framework of indirect reciprocity, there are randomly chosen pairwise encounters between members of a population; the same two individuals need not meet again. One individual acts as donor, the other as recipient. The donor can decide whether or not to cooperate. The interaction is observed by a subset of the population who might inform others. Reputation allows evolution of cooperation by indirect reciprocity. Natural selection favors strategies that base the decision to help on the reputation of the recipient: studies show that people who are more helpful are more likely to receive help." [3] In many situations cooperation is favoured and it even benefits an individual to forgive an occasional defection but cooperative societies are always unstable because mutants inclined to defect can upset any balance. [4]
The calculations of indirect reciprocity are complicated, but again a simple rule has emerged. [5] Indirect reciprocity can only promote cooperation if the probability, q, of knowing someone’s reputation exceeds the cost-to-benefit ratio of the altruistic act:
One important problem with this explanation is that individuals may be able to evolve the capacity to obscure their reputation, reducing the probability, q, that it will be known. [6]
Individual acts of indirect reciprocity may be classified as "upstream" or "downstream": [7]
Real populations are not well mixed, but have spatial structures or social networks which imply that some individuals interact more often than others. One approach of capturing this effect is evolutionary graph theory, [8] in which individuals occupy the vertices of a graph. The edges determine who interacts with whom. If a cooperator pays a cost, c, for each neighbor to receive a benefit, b, and defectors have no costs, and their neighbors receive no benefits, network reciprocity can favor cooperation. [9] The benefit-to-cost ratio must exceed the average number of people, k, per individual:
Recent work [10] shows that the benefit-to-cost ratio must exceed the mean degree of nearest neighbors, ⟨knn⟩:
An ethical concept known as "generalized reciprocity" holds that people should show kindness to others without anticipating prompt return favors. [11] This kind of reciprocity emphasizes the intrinsic value of humanitarian acts and goes beyond transactional expectations. In the field of social dynamics, generalized reciprocity encourages people to have a culture of giving and unity. When people engage in this type of reciprocity, they give without thinking about what they could get back, showing that they care about the general welfare of the community. [12] It portrays a kind of social connection in where individuals give, share, or assist without anticipating anything in return.
This selfless involvement spreads outside of close circles, creating a domino effect that improves the well-being of everybody. Therefore, generalized reciprocity is evidence of the persistent value of selfless contributions in building strong, cohesive communities. Adopting this idea means being committed to the timeless values of giving and having faith in the natural flow of advantages for both parties. [13]
Altruism is the principle and practice of concern for the well-being and/or happiness of other humans or animals above oneself. While objects of altruistic concern vary, it is an important moral value in many cultures and religions. It may be considered a synonym of selflessness, the opposite of selfishness.
The Evolution of Cooperation is a 1984 book written by political scientist Robert Axelrod that expands upon a paper of the same name written by Axelrod and evolutionary biologist W.D. Hamilton. The article's summary addresses the issue in terms of "cooperation in organisms, whether bacteria or primates".
In evolutionary biology, reciprocal altruism is a behaviour whereby an organism acts in a manner 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.
Kin selection is a process whereby natural selection favours a trait due to its positive effects on the reproductive success of an organism's relatives, even when at a cost to the organism's own survival and reproduction. Kin selection can lead to the evolution of altruistic behaviour. Kin selection is related to the concept of inclusive fitness, which combines the number of offspring produced with the number an individual can ensure the production of by supporting others. A broader definition of kin selection includes selection acting on interactions between individuals who share a gene of interest even if the gene is not shared due to common ancestry.
Group selection is a proposed mechanism of evolution in which natural selection acts at the level of the group, instead of at the level of the individual or gene.
In evolutionary biology, inclusive fitness is one of two metrics of evolutionary success as defined by W. D. Hamilton in 1964:
Evolutionary game theory (EGT) is the application of game theory to evolving populations in biology. It defines a framework of contests, strategies, and analytics into which Darwinian competition can be modelled. It originated in 1973 with John Maynard Smith and George R. Price's formalisation of contests, analysed as strategies, and the mathematical criteria that can be used to predict the results of competing strategies.
Martin Andreas Nowak is an Austrian-born professor of mathematics and biology at Harvard University. He is one of the leading researchers in the field of mathematical biology. He made contributions to the theory of evolution, cooperation, virus dynamics, and cancer dynamics. Nowak held professorships at Oxford University and at the Institute for Advanced Study, Princeton, before being recruited by Harvard in 2003. He was the director of Harvard's program for evolutionary dynamics from 2003 until 2020. He is a professor in the Department of Mathematics and in the Department of Organismic and Evolutionary Biology.
In biology, altruism refers to behaviour by an individual that increases the fitness of another individual while decreasing their own. Altruism in this sense is different from the philosophical concept of altruism, in which an action would only be called "altruistic" if it was done with the conscious intention of helping another. In the behavioural sense, there is no such requirement. As such, it is not evaluated in moral terms—it is the consequences of an action for reproductive fitness that determine whether the action is considered altruistic, not the intentions, if any, with which the action is performed.
Evolutionary graph theory is an area of research lying at the intersection of graph theory, probability theory, and mathematical biology. Evolutionary graph theory is an approach to studying how topology affects evolution of a population. That the underlying topology can substantially affect the results of the evolutionary process is seen most clearly in a paper by Erez Lieberman, Christoph Hauert and Martin Nowak.
In evolution, cooperation is the process where groups of organisms work or act together for common or mutual benefits. It is commonly defined as any adaptation that has evolved, at least in part, to increase the reproductive success of the actor's social partners. For example, territorial choruses by male lions discourage intruders and are likely to benefit all contributors.
The concept of the evolution of morality refers to the emergence of human moral behavior over the course of human evolution. Morality can be defined as a system of ideas about right and wrong conduct. In everyday life, morality is typically associated with human behavior rather than animal behavior. The emerging fields of evolutionary biology, and in particular evolutionary psychology, have argued that, despite the complexity of human social behaviors, the precursors of human morality can be traced to the behaviors of many other social animals. Sociobiological explanations of human behavior remain controversial. Social scientists have traditionally viewed morality as a construct, and thus as culturally relative, although others such as Sam Harris argue that there is an objective science of morality.
Strong reciprocity is an area of research in behavioral economics, evolutionary psychology, and evolutionary anthropology on the predisposition to cooperate even when there is no apparent benefit in doing so. This topic is particularly interesting to those studying the evolution of cooperation, as these behaviors seem to be in contradiction with predictions made by many models of cooperation. In response, current work on strong reciprocity is focused on developing evolutionary models which can account for this behavior. Critics of strong reciprocity argue that it is an artifact of lab experiments and does not reflect cooperative behavior in the real world.
Microorganisms engage in a wide variety of social interactions, including cooperation. A cooperative behavior is one that benefits an individual other than the one performing the behavior. This article outlines the various forms of cooperative interactions seen in microbial systems, as well as the benefits that might have driven the evolution of these complex behaviors.
Third-party punishment, or altruistic punishment, is punishment of a transgressor which is administered, not by a victim of the transgression, but rather by a third party not directly affected by the transgression. It has been argued that third-party punishments are the essence of social norms, as they are an evolutionarily stable strategy, unlike second-party punishments. It has also been shown that third-party punishments are exhibited in all examined populations, though the magnitude of the punishments varies greatly, and that costly punishment co-varies with altruistic behavior. Differences between within-group and inter-group altruistic punishments have also been observed.
Male reproductive alliances can best be understood within the context of traditional male–male competition, as a specific case of cooperative competition. Such cooperative behavior, however, does not necessarily result in the equal sharing of resources among cooperating individuals. Cooperation often requires that individuals decrease their own fitness to increase the fitness of another. This behavior becomes even more striking when it occurs within the context of cooperative reproduction, where individuals decrease their own reproductive fitness to improve the reproductive fitness of another.
Evolutionary biologists have developed various theoretical models to explain the evolution of food-sharing behavior—"[d]efined as the unresisted transfer of food" from one food-motivated individual to another—among humans and other animals.
Reciprocal altruism in humans refers to an individual behavior that gives benefit conditionally upon receiving a returned benefit, which draws on the economic concept – ″gains in trade″. Human reciprocal altruism would include the following behaviors : helping patients, the wounded, and the others when they are in crisis; sharing food, implement, knowledge.
Generalized exchange is a type of social exchange in which a desired outcome that is sought by an individual is not dependent on the resources provided by that individual. It is assumed to be a fundamental social mechanism that stabilizes relations in society by unilateral resource giving in which one's giving is not necessarily reciprocated by the recipient, but by a third party. Thus, in contrast to direct or restricted exchange or reciprocity, in which parties exchange resources with each other, generalized exchange naturally involves more than two parties. Examples of generalized exchange include; matrilateral cross-cousin marriage and helping a stranded driver on a desolate road.
Parochial altruism is a concept in the fields of social psychology, evolutionary biology, and anthropology that describes altruism towards an in-group, often accompanied by hostility towards an out-group. It is a combination of altruism, defined as behavior done for the benefit of others without direct effect to the self, and parochialism, which refers to having a limited viewpoint. Together, these concepts create parochial altruism, or altruism that is limited in scope to one's in-group. Parochial altruism is closely related to the concepts of in-group favoritism and out-group discrimination. Research has suggested that parochial altruism may have evolved in humans to promote high levels of in-group cooperation, which is advantageous for group survival. Parochial altruism is often evoked to explain social behaviors within and between groups, such as why people are cooperative within their social groups and why they may be aggressive towards other social groups.