Reciprocity as a foundation of financial economics

This paper argues that the subsistence of the fundamental theorem of contemporary financial mathematics is the ethical concept ‘reciprocity’. The argument is based on identifying an equivalence between the contemporary, and ostensibly ‘value neutral’, Fundamental Theory of Asset Pricing with theories of mathematical probability that emerged in the seventeenth century in the context of the ethical assessment of commercial contracts in a framework of Aristotelian ethics. This observation, the main claim of the paper, is justified on the basis of results from the Ultimatum Game and is analysed within a framework of Pragmatic philosophy. The analysis leads to the explanatory hypothesis that markets are centres of communicative action with reciprocity as a rule of discourse. The purpose of the paper is to reorientate financial economics to emphasise the objectives of cooperation and social cohesion and to this end, we offer specific policy advice

Influence of opinion dynamics on the evolution of games

Under certain circumstances such as lack of information or bounded rationality, human players can take decisions on which strategy to choose in a game on the basis of simple opinions. These opinions can be modified after each round by observing own or others payoff results but can be also modified after interchanging impressions with other players. In this way, the update of the strategies can become a question that goes beyond simple evolutionary rules based on fitness and become a social issue. In this work, we explore this scenario by coupling a game with an opinion dynamics model. The opinion is represented by a continuous variable that corresponds to the certainty of the agents respect to which strategy is best. The opinions transform into actions by making the selection of an strategy a stochastic event with a probability regulated by the opinion. A certain regard for the previous round payoff is included but the main update rules of the opinion are given by a model inspired in social interchanges. We find that the dynamics fixed points of the coupled model is different from those of the evolutionary game or the opinion models alone. Furthermore, new features emerge such as the resilience of the fraction of cooperators to the topology of the social interaction network or to the presence of a small fraction of extremist players.Comment: 7 pages, 5 figure

On the Perception of Newcomers: Toward an Evolved Psychology of Intergenerational Coalitions

Human coalitions frequently persist through multiple, overlapping membership generations, requiring new members to cooperate and coordinate with veteran members. Does the mind contain psychological adaptations for interacting within these intergenerational coalitions? In this paper, we examine whether the mind spontaneously treats newcomers as a motivationally privileged category. Newcomers—though capable of benefiting coalitions—may also impose considerable costs (e.g., they may free ride on other members, they may be poor at completing group tasks). In three experiments we show (1) that the mind categorizes coalition members by tenure, including newcomers; (2) that tenure categorization persists in the presence of orthogonal and salient social dimensions; and (3) that newcomers elicit a pattern of impressions consistent with their probable ancestral costs. These results provide preliminary evidence for a specialized component of human coalitional psychology: an evolved concept of newcomer

Conflicted Emotions Following Trust-based Interaction

We investigated whether 20 emotional states, reported by 170 participants after participating in a Trust game, were experienced in a patterned way predicted by the “Recalibrational Model” or Valence Models. According to the Recalibrational Model, new information about trust-based interaction outcomes triggers specific sets of emotions. Unlike Valence Models that predict reports of large sets of either positive or negative emotional states, the Recalibrational Model predicts the possibility of conflicted (concurrent positive and negative) emotional states. Consistent with the Recalibrational Model, we observed reports of conflicted emotional states activated after interactions where trust was demonstrated but trustworthiness was not. We discuss the implications of having conflicted goals and conflicted emotional states for both scientific and well-being pursuits

Vascular Dysfunction Induced in Offspring by Maternal Dietary Fat Involves Altered Arterial Polyunsaturated Fatty Acid Biosynthesis

Nutrition during development affects risk of future cardiovascular disease. Relatively little is known about whether the amount and type of fat in the maternal diet affect vascular function in the offspring. To investigate this, pregnant and lactating rats were fed either 7%(w/w) or 21%(w/w) fat enriched in either18:2n-6, trans fatty acids, saturated fatty acids, or fish oil. Their offspring were fed 4%(w/w) soybean oil from weaning until day 77. Type and amount of maternal dietary fat altered acetylcholine (ACh)-mediated vaso-relaxation in offspring aortae and mesenteric arteries, contingent on sex. Amount, but not type, of maternal dietary fat altered phenylephrine (Pe)-induced vasoconstriction in these arteries. Maternal 21% fat diet decreased 20:4n-6 concentration in offspring aortae. We investigated the role of Δ6 and Δ5 desaturases, showing that their inhibition in aortae and mesenteric arteries reduced vasoconstriction, but not vaso-relaxation, and the synthesis of specific pro-constriction eicosanoids. Removal of the aortic endothelium did not alter the effect of inhibition of Δ6 and Δ5 desaturases on Pe-mediated vasoconstriction. Thus arterial smooth muscle 20:4n-6 biosynthesis de novo appears to be important for Pe-mediated vasoconstriction. Next we studied genes encoding these desaturases, finding that maternal 21% fat reduced Fads2 mRNA expression and increased Fads1 in offspring aortae, indicating dysregulation of 20:4n-6 biosynthesis. Methylation at CpG −394 bp 5′ to the Fads2 transcription start site predicted its expression. This locus was hypermethylated in offspring of dams fed 21% fat. Pe treatment of aortae for 10 minutes increased Fads2, but not Fads1, mRNA expression (76%; P<0.05). This suggests that Fads2 may be an immediate early gene in the response of aortae to Pe. Thus both amount and type of maternal dietary fat induce altered regulation of vascular tone in offspring though differential effects on vaso-relaxation, and persistent changes in vasoconstriction via epigenetic processes controlling arterial polyunsaturated fatty acid biosynthesis

A new species of Tanyuromys Pine, Timm, and Weksler, 2012 (Rodentia: Cricetidae: Oryzomyini), with comments on relationships within the Oryzomyini

We name and describe a new species of long-tailed sigmodontine rodent of the genus Tanyuromys, based on 3 specimens collected from 3 different localities in northern Ecuador, during the period 1953–2008. All 3 localities are at middle elevations on the Pacific Andean slopes and specimens were taken both in intact and disturbed forest areas. Tanyuromys previously has been treated as including a single species—T. aphrastus (Harris, 1932); however, using morphological and molecular characters (mitochondrial cytochrome b, Cytb; 1,143 bp), we herein recognize 2 species: T. aphrastus proper, which, so far as known, occurs only in Costa Rica and Panama, and a new species known only from Ecuador. The Ecuadoran species, like T. aphrastus, is characterized by a long tail (ca. 1.5 × length of head plus body); large, complexly constructed, pentalophodont molars; braincase with beaded supraorbital margins continuous with raised temporal ridges; short, anteriorly constricted incisive foramina; short, narrow palatines; and small auditory bullae. Although similar morphologically, which explains why the 2 species have hitherto been regarded as 1, the few specimens available of each differ in that the new species has, among other traits, a narrower interorbital breadth, narrower zygomatic plate, invariably (thus far) distinct supraorbital bead continuing posteriorly over parietal to lambdoidal crests as a prominent raised ridge, relatively large lateral wing of the parietal, skull with more angular rather than more rounded contours. Molecular and morphological characters confirm that specimens of T. aphrastus from Costa Rica and Panama are quite similar; they differ in Cytb sequences by 1.2%. The new species from Ecuador, in contrast, differs from the Central American T. aphrastus in Cytb sequences by 10.2%. The 2 species form a well-supported clade; we infer the genus’ phylogenetic associations within the Oryzomyini, based on the complete cytochrome b sequence. Nombramos y describimos una nueva especie de roedor sigmodontino en el género Tanyuromys Pine, Timm y Weksler, 2012, a partir de tres especímenes recolectados entre 1953 y 2008 en tres localidades diferentes en el norte de Ecuador. Las tres localidades se encuentran a altitudes medias en las laderas Andinas del lado Pacífico. Los especímenes fueron recolectados tanto en bosque intacto como perturbado. Hasta el momento, se ha considerado que Tanyuromys incluye una sola especie: T. aphrastus (Harris, 1932). Sin embargo, mediante datos tanto morfológicos como moleculares (del gen mitocondrial citocromo b, Cytb; de 1,143 pares de bases de longitud), reconocemos en el presente trabajo a dos especies: T. aphrastus propiamente dicho, el cual que se sepa solo habita Costa Rica y Panamá, así como una nueva especie que por el momento solo se conoce de Ecuador. La especie ecuatoriana se caracteriza—al igual que T. aphastus—por tener la cola extremadamente larga (aproximadamente 1.5 × el largo de la longitud cabeza-cuerpo; molares pentalofodontos grandes, de estructura compleja; caja cefálica con márgenes supraorbitarios rebordeados y continuos con una cresta temporal moderadamente elevada; los forámenes incisivos cortos, con constricción anterior; huesos palatinos cortos y estrechos; y bulla timpánica pequeña. Aunque las dos especies son similares (lo cual explica porque hasta ahora se han considerado una sola), los pocos especímenes de cada una difieren entre sí en que la nueva especie tiene, entre otras características, una anchura interorbitaria más estrecha; la placa cigomática más estrecha; el rebordeado supraorbitario prominentemente elevado, tal marcada cresta (en los especímenes que se conocen hasta el momento), continuando en dirección posterior sobre el hueso parietal hasta las crestas lambdoidales; las alas laterales de los parietales relativamente grandes; y los contornos del cráneo más angulares que redondeados. Los análisis moleculares y morfológicos coinciden en que los especímenes de Costa Rica y Panamá difieren poco entre sí: sus secuencias de ADN mitocondrial del citocromo b solo se distinguen en un 1.2%. En cambio, la nueva especie de Ecuador difiere de T. aphrastus centroamericano en 10.2%. Las dos especies forman un clado bien definido y apoyado. En este trabajo, inferimos las asociaciones filogenéticas del género Tanyuromys entre los Oryzomyini con base en secuencias completas del citocromo b