Using data from a popular online social network site, this paper explores the relationship between profile structure (namely, which fields are completed) and number of friends, giving designers insight into the importance of the profile and how it works to encourage connections and articulated relationships between users. We describe a theoretical framework that draws on aspects of signaling theory, common ground theory, and transaction costs theory to generate an understanding of why certain profile fields may be more predictive of friendship articulation on the site. Using a dataset consisting of 30,773 Facebook profiles, we determine which profile elements are most likely to predict friendship links and discuss the theoretical and design implications of our findings. Author Keywords social network sites, profile elements, signaling theory,

We propose an explanation of cooperation among unrelated members of a social group, in which providing group benefits evolves because it constitutes an honest signal of the member’s quality as a mate, coalition partner or competitor, and therefore results in advantageous alliances for those signaling in this manner. Our model is framed as an n-player game that involves no repeated or assortative interactions, and assumes a payoff structure that would conform to an n-player public goods game in which non-cooperation would be a dominant strategy if there were no signaling benefits. We show that honest signaling of underlying quality by providing a public good to group members can be evolutionarily stable. We also show that this behavior is capable of proliferating in a population in which it is initially rare. Our model applies to a range of cooperative interactions, including providing individually consumable resources, participating in group raiding or defense, and punishing free-riding or other violations of social norms. Our signaling model is distinctive in applying to group rather than dyadic interactions and in determining endogenously the fraction of the group that signals high quality in equilibrium.

This article reviews theories of organizational communication with a special emphasis on theories that have been used to explain computer-mediated communication phenomena. Among the theories reviewed, two—social presence and media richness—are identified as problematic and as posing obstacles to future theoretical development. While shortcomings of these theories have been identified in the past, some of these theories ’ predictions have been supported by empirical evidence. It is argued that this theoretical dilemma can be resolved based upon principles derived from a modern version of Darwin’s theory of evolution by natural selection and the application of those principles to the understanding of human evolution. A new theoretical model called the psychobiological model is developed, which predicts variations in cognitive effort in computer-mediated collaborative tasks. The model proposes that there is a negative causal link between the “naturalness ” of a computer-mediated communication medium, which is the similarity of the medium to the face-to-face medium, and the cognitive effort required from an individual using the medium for knowledge transfer. The model also states that this link is counterbalanced by what are referred to as “schema alignment ” and “cognitive adaptation. ” The schema alignment construct refers to the similarity between the mental schemas of an individual and those of other participant(s). The cognitive adaptation construct refers to an individual’s level of schema development associated with the use of a particular medium. Finally, the model states that the degree to which the medium supports an individual’s ability to convey and listen to speech is particularly significant in defining its naturalness, more so than the medium’s degree of

Conspicuous displays of consumption and benevolence might serve as “costly signals ” of desirable mate qualities. If so, they should vary strategically with manipulations of mating-related motives. The authors examined this possibility in 4 experiments. Inducing mating goals in men increased their willingness to spend on conspicuous luxuries but not on basic necessities. In women, mating goals boosted public—but not private—helping. Although mating motivation did not generally inspire helping in men, it did induce more helpfulness in contexts in which they could display heroism or dominance. Conversely, although mating motivation did not lead women to conspicuously consume, it did lead women to spend more publicly on helpful causes. Overall, romantic motives seem to produce highly strategic and sex-specific self-presentations best understood within a costly signaling framework. Key words: costly signaling, altruism, conspicuous consumption, mating goals, self-presentation We should often blush at our noblest deeds if the world were to see all their underlying motives.—Francois de La Rochefoucauld On Valentine’s Day 2003, America’s leading authority on philanthropy announced that real estate mogul Donald Trump had pledged $1 million to charity (Foundation Center, 2003). A few

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commitment, conscientiousness, costly signaling theory, equilibrium selection, emotion, empathy, ethics, evolutionary psychology, fitness indicators, genetic correlations, good genes, good parents, good partners, human courtship, kin selection, kindness, individual differences, intelligence, mate choice, mental health, moral virtues, mutation load, mutual choice, person perception, personality, reciprocal altruism, sexual fidelity, sexual selection, social cognition, virtue ethics “Human good turns out to be the activity of the soul exhibiting excellence.” Aristotle (350 BC) Moral evolution theories have emphasized kinship, reciprocity, group selection, and equilibrium selection. Yet, moral virtues are also sexually attractive. Darwin suggested that sexual attractiveness may explain many aspects of human morality. This paper updates his argument by integrating recent research on mate choice, person perception, individual differences, costly signaling, and virtue ethics. Many human virtues may have evolved in both sexes through mutual mate choice to advertise good genetic quality, parenting abilities, and/or partner traits. Such virtues may include kindness, fidelity, magnanimity, and heroism, as well as quasi-moral traits like conscientiousness, agreeableness, mental health, and intelligence. This theory leads to many testable predictions about the phenotypic features, genetic bases, and social-cognitive responses to human moral virtues. A

The existence of a beauty premium in the labor market and the malefemale wage gap suggests that appearance can matter in the real world. We explore beauty and gender in a public goods experiment and find similar effects. We find a beauty premium, even though beautiful people contribute, on average, no more or less than others. The beauty premium, however, disappears when we provide information on individual contributions, and becomes a beauty penalty. Players seem to expect beautiful people to be more cooperative. Relative to these expectations, they appear more selfish, which in turn results in less cooperation by others. These appear to be clear examples of stereotyping. We also find a substantial benefit tobeing male, especially with information. This is primarily due to men being better “leaders.” Men tend to make large contributions, and people follow their example and give more in later rounds.

1. Among the commonest sexual signals of birds are the red-yellow traits pigmented by carotenoids, but how they reliably advertise individual quality remain poorly understood. Here we tested the hypothesis that carotenoid-based signalling is enhanced by testosterone but reduced by parasites, and that the dual action of testosterone on ornament expression and parasite resistance ensures reliable signalling. 2. Tetraonid birds such as the red grouse Lagopus lagopus scoticus have bright red combs pigmented by carotenoids, which function in intra- and inter-sexual selection. In separate experiments, we manipulated a main nematode parasite, Trichostrongylus tenuis (using deparasitation and re-infection) and testosterone (using testosterone or combined Flutamide/ATD treatments) in free-living males and investigated effects on plasma carotenoids and comb colour. 3. In untreated males, comb redness positively correlated with plasma carotenoids, testosterone concentration and condition. Plasma carotenoids and comb redness both negatively correlated with T. tenuis abundance. 4. Plasma carotenoids decreased in response to a challenge from T. tenuis, but increased

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This chapter advances a new theory of altruism, competitive altruism, which might account for the uniquely moral altruistic tendency of humans. The need to form coalitions with non-kin for dealing with internal and external group threats created selective advantages for people with altruistic reputations. We present evidence from the anthropological, social psychological and nonhuman literatures, which by and large support competitive altruism theory. Finally, we discuss some implications of this theory for the establishment of reputation-based cooperation in modern human society.