Male shrikes punish unfaithful females

The costs to females of participating in extrapair copulationsis an interesting but hitherto neglected topic in behavioralecology. An obvious potential cost to females is male physicalsanctions. However, although retaliation and punishment by malepartners has been proposed as a basic cost for female extrapairbehavior in theory, it has not been experimentally demonstrated.We studied the breeding biology of the lesser gray shrike (Laniusminor) and combined field observations and a field experimentto show that (1) there is a high intrusion rate during the female'sfertile period, and extrapair copulations occur in this population;(2) by detaining females during the fertile phase, males wereinduced to retaliate physically against their partners, therebyincreasing costs related to female extrapair behavior; and (3)there were no obvious costs to males of punishing their mates.DNA fingerprinting reveals that extrapair paternity is rareor absent in this population. Although we cannot conclude thatmonogamy at the genetic level is the result of male retaliation,we do show that male physical sanction is a cost that deceptivefemales have to assume. Males' strategies based on coercionshould be considered when explaining variation in extrapairpaternity across species.     

When does optional participation allow the evolution of cooperation?

Altruistic punishment has been shown to invade when rare if individuals are allowed to opt out of cooperative ventures. Individuals that opt out do not contribute to the common enterprise or derive benefits from it. This result is potentially significant because it offers an explanation for the origin of large-scale cooperation in one-shot interactions among unrelated individuals. Here, we show that this result is not a general consequence of optional participation in cooperative activities, but depends on special assumptions about cooperative pay-offs. We extend the pay-off structure of optional participation models to consider the effects of economies and diseconomies of scale in public-goods production, rival and non-rival consumption of goods, and different orderings of the pay-offs of freeriding and opting out. This more general model highlights the kinds of pay-offs for which optional participation favours cooperation, and those in which it does not.     

Within-group aggression and the value of group members: theory and a field test with social wasps

We present a simple, general model of how the optimal levelof intra-group aggression should vary in different social contexts.A key component of this model is the value of the recipientof aggression to a potential aggressor (i.e., the ratio of expectedlong-term group productivity with the recipient present to theexpected group productivity with the recipient absent). Therecipient's value measures its contribution to group reproductivesuccess. We demonstrate theoretically that if aggression increasesthe aggressor's share of the group's expected total reproductiveoutput, but at the same time decreases the magnitude of thisoverall reproductive output, then the optimal level of aggressiontoward a recipient will decrease with increasing recipient'svalue. This proof establishes a rigorous theoretical connectionbetween the level of aggression within a group and the benefitsof belonging to such a group and can be tested by experimentallymanipulating the values of group members to each other. We test,and thus illustrate the utility of, this model by examiningaggression within experimentally-manipulated foundress associationsof social wasps. We show that the value of co-foundresses toeach other in the social wasp Polistes fuscatus lies in theirability to provide insurance against colony failure caused bythe loss of all tending foundresses. Removals of worker-destinedeggs and pupae, which increase the value of co-foundresses,both lead to significant reductions in aggression by the dominantfoundress, despite the fact that the immediate, selfish benefitsof competitive aggression should increase when empty brood cellsare present Removal of reproductive-destined eggs, which doesnot affect co-foundress value, but increases the benefits ofselfish aggression, causes a significant increase in aggressionby beta foundresses. Finally, wing reduction of subordinateco-foundresses significantly increases aggression by dominantfoundresses, as expected since the subordinate's value is reduced.Our results indicate that foundress aggression is sensitiveto the value of future cooperation, as predicted by the optimalaggression model. The model may apply widely to both invertebrateand vertebrate societies     

God’s punishment and public goods

Cooperation towards public goods relies on credible threats of punishment to deter cheats. However, punishing is costly, so it remains unclear who incurred the costs of enforcement in our evolutionary past. Theoretical work suggests that human cooperation may be promoted if people believe in supernatural punishment for moral transgressions. This theory is supported by new work in cognitive psychology and by anecdotal ethnographic evidence, but formal quantitative tests remain to be done. Using data from 186 societies around the globe, I test whether the likelihood of supernatural punishment—indexed by the importance of moralizing “high gods”—is associated with cooperation. Dominic Johnson is a fellow in the Princeton University Society of Fellows. He holds a D.Phil. in biology from Oxford University and a Ph.D. in political science from Geneva University. His research revolves around the evolutionary biology of human behavior and how this impacts on conflict, cooperation, politics, and religion. His recent book, Overconfidence and War: The Havoc and Glory of Positive Illusions, was published in 2004 by Harvard University Press.     

The evolution of punishment through reputation

Punishment of non-cooperators has been observed to promote cooperation. Such punishment is an evolutionary puzzle because it is costly to the punisher while beneficial to others, for example, through increased social cohesion. Recent studies have concluded that punishing strategies usually pay less than some non-punishing strategies. These findings suggest that punishment could not have directly evolved to promote cooperation. However, while it is well established that reputation plays a key role in human cooperation, the simple threat from a reputation of being a punisher may not have been sufficiently explored yet in order to explain the evolution of costly punishment. Here, we first show analytically that punishment can lead to long-term benefits if it influences one''s reputation and thereby makes the punisher more likely to receive help in future interactions. Then, in computer simulations, we incorporate up to 40 more complex strategies that use different kinds of reputations (e.g. from generous actions), or strategies that not only include punitive behaviours directed towards defectors but also towards cooperators for example. Our findings demonstrate that punishment can directly evolve through a simple reputation system. We conclude that reputation is crucial for the evolution of punishment by making a punisher more likely to receive help in future interactions, and that experiments investigating the beneficial effects of punishment in humans should include reputation as an explicit feature.     

Predictors of Views about Punishing Animal Abuse

The current study used scenarios of animal cruelty based on actual events to explore what factors predict perceptions of punishments for animal cruelty. Five hundred thirty-eight university undergraduates participated in the study. Participants read scenarios based on an actual event of animal cruelty and with information on statutes addressing animal cruelty in their state. Participants were then asked to give ratings for punishment of the animal cruelty perpetrator. A canonical correlation analysis was used to test the multivariate shared relationship between the set of eight predictor variables and the criterion variable set of 15 punishment ratings. The response distributions were highly skewed for seven of the 15 criterion variables, highlighting the strong sentiments participants expressed against animal cruelty. The canonical correlation analysis identified significant criterion variables that were predicted by two of the empirically manipulated predictor variables (Perpetrator Age and Location of Crime) along with one subject variable (Participant Femininity). This set of predictor variables correlated with the criterion variable set that included Allowed with Children and Amount of Fine for Suffering. There was a main effect for Perpetrator Age, such that the degree to which participants thought a perpetrator of animal cruelty should be allowed alone with children depends on the age of the perpetrator. Mean responses were stronger for scenarios with perpetrators aged 28 than with perpetrators aged 12. The average response to Amount of Fine for Suffering was larger when the animal cruelty happened at a pet kennel than if the crime occurred at an animal shelter. Implications for these significant predictor and criterion variables are discussed in the context of interdisciplinary theory and practical implications for public policy.     

How institutions shaped the last major evolutionary transition to large-scale human societies

What drove the transition from small-scale human societies centred on kinship and personal exchange, to large-scale societies comprising cooperation and division of labour among untold numbers of unrelated individuals? We propose that the unique human capacity to negotiate institutional rules that coordinate social actions was a key driver of this transition. By creating institutions, humans have been able to move from the default ‘Hobbesian’ rules of the ‘game of life’, determined by physical/environmental constraints, into self-created rules of social organization where cooperation can be individually advantageous even in large groups of unrelated individuals. Examples include rules of food sharing in hunter–gatherers, rules for the usage of irrigation systems in agriculturalists, property rights and systems for sharing reputation between mediaeval traders. Successful institutions create rules of interaction that are self-enforcing, providing direct benefits both to individuals that follow them, and to individuals that sanction rule breakers. Forming institutions requires shared intentionality, language and other cognitive abilities largely absent in other primates. We explain how cooperative breeding likely selected for these abilities early in the Homo lineage. This allowed anatomically modern humans to create institutions that transformed the self-reliance of our primate ancestors into the division of labour of large-scale human social organization.     

Persistent conditioned place preference to aggression experience in adult male sexually‐experienced CD‐1 mice

We recently developed a conditioned place preference (CPP) procedure, commonly used to study rewarding drug effects, to demonstrate that dominant sexually‐experienced CD‐1 male mice form CPP to contexts previously associated with defeating subordinate male C57BL/6J mice. Here we further characterized conditioned and unconditioned aggression behavior in CD‐1 mice. In Exp. 1 we used CD‐1 mice that displayed a variable spectrum of unconditioned aggressive behavior toward younger subordinate C57BL/6J intruder mice. We then trained the CD‐1 mice in the CPP procedure where one context was intruder‐paired, while a different context was not. We then tested for aggression CPP 1 day after training. In Exp. 2, we tested CD‐1 mice for aggression CPP 1 day and 18 days after training. In Exp. 3–4, we trained the CD‐1 mice to lever‐press for palatable food and tested them for footshock punishment‐induced suppression of food‐reinforced responding. In Exp. 5, we characterized unconditioned aggression in hybrid CD‐1 × C57BL/6J D1‐Cre or D2‐Cre F1 generation crosses. Persistent aggression CPP was observed in CD‐1 mice that either immediately attacked C57BL/6J mice during all screening sessions or mice that gradually developed aggressive behavior during the screening phase. In contrast, CD‐1 mice that did not attack the C57BL/6J mice during screening did not develop CPP to contexts previously paired with C57BL/6J mice. The aggressive phenotype did not predict resistance to punishment‐induced suppression of food‐reinforced responding. CD‐1 × D1‐Cre or D2‐Cre F1 transgenic mice showed strong unconditioned aggression. Our study demonstrates that aggression experience causes persistent CPP and introduces transgenic mice for circuit studies of aggression.     

The evolution of cooperation and altruism--a general framework and a classification of models

One of the enduring puzzles in biology and the social sciences is the origin and persistence of intraspecific cooperation and altruism in humans and other species. Hundreds of theoretical models have been proposed and there is much confusion about the relationship between these models. To clarify the situation, we developed a synthetic conceptual framework that delineates the conditions necessary for the evolution of altruism and cooperation. We show that at least one of the four following conditions needs to be fulfilled: direct benefits to the focal individual performing a cooperative act; direct or indirect information allowing a better than random guess about whether a given individual will behave cooperatively in repeated reciprocal interactions; preferential interactions between related individuals; and genetic correlation between genes coding for altruism and phenotypic traits that can be identified. When one or more of these conditions are met, altruism or cooperation can evolve if the cost-to-benefit ratio of altruistic and cooperative acts is greater than a threshold value. The cost-to-benefit ratio can be altered by coercion, punishment and policing which therefore act as mechanisms facilitating the evolution of altruism and cooperation. All the models proposed so far are explicitly or implicitly built on these general principles, allowing us to classify them into four general categories.     

The psychology of deterrence explains why group membership matters for third-party punishment

Humans regularly intervene in others' conflicts as third-parties. This has been studied using the third-party punishment game: A third-party can pay a cost to punish another player (the “dictator”) who treated someone else poorly. Because the game is anonymous and one-shot, punishers are thought to have no strategic reasons to intervene. Nonetheless, punishers often punish dictators who treat others poorly. This result is central to a controversy over human social evolution: Did third-party punishment evolve to maintain group norms or to deter others from acting against one's interests? This paper provides a critical test. We manipulate the ingroup/outgroup composition of the players while simultaneously measuring the inferences punishers make about how the dictator would treat them personally. The group norm predictions were falsified, as outgroup defectors were punished most harshly, not ingroup defectors (as predicted by ingroup fairness norms) and not outgroup members generally (as predicted by norms of parochialism). The deterrence predictions were validated: Punishers punished the most when they inferred that they would be treated the worst by dictators, especially when better treatment would be expected given ingroup/outgroup composition.