Gift-giving in romantic couples serves as a commitment signal: Relational mobility is associated with more frequent gift-giving
Publication date: Available online 16 October 2018Source: Evolution and Human BehaviorAuthor(s): Asuka Komiya, Yohsuke Ohtsubo, Daisuke Nakanishi, Shigehiro OishiAbstractThe present study explored why married couples periodically exchange gifts. Based on the commitment signal hypothesis, we tested whether relational mobility, which was operationalized as divorce rate in Study 1 and relational opportunities in Study 2, is positively correlated with the frequency of gift exchanges among married couples. In Study 1, we found that married couples in the U.S., which is associated with a relatively high divorce rate, were more l...
Source: Evolution and Human Behavior - October 17, 2018 Category: Psychiatry & Psychology Source Type: research
The face of another: anonymity and facial symmetry influence cooperation in social dilemmas
Publication date: Available online 15 September 2018Source: Evolution and Human BehaviorAuthor(s): Claudia Rodríguez-Ruiz, Santiago Sanchez-Pages, Enrique TuriéganoAbstractIn the present paper, we study how the morphological features related to developmental physiology of other participants influence the decision to cooperate in a social dilemma. To that end, we let a large sample of men play a prisoner's dilemma game, both anonymously and against a series of counterparts whose photographs were shown. We focus on three characteristics already linked to cooperative behavior and with described effects on the adult facial s...
Source: Evolution and Human Behavior - September 16, 2018 Category: Psychiatry & Psychology Source Type: research
What people prefer and what they think they prefer in short- and long-term partners. The effects of the phase of the menstrual cycle, hormonal contraception, pregnancy, and the marital and the parenthood status on partner preferences
Publication date: Available online 15 September 2018Source: Evolution and Human BehaviorAuthor(s): Jaroslav Flegr, Amy E. Blum, Ondřej Nekola, Šebestián KroupaAbstractThe issue with most studies concerned with mate selection preferences in humans is that they rely on declarations and rational actions of experimental subjects, which are affected by their pre-conceived opinions and prejudices. Moreover, current research suggests that subcortical structures and processes, rather than the neocortex, play the principal role in actual partner choice behaviour. Consequently, we have only limited information on how relevant our...
Source: Evolution and Human Behavior - September 15, 2018 Category: Psychiatry & Psychology Source Type: research
Why are conversations limited to about four people? A theoretical exploration of the conversation size constraint
Publication date: Available online 10 September 2018Source: Evolution and Human BehaviorAuthor(s): Jaimie Arona Krems, Jason WilkesAbstractIt is genuinely difficult to sustain a casual conversation that includes more than four speakers. Add a fifth speaker, and the conversation often quickly fissions into smaller groups. Termed ‘the dinner party problem,’ this four-person conversation size limit is believed to be caused by evolved cognitive constraints on human mentalizing capacities. In this view, people can mentally manage three other minds at any one time, leading to four-person conversations. But whereas existing w...
Source: Evolution and Human Behavior - September 11, 2018 Category: Psychiatry & Psychology Source Type: research
The heritability of fertility makes world population stabilization unlikely in the foreseeable future
Publication date: Available online 5 September 2018Source: Evolution and Human BehaviorAuthor(s): Jason Collins, Lionel PageAbstractThe forecasting of the future growth of world population is of critical importance to anticipate and address a wide range of global challenges. The United Nations produces forecasts of fertility and world population every two years. As part of these forecasts, they model fertility levels in post-demographic transition countries as tending toward a long-term mean, leading to forecasts of flat or declining population in these countries. We substitute this assumption of constant long-term fertili...
Source: Evolution and Human Behavior - September 6, 2018 Category: Psychiatry & Psychology Source Type: research
Gossip as an intrasexual competition strategy: Predicting information sharing from potential mate versus competitor mating strategies
Publication date: Available online 31 August 2018Source: Evolution and Human BehaviorAuthor(s): Joy P. Wyckoff, Kelly Asao, David M. BussAbstractWe propose that one function of competitive information sharing is success in intrasexual competition. We posit that the decision to share potentially damaging information about a competitor is sensitive to the probability of that information diminishing a competitor's mate value. According to Sexual Strategies Theory (Buss & Schmitt, 1993), men and women have evolved different psychological mechanisms underlying short-term and long-term mating strategies, and display somewhat dif...
Source: Evolution and Human Behavior - September 1, 2018 Category: Psychiatry & Psychology Source Type: research
Humans reciprocate by discriminating against group peers
Publication date: Available online 30 August 2018Source: Evolution and Human BehaviorAuthor(s): David Hugh-Jones, Itay Ron, Ro'i ZultanAbstractMotivated by cycles of intergroup revenge in real-world conflicts, we experimentally test the hypothesis that humans practice group-based reciprocity: if someone harms or helps them, they harm or help other members of that person's group. Subjects played a trust game, then allocated money between other people. Senders whose partners returned more in the trust game gave more to that partner's group members. The effect was about half as large as the effect of direct reciprocity. Recei...
Source: Evolution and Human Behavior - August 30, 2018 Category: Psychiatry & Psychology Source Type: research
Consistency of mate choice in eye and hair colour: Testing possible mechanisms
Publication date: Available online 20 August 2018Source: Evolution and Human BehaviorAuthor(s): Zuzana Štěrbová, Petr Tureček, Karel Kleisner (Source: Evolution and Human Behavior)
Source: Evolution and Human Behavior - August 21, 2018 Category: Psychiatry & Psychology Source Type: research
A Friend in need is a friend indeed: Need-based sharing, rather than cooperative assortment, predicts experimental resource transfers among Agta hunter-gatherers
Publication date: Available online 16 August 2018Source: Evolution and Human BehaviorAuthor(s): Daniel Smith, Mark Dyble, Katie Major, Abigail E. Page, Nikhil Chaudhary, Gul Deniz Salali, James Thompson, Lucio Vinicius, Andrea Bamberg Migliano, Ruth MaceAbstractDespite much theorizing, the evolutionary reasons why humans cooperate extensively with unrelated individuals are still largely unknown. While reciprocity explains many instances of non-kin cooperation, much remains to be understood. A recent suite of models based upon ‘cooperative assortativity’ suggest that non-kin cooperation can evolve if individuals prefere...
Source: Evolution and Human Behavior - August 17, 2018 Category: Psychiatry & Psychology Source Type: research
Capital and punishment: Resource scarcity increases endorsement of the death penalty
Publication date: Available online 10 August 2018Source: Evolution and Human BehaviorAuthor(s): Keelah E.G. Williams, Ashley M. Votruba, Steven L. Neuberg, Michael J. SaksAbstractFaced with punishing serious offenders, why do some prefer imprisonment whereas others impose death? Previous research exploring death penalty attitudes has primarily focused on individual and cultural factors. Adopting a functional perspective, we propose that environmental features may also shape our punishment strategies. Individuals are attuned to the availability of resources within their environments. Due to heightened concerns with the cost...
Source: Evolution and Human Behavior - August 10, 2018 Category: Psychiatry & Psychology Source Type: research
How do we decide when (not) to free-ride? Risk tolerance predicts behavioral plasticity in cooperation
This study addresses human cooperation under such marginally diminishing group productivity, focusing on the plasticity of cooperative choices. We conducted a two-part “team foraging” experiment, in which the most- or least-cooperative members in the first part were re-grouped separately for the second part. We observed that cooperating and defecting “types” emerged within a group over time but did not completely persist across groups, with some of the most cooperative members switching to become the least cooperative (and vice versa). Risk attitude was a key factor in this switching behavior: greater risk-takers s...
Source: Evolution and Human Behavior - August 8, 2018 Category: Psychiatry & Psychology Source Type: research
Chimpanzees and children avoid mutual defection in a social dilemma
Publication date: Available online 4 August 2018Source: Evolution and Human BehaviorAuthor(s): Alejandro Sánchez-Amaro, Shona Duguid, Josep Call, Michael TomaselloAbstractCooperation often comes with the temptation to defect and benefit at the cost of others. This tension between cooperation and defection is best captured in social dilemmas like the Prisoner's Dilemma. Adult humans have specific strategies to maintain cooperation during Prisoner's Dilemma interactions. Yet, little is known about the ontogenetic and phylogenetic origins of human decision-making strategies in conflict scenarios. To shed light on this questi...
Source: Evolution and Human Behavior - August 5, 2018 Category: Psychiatry & Psychology Source Type: research
The ecological rationality of helping others: Potential helpers integrate cues of recipients' need and willingness to sacrifice
Publication date: Available online 23 July 2018Source: Evolution and Human BehaviorAuthor(s): Daniel Sznycer, Andrew W. Delton, Theresa E. Robertson, Leda Cosmides, John ToobyAbstractWhy do humans help others? Many theories focus on dimensions like kinship or reciprocity. On their surface, these theories seem unable to explain help directed at fleeting strangers. In response to this puzzle, researchers have proposed that the mind has ecologically rational systems for providing aid. These systems respond to cues that predicted adaptive behavior during human evolution, regardless of whether such cues continue to be predictiv...
Source: Evolution and Human Behavior - July 23, 2018 Category: Psychiatry & Psychology Source Type: research
Effects of anger on dominance-seeking and aggressive behaviors
Publication date: Available online 22 July 2018Source: Evolution and Human BehaviorAuthor(s): João Carlos Centurion Cabral, Rosa Maria Martins de AlmeidaAbstractAnger may have evolved to orchestrate social bargaining behaviors, which ultimately can lead to establishment of dominance hierarchies. Although the relationship between anger and dominance has strong empirical support, most studies have focused on visual cues of dominance. Across two experiments, we tested the hypothesis that anger increases dominance-seeking and agonistic behaviors in those who feel it. In the first experiment (n = 82), we induced anger thro...
Source: Evolution and Human Behavior - July 23, 2018 Category: Psychiatry & Psychology Source Type: research
The appropriate response of Spanish Gitanos: short-run orientation beyond current socio-economic status
Publication date: Available online 20 July 2018Source: Evolution and Human BehaviorAuthor(s): Jesús Martín, Pablo Brañas-Garza, Antonio M. Espín, Juan F. Gamella, Benedikt HerrmannAbstractHumans differ greatly in their tendency to discount future events, but the reasons underlying such inter-individual differences remain poorly understood. Based on the evolutionary framework of Life History Theory, influential models predict that the extent to which individuals discount the future should be influenced by socio-ecological factors such as mortality risk, environmental predictability and resource scarcity. However, little...
Source: Evolution and Human Behavior - July 21, 2018 Category: Psychiatry & Psychology Source Type: research
