Sex differences in response to coalitional threat

Intergroup conflict poses a different kind of threat for men and women — a difference that can be expected to have implications for cognitive as well as behavioral processes. Participants were primed with a threat from a rival coalition vs. a control condition. Reaction times were measured on a lexical-decision task in response to ideation consistent with coalitions or with friendship/protective care. When primed for coalitional threat, men showed fast access to positive coalitional ideation (suggesting facilitation). In contrast, women showed exceptionally fast access to positive friendship/protective care ideation. Findings were interpreted as reflecting sexually dimorphic responses to coalitional threat that are consistent with differential advertising of their assets to others.     

May God Guide Our Guns

The perceived support of supernatural agents has been historically, ethnographically, and theoretically linked with confidence in engaging in violent intergroup conflict. However, scant experimental investigations of such links have been reported to date, and the extant evidence derives largely from indirect laboratory methods of limited ecological validity. Here, we experimentally tested the hypothesis that perceived supernatural aid would heighten inclinations toward coalitional aggression using a realistic simulated coalitional combat paradigm: competitive team paintball. In a between-subjects design, US paintball players recruited for the study were experimentally primed with thoughts of supernatural support using a guided visualization exercise analogous to prayer, or with a control visualization of a nature scene. The participants then competed in a team paintball battle game modeled after “Capture the Flag.” Immediately before and after the battle, participants completed surveys assessing confidence in their coalitional and personal battle performance. Participants assessed their coalition’s prospects of victory and performance more positively after visualizing supernatural aid. Participants primed with supernatural support also reported inflated assessments of their own performance. Importantly, however, covarying increases in assessments of their overall coalition’s performance accounted for the latter effect. This study provided support for the hypothesis that perceived supernatural support can heighten both prospective confidence in coalitional victory and retrospective confidence in the combat performance of one’s team, while highlighting the role of competitive play in evoking the coalitional psychology of intergroup conflict. These results accord with and extend convergent prior findings derived from laboratory paradigms far removed from the experience of combat. Accordingly, the field study approach utilized here shows promise as a method for investigating coalitional battle dynamics in a realistic, experientially immersive manner.     

Optimal patterns of scent marks in klipspringer (Oreotragus oreotragus) territories

The distribution of preorbital gland scent marks and dung middens within three territories of wild klipspringers in Zimbabwe are described. Nearest-neighbour analyses revealed that scent marks were distributed non-randomly and in a rough ring some distance within the territory boundary. Marking densities were greatest at about half the territory radius. In two territories, marking densities were shown to be sensitive to intrusion pressure at the periphery, being higher along contested boundaries than where territories were not contiguous. Marks were placed on branches facing neighbouring territories, where they are more likely to be detected, along contested boundaries but not in other areas. An analytical model is developed which tests the efficacy of scent-marking strategies along the continuum between extreme hinterland and extreme perimeter marking. This shows that the optimal position for a ring of scent marks is at 0.78 of the territory radius and is the product of a trade-off between maximizing the probability of mark detection by intruders and minimizing the cost of intrusion.     

It pays to cheat: tactical deception in a cephalopod social signalling system

Signals in intraspecific communication should be inherently honest; otherwise the system is prone to collapse. Theory predicts, however, that honest signalling systems are susceptible to invasion by cheats, the extent of which is largely mediated by fear of reprisal. Cuttlefish facultatively change their shape and colour, an ability that evolved to avoid predators and capture prey. Here, we show that this ability is tactically employed by male mourning cuttlefish (Sepia plangon) to mislead conspecifics during courtship in a specific social context amenable to cheating 39 per cent of the time, while it was never employed in other social contexts. Males deceive rival males by displaying male courtship patterns to receptive females on one side of the body, and simultaneously displaying female patterns to a single rival male on the other, thus preventing the rival from disrupting courtship. The use of tactical deception in such a complex communication network indicates that sociality has played a key role in the cognitive evolution of cephalopods.     

The effects of perch height, time in residence and distance from opponent on aggressive display in male lizards

In antagonistic encounters individuals' displays reflect both the quality of the resource under dispute and their perception of the threat posed by their rival. All else being equal, as the value or threat to contested resources increases, so should an individual's level of aggression. Using a territorial species of Australian agamid lizard, the tawny dragon (Ctenophorus decresii), we tested three hypotheses about the relationship between territory quality and aggression. In three experiments we measured aggression whilst manipulating time in residence, perch height as a measure of territory quality and distance to an opponent's territory. Our measurement of aggression was a summary of behaviours used by tawny dragons in antagonistic displays (wrestling, hind-leg push-up display, chasing, raising of nuchal or vertebral crests, back arching, lateral compression, lowering dewlap, jerky walk and tail flick). Animals had significantly lower aggression scores when the opponent's territory was further away, but time in residence and perch height did not affect our measures of aggression. These experimental results provide good grounding for further tests of these hypotheses in field scenarios specifically manipulating distance between neighbours to determine what maintains the spatial distribution of tawny dragons in the wild.     

Evidence that accent is a dedicated dimension of social categorization,not a byproduct of coalitional categorization

The present studies explore whether accent behaves like a byproduct of coalitional categorization, or like a dedicated dimension of social categorization. An experimental manipulation which has previously been shown to reduce coalitional byproducts, such as race, but not affect dedicated dimensions, such as sex and age, was used to test between these two possibilities. Accent behaved like a dedicated dimension, remaining unaffected by the same coalitional manipulation that reduces categorization by race. A second study verified that the exact same coalitional manipulation used with accent in fact reduces categorization by race. These results suggest that accent is not a byproduct of coalitional psychology, unlike race. Implications for the differing proximate psychologies underlying race and accent, and for the construct group, are discussed.     

Early Comers Become Owners: Effect of Residency Experience on Territorial Contest Dynamics in a Lycaenid Butterfly

A positive relationship between ownership and contest success is widespread among territorial butterflies. We tested the hypothesis that owners win simply because they have a longer experience occupying a given territory than do intruders in territorial butterflies. Using the lycaenid butterfly Chrysozephyrus smaragdinus , we staged contests between two males that had experienced different residency periods at the same contested territory, similar to owners and intruders in natural contests. We found that males that had occupied the contested territory for a longer period (a day) always defeated the shorter occupancy males (15 min). Therefore, residency period plays a key role in settling territorial contests. As residency confers advantages in a time-dependent manner, the mechanism of owner dominance could be an increase in motivation to fight as local familiarity increases. Moreover, this result predicts a population-level territorial dynamics. If residency period per se confers advantages in each contest, males arriving at a territory early in their adult season should acquire territorial dominance because they can remain there for a certain period with only a few rivals; late-appearing males do not have this advantage. As predicted, we found that males appearing at territory sites early in the season were more likely to hold their territories. This finding provides new evidence for the evolution of protandry in butterflies.     

On the Perception of Newcomers

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.     

The day after: effects of vocal interactions on territory defence in nightingales

1. Models on territory acquisition and tenure predict that territorial animals benefit by adjusting territorial defence behaviour to previous challenges they had experienced within the socially complex environment of communication networks. 2. Here, we addressed such issues of social cognition by investigating persisting effects of vocal contests on territory defence behaviour in nightingales Luscinia megarhynchos (Brehm). 3. Using interactive playback during nocturnal song of subjects, a rival was simulated to countersing either aggressively (by song overlapping) or moderately (by song alternating) from outside the subjects' territory. Thereby, the time-specific singing strategy provided an experimentally controlled source of information on the motivation of an unfamiliar rival. 4. Expecting that nightingales integrate information with time, the same rival was simulated to return as a moderately singing intruder on the following morning. 5. The results show that the vigour with which male nightingales responded to the simulated intrusion of an opponent during the day depended on the nature of the nocturnal vocal interaction experienced several hours before. 6. Males that had received the song overlapping playback the preceding night approached the simulated intruder more quickly and closer and sang more songs near the loudspeaker than did males that had received a song alternating playback. 7. This adjustment of territory defence strategies depending on information from prior signalling experience suggests that integrating information with time plays an important part in territory defence by affecting a male's decision making in a communication network.     

What Are Punishment and Reputation for?

Why did punishment and the use of reputation evolve in humans? According to one family of theories, they evolved to support the maintenance of cooperative group norms; according to another, they evolved to enhance personal gains from cooperation. Current behavioral data are consistent with both hypotheses (and both selection pressures could have shaped human cooperative psychology). However, these hypotheses lead to sharply divergent behavioral predictions in circumstances that have not yet been tested. Here we report results testing these rival predictions. In every test where social exchange theory and group norm maintenance theory made different predictions, subject behavior violated the predictions of group norm maintenance theory and matched those of social exchange theory. Subjects do not direct punishment toward those with reputations for norm violation per se; instead, they use reputation self-beneficially, as a cue to lower the risk that they personally will experience losses from defection. More tellingly, subjects direct their cooperative efforts preferentially towards defectors they have punished and away from those they haven’t punished; they avoid expending punitive effort on reforming defectors who only pose a risk to others. These results are not consistent with the hypothesis that the psychology of punishment evolved to uphold group norms. The circumstances in which punishment is deployed and withheld–its circuit logic–support the hypothesis that it is generated by psychological mechanisms that evolved to benefit the punisher, by allowing him to bargain for better treatment.     

Football Fan Aggression: The Importance of Low Basal Cortisol and a Fair Referee

Fan aggression in football (soccer) is a societal problem that affects many countries worldwide. However, to date, most studies use an epidemiological or survey approach to explain football fan aggression. This study used a controlled laboratory study to advance a model of predictors for fan aggression. To do so, football fans (n = 74) saw a match summary in which their favorite team lost against their most important rival. Next, we measured levels of aggression with the hot sauce paradigm, in which fans were given the opportunity to administer a sample of hot sauce that a rival football supporter had to consume. To investigate if media exposure had the ability to reduce aggression, before the match fans saw a video in which fans of the rival team commented in a neutral, negative, or positive manner on their favorite team. Results showed that the media exposure did not affect aggression. However, participants displayed high levels of aggression and anger after having watched the match. Also, aggression was higher in fans with lower basal cortisol levels, which suggests that part of the aggression displayed was proactive and related to anti-social behavior. Furthermore, aggression was higher when the referee was blamed and aggression was lower when the performance of the participants’ favorite team was blamed for the match result. These results indicate that aggression increased when the match result was perceived as unfair. Interventions that aim to reduce football fan aggression should give special attention to the perceived fairness of the match result.     

Social exchange and solidarity: in-group love or out-group hate?

Men exhibit a stronger tendency to favor the in-group over the out-group compared to women. We examined whether this male-specific “coalitional psychology” represents in-group love or out-group hate. One hundred thirty-three college freshmen played a prisoner's dilemma game with a member of their own group and a member of another group. Both groups consisted of same-sex participants. An in-group bias (cooperation with the in-group at a level higher than cooperation with the out-group) based on expectations of cooperation from the in-group was observed for both men and women. When such expectations were experimentally eliminated, women did not show any in-group bias, whereas men still exhibited an in-group bias. This male-specific in-group bias was found to be a product of intragroup cooperation (in-group love) rather than a product of intergroup competition (out-group hate). These findings suggest that the male-specific coalitional psychology caters more toward the promotion of within-group solidarity than aggression against the out-group.     

How Psychological and Behavioral Team States Change during Positive and Negative Momentum

In business and sports, teams often experience periods of positive and negative momentum while pursuing their goals. However, researchers have not yet been able to provide insights into how psychological and behavioral states actually change during positive and negative team momentum. In the current study we aimed to provide these insights by introducing an experimental dynamical research design. Rowing pairs had to compete against a virtual opponent on rowing ergometers, while a screen in front of the team broadcasted the ongoing race. The race was manipulated so that the team’s rowing avatar gradually progressed (positive momentum) or regressed (negative momentum) in relation to the victory. The participants responded verbally to collective efficacy and task cohesion items appearing on the screen each minute. In addition, effort exertion and interpersonal coordination were continuously measured. Our results showed negative psychological changes (perceptions of collective efficacy and task cohesion) during negative team momentum, which were stronger than the positive changes during positive team momentum. Moreover, teams’ exerted efforts rapidly decreased during negative momentum, whereas positive momentum accompanied a more variable and adaptive sequence of effort exertion. Finally, the interpersonal coordination was worse during negative momentum than during positive momentum. These results provide the first empirical insights into actual team momentum dynamics, and demonstrate how a dynamical research approach significantly contributes to current knowledge on psychological and behavioral processes.     

The Advantage of Playing Home in NBA: Microscopic,Team-Specific and Evolving Features

The idea that the success rate of a team increases when playing home is broadly accepted and documented for a wide variety of sports. Investigations on the so-called “home advantage phenomenon” date back to the 70’s and ever since has attracted the attention of scholars and sport enthusiasts. These studies have been mainly focused on identifying the phenomenon and trying to correlate it with external factors such as crowd noise and referee bias. Much less is known about the effects of home advantage in the “microscopic” dynamics of the game (within the game) or possible team-specific and evolving features of this phenomenon. Here we present a detailed study of these previous features in the National Basketball Association (NBA). By analyzing play-by-play events of more than sixteen thousand games that span thirteen NBA seasons, we have found that home advantage affects the microscopic dynamics of the game by increasing the scoring rates and decreasing the time intervals between scores of teams playing home. We verified that these two features are different among the NBA teams, for instance, the scoring rate of the Cleveland Cavaliers team is increased ≈0.16 points per minute (on average the seasons 2004–05 to 2013–14) when playing home, whereas for the New Jersey Nets (now the Brooklyn Nets) this rate increases in only ≈0.04 points per minute. We further observed that these microscopic features have evolved over time in a non-trivial manner when analyzing the results team-by-team. However, after averaging over all teams some regularities emerge; in particular, we noticed that the average differences in the scoring rates and in the characteristic times (related to the time intervals between scores) have slightly decreased over time, suggesting a weakening of the phenomenon. This study thus adds evidence of the home advantage phenomenon and contributes to a deeper understanding of this effect over the course of games.     

Human mate guarding

Long-term committed mating is a fundamental strategy in the human repertoire. Successful enactment of this strategy requires solving two related adaptive problems--fending off potential mate poachers and preventing a mates from defecting. Mate guarding adaptations evolved to solve these persistent problems. Those who failed in mate guarding risked suffering substantial reproductive costs ranging from genetic cuckoldry to reputational damage to the entire loss of a mate. Because the precise nature of the adaptive problems confronted differed historically for the sexes, men and women evolved corresponding differences in the underlying psychology of mate guarding. Men's mate guarding, relative to that of women's, is strongly triggered as a consequence of being mated to young and physically attractive women, being confronted by interested rivals who have superior economic resources or prospects, and having a mate who displays signs of sexual involvement with a rival. Women's mate guarding, relative to that of men's, is triggered as a consequence of being mated to men high in income and status striving, rivals who are more physically attractive, and having a partner who shows signs of emotional involvement with another woman. Behavioral output of mate guarding adaptations range from vigilance to violence.     

Physical strength predicts political violence

Research has revealed an association between individual physical strength and attitudinal support for modern war. Physical strength of one individual has an infinitesimal effect on the outcomes of state-level aggression involving large-scale armies and complex military technology. The fact that stronger individuals do support such aggression hints at an evolved psychology specialized for small-scale coalitional aggression, where strength of coalition members non-negligibly contribute to the net coalition strength. Here, I examined whether strength also accounts for participation in modern political aggression, as contrasted to mere support. Given that contemporary political aggression primarily occurs within—not between—states, I focused on intra-state forms of political violence, specifically violent antigovernment protests. To enhance external and ecological validity, I relied on large probability samples from both non-WEIRD and WEIRD countries experiencing political violence (N = 6283; interviewees were quota-sampled from YouGov online panels to generate representative samples of online adult populations). Multinational analyses revealed that self-perceived strength significantly predicts intentions to participate in political violence and self-reported participation, and that this association is stronger among young interviewees, but not among men (compared to women). The predictive power of strength was modest but comparable to that of gender, an established predictor of aggression. I discuss why the fact that strength—a physiological variable—relates to political violence—a complex modern phenomenon—is remarkable. Subsequently, I suggest a new research agenda that draws on insights from evolutionary research to study modern political violence.     

Sleep and physiological systems: a functional perspective

The knowledge of sleep evaluation and its regulation processes has evolved dramatically over the last half-century. Sleep state and the preoccupied view of its obligation to perform positive function for the organism have kept enthusiastic research flourishing. The restoration of macromolecular synthesis and repair players, energy conservation, neural plasticity and synaptogenesis are cellular and biochemical-level functional implications of sleep. The demarcation between molecular, cellular and systemic strata is not mutually exclusive at organism level. Sleep functions have been researched with their focus at each of these strata. The review discusses the systemic-level functions of sleep in brief with special reference to respiration, reproduction, digestion, cardiovascular, endocrine, immune and integumentary systems. Sleep and physiological system relations are usually bidirectional and are operationally mediated by intercellular message transmitters like hormones, cytokines and/or continuum of direct anatomical connections with the neuroanatomy of sleep management.     

The radial arrangement of the human chromosome 7 in the lymphocyte cell nucleus is associated with chromosomal band gene density

In the nuclei of human lymphocytes, chromosome territories are distributed according to the average gene density of each chromosome. However, chromosomes are very heterogeneous in size and base composition, and can contain both very gene-dense and very gene-poor regions. Thus, a precise analysis of chromosome organisation in the nuclei should consider also the distribution of DNA belonging to the chromosomal bands in each chromosome. To improve our understanding of the chromatin organisation, we localised chromosome 7 DNA regions, endowed with different gene densities, in the nuclei of human lymphocytes. Our results showed that this chromosome in cell nuclei is arranged radially with the gene-dense/GC-richest regions exposed towards the nuclear interior and the gene-poorest/GC-poorest ones located at the nuclear periphery. Moreover, we found that chromatin fibres from the 7p22.3 and the 7q22.1 bands are not confined to the territory of the bulk of this chromosome, protruding towards the inner part of the nucleus. Overall, our work demonstrates the radial arrangement of the territory of chromosome 7 in the lymphocyte nucleus and confirms that human genes occupy specific radial positions, presumably to enhance intra- and inter-chromosomal interaction among loci displaying a similar expression pattern, and/or similar replication timing.     

Territorial dynamics and stable home range formation for central place foragers

Uncovering the mechanisms behind territory formation is a fundamental problem in behavioural ecology. The broad nature of the underlying conspecific avoidance processes are well documented across a wide range of taxa. Scent marking in particular is common to a large range of terrestrial mammals and is known to be fundamental for communication. However, despite its importance, exact quantification of the time-scales over which scent cues and messages persist remains elusive. Recent work by the present authors has begun to shed light on this problem by modelling animals as random walkers with scent-mediated interaction processes. Territories emerge as dynamic objects that continually change shape and slowly move without settling to a fixed location. As a consequence, the utilisation distribution of such an animal results in a slowly increasing home range, as shown for urban foxes (Vulpes vulpes). For certain other species, however, home ranges reach a stable state. The present work shows that stable home ranges arise when, in addition to scent-mediated conspecific avoidance, each animal moves as a central place forager. That is, the animal's movement has a random aspect but is also biased towards a fixed location, such as a den or nest site. Dynamic territories emerge but the probability distribution of the territory border locations reaches a steady state, causing stable home ranges to emerge from the territorial dynamics. Approximate analytic expressions for the animal's probability density function are derived. A programme is given for using these expressions to quantify both the strength of the animal's movement bias towards the central place and the time-scale over which scent messages persist. Comparisons are made with previous theoretical work modelling central place foragers with conspecific avoidance. Some insights into the mechanisms behind allometric scaling laws of animal space use are also given.