Arquivo da tag: Reciprocidade

Darwinismo 2.0 (Valor Econômico)

JC e-mail 4976, de 24 de junho de 2014

Artigo de José Eli da Veiga publicado no Valor Econômico

Até o início dos anos 1980 o darwinismo foi amesquinhado pela concepção de que a sobrevivência dos mais aptos só decorreria da feroz competição que caracterizaria a “luta” pela existência. Por oitenta anos foi rejeitada a desviante interpretação das obras de Darwin proposta em “Ajuda Mútua: um Fator de Evolução”, livro com argutas observações sobre a extraordinária cooperação que caracteriza as vidas de abelhas, formigas e vários outros animais, publicado em 1902, no exílio londrino, pelo sessentão príncipe russo Piotr Kropotkin.

Mesmo que não tenha havido reconhecimento explícito, a perspicácia desse expoente do anarquismo começou a ser redimida quando um dos então mais promissores ramos da matemática – a Teoria dos Jogos – foi mobilizado para solucionar uma das questões que mais intrigava os pesquisadores, especialmente os das humanidades: num mundo de egoístas, desprovido de governo central, em que condições pode emergir a cooperação?

Resposta original e persuasiva foi dada em 1981 pelo cientista político da Universidade de Michigan, Robert Axelrod, que três anos depois lançou o hoje clássico “A Evolução da Cooperação” (Ed. Leopardo, 2010). Um livro que deveria tomar o lugar daquelas bíblias gratuitas achadas nos criados-mudos dos hotéis, diz Richard Dawkins, o célebre autor de “O Gene Egoísta” em prefácio à edição de 2006.

A proeza de Axelrod foi executar inéditas simulações computacionais que confirmaram hipóteses formuladas na década anterior por biólogos evolutivos: nepotismo e reciprocidade seriam os dois fatores determinantes da cooperação. Na ausência do primeiro, ela estaria na dependência de um padrão comportamental em que cada um dos atores repete o movimento do outro, reagindo positivamente a atitudes cooperativas e negativamente a gestos hostis.

Ainda em plena Guerra Fria, quando o risco de um “inverno nuclear” exigia a cooperação bipolar entre EUA e URSS, o que poderia fazer mais sucesso do que essa orientação apelidada de “tit-for-tat”, título de uma das populares comédias da dupla “O Gordo e o Magro”? Embora seja traduzida por “olho-por-olho, dente-por-dente”, essa expressão está mais próxima do “toma-lá-dá-cá”, pois é uma estratégia que exige prévio arranque cooperativo.

Como sempre ocorre na ciência, boa resposta a uma grande questão faz com que pipoquem novas dúvidas. Por exemplo: se por mera razão acidental um dos atores falhar em fazer o esperado movimento positivo, isso por si só inviabiliza a continuidade da cooperação? E o que ocorreria quando o esquema de cooperação envolvesse mais do que dois atores? Foram questões como essas que alavancaram o fulgurante avanço da biologia matemática nos últimos vinte anos. O padrão “toma-lá-dá-cá” hoje não passa de uma das três modalidades de uma das cinco dinâmicas de cooperação evidenciadas.

O “tit-for-tat” é manifestação rudimentar do que passou a ser chamado de “reciprocidade direta”. Novas simulações indicaram que eventual passo em falso pode engendrar uma segunda chance, em estratégia apelidada de “toma-lá-dá-cá generoso”, a origem evolutiva do perdão. E desdobramentos ainda mais sofisticados revelaram a existência de uma terceira forma de reciprocidade direta, na qual o agente inverte sua atitude anterior quando nota que as coisas vão mal, mas logo depois volta a cooperar. Algo que já era bem conhecido na etologia como comportamento “Win-Stay, Lose-Shift”, comum entre pombos, macacos, ratos e camundongos.

O segundo vetor da cooperação, chamado de “reciprocidade indireta”, foi crucial para a evolução da linguagem e para o próprio desenvolvimento do cérebro humano, pois se baseia no fenômeno da reputação. Neste caso, o que condiciona as atitudes dos atores são comportamentos anteriores em relações com terceiros. A cooperação avança quando a probabilidade de um agente se inteirar sobre a reputação do outro compensa o custo/benefício do ato altruísta.

Os demais determinantes da cooperação são as três formas em que ocorre a seleção natural, pois, além da já mencionada nepotista (de parentesco), ela não opera apenas entre indivíduos, mas também entre grupos (multinível) e nas redes (espacial).

Mesmo que as observações acima não sejam suficientes para que se possa ter uma boa ideia das descobertas da biologia matemática no âmbito da dinâmica evolutiva, elas certamente permitem notar que o darwinismo aponta tanto para “luta” quanto para “acomodação” pela existência. Exposição rigorosa e extremamente amigável desse darwinismo 2.0 está em “SuperCooperators – Altruism, Evolution, and Why We Need Each Other to Succeed” (Free Press, 2011), do austríaco Martin A. Nowak, biólogo matemático que está em Harvard depois de ter brilhado em Oxford e Princeton, e que contou com a inestimável ajuda do jornalista científico britânico Roger Highfield.

Esse sim é um livro que mereceria ser distribuído gratuitamente. Não para substituir bíblias cristãs, mas para promover o entendimento das origens naturais dos códigos de ética de todas as grandes religiões.

José Eli da Veiga é professor sênior do Instituto de Energia e Ambiente da USP e autor de “A desgovernança mundial da sustentabilidade” (Editora 34, 2013). Escreve mensalmente às terças-feiras. http://www.zeeli.pro.br

(Valor Econômico)
http://www.valor.com.br/opiniao/3591840/darwinismo-20#ixzz35ZWruc22

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They Finally Tested The ‘Prisoner’s Dilemma’ On Actual Prisoners — And The Results Were Not What You Would Expect (Business Insider Australia)

, 21 July 2013

Alcatraz Jail Prison

The “prisoner’s dilemma” is a familiar concept to just about anybody that took Econ 101.

The basic version goes like this. Two criminals are arrested, but police can’t convict either on the primary charge, so they plan to sentence them to a year in jail on a lesser charge. Each of the prisoners, who can’t communicate with each other, are given the option of testifying against their partner. If they testify, and their partner remains silent, the partner gets 3 years and they go free. If they both testify, both get two. If both remain silent, they each get one.

In game theory, betraying your partner, or “defecting” is always the dominant strategy as it always has a slightly higher payoff in a simultaneous game. It’s what’s known as a “Nash Equilibrium,” after Nobel Prize winning mathematician and A Beautiful Mind subject John Nash.

In sequential games, where players know each other’s previous behaviour and have the opportunity to punish each other, defection is the dominant strategy as well.

However, on a Pareto basis, the best outcome for both players is mutual cooperation.

Yet no one’s ever actually run the experiment on real prisoners before, until two University of Hamburg economists tried it out in a recent study comparing the behaviour of inmates and students.

Surprisingly, for the classic version of the game, prisoners were far more cooperative  than expected.

Menusch Khadjavi and Andreas Lange put the famous game to the test for the first time ever, putting a group of prisoners in Lower Saxony’s primary women’s prison, as well as students through both simultaneous and sequential versions of the game.The payoffs obviously weren’t years off sentences, but euros for students, and the equivalent value in coffee or cigarettes for prisoners.

They expected, building off of game theory and behavioural economic research that show humans are more cooperative than the purely rational model that economists traditionally use, that there would be a fair amount of first-mover cooperation, even in the simultaneous simulation where there’s no way to react to the other player’s decisions.

And even in the sequential game, where you get a higher payoff for betraying a cooperative first mover, a fair amount will still reciprocate.

As for the difference between student and prisoner behaviour, you’d expect that a prison population might be more jaded and distrustful, and therefore more likely to defect.

The results went exactly the other way for the simultaneous game, only 37% of students cooperate. Inmates cooperated 56% of the time.

On a pair basis, only 13% of student pairs managed to get the best mutual outcome and cooperate, whereas 30% of prisoners do.

In the sequential game, way more students (63%) cooperate, so the mutual cooperation rate skyrockets to 39%. For prisoners, it remains about the same.

What’s interesting is that the simultaneous game requires far more blind trust out from both parties, and you don’t have a chance to retaliate or make up for being betrayed later. Yet prisoners are still significantly more cooperative in that scenario.

Obviously the payoffs aren’t as serious as a year or three of your life, but the paper still demonstrates that prisoners aren’t necessarily as calculating, self-interested, and un-trusting as you might expect, and as behavioural economists have argued for years, as mathematically interesting as Nash equilibrium might be, they don’t line up with real behaviour all that well.

UCSB anthropologist studies reciprocity among chimpanzees and bonobos (UC Santa Barbara)

20-Nov-2012
By Andrea Estrada

Primate behavior may reveal clues to evolution of favor exchange in humans

Adrian Jaeggi, a postdoctoral researcher in anthropology at UC Santa Barbara, and a junior research fellow at the campus’s SAGE Center for the Study of the Mind, is studying this question of reciprocity, using chimpanzees and bonobos as his test subjects. His findings appear in the current online issue of the journal Evolution & Human Behavior.(Santa Barbara, Calif.) –– When your neighbor asks to borrow a cup of sugar and you readily comply, is your positive response a function of the give and take that characterize your longstanding relationship? Or does it represent payment –– or prepayment –– for the cup of sugar you borrowed last week, or may need to borrow a month from now?

“The article focuses on the question of whether individuals do favors because they expect them to be reciprocated at some other time, and, more specifically, whether such exchanges have to happen immediately, or can take place over longer time spans,” Jaeggi explained. “We studied the question in chimpanzees and bonobos –– our two closest living relatives –– and looked at the exchanges of grooming and food sharing, which are two common types of favors among these apes.”

Two female chimpanzees take food from a male (center).

According to Jaeggi, while results of his research provide some evidence for immediate exchanges, they more strongly support the notion that favors are exchanged over long periods of time. Calculated exchanges, in which individuals keep a detailed score of past interactions, are much less common than the more loosely balanced exchanges that take place in stable relationships.

“In the chimp group we studied, we knew there was a lot of this long-term exchange,” said Jaeggi. “We didn’t find any evidence for a short-term effect.” Chimpanzees live in stable social groups, he continued, and have a relatively long life span. They recognize others in the group, form long-term relationships, and associate with individuals who have helped them in the past.

“In the wild, for example, chimps hunt for smaller monkeys, and they commonly share the meat. It’s similar to what hunters and gatherers do,” Jaeggi said. “Our experiment is meant to mimic the situation in which you have a large monopolized food item.” Using grooming as the favor, the researchers studied whether or not a chimp that had just been groomed was more likely to share food with the pal who had groomed him. “That would provide evidence for keeping track of who has done a favor,” Jaeggi said. However, grooming releases endorphins, he added, and that general sense of wellbeing on the part of the food owner might lead to more indiscriminate food sharing.

One female bonobo rests her hand on another’s shoulder.

Bonobos, on the other hand, presented a different result. While chimpanzees have a formalized dominance hierarchy, food is available to most individuals, no matter what their group status. That is not the case with bonobos. Bonobos don’t establish formal hierarchies, so they don’t know on an individual basis where they fit within the group. Also, they don’t form coalitions as much as chimpanzees do. “The food sharing situation sort of freaked them out,” said Jaeggi. “All of a sudden there’s all this food that’s owned by one individual, and they don’t really know what to do about it. They want to get it, but they don’t dare, because they don’t know what the consequence will be.””We found that sharing was predicted by who the chimps’ long-term friends and partners were,” he said. “Grooming just before didn’t play a role. Food owners didn’t share specifically with their groomers. Nor did the groomers act in return. They didn’t pay for the food, and they didn’t reward the food owner’s generosity afterward.”

Jaeggi added that bonobos did a lot more grooming, most likely because they sought the calming effects of the endorphins. “And there we did see an effect of grooming on sharing,” he said. “Chimps would go and take food pretty confidently, but Bonobos were more reticent. They’d reach out and then groom. It seemed to be that they’d groom to release tension, and then there would be these short-term reciprocal exchanges.”

But even those exchanges seem to be more a byproduct of the need to reduce tension, he noted, rather than short-term contingencies used to establish reciprocity.

So, what do these findings tell us about ourselves? Jaeggi suggests we should take seriously this evidence of long-term reciprocity in animals. “It’s really not qualitatively different from what people do,” he said. “They establish these lasting relationships, and within them, services are exchanged without the participants keeping close track of who’s doing what for whom.”

However, humans also have the capacity for more contingent reciprocity, which raises questions about its purpose, and how it developed. “Maybe that’s something that’s more culturally learned,” said Jaeggi.

Reciprocity an Important Component of Prosocial Behavior: Scorekeeping of Past Favors Isn’t, However, a Factor (Science Daily)

ScienceDaily (Sep. 3, 2012) — While exchanging favors with others, humans tend to think in terms of tit-for-tat, an assumption easily extended to other animals. As a result, reciprocity is often viewed as a cognitive feat requiring memory, perhaps even calculation. But what if the process is simpler, not only in other animals but in humans as well?

Researchers at the Yerkes National Primate Research Center, Emory University, have determined monkeys may gain the advantages of reciprocal exchange of favors without necessarily keeping precise track of past favors. Malini Suchak, a graduate student at Emory University, and Frans de Waal, PhD, director of the Living Links Center at Yerkes and C.H. Candler Professor of Psychology at Emory, led the study. Their findings will appear in an Early Online Edition of theProceedings of the National Academy of Sciences this week.

“Prosocial is defined as a motivation to assist others regardless of benefits for self, explained Suchak. “We used a prosocial choice test to study whether direct reciprocity could promote generosity among brown capuchin monkeys. We found one monkey willing to do another favors if the first monkey was the only one to choose, and we found the monkeys became even more prosocial if they could alternate and help each other. We did not find any evidence that the monkeys paid close attention to each other’s past choices, so they were prosocial regardless of what their partner had just done,” she continued.

Suchak and de Waal suggest the synchronization of the same actions in alternation creates a more positive attitude the same way humans who row a boat together or work toward a shared goal develop a more positive attitude about each other.

Another interesting finding according to the researchers is the capuchin monkeys were prosocial whether they were paired with a familiar partner from their own group {in-group} or a partner from a different social group {out-group}.

According to de Waal, “This research has several implications for better understanding human behavior. First, we observed an increase in prosocial behavior as a result of reciprocity, but the monkeys did not develop a contingency between their own and their partners’ behaviors. Like humans, the capuchins may have understood the benefits of reciprocity and used this understanding to maximize their own benefits. Second, that the capuchins responded similarly to in-group and out-group partners has implications for the commonly held view that humans are unique in their ability to cooperate with strangers,” de Waal explained.

According to the researchers, capuchin monkeys (Cebus apella) are ideal subjects for this type of study given the numerous observations of cooperative and prosocial behavior in the field, their sensitivity to other monkeys’ efforts in coordination experiments, and their robust, spontaneous prosocial behavior in the prosocial choice test compared with, for example, chimpanzees, which seem more sensitive to methodological variables.

In this study, the researchers tested 12 brown capuchin monkeys in pairs on a prosocial choice task. The monkeys had the choice between a selfish token that benefited only them and a prosocial token that benefited themselves and a partner. By comparing each monkey’s behavior with a familiar partner from the monkey’s own group and a partner from a different social group, the researchers examined the influence of each monkey’s relationship outside the experimental context on prosocial behavior. There was no difference between in-group and out-group pairs in any of the test conditions. To test the role of reciprocity, the researchers allowed the monkeys to take turns making choices and found this greatly increased prosocial behavior, but the researchers did not observe any tit-for-tat behavior. The researchers also tested whether the monkeys could overcome their aversion for inequity by creating a situation in which both individuals could provide each other with superior rewards, making reciprocity an even more attractive strategy. The monkeys did, but again without keeping track of each other’s choices. Finally, through a series of control conditions, the researchers established the monkeys were responding to their partners’ behaviors, rather than the rewards delivered by their partners, and that the monkeys understood the values of the tokens and were flexibly responding to changing conditions throughout the test sessions.

This research opens several avenues for future research, including further examining the emergence of reciprocity among humans without the cognition required for tit-for-tat and the tendency to cooperate with out-group partners.

Journal Reference:

  1. Malini Suchak and Frans B. M. de Waal. Monkeys benefit from reciprocity without the cognitive burden.Proceedings of the National Academy of Sciences, 2012; DOI: 10.1073/pnas.1213173109