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At the conclusion of 2017, to the dismay of journalists, pundits, and academics, large numbers of adolescents began consuming Tide Pods, a form of laundry detergent that is candy-like in appearance. This paper argues that purposeful consumption of laundry detergent may in fact be individually rational for adolescents. The consumption of Tide Pods may allow adolescents to successfully signal status in accordance with the Handicap Principle, which explains the beauty of a peacock's tail and the practice of stotting by gazelles in the wild. The Handicap Principle is also a common explanation of adolescents' willingness to engage in dangerous activities, like drug use. A subtext of the thesis of this paper is the veracity of rational choice explanations in unconventional contexts distant from its original applications. [ABSTRACT FROM AUTHOR]

The ethnically homogeneous middleman groups (EHMGs), which are informal trading networks, are ubiquitous in less-developed economies where the legal infrastructure for contract enforcement is not well developed. This paper develops a formal model of social interaction among members of the EHMG as well as in more general situations in a multi-ethnic or multi-cultural society consisting of identifiable ethnic or linguistic groups. Behavioral patterns are transmitted between generations and altered via imitation in social contacts. The model demonstrates how different discriminatory behavioral patterns can evolve and persist over time. One result is that the trust between such groups can increase due to a higher frequency of inter-group contacts. In concluding the paper, we speculate about how the model can be expanded to include changes in legal structures, especially contract law. This could lead to an increase in the trust between the different groups. [ABSTRACT FROM AUTHOR]

The “Deep Roots” literature investigates the effects of ancient cultural variables on economic outcomes. We extend Putterman and Weil’s (Q J Econ 125(4):1627-1682, 2010) inquiry into the effects of State History and Agricultural History to the economic output in ethnically and racially diverse fifty U.S. States. The ethnic and racial differences across the populations of the fifty U.S. states vary considerably due to historical immigration and slave flows that, as a result, produced radically different State History and Agricultural History scores across the states. Results derived from Putterman and Weil’s methodology do not robustly predict per capita levels of economic output across U.S. States. We also investigate the institutions channel, and find that they impact some measures of institutions, but they do not impact the quality of economic institutions which may be essential for promoting economic growth and development. [ABSTRACT FROM AUTHOR]

Historically, some societies around the world killed newborn twins, though the practice was forsaken in the early twentieth century. Anthropologists have proposed different theses: (1) the delivery of twins occurred when the mother cheated on her husband, or committed a great sin, and killing the twins was the penalty, (2) twin-killing was done to assert that human beings were different from animals among which multiple births in the same delivery were seen, (3) twins brought a dilemma to the kinship structure of societies and to cope with it different rules were adopted, twin-killing being the extreme one, (4) twin-killing was a means to face resource stress. We argue that although those interpretations are useful, we can improve the understanding of that phenomenon by adding an identity economics model, where twins are a taboo. Identity economics helps us explain the persistence of the practice and its eventual decline. We make our case with examples from the Igbo of Nigeria. [ABSTRACT FROM AUTHOR]

Social vertebrates have a rich repertoire of communication signals and modalities. Recent work on the social insects has uncovered a diverse set of communication modalities including chemical, tactile, visual, and auditory signals to communicate a wide variety of information on the location of distant food sites, distress, and aggression. Here, we investigated abdominal wagging in the fire ant, Solenopsis invicta. We found that the abdominal 'wagging' that occurred inside the fire ant nests differed significantly from the abdominal 'flagging' that is known to occur outside the fire ant nests. Neither sounds nor venom was emitted during abdominal wagging inside the fire ant nests. Moreover, the incidence and duration of abdominal wagging was greater when workers were tending brood or ingesting food than when engaged in non-brood related tasks or in donating food. Lastly, inside the nests, abdominal wagging neither attracted nor repelled nearby workers. Thus, we speculate that wagging is an expression of pleasure while tending brood or ingesting food that falls along the continuum between the aggressive nature of abdominal flagging and the distress call of abdominal stridulation. [ABSTRACT FROM AUTHOR]

The fire ant, Solenipsis invicta, has successfully invaded and colonized ecosystems worldwide. Like humans, fire ants build permanent domiciles to house family members, establish well-defined territories for foraging and fight to the death when invading neighbors breach the borders. One of the more striking behaviors of fire ants is their ability to form a living raft when springtime rains flood their domiciles. What are the survival benefits, if any, to collective behavior during a flood? To address this question, we quantified the survival of individuals as solitary swimmers compared to cooperative rafters. We found that large workers and matriarchs survived equally well as solitary swimmers or rafters. In contrast, small workers drowned whether they were solitary swimmers or rafters. However, when rafting with large workers or matriarchs, the mortality of small workers declined three-fold. We propose a behavior phenotype classification scheme to catalog the diverse behaviors observed in this series of experiments. Although the ultimate goal of rafting behavior by fire ant workers is to protect their matriarch, the proximate goal for the vast majority of fire ants is to save themselves first and to save others if the opportunity arises. [ABSTRACT FROM AUTHOR]

This paper develops a bioeconomic model applying evolutionary game theory to the notion of poverty traps. We study the evolution of the social norm of being either a high-type or low-type in a dynamic environment where agents are driven by an imitative behavior. History matters because given initial conditions, agents imitate according to their current success in payoffs and the current profile of economic agents in the economy. We define a poverty trap as an evolutionarily stable strategic profile and steady state of the replicator dynamics. We show that in poor economies with a large fraction of low-type agents imitative strategies do not support a take-off into sustained growth. To achieve that take-off, society should subsidize critical parameters of the expected payoffs such that economic agents may change the initial conditions and the economy gets a critical mass of high-type economic agents, and so to overcome the poverty trap. [ABSTRACT FROM AUTHOR]

Endemic to a small island off the coast of China, the Shedao pit viper, Gloydius shedaoensis, is known for its 'accidental altruism.' Juvenile pit vipers often kill passerine birds too large to swallow. Large prey carcasses are scavenged by neighboring adults. In turn, adult pit vipers kill hawks that prey on juvenile pit-vipers, but are not a threat to the adults themselves. Using agent-based computer simulations, we quantified the lifetime fitness of pit viper breeders with one of three genotypes: selfish, altruistic or both selfish and altruistic. Our simulation was based on a four-dimensional (4D) model of social behavior which included interactions of pit viper offspring with predators and prey as well as conspecifics. Results showed that, over ten breeding seasons, pit viper breeders with flexible altruistic and selfish genotypes averaged seven times the number of surviving offspring relative to breeders with pure-selfish genotypes, and 23 times the number of surviving offspring as breeders with pure-altruistic genotypes. In summary, viewing animal behavior through the lens of the 4D model will extend our understanding of the evolutionary pathway to social behaviors through natural selection processes. [ABSTRACT FROM AUTHOR]

According to a bioeconomic model called skew selection, individuals form cooperative hierarchies when coping with high risk environments that include predators and cycles of scarce resources. This paper reports a study that used agent-based computer simulations to experimentally test the predictions of skew selection. Results of the experiment showed that successful face-to-face transaction strategies varied with environmental risks. Risks involving resource scarcity favored clustering and stealing. Risks involving predators favored clustering and hoarding. A combination of risks involving resource scarcity and predators favored clustering and sharing. Wealthy donors gained safety-in-numbers to protect them from predators; at the same time, marginal recipients gained resources to protect them from starving. In summary, our findings show that even though natural selection is not a moral process, it can produce moral behavior. [ABSTRACT FROM AUTHOR]

This article responds to some of the very valuable comments on my target article (Landa, J Bioeconomics 10(3):259–278, 2008) on homogeneous middleman groups (HMGs) as adaptive units. In addition to viewing HMGs as adaptive units, I discuss the idea of viewing HMGs as superorganisms and as endogamous ethnic groups, as well as re-emphasizing the importance of HMGs as trust networks. My theory of HMGs as adaptive units shares some similarities with biologists’ ‘biological market theory’ of mutualistic interactions between species. [ABSTRACT FROM AUTHOR]

This article critiques the efforts by Janet Landa, David Sloan Wilson and others to use group selection paradigms to explain the success of homogenous middlemen groups (HMGs). It argues that group selection theory cannot explain the conflicts of interests that arise within HMGs or why they dissolve in certain occasions. Landa’s earlier explanations, which stressed the combination of genetic (kinship) and social bonds in the creation of trust and cooperation in the extension of credit and the creation of local public goods, better predicts both the strength and weaknesses of HMGs. [ABSTRACT FROM AUTHOR]

The paper presents a bioeconomics theory of homogeneous middleman groups (HMGs) as adaptive units as well as empirical evidence in the form of a number of historical case studies of HMGs functioning as adaptive units in less-developed economies lacking infrastructure. The evidence presented is not new: most of the case studies have been published [Landa (in Jenkins (Ed.) The informal sector: Including the excluded, 1988)]. What is new, however, is analyzing the phenomena of HMGs in a new way—as adaptive units viewed from a group selection perspective. In doing so, the case studies in this paper present empirical evidence of the existence and importance of group selection in human society. [ABSTRACT FROM AUTHOR]

In spite of its checkered intellectual history, and in spite of the myriad proposals of alternative models that claim both to account for the range of human behavior and to dispense with the need for selection above the organism level, a multilevel selection framework allowing for biological as well as cultural group selection remains the only coherent means of accounting for the persistence and spread of behavioral inclinations which, at least upon first appearance at low frequency, would have been biologically altruistic. This argument is advanced on three tracks: through a review of experimental and observational evidence inconsistent with a narrow version of rational choice theory, through a critique of models or explanations purporting to account for prosocial behavior through other means, and via elaboration of the mechanisms, plausibility, and intellectual history of biological group selection. [ABSTRACT FROM AUTHOR]

Systems of numerical representation and computation are crucial for the operation of modern market economies. Surprisingly, however, numerical institutions and people’s numerical abilities are usually taken as given in economic analysis. To develop a richer vision of economic agents, this article investigates the interplay of biological and economic factors in the development of systematic numerical cognition and economic calculation in human societies. In investigating the economic basis of numeracy, we emphasize that it is the relevance of economic objects to need satisfaction and their scarcity that initially makes people seek to quantify goods and to develop numerical tools. As for biological aspects, we identify the pre-numerical (iconic) quantitative capacities that we share with other species as part of our biological endowment. We then investigate the fully-fledged symbolic systems of numerical representation that are unique to humans. We examine the scope for economic exchange in societies in which agents are endowed with natural iconic means for representing set sizes but lack a conventionalized number system. We also investigate the minimal set of quantitative representations that people need to have in order to engage in monetary exchange and precise economic calculation. [ABSTRACT FROM AUTHOR]

Two competing models, reproductive skew and skew selection, have been constructed to explain the evolution of cooperation among unrelated breeders. Reproductive skew is a trade-off model that assumes breeding occurs under scarce resource conditions. One breeder gains units of fecundity at the expense of other breeders during aggressive, altruistic or tug-of-war transactions. After joining, the distribution of fecundity among breeders shifts from symmetrical to asymmetrical. In contrast, skew selection is a surplus model that assumes breeding occurs during a springtime glut. Skew selection assumes that fecundity among breeders is initially asymmetrical and that joining reduces the asymmetry of fecundity. This paper reports findings from a breeding experiment on the fire ant, Solenopsis invicta, which supported skew selection rather than reproductive skew. Joining was a win-win strategy for alpha and beta breeders; beta breeders gained within-group survival benefits; alpha breeders gained between-group survival benefits. In summary, skew selection extends Darwin’s theory of natural selection by revealing the self-interested core of cooperative breeding. [ABSTRACT FROM AUTHOR]