The Evolution of Cooperation
Encyclopedia
The evolution of cooperation can refer to:
This article is an introduction to how game theory
and computer modeling are illuminating certain aspects of moral
and political philosophy
, particularly the role of individuals in groups, the "biology of selfishness and altruism
", and how cooperation
can be evolutionarily advantageous.
in World War II to improve military operations. One famous example involved how the Royal Air Force hunted submarines in the Bay of Biscay.
It had seemed to make sense to patrol the areas where submarines were most frequently seen. Then it was pointed out that "seeing the most submarines" depended not only on the number of submarines present, but also on the number of eyes looking; i.e., patrol density. Making an allowance for patrol density showed that patrols were more efficient – that is, found more submarines per patrol – in other areas. Making appropriate adjustments increased the overall effectiveness.
and Oskar Morgenstern
's Theory of Games and Economic Behavior
on the use of game theory
for developing and analyzing optimal strategies for military and other uses, and publication of John William's The Compleat Strategyst, a popular exposition of game theory, led to a greater appreciation of mathematical analysis of human behavior.
But game theory had a little crisis: it could not find a strategy for a simple game called "The Prisoner's Dilemma
" (PD) where two players have the option to cooperate together for mutual gain, but each also takes a risk of being suckered.
game (invented around 1950 by Merrill Flood and Melvin Dresher) takes its name from the following scenario: you and a criminal associate have been busted. Fortunately for you, most of the evidence was shredded, so you are facing only a year in prison. But the prosecutor wants to nail someone, so he offers you a deal: if you squeal on your associate – which will result in his getting a five year stretch – the prosecutor will see that six months is taken off of your sentence. Which sounds good, until you learn your associate is being offered the same deal – which would get you five years.
So what do you do? The best that you and your associate can do together is to not squeal: that is, to cooperate (with each other, not the prosecutor!) in a mutual bond of silence, and do your year. But wait: if your associate cooperates (that sucker!), can you do better by squealing ("defecting") to get that six month reduction? It's tempting, but then he's also tempted. And if you both squeal, oh, no, it's four and half years each. So perhaps you should cooperate – but wait, that's being a sucker yourself, as your associate will undoubtedly defect, and you won't even get the six months off. So what is the best strategy to minimize your incarceration (aside from going straight in the first place)?
To cooperate, or not cooperate? This simple question (and the implicit question of whether to trust, or not), expressed in an extremely simple game, is a crucial issue across a broad range of life. Why shouldn't a shark eat the little fish that has just cleaned it of parasites: in any given exchange who would know? Fig wasps collectively limit the eggs they lay in fig trees (otherwise, the trees would suffer). But why shouldn't any one fig wasp cheat and leave a few more eggs than her rivals? At the level of human society, why shouldn't each of the villagers that share a common but finite resource try to exploit it more than the others? At the core of these and myriad other examples is a conflict formally equivalent to the Prisoner's Dilemma. Yet sharks, fig wasps, and villagers all cooperate. It has been a vexatious problem in evolutionary studies to explain how such cooperation should evolve, let alone persist, in a world of self-maximizing egoists.
's theory of how evolution
works ("By Means of Natural Selection
") is explicitly competitive ("survival of the fittest
"), Malthusian ("struggle for existence"), even gladiatorial ("nature, red in tooth and claw"). Species are pitted against species for shared resources,
similar species with similar needs and niches even more so, and individuals within species most of all. All this comes down to one factor: out-competing all rivals and predators in producing progeny.
Darwin's explanation of how preferential survival of the slightest benefits can lead to advanced forms is the most important explanatory principle in biology, and extremely powerful in many other fields. Such success has reinforced notions that life is in all respects a war of each against all, where every individual has to look out for himself, that your gain is my loss.
In such a struggle for existence altruism
(voluntarily yielding a benefit to a non-relative) and even cooperation (working with another for a mutual benefit) seem so antithetical to self-interest as to be the very kind of behavior that should be selected against. Yet cooperation and seemingly even altruism have evolved and persist, and naturalists have been hard pressed to explain why.
" (roughly, those who would use the "survival of the fittest" of Darwinian evolution to justify the cutthroat competitiveness of laissez-faire
capitalism)
declaim that the world is an inherently competitive "dog eat dog" jungle, where every individual has to look out for himself. The philosopher Ayn Rand
damned "altruism
" and declared selfishness a virtue.
The Social Darwinists' view is derived from Charles Darwin
's interpretation of evolution by natural selection
, which is explicitly competitive ("survival of the fittest"), Malthusian ("struggle for existence"), even gladiatorial ("red in tooth and claw"), and permeated by the Victorian laissez-faire ethos of Darwin and his disciples (such as T. H. Huxley and Herbert Spencer
). What they read into the theory was then read out by Social Darwinians as scientific justification for their social and economic views (such as poverty being a natural condition and social reform an unnatural meddling).
Such views of evolution, competition, and the survival of the fittest are explicit in the ethos of modern capitalism
, as epitomized by industrialist Andrew Carnegie
in The Gospel of Wealth
:
While the validity of extrapolating moral and political views from science is questionable, the significance of such views in modern society is undoubtable.
" is necessary for human society, but saw no way of attaining that short of a coercive authority.
As Thomas Hobbes
wrote in Leviathan
:
And Jean Jacques Rousseau in The Social Contract
:
Even Herman Melville
, in Moby-Dick
, has the cannibal harpooner Queequeg explain why he has saved the life of someone who had been jeering him as so:
The original role of government is to provide the coercive power to enforce the social contract (and in commercial societies, contracts and covenants generally). Where government does not exist or cannot reach it is often deemed the role of religion to promote prosocial and moral behavior, but this tends to depend on threats of hell-fire (what Hobbes called "the terror of some power"); such inducements seem more mystical than rational, and philosophers have been hard-pressed to explain why self-interest should yield to morality, why there should be any duty to be "good".
Yet cooperation, and even altruism and morality, are prevalent, even in the absence of coercion, even though it seems that a properly self-regarding individual should reject all such social strictures and limitations. As early as 1890 the Russian naturalist Petr Kropotkin observed that the species that survived were where the individuals cooperated, that "mutual aid" (cooperation) was found at all levels of existence. By the 1960s biologists and zoologists were noting many instances in the real "jungle" where real animals – presumably unfettered by conscience and not corrupted by altruistic liberals – and even microbes (see microbial cooperation
) were cooperating.
Darwin's theory of natural selection is a profoundly powerful explanation of how evolution works; its undoubted success strongly suggests an inherently antagonistic relationship between unrelated individuals. Yet cooperation is prevalent, seems beneficial, and even seems to be essential to human society. Explaining this seeming contradiction, and accommodating cooperation, and even altruism, within Darwinian theory is a central issue in the theory of cooperation.
– which by definition reduces personal fitness – can arise by natural selection is a particular problem, and the central theoretical problem of sociobiology
.
A possible explanation of altruism is provided by the theory of group selection
(first suggested by Darwin himself while grappling with issue of social insects) which argues that natural selection can act on groups: groups that are more successful – for any reason, including learned behaviors – will benefit the individuals of the group, even if they are not related. It has had a powerful appeal, but has not been fully persuasive, in part because of difficulties regarding cheaters that participate in the group without contributing.
Another explanation is provided by the genetic kinship theory
of William D. Hamilton
: if a gene causes an individual to help other individuals that carry copies of that gene, then the gene has a net benefit even with the sacrifice of a few individuals. The classic example is the social insects, where the workers – which are sterile, and therefore incapable of passing on their genes – benefit the queen, who is essentially passing on copies of "their" genes. This is further elaborated in the "selfish gene" theory of Richard Dawkins
, that the unit of evolution is not the individual organism, but the gene. (As stated by Wilson: "the organism is only DNA's way of making more DNA.") However, kinship selection works only where the individuals involved are closely related; it fails to explain the presence of altruism and cooperation between unrelated individuals, particularly across species.
In a 1971 paper Robert Trivers
demonstrated how reciprocal altruism
can evolve between unrelated individuals, even between individuals of entirely different species. And the relationship of the individuals involved is exactly analogous to the situation in a certain form of the Prisoner's Dilemma. The key is that in the iterated Prisoner's Dilemma, or IPD, both parties can benefit from the exchange of many seemingly altruistic acts. As Trivers says, it "take[s] the altruism out of altruism." The Randian premise that self-interest is paramount is largely unchallenged, but turned on its head by recognition of a broader, more profound view of what constitutes self-interest.
It does not matter why the individuals cooperate. The individuals may be prompted to the exchange of "altruistic" acts by entirely different genes, or no genes in particular, but both individuals (and their genomes) can benefit simply on the basis of a shared exchange. In particular, "the benefits of human altruism are to be seen as coming directly from reciprocity – not indirectly through non-altruistic group benefits".
Trivers' theory is very powerful. Not only can it replace group selection, it also predicts various observed behavior, including moralistic aggression, gratitude and sympathy, guilt and reparative altruism, and development of abilities to detect and discriminate against subtle cheaters.
The benefits of such reciprocal altruism was dramatically demonstrated by a pair of tournaments held by Robert Axelrod around 1980.
game, and scored on the total points accumulated through the tournament. The winner was a very simple strategy submitted by Anatol Rapoport
called "TIT FOR TAT
" (TFT) that cooperates on the first move, and subsequently echoes (reciprocates) what the other player did on the previous move. The results of the first tournament were analyzed and published, and a second tournament held to see if anyone could find a better strategy. TIT FOR TAT won again. Axelrod analyzed the results, and made some interesting discoveries about the nature of cooperation, which he describes in his book
In both actual tournaments and various replays the best performing strategies were nice: that is, they were never the first to defect. Many of the competitors went to great lengths to gain an advantage over the "nice" (and usually simpler) strategies, but to no avail: tricky strategies fighting for a few points generally could not do as well as nice strategies working together. TFT (and other "nice" strategies generally) "won, not by doing better than the other player, but by eliciting cooperation [and] by promoting the mutual interest rather than by exploiting the other's weakness."
Being "nice" can be beneficial, but it can also lead to being suckered. To obtain the benefit – or avoid exploitation – it is necessary to be provocable to both retaliation and forgiveness. When the other player defects, a nice strategy must immediately be provoked into retaliatory defection. The same goes for forgiveness: return to cooperation as soon as the other player does. Overdoing the punishment risks escalation, and can lead to an "unending echo of alternating defections" that depresses the scores of both players.
Most of the games that game theory had heretofore investigated are "zero-sum
" – that is, the total rewards are fixed, and a player does well only at the expense of other players. But real life is not zero-sum. Our best prospects are usually in cooperative efforts. In fact, TFT cannot score higher than its partner; at best it can only do "as good as". Yet it won the tournaments by consistently scoring a strong second-place with a variety of partners. Axelrod summarizes this as don't be envious; in other words, don't strive for a payoff greater than the other player's.
In any IPD game there is a certain maximum score each player can get by always cooperating. But some strategies try to find ways of getting a little more with an occasional defection (exploitation). This can work against some strategies that are less provocable or more forgiving than TIT FOR TAT, but generally they do poorly. "A common problem with these rules is that they used complex methods of making inferences about the other player [strategy] – and these inferences were wrong." Against TFT (and "nice" strategies generally) one can do no better than to simply cooperate. Axelrod calls this clarity. Or: don't be too clever.
The success of any strategy depends on the nature of the particular strategies it encounters, which depends on the composition of the overall population. To better model the effects of reproductive success Axelrod also did an "ecological" tournament, where the prevalence of each type of strategy in each round was determined by that strategy's success in the previous round. The competition in each round becomes stronger as weaker performers are reduced and eliminated. The results were amazing: a handful of strategies – all "nice" – came to dominate the field. In a sea of non-nice strategies the "nice" strategies – provided they were also provokable – did well enough with each other to offset the occasional exploitation.
As cooperation became general the non-provocable strategies were exploited and eventually eliminated, whereupon the exploitive (non-cooperating) strategies were out-performed by the cooperative strategies.
In summary, success in an evolutionary "game" correlated with the following characteristics:
Curiously, rationality and deliberate choice are not necessary, nor trust nor even consciousness, as long as there is a pattern that benefits both players (e.g., increases fitness), and some probability of future interaction. Often the initial mutual cooperation is not even intentional, but having "discovered" a beneficial pattern both parties respond to it by continuing the conditions that maintain it.
This implies two requirements for the players, aside from whatever strategy they may adopt. First, they must be able to recognize other players, to avoid exploitation by cheaters. Second, they must be able to track their previous history with any given player, in order to be responsive to that player's strategy.
Even when the discount parameter ω is high enough to permit reciprocal cooperation there is still a question of whether and how cooperation might start. One of Axelrod's findings is that when the existing population never offers cooperation nor reciprocates it – the case of ALL D – then no nice strategy can get established by isolated individuals; cooperation is strictly a sucker bet. (The "futility of isolated revolt".) But another finding of great significance is that clusters of nice strategies can get established. Even a small group of individuals with nice strategies with infrequent interactions can yet do so well on those interactions to make up for the low level of exploitation from non-nice strategies.
To fully review this literature is infeasible. What follows are therefore only a few selected highlights.
Axelrod has a subsequent book, The Complexity of Cooperation
,
which he considers a sequel to The Evolution of Cooperation. Other work on the evolution of cooperation has expanded to cover prosocial behavior generally,
and in religion,
other mechanisms for generating cooperation,
the IPD under different conditions and assumptions,
and the use of other games such as the Public Goods
and Ultimatum
games to explore deep-seated notions of fairness and fair play.
It has also been used to challenge the rational and self-regarding "economic man" model of economics,
and as a basis for replacing Darwinian sexual selection
theory with a theory of social selection.
Nice strategies are better able to invade if they have social structures or other means of increasing their interactions. Axelrod discusses this in chapter 8; in a later paper he and Rick Riolo and Michael Cohen use computer simulations to show cooperation rising among agents who have negligible chance of future encounters but can recognize similarity of an arbitrary characteristic (such as a green beard).
When an IPD tournament introduces noise (errors or misunderstandings) TFT strategies can get trapped into a long string of retaliatory defections, thereby depressing their score. TFT also tolerates "ALL C" (always cooperate) strategies, which then give an opening to exploiters.
In 1992 Martin Nowak and Karl Sigmund demonstrated a strategy called Pavlov (or "win–stay, lose–shift") that does better in these circumstances.
Pavlov looks at its own prior move as well as the other player's move. If the payoff was R or P (see "Prisoner's Dilemma", above) it cooperates; if S or T it defects.
In a 2006 paper Nowak listed five mechanisms by which natural selection can lead to cooperation.
In addition to kin selection and direct reciprocity, he shows that:
The payoffs in the Prisoner's Dilemma game are fixed, but in real life defectors are often punished by cooperators. Where punishment is costly there is a second-order dilemma amongst cooperators between those who pay the cost of enforcement and those who do not.
Other work has shown that while individuals given a choice between joining a group that punishes free-riders and one that does not initially prefer the sanction-free group, yet after several rounds they will join the sanctioning group, seeing that sanctions secure a better payoff.
And there is the very intriguing paper "The Coevolution of Parochial Altruism and War" by Jung-Kyoo Choi and Samuel Bowles. From their summary:
They do not claim that humans have actually evolved in this way, but that computer simulations show how war could be promoted by the interaction of these behaviors.
, he reinterpreted the basis of evolution, and therefore of altruism. He was "not advocating a morality based on evolution",
and even felt that "we must teach our children altruism, for we cannot expect it to be part of their biological nature."
But John Maynard Smith
was showing that behavior could be subject to evolution, Robert Trivers had shown that reciprocal altruism is strongly favored by natural selection to lead to complex systems of altruistic behavior (supporting Kropotkin's argument that cooperation is as much a factor of evolution as competition), and Axelrod's dramatic results showed that in a very simple game the conditions for survival (be "nice", be provocable, promote the mutual interest) seem to be the essence of morality. While this does not yet amount to a science of morality
, the game theoretic approach has clarified the conditions required for the evolution and persistence of cooperation, and shown how Darwinian natural selection can lead to complex behavior, including notions of morality, fairness, and justice. It is shown that the nature of self-interest is more profound than previously considered, and that behavior that seems altruistic may, in a broader view, be individually beneficial. Extensions of this work to morality and the social contract
may yet resolve the old issue of individual interests versus group interests.
- the study of how cooperationCooperationCooperation or co-operation is the process of working or acting together. In its simplest form it involves things working in harmony, side by side, while in its more complicated forms, it can involve something as complex as the inner workings of a human being or even the social patterns of a...
can emerge and persist (also known as cooperation theory) as elucidated by application of game theoryGame theoryGame theory is a mathematical method for analyzing calculated circumstances, such as in games, where a person’s success is based upon the choices of others...
, - a 1981 paper by political scientist Robert AxelrodRobert AxelrodRobert M. Axelrod is an American political scientist. He is Professor of Political Science and Public Policy at the University of Michigan where he has been since 1974. He is best known for his interdisciplinary work on the evolution of cooperation, which has been cited in numerous articles...
and evolutionary biologist W. D. HamiltonW. D. HamiltonWilliam Donald Hamilton FRS was a British evolutionary biologist, widely recognised as one of the greatest evolutionary theorists of the 20th century....
in the scientific literature, or - a 1984 book by Axelrod that expanded on the paper and popularized the study.
This article is an introduction to how game theory
Game theory
Game theory is a mathematical method for analyzing calculated circumstances, such as in games, where a person’s success is based upon the choices of others...
and computer modeling are illuminating certain aspects of moral
Ethics
Ethics, also known as moral philosophy, is a branch of philosophy that addresses questions about morality—that is, concepts such as good and evil, right and wrong, virtue and vice, justice and crime, etc.Major branches of ethics include:...
and political philosophy
Political philosophy
Political philosophy is the study of such topics as liberty, justice, property, rights, law, and the enforcement of a legal code by authority: what they are, why they are needed, what, if anything, makes a government legitimate, what rights and freedoms it should protect and why, what form it...
, particularly the role of individuals in groups, the "biology of selfishness and altruism
Altruism
Altruism is a concern for the welfare of others. It is a traditional virtue in many cultures, and a core aspect of various religious traditions, though the concept of 'others' toward whom concern should be directed can vary among cultures and religions. Altruism is the opposite of...
", and how cooperation
Cooperation
Cooperation or co-operation is the process of working or acting together. In its simplest form it involves things working in harmony, side by side, while in its more complicated forms, it can involve something as complex as the inner workings of a human being or even the social patterns of a...
can be evolutionarily advantageous.
Operations research
The idea that human behavior can be usefully analyzed mathematically gained great credibility following the application of operations researchOperations research
Operations research is an interdisciplinary mathematical science that focuses on the effective use of technology by organizations...
in World War II to improve military operations. One famous example involved how the Royal Air Force hunted submarines in the Bay of Biscay.
It had seemed to make sense to patrol the areas where submarines were most frequently seen. Then it was pointed out that "seeing the most submarines" depended not only on the number of submarines present, but also on the number of eyes looking; i.e., patrol density. Making an allowance for patrol density showed that patrols were more efficient – that is, found more submarines per patrol – in other areas. Making appropriate adjustments increased the overall effectiveness.
Game Theory
Accounts of the success of operations research during the war, publication in 1944 of John von NeumannJohn von Neumann
John von Neumann was a Hungarian-American mathematician and polymath who made major contributions to a vast number of fields, including set theory, functional analysis, quantum mechanics, ergodic theory, geometry, fluid dynamics, economics and game theory, computer science, numerical analysis,...
and Oskar Morgenstern
Oskar Morgenstern
Oskar Morgenstern was a German-born Austrian-School economist. He, along with John von Neumann, helped found the mathematical field of game theory ....
's Theory of Games and Economic Behavior
Theory of Games and Economic Behavior
Theory of Games and Economic Behavior, published in 1944 by Princeton University Press, is a book by mathematician John von Neumann and economist Oskar Morgenstern which is considered the groundbreaking text that created the interdisciplinary research field of game theory...
on the use of game theory
Game theory
Game theory is a mathematical method for analyzing calculated circumstances, such as in games, where a person’s success is based upon the choices of others...
for developing and analyzing optimal strategies for military and other uses, and publication of John William's The Compleat Strategyst, a popular exposition of game theory, led to a greater appreciation of mathematical analysis of human behavior.
But game theory had a little crisis: it could not find a strategy for a simple game called "The Prisoner's Dilemma
Prisoner's dilemma
The prisoner’s dilemma is a canonical example of a game, analyzed in game theory that shows why two individuals might not cooperate, even if it appears that it is in their best interest to do so. It was originally framed by Merrill Flood and Melvin Dresher working at RAND in 1950. Albert W...
" (PD) where two players have the option to cooperate together for mutual gain, but each also takes a risk of being suckered.
Prisoner's dilemma
The prisoner's dilemmaPrisoner's dilemma
The prisoner’s dilemma is a canonical example of a game, analyzed in game theory that shows why two individuals might not cooperate, even if it appears that it is in their best interest to do so. It was originally framed by Merrill Flood and Melvin Dresher working at RAND in 1950. Albert W...
game (invented around 1950 by Merrill Flood and Melvin Dresher) takes its name from the following scenario: you and a criminal associate have been busted. Fortunately for you, most of the evidence was shredded, so you are facing only a year in prison. But the prosecutor wants to nail someone, so he offers you a deal: if you squeal on your associate – which will result in his getting a five year stretch – the prosecutor will see that six months is taken off of your sentence. Which sounds good, until you learn your associate is being offered the same deal – which would get you five years.
So what do you do? The best that you and your associate can do together is to not squeal: that is, to cooperate (with each other, not the prosecutor!) in a mutual bond of silence, and do your year. But wait: if your associate cooperates (that sucker!), can you do better by squealing ("defecting") to get that six month reduction? It's tempting, but then he's also tempted. And if you both squeal, oh, no, it's four and half years each. So perhaps you should cooperate – but wait, that's being a sucker yourself, as your associate will undoubtedly defect, and you won't even get the six months off. So what is the best strategy to minimize your incarceration (aside from going straight in the first place)?
To cooperate, or not cooperate? This simple question (and the implicit question of whether to trust, or not), expressed in an extremely simple game, is a crucial issue across a broad range of life. Why shouldn't a shark eat the little fish that has just cleaned it of parasites: in any given exchange who would know? Fig wasps collectively limit the eggs they lay in fig trees (otherwise, the trees would suffer). But why shouldn't any one fig wasp cheat and leave a few more eggs than her rivals? At the level of human society, why shouldn't each of the villagers that share a common but finite resource try to exploit it more than the others? At the core of these and myriad other examples is a conflict formally equivalent to the Prisoner's Dilemma. Yet sharks, fig wasps, and villagers all cooperate. It has been a vexatious problem in evolutionary studies to explain how such cooperation should evolve, let alone persist, in a world of self-maximizing egoists.
Darwinian context
Charles DarwinCharles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
's theory of how evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
works ("By Means of Natural Selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
") is explicitly competitive ("survival of the fittest
Survival of the fittest
"Survival of the fittest" is a phrase originating in evolutionary theory, as an alternative description of Natural selection. The phrase is today commonly used in contexts that are incompatible with the original meaning as intended by its first two proponents: British polymath philosopher Herbert...
"), Malthusian ("struggle for existence"), even gladiatorial ("nature, red in tooth and claw"). Species are pitted against species for shared resources,
similar species with similar needs and niches even more so, and individuals within species most of all. All this comes down to one factor: out-competing all rivals and predators in producing progeny.
Darwin's explanation of how preferential survival of the slightest benefits can lead to advanced forms is the most important explanatory principle in biology, and extremely powerful in many other fields. Such success has reinforced notions that life is in all respects a war of each against all, where every individual has to look out for himself, that your gain is my loss.
In such a struggle for existence altruism
Altruism
Altruism is a concern for the welfare of others. It is a traditional virtue in many cultures, and a core aspect of various religious traditions, though the concept of 'others' toward whom concern should be directed can vary among cultures and religions. Altruism is the opposite of...
(voluntarily yielding a benefit to a non-relative) and even cooperation (working with another for a mutual benefit) seem so antithetical to self-interest as to be the very kind of behavior that should be selected against. Yet cooperation and seemingly even altruism have evolved and persist, and naturalists have been hard pressed to explain why.
Social Darwinism
The popularity of the evolution of cooperation – the reason it is not an obscure technical issue of interest to only a small number of specialists – is in part because it mirrors a larger issue where the realms of political philosophy, ethics, and biology intersect: the ancient issue of individual interests versus group interests. On one hand, the so-called "Social DarwiniansSocial Darwinism
Social Darwinism is a term commonly used for theories of society that emerged in England and the United States in the 1870s, seeking to apply the principles of Darwinian evolution to sociology and politics...
" (roughly, those who would use the "survival of the fittest" of Darwinian evolution to justify the cutthroat competitiveness of laissez-faire
Laissez-faire
In economics, laissez-faire describes an environment in which transactions between private parties are free from state intervention, including restrictive regulations, taxes, tariffs and enforced monopolies....
capitalism)
declaim that the world is an inherently competitive "dog eat dog" jungle, where every individual has to look out for himself. The philosopher Ayn Rand
Ayn Rand
Ayn Rand was a Russian-American novelist, philosopher, playwright, and screenwriter. She is known for her two best-selling novels The Fountainhead and Atlas Shrugged and for developing a philosophical system she called Objectivism....
damned "altruism
Altruism
Altruism is a concern for the welfare of others. It is a traditional virtue in many cultures, and a core aspect of various religious traditions, though the concept of 'others' toward whom concern should be directed can vary among cultures and religions. Altruism is the opposite of...
" and declared selfishness a virtue.
The Social Darwinists' view is derived from Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
's interpretation of evolution by natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
, which is explicitly competitive ("survival of the fittest"), Malthusian ("struggle for existence"), even gladiatorial ("red in tooth and claw"), and permeated by the Victorian laissez-faire ethos of Darwin and his disciples (such as T. H. Huxley and Herbert Spencer
Herbert Spencer
Herbert Spencer was an English philosopher, biologist, sociologist, and prominent classical liberal political theorist of the Victorian era....
). What they read into the theory was then read out by Social Darwinians as scientific justification for their social and economic views (such as poverty being a natural condition and social reform an unnatural meddling).
Such views of evolution, competition, and the survival of the fittest are explicit in the ethos of modern capitalism
Capitalism
Capitalism is an economic system that became dominant in the Western world following the demise of feudalism. There is no consensus on the precise definition nor on how the term should be used as a historical category...
, as epitomized by industrialist Andrew Carnegie
Andrew Carnegie
Andrew Carnegie was a Scottish-American industrialist, businessman, and entrepreneur who led the enormous expansion of the American steel industry in the late 19th century...
in The Gospel of Wealth
The Gospel of Wealth
"Wealth", more commonly known as "The Gospel of Wealth", "the Richest man in the World," is an essay written by Andrew Carnegie in 1889 that described the responsibility of philanthropy by the new upper class of self-made rich...
:
[W]hile the law [of competition] may be sometimes hard for the individual, it is best for the race, because it ensures the survival of the fittest in every department. We accept and welcome, therefore, as conditions to which we must accommodate ourselves, great inequality of environment; the concentration of business, industrial and commercial, in the hands of the few; and the law of competition between these, as being not only beneficial, but essential to the future progress of the race.
While the validity of extrapolating moral and political views from science is questionable, the significance of such views in modern society is undoubtable.
The social contract and morality
On the other hand, other philosophers have long observed that cooperation in the form of a "social contractSocial contract
The social contract is an intellectual device intended to explain the appropriate relationship between individuals and their governments. Social contract arguments assert that individuals unite into political societies by a process of mutual consent, agreeing to abide by common rules and accept...
" is necessary for human society, but saw no way of attaining that short of a coercive authority.
As Thomas Hobbes
Thomas Hobbes
Thomas Hobbes of Malmesbury , in some older texts Thomas Hobbs of Malmsbury, was an English philosopher, best known today for his work on political philosophy...
wrote in Leviathan
Leviathan (book)
Leviathan or The Matter, Forme and Power of a Common Wealth Ecclesiasticall and Civil — commonly called simply Leviathan — is a book written by Thomas Hobbes and published in 1651. Its name derives from the biblical Leviathan...
:
[T]here must be some coercive power to compel men equally to the performance of their covenants by the terror of some punishment greater than the benefit they expect by the breach of their covenant....
[C]ovenants without the sword are but words....
And Jean Jacques Rousseau in The Social Contract
Social Contract (Rousseau)
Of The Social Contract, Or Principles of Political Right by Jean-Jacques Rousseau, is the book in which Rousseau theorized about the best way in which to set up a political community in the face of the problems of commercial society which he had already identified in his Discourse on Inequality...
:
[The social contract] can arise only where several persons come together: but, as the force and liberty of each man are the chief instruments of his self-preservation, how can he pledge them without harming his own interests, and neglecting the care he owes himself?
In order then that the social compact may not be an empty formula, it tacitly includes the undertaking, which alone can give force to the rest, that whoever refuses to obey the general will shall be compelled to do so by the whole body. This means nothing less than that he will be forced to be free....
Even Herman Melville
Herman Melville
Herman Melville was an American novelist, short story writer, essayist, and poet. He is best known for his novel Moby-Dick and the posthumous novella Billy Budd....
, in Moby-Dick
Moby-Dick
Moby-Dick; or, The Whale, was written by American author Herman Melville and first published in 1851. It is considered by some to be a Great American Novel and a treasure of world literature. The story tells the adventures of wandering sailor Ishmael, and his voyage on the whaleship Pequod,...
, has the cannibal harpooner Queequeg explain why he has saved the life of someone who had been jeering him as so:
"It's a mutual, joint-stock world, in all meridians. We cannibals must help these Christians."
The original role of government is to provide the coercive power to enforce the social contract (and in commercial societies, contracts and covenants generally). Where government does not exist or cannot reach it is often deemed the role of religion to promote prosocial and moral behavior, but this tends to depend on threats of hell-fire (what Hobbes called "the terror of some power"); such inducements seem more mystical than rational, and philosophers have been hard-pressed to explain why self-interest should yield to morality, why there should be any duty to be "good".
Yet cooperation, and even altruism and morality, are prevalent, even in the absence of coercion, even though it seems that a properly self-regarding individual should reject all such social strictures and limitations. As early as 1890 the Russian naturalist Petr Kropotkin observed that the species that survived were where the individuals cooperated, that "mutual aid" (cooperation) was found at all levels of existence. By the 1960s biologists and zoologists were noting many instances in the real "jungle" where real animals – presumably unfettered by conscience and not corrupted by altruistic liberals – and even microbes (see microbial cooperation
Microbial cooperation
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...
) were cooperating.
Darwin's theory of natural selection is a profoundly powerful explanation of how evolution works; its undoubted success strongly suggests an inherently antagonistic relationship between unrelated individuals. Yet cooperation is prevalent, seems beneficial, and even seems to be essential to human society. Explaining this seeming contradiction, and accommodating cooperation, and even altruism, within Darwinian theory is a central issue in the theory of cooperation.
Modern developments
Darwin's explanation of how evolution works is quite simple, but the implications of how it might explain complex phenomena are not at all obvious; it has taken over a century to elaborate (see modern synthesis). Explaining how altruismAltruism
Altruism is a concern for the welfare of others. It is a traditional virtue in many cultures, and a core aspect of various religious traditions, though the concept of 'others' toward whom concern should be directed can vary among cultures and religions. Altruism is the opposite of...
– which by definition reduces personal fitness – can arise by natural selection is a particular problem, and the central theoretical problem of sociobiology
Sociobiology
Sociobiology is a field of scientific study which is based on the assumption that social behavior has resulted from evolution and attempts to explain and examine social behavior within that context. Often considered a branch of biology and sociology, it also draws from ethology, anthropology,...
.
A possible explanation of altruism is provided by the theory of group selection
Group selection
In evolutionary biology, group selection refers to the idea that alleles can become fixed or spread in a population because of the benefits they bestow on groups, regardless of the alleles' effect on the fitness of individuals within that group....
(first suggested by Darwin himself while grappling with issue of social insects) which argues that natural selection can act on groups: groups that are more successful – for any reason, including learned behaviors – will benefit the individuals of the group, even if they are not related. It has had a powerful appeal, but has not been fully persuasive, in part because of difficulties regarding cheaters that participate in the group without contributing.
Another explanation is provided by the genetic kinship theory
Kin selection
Kin selection refers to apparent strategies in evolution that favor the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction. Charles Darwin was the first to discuss the concept of group/kin selection...
of William D. Hamilton
W. D. Hamilton
William Donald Hamilton FRS was a British evolutionary biologist, widely recognised as one of the greatest evolutionary theorists of the 20th century....
: if a gene causes an individual to help other individuals that carry copies of that gene, then the gene has a net benefit even with the sacrifice of a few individuals. The classic example is the social insects, where the workers – which are sterile, and therefore incapable of passing on their genes – benefit the queen, who is essentially passing on copies of "their" genes. This is further elaborated in the "selfish gene" theory of Richard Dawkins
Richard Dawkins
Clinton Richard Dawkins, FRS, FRSL , known as Richard Dawkins, is a British ethologist, evolutionary biologist and author...
, that the unit of evolution is not the individual organism, but the gene. (As stated by Wilson: "the organism is only DNA's way of making more DNA.") However, kinship selection works only where the individuals involved are closely related; it fails to explain the presence of altruism and cooperation between unrelated individuals, particularly across species.
In a 1971 paper Robert Trivers
Robert Trivers
Robert L. Trivers is an American evolutionary biologist and sociobiologist and Professor of Anthropology and Biological Sciences at Rutgers University. Trivers is most noted for proposing the theories of reciprocal altruism , parental investment , facultative sex ratio determination , and...
demonstrated how reciprocal altruism
Reciprocal altruism
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...
can evolve between unrelated individuals, even between individuals of entirely different species. And the relationship of the individuals involved is exactly analogous to the situation in a certain form of the Prisoner's Dilemma. The key is that in the iterated Prisoner's Dilemma, or IPD, both parties can benefit from the exchange of many seemingly altruistic acts. As Trivers says, it "take[s] the altruism out of altruism." The Randian premise that self-interest is paramount is largely unchallenged, but turned on its head by recognition of a broader, more profound view of what constitutes self-interest.
It does not matter why the individuals cooperate. The individuals may be prompted to the exchange of "altruistic" acts by entirely different genes, or no genes in particular, but both individuals (and their genomes) can benefit simply on the basis of a shared exchange. In particular, "the benefits of human altruism are to be seen as coming directly from reciprocity – not indirectly through non-altruistic group benefits".
Trivers' theory is very powerful. Not only can it replace group selection, it also predicts various observed behavior, including moralistic aggression, gratitude and sympathy, guilt and reparative altruism, and development of abilities to detect and discriminate against subtle cheaters.
The benefits of such reciprocal altruism was dramatically demonstrated by a pair of tournaments held by Robert Axelrod around 1980.
Axelrod's Tournaments
Axelrod initially solicited strategies from other game theorists to compete in the first tournament. Each strategy was paired with each other strategy for 200 iterations of a Prisoner's DilemmaPrisoner's dilemma
The prisoner’s dilemma is a canonical example of a game, analyzed in game theory that shows why two individuals might not cooperate, even if it appears that it is in their best interest to do so. It was originally framed by Merrill Flood and Melvin Dresher working at RAND in 1950. Albert W...
game, and scored on the total points accumulated through the tournament. The winner was a very simple strategy submitted by Anatol Rapoport
Anatol Rapoport
Anatol Rapoport was a Russian-born American Jewish mathematical psychologist. He contributed to general systems theory, mathematical biology and to the mathematical modeling of social interaction and stochastic models of contagion.-Biography:...
called "TIT FOR TAT
Tit for tat
Tit for tat is an English saying meaning "equivalent retaliation". It is also a highly effective strategy in game theory for the iterated prisoner's dilemma. It was first introduced by Anatol Rapoport in Robert Axelrod's two tournaments, held around 1980. An agent using this strategy will initially...
" (TFT) that cooperates on the first move, and subsequently echoes (reciprocates) what the other player did on the previous move. The results of the first tournament were analyzed and published, and a second tournament held to see if anyone could find a better strategy. TIT FOR TAT won again. Axelrod analyzed the results, and made some interesting discoveries about the nature of cooperation, which he describes in his book
In both actual tournaments and various replays the best performing strategies were nice: that is, they were never the first to defect. Many of the competitors went to great lengths to gain an advantage over the "nice" (and usually simpler) strategies, but to no avail: tricky strategies fighting for a few points generally could not do as well as nice strategies working together. TFT (and other "nice" strategies generally) "won, not by doing better than the other player, but by eliciting cooperation [and] by promoting the mutual interest rather than by exploiting the other's weakness."
Being "nice" can be beneficial, but it can also lead to being suckered. To obtain the benefit – or avoid exploitation – it is necessary to be provocable to both retaliation and forgiveness. When the other player defects, a nice strategy must immediately be provoked into retaliatory defection. The same goes for forgiveness: return to cooperation as soon as the other player does. Overdoing the punishment risks escalation, and can lead to an "unending echo of alternating defections" that depresses the scores of both players.
Most of the games that game theory had heretofore investigated are "zero-sum
Zero-sum
In game theory and economic theory, a zero-sum game is a mathematical representation of a situation in which a participant's gain of utility is exactly balanced by the losses of the utility of other participant. If the total gains of the participants are added up, and the total losses are...
" – that is, the total rewards are fixed, and a player does well only at the expense of other players. But real life is not zero-sum. Our best prospects are usually in cooperative efforts. In fact, TFT cannot score higher than its partner; at best it can only do "as good as". Yet it won the tournaments by consistently scoring a strong second-place with a variety of partners. Axelrod summarizes this as don't be envious; in other words, don't strive for a payoff greater than the other player's.
In any IPD game there is a certain maximum score each player can get by always cooperating. But some strategies try to find ways of getting a little more with an occasional defection (exploitation). This can work against some strategies that are less provocable or more forgiving than TIT FOR TAT, but generally they do poorly. "A common problem with these rules is that they used complex methods of making inferences about the other player [strategy] – and these inferences were wrong." Against TFT (and "nice" strategies generally) one can do no better than to simply cooperate. Axelrod calls this clarity. Or: don't be too clever.
The success of any strategy depends on the nature of the particular strategies it encounters, which depends on the composition of the overall population. To better model the effects of reproductive success Axelrod also did an "ecological" tournament, where the prevalence of each type of strategy in each round was determined by that strategy's success in the previous round. The competition in each round becomes stronger as weaker performers are reduced and eliminated. The results were amazing: a handful of strategies – all "nice" – came to dominate the field. In a sea of non-nice strategies the "nice" strategies – provided they were also provokable – did well enough with each other to offset the occasional exploitation.
As cooperation became general the non-provocable strategies were exploited and eventually eliminated, whereupon the exploitive (non-cooperating) strategies were out-performed by the cooperative strategies.
In summary, success in an evolutionary "game" correlated with the following characteristics:
- Be nice: cooperate, never be the first to defect.
- Be provocable: return defection for defection, cooperation for cooperation.
- Don't be envious:: be fair with your partner.
- Don't be too clever: or, don't try to be tricky.
Foundation of reciprocal cooperation
The lessons described above apply in environments that support cooperation, but whether cooperation is supported at all depends crucially on the probability (called ω [omega]) that the players will meet again, also called the discount parameter or, poetically, the shadow of the future. When ω is low – that is, the players have a negligible chance of meeting again – each interaction is effectively a single-shot Prisoner's Dilemma game, and one might as well defect in all cases (a strategy called "ALL D"), because even if one cooperates there is no way to keep the other player from exploiting that. But in the iterated PD the value of repeated cooperative interactions can become greater than the benefit/risk of a single exploitation (which is all that a strategy like TFT will tolerate).Curiously, rationality and deliberate choice are not necessary, nor trust nor even consciousness, as long as there is a pattern that benefits both players (e.g., increases fitness), and some probability of future interaction. Often the initial mutual cooperation is not even intentional, but having "discovered" a beneficial pattern both parties respond to it by continuing the conditions that maintain it.
This implies two requirements for the players, aside from whatever strategy they may adopt. First, they must be able to recognize other players, to avoid exploitation by cheaters. Second, they must be able to track their previous history with any given player, in order to be responsive to that player's strategy.
Even when the discount parameter ω is high enough to permit reciprocal cooperation there is still a question of whether and how cooperation might start. One of Axelrod's findings is that when the existing population never offers cooperation nor reciprocates it – the case of ALL D – then no nice strategy can get established by isolated individuals; cooperation is strictly a sucker bet. (The "futility of isolated revolt".) But another finding of great significance is that clusters of nice strategies can get established. Even a small group of individuals with nice strategies with infrequent interactions can yet do so well on those interactions to make up for the low level of exploitation from non-nice strategies.
Subsequent work
In 1984 Axelrod estimated that there were "hundreds of articles on the Prisoner's Dilemma cited in Psychological Abstracts", and estimated that citations to The Evolution of Cooperation alone were "growing at the rate of over 300 per year".To fully review this literature is infeasible. What follows are therefore only a few selected highlights.
Axelrod has a subsequent book, The Complexity of Cooperation
The Complexity of Cooperation
The Complexity of Cooperation is the sequel to The Evolution of Cooperation. It is a compendium of seven articles that previously appeared in journals on a variety of subjects...
,
which he considers a sequel to The Evolution of Cooperation. Other work on the evolution of cooperation has expanded to cover prosocial behavior generally,
and in religion,
other mechanisms for generating cooperation,
the IPD under different conditions and assumptions,
and the use of other games such as the Public Goods
Public goods game
The Public goods game is a standard of experimental economics. In the basic game, subjects secretly choose how many of their private tokens to put into the public pot. The tokens in the pot are multiplied by a factor and this "public good" payoff is evenly divided among players...
and Ultimatum
Ultimatum
An ultimatum is a demand whose fulfillment is requested in a specified period of time and which is backed up by a threat to be followed through in case of noncompliance. An ultimatum is generally the final demand in a series of requests...
games to explore deep-seated notions of fairness and fair play.
It has also been used to challenge the rational and self-regarding "economic man" model of economics,
and as a basis for replacing Darwinian sexual selection
Sexual selection
Sexual selection, a concept introduced by Charles Darwin in his 1859 book On the Origin of Species, is a significant element of his theory of natural selection...
theory with a theory of social selection.
Nice strategies are better able to invade if they have social structures or other means of increasing their interactions. Axelrod discusses this in chapter 8; in a later paper he and Rick Riolo and Michael Cohen use computer simulations to show cooperation rising among agents who have negligible chance of future encounters but can recognize similarity of an arbitrary characteristic (such as a green beard).
When an IPD tournament introduces noise (errors or misunderstandings) TFT strategies can get trapped into a long string of retaliatory defections, thereby depressing their score. TFT also tolerates "ALL C" (always cooperate) strategies, which then give an opening to exploiters.
In 1992 Martin Nowak and Karl Sigmund demonstrated a strategy called Pavlov (or "win–stay, lose–shift") that does better in these circumstances.
Pavlov looks at its own prior move as well as the other player's move. If the payoff was R or P (see "Prisoner's Dilemma", above) it cooperates; if S or T it defects.
In a 2006 paper Nowak listed five mechanisms by which natural selection can lead to cooperation.
In addition to kin selection and direct reciprocity, he shows that:
- Indirect reciprocity is based on knowing the other player's reputation, which is the player's history with other players. Cooperation depends on a reliable history being projected from past partners to future partners.
- Network reciprocity relies on geographical or social factors to increase the interactions with nearer neighbors; it is essentially a virtual group.
- Group selection assumes that groups with cooperators (even altruists) will be more successful as a whole, and this will tend to benefit all members.
The payoffs in the Prisoner's Dilemma game are fixed, but in real life defectors are often punished by cooperators. Where punishment is costly there is a second-order dilemma amongst cooperators between those who pay the cost of enforcement and those who do not.
Other work has shown that while individuals given a choice between joining a group that punishes free-riders and one that does not initially prefer the sanction-free group, yet after several rounds they will join the sanctioning group, seeing that sanctions secure a better payoff.
And there is the very intriguing paper "The Coevolution of Parochial Altruism and War" by Jung-Kyoo Choi and Samuel Bowles. From their summary:
Altruism—benefiting fellow group members at a cost to oneself —and parochialism—hostility towards individuals not of one's own ethnic, racial, or other group—are common human behaviors. The intersection of the two—which we term "parochial altruism"—is puzzling from an evolutionary perspective because altruistic or parochial behavior reduces one's payoffs by comparison to what one would gain from eschewing these behaviors. But parochial altruism could have evolved if parochialism promoted intergroup hostilities and the combination of altruism and parochialism contributed to success in these conflicts.... [Neither] would have been viable singly, but by promoting group conflict they could have evolved jointly.
They do not claim that humans have actually evolved in this way, but that computer simulations show how war could be promoted by the interaction of these behaviors.
Conclusion
When Richard Dawkins set out to "examine the biology of selfishness and altruism" in The Selfish GeneThe Selfish Gene
The Selfish Gene is a book on evolution by Richard Dawkins, published in 1976. It builds upon the principal theory of George C. Williams's first book Adaptation and Natural Selection. Dawkins coined the term "selfish gene" as a way of expressing the gene-centred view of evolution as opposed to the...
, he reinterpreted the basis of evolution, and therefore of altruism. He was "not advocating a morality based on evolution",
and even felt that "we must teach our children altruism, for we cannot expect it to be part of their biological nature."
But John Maynard Smith
was showing that behavior could be subject to evolution, Robert Trivers had shown that reciprocal altruism is strongly favored by natural selection to lead to complex systems of altruistic behavior (supporting Kropotkin's argument that cooperation is as much a factor of evolution as competition), and Axelrod's dramatic results showed that in a very simple game the conditions for survival (be "nice", be provocable, promote the mutual interest) seem to be the essence of morality. While this does not yet amount to a science of morality
Science of morality
Science of morality can refer to a number of ethically naturalistic views. Historically, the term was introduced by Jeremy Bentham . In meta-ethics, ethical naturalism bases morality on rational and empirical consideration of the natural world...
, the game theoretic approach has clarified the conditions required for the evolution and persistence of cooperation, and shown how Darwinian natural selection can lead to complex behavior, including notions of morality, fairness, and justice. It is shown that the nature of self-interest is more profound than previously considered, and that behavior that seems altruistic may, in a broader view, be individually beneficial. Extensions of this work to morality and the social contract
may yet resolve the old issue of individual interests versus group interests.