Limited resources lead animals into conflicts of interest, which are resolved when an individual withdraws from a direct contest. Current theory suggests that the decision to withdraw can be based on a threshold derived from an individual's own state (selfassessment) or on a comparison between their own state and their opponent's (mutual assessment). The observed variation between these assessment strategies in nature does not conform to theory. Thus, we require theoretical developments that explain the functional significance of different assessment strategies. We consider a hawkdove game with two discrete classes that differ in fighting ability, in which the players strategically decide on their investment toward mutual assessment. Analysis of the model indicates that there are simultaneous trade-offs relating to assessment strategies. First, weak individuals in a population must decide on whether to acquire information about their opponents at the cost of providing opponents with information about themselves. Secondly, all individuals must decide between investing in mutual assessment and being persistent in contests. Our analysis suggests that the potential for individuals to make errors during contests and differences in the consequences of sharing information within a population may serve as fundamental concepts for explaining variation in assessment strategy.

Research shows that gender inequality is still a major issue in academic science, yet academic societies may serve as underappreciated and effective avenues for promoting female leadership. That is, society membership is often self-selective, and board positions are elected (with a high turnover compared to institutions)—these characteristics, among others, may thus create an environment conducive to gender equality. We therefore investigate this potential using an information-theoretic approach to quantify gender equality (male:female ratios) in zoology society boards around the world. We compare alternative models to analyze how society characteristics might predict or correlate with the proportion of female leaders, and find that a cultural model, including society age, size of board and whether or not a society had an outward commitment or statement of equality, was the most informative predictor for the gender ratio of society boards and leadership positions. This model was more informative than alternatives that considered, for instance, geographic location, discipline of study or taxonomic focus. While women were more highly represented in society leadership than in institutional academic leadership, this representation was still far short of equal (~30%): we thus also provide a checklist and recommendations for societies to contribute to global gender equality in science.

prestige-biased social learning occurs when individuals preferentially learn from others who are highly respected, admired, copied, or attended to in their group. this form of social learning is argued to reflect novel forms of social hierarchy in human societies, and, by providing an efficient shortcut to acquiring adaptive information, underpin the cumulative cultural evolution that has contributed to our species' ecological success. Despite these potentially important consequences, little empirical work to date has tested the basic predictions of prestige-biased social learning. Here we provide evidence supporting the key predictions that prestige-biased social learning is used when it constitutes an indirect cue of success, and when success-biased social learning is unavailable. We ran an online experiment (n = 269) in which participants could copy each other in real-time to score points on a general-knowledge quiz. our implementation of 'prestige' was the number of times someone had previously been copied by others. importantly, prestige was an emergent property of participants' behaviour during the experiment; no deception or manipulation of prestige was employed at any time. We found that, as predicted, participants used prestige-biased social learning when the prestige cue was an indirect cue of success, and when direct success information was unavailable. this highlights how people flexibly and adaptively employ social learning strategies based on the reliability of the information that such strategies provide. Prestige-biased social learning occurs when individuals preferentially learn from others who are highly respected, admired, copied, or attended to in their group 1,2. This social learning bias is argued to reflect novel forms of social hierarchy in human societies 1 , and, by providing an efficient shortcut to acquiring adaptive information, to underpin the cumulative cultural evolution that has contributed to our species' ecological success 3,4. Social learning in general allows humans to acquire vast amounts of adaptive information from others, from acquiring detailed tool-making skills face-to-face, to online information exchange that pervades society today. However, for social learning to be adaptive, people need to be selective in who they copy, and extensive research in the last few decades has identified particular learning biases that facilitate the efficient acquisition of relevant knowledge and skills 5-8. These include success bias, where people preferentially copy successful individuals, and prestige bias, where people use indirect cues of success to preferentially copy the most prestigious individual in the population. Prestige as an indirect cue to success was first suggested by Boyd and Richerson 9 and further developed by Henrich and Gil-White 1. The latter authors proposed that, given variation across potential demonstrators in skill and/or knowledge, the tendency to copy the most skilled or knowledgeable demonstrator (known as success-biased or payoff-biased transmission) would c...

No abstract

Humans frequently perform extravagant and seemingly costly behaviors, such as widely sharing hunted resources, erecting conspicuous monumental structures, and performing dramatic acts of religious devotion. Evolutionary anthropologists and archeologists have used signaling theory to explain the function of such displays, drawing inspiration from behavioral ecology, economics, and the social sciences. While signaling theory is broadly aimed at explaining honest communication, it has come to be strongly associated with the handicap principle, which proposes that such costly extravagance is in fact an adaptation for signal reliability. Most empirical studies of signaling theory have focused on obviously costly acts, and consequently anthropologists have likely overlooked a wide range of signals that also promote reliable communication. Here, we build on recent developments in signaling theory and animal communication, developing an updated framework that highlights the diversity of signal contents, costs, contexts, and reliability mechanisms present within human signaling systems. By broadening the perspective of signaling theory in human systems, we strive to identify promising areas for further empirical and theoretical work.

No abstract

Guidelines do not recommend resection surgery for oligometastatic pancreatic ductal adenocarcinoma (PDAC). However, reports in small samples of selected patients suggest that surgery extends survival. Thus, this study aims to gather evidence for the benefits of cancer-directed surgery (CDS) by analyzing a national cohort and identifying prognostic factors that aid the selection of candidates for CDS or recruitment into experimental trials. Data for patients with PDAC and hepatic metastasis were extracted from the population-based Surveillance, Epidemiology, and End Results database (SEER). The bias between CDS and non-CDS groups was minimized with Propensity Score Matching (PSM), and the prognostic role of CDS was investigated by comparing Kaplan-Meier estimators and Cox proportional hazard models. A total of 12,018 patients were extracted from the database, including 259 patients who underwent CDS that were 1:1 propensity score-matched with patients who did not receive CDS. CDS appeared to significantly prolong median overall survival from 5 to 10 months. Multivariate analysis revealed chemotherapy as a protective prognostic, whilst survival was impaired by old age and tumors that were poorly differentiated (Grades III–IV). These factors can be used to select patients likely to benefit from CDS treatment, which may facilitate recruitment into randomized controlled trials.

Animals change the strategy that they use to select breeding sites at the spatial 11 scales of habitat, patch and microhabitat. In this regard, breeding site-fidelity is 12 expected to vary according to environmental predictability, which, in turn, is 13 expected to differ between each spatial scale. However, whether or not animals 14 change their degree of site-fidelity at different spatial scales remains unclear. We 15 captured and released males of the terrestrial frog Pseudophryne bibronii into 16 alternative patches within a breeding habitat and determined the extent to which 17 site-fidelity influenced individual nest-site choice. We found that males tended to 18 return to their original patch rather than re-settle in an alternative patch. 19 However, males were unlikely to return to their original nest-sites within the 20 patch. We suggest that site fidelity in this species may be scale dependent because 21 information from previous breeding seasons can predict the quality of patches, but 22 not nest-sites. This behavioural variation is consistent with a hypothetical 23 relationship between spatial scale and environmental predictability, which may 24 have important implications for decision making processes that extend over 25 multiple spatial scales. 26 27