The restart effect in social dilemmas shows humans are self-interested not altruistic.

Do economic games show evidence of altruistic or self-interested motivations in humans? A huge body of empirical work has found contrasting results. While many participants routinely make costly decisions that benefit strangers, consistent with the hypothesis that humans exhibit a biologically novel form of altruism (or "prosociality"), many participants also typically learn to pay fewer costs with experience, consistent with self-interested individuals adapting to an unfamiliar environment. Key to resolving this debate is explaining the famous "restart effect," a puzzling enigma whereby failing cooperation in public goods games can be briefly rescued by a surprise restart. Here we replicate this canonical result, often taken as evidence of uniquely human altruism, and show that it 1) disappears when cooperation is invisible, meaning individuals can no longer affect the behavior of their groupmates, consistent with strategically motivated, self-interested, cooperation; and 2) still occurs even when individuals are knowingly grouped with computer players programmed to replicate human decisions, consistent with confusion. These results show that the restart effect can be explained by a mixture of self-interest and irrational beliefs about the game's payoffs, and not altruism. Consequently, our results suggest that public goods games have often been measuring self-interested but confused behaviors and reject the idea that conventional theories of evolution cannot explain the results of economic games.

Defining remission in childhood-onset lupus: PReS-endorsed consensus definitions by an international task force.

OBJECTIVE: To derive childhood-onset SLE (cSLE) specific remission definitions for future treat-to-target (T2T) trials, observational studies, and clinical practice. METHODS: The cSLE International T2T Task Force conducted Delphi surveys exploring paediatric perspectives on adult-onset SLE remission targets. A modified nominal group technique was used to discuss, refine, and agree on the cSLE remission target criteria. RESULTS: The Task Force proposed two definitions of remission: 'cSLE clinical remission on steroids (cCR)' and 'cSLE clinical remission off steroids (cCR-0)'. The common criteria are: (1) Clinical-SLEDAI-2 K = 0; (2) PGA score < 0.5 (0-3 scale); (4) stable antimalarials, immunosuppressive, and biologic therapy (changes due to side-effects, adherence, weight, or when building up to target dose allowed). Criterion (3) in cCR is the prednisolone dose ≤0.1 mg/kg/day (maximum 5 mg/day), whereas in cCR-0 it is zero. CONCLUSIONS: cSLE definitions of remission have been proposed, maintaining sufficient alignment with the adult-SLE definition to facilitate life-course research.

Differential effects of high-fat diet on endocrine, metabolic and depressive-like behaviors in male and female rats.

The complications of obesity extend beyond the periphery to the central nervous system (CNS) and include an increased risk of developing neuropsychiatric co-morbidities like depressive illness. Preclinical studies support this concept, including studies that have examined the effects of a high-fat diet (HFD) on depressive-like behaviors. Although women are approximately two-fold more likely to develop depressive illness compared to men, most preclinical studies have focused on the effects of HFD in male rodents. Accordingly, the goal of this study was to examine depressive-like behaviors in male and female rats provided access to a HFD. In agreement with prior studies, male and female rats provided a HFD segregate into an obesity phenotype (i.e., diet-induced obesity; DIO) or a diet resistant (DR) phenotype. Upon confirmation of the DR and DIO phenotypes, behavioral assays were performed in control chow, DR, and DIO rats. In the sucrose preference test, male DIO rats exhibited significant decreases in sucrose consumption (i.e., anhedonia) compared to male DR and male control rats. In the forced swim test (FST), male DIO rats exhibited increases in immobility and decreases in climbing behaviors in the pre-test sessions. Interestingly, male DR rats exhibited these same changes in both the pre-test and test sessions of the FST, suggesting that consumption of a HFD, even in the absence of the development of an obesity phenotype, has behavioral consequences. Female rats did not exhibit differences in sucrose preference, but female DIO rats exhibited increases in immobility exclusively in the test session of the FST, behavioral changes that were not affected by the stage of the estrous cycle. Collectively, these studies demonstrate that access to a HFD elicits different behavioral outcomes in male and female rats.

PReS-endorsed international childhood lupus T2T task force definition of childhood lupus low disease activity state (cLLDAS).

OBJECTIVE: To achieve a consensus-based definition of Low Disease Activity (LDA) for use in cSLE trials. METHODS: The International cSLE T2T Task Force, comprising of paediatric rheumatologists/nephrologists, and adult rheumatologists undertook a series of Delphi surveys/consensus meetings to discuss, refine, and vote upon cSLE LDA criteria. RESULTS: The Task Force agreed that LDA should be based upon the adult-SLE Lupus Low Disease Activity State definition (LLDAS), with modifications to make it applicable to cSLE (cLLDAS). They agreed upon five cLLDAS criteria: (1) SLE Disease Activity Index (SLEDAI)-2 K ≤4, with no activity in major organ systems; (2) no new features of lupus disease activity compared with the last assessment; (3) Physician Global Assessment score of ≤1 (0-3 scale); (4) prednisolone dose of ≤0.15 mg/kg/day, 7.5 mg/day/maximum; while on (5) stable antimalarials, immunosuppressives, and biologics. CONCLUSIONS: A cSLE-appropriate definition of cLLDAS has been generated, maintaining alignment with the adult-SLE definition to promote life-course research.

Using a Contemporary Portable Metabolic Gas Exchange System for Assessing Energy Expenditure: A Validity and Reliability Study.

There are several methods available to assess energy expenditure, all associated with inherent pros and cons that must be adequately considered for use in specific environments and populations. A requirement of all methods is that they must be valid and reliable in their capability to accurately measure oxygen consumption (VO2) and carbon dioxide production (VCO2). The purpose of this study was to evaluate the reliability and validity of the mobile CO2/O2 Breath and Respiration Analyzer (COBRA) relative to a criterion system (Parvomedics TrueOne 2400®, PARVO) with additional measurements to compare the COBRA to a portable system (Vyaire Medical, Oxycon Mobile®, OXY). Fourteen volunteers with a mean of 24 years old, body weight of 76 kg, and a VO2peak of 3.8 L∙min-1 performed four repeated trials of progressive exercises. Simultaneous steady-state measurements of VO2, VCO2, and minute ventilation (VE) by the COBRA/PARVO and OXY systems were conducted at rest, while walking (23-36% VO2peak), jogging (49-67% VO2peak), and running (60-76% VO2peak). Data collection was randomized by the order of system tested (COBRA/PARVO and OXY) and was standardized to maintain work intensity (rest to run) progression across study trials and days (two trials/day over two days). Systematic bias was examined to assess the accuracy of the COBRA to PARVO and OXY to PARVO across work intensities. Intra- and inter-unit variability were assessed with interclass correlation coefficients (ICC) and a 95% limit of agreement intervals. The COBRA and PARVO produced similar measures for VO2 (Bias ± SD, 0.01 ± 0.13 L·min-1; 95% LoA, (-0.24, 0.27 L·min-1); R2 = 0.982), VCO2 (0.06 ± 0.13 L·min-1; (-0.19, 0.31 L·min-1); R2 = 0.982), VE (2.07 ± 2.76 L·min-1; (-3.35, 7.49 L·min-1); R2 = 0.991) across work intensities. There was a linear bias across both the COBRA and OXY with increased work intensity. The coefficient of variation for the COBRA ranged from 7 to 9% across measures for VO2, VCO2, and VE. COBRA was reliable across measurements for VO2 (ICC = 0.825; 0.951), VCO2 (ICC = 0.785; 0.876), and VE (ICC = 0.857; 0.945) for intra-unit reliability, respectively. The COBRA is an accurate and reliable mobile system for measuring gas exchange at rest and across a range of work intensities.

The reliability of a portable steam sauna pod for the whole-body passive heating of humans.

INTRODUCTION: Passive heating is receiving increasing attention within human performance and health contexts. A low-cost, portable steam sauna pod may offer an additional tool for those seeking to manipulate physiological (cardiovascular, thermoregulatory and sudomotor) and perceptual responses for improving sporting or health profiles. This study aimed to 1) report the different levels of heat stress and determine the pods' inter-unit reliability, and 2) quantify the reliability of physiological and perceptual responses to passive heating. METHOD: In part 1, five pods were assessed for temperature and relative humidity (RH) every 5 min across 70 min of heating for each of the 9 settings. In part 2, twelve males (age: 24 ± 4 years) completed two 60 min trials of passive heating (3 × 20 min at 44 °C/99% RH, separated by 1 week). Heart rate (HR), rectal (Trectal) and tympanic temperature (Ttympanic) were recorded every 5 min, thermal comfort (Tcomfort) and sensation (Tsensation) every 10 min, mean arterial pressure (MAP) at each break period and sweat rate (SR) after exiting the pod. RESULTS: In part 1, setting 9 provided the highest temperature (44.3 ± 0.2 °C) and longest time RH remained stable at 99% (51±7 min). Inter-unit reliability data demonstrated agreement between pods for settings 5-9 (intra-class correlation [ICC] >0.9), but not for settings 1-4 (ICC <0.9). In part 2, between-visits, high correlations, and low typical error of measurement (TEM) and coefficient of variation (CV) were found for Trectal, HR, MAP, SR, and Tcomfort, but not for Ttympanic or Tsensation. A peak Trectal of 38.09 ± 0.30 °C, HR of 124 ± 15 b min-1 and a sweat loss of 0.73 ± 0.33 L were reported. No between-visit differences (p > 0.05) were observed for Trectal, Ttympanic, Tsensation or Tcomfort, however HR (+3 b.min-1) and MAP (+4 mmHg) were greater in visit 1 vs. 2 (p < 0.05). CONCLUSION: Portable steam sauna pods generate reliable heat stress between-units. The highest setting (44 °C/99% RH) also provides reliable but modest adjustments in physiological and perceptual responses.

A preference to learn from successful rather than common behaviours in human social dilemmas.

Human cooperation is often claimed to be special and requiring explanations based on gene-culture coevolution favouring a desire to copy common social behaviours. If this is true, then individuals should be motivated to both observe and copy common social behaviours. Previous economic experiments, using the public goods game, have suggested individuals' desire to sacrifice for the common good and to copy common social behaviours. However, previous experiments have often not shown examples of success. Here we test, on 489 participants, whether individuals are more motivated to learn about, and more likely to copy, either common or successful behaviours. Using the same social dilemma and standard instructions, we find that individuals were primarily motivated to learn from successful rather than common behaviours. Consequently, social learning disfavoured costly cooperation, even when individuals could observe a stable, pro-social level of cooperation. Our results call into question explanations for human cooperation based on cultural evolution and/or a desire to conform with common social behaviours. Instead, our results indicate that participants were motivated by personal gain, but initially confused, despite receiving standard instructions. When individuals could learn from success, they learned to cooperate less, suggesting that human cooperation is maybe not so special after all.

Decoupling cooperation and punishment in humans shows that punishment is not an altruistic trait.

Economic experiments have suggested that cooperative humans will altruistically match local levels of cooperation (conditional cooperation) and pay to punish non-cooperators (altruistic punishment). Evolutionary models have suggested that if altruists punish non-altruists this could favour the evolution of costly helping behaviours (cooperation) among strangers. An often-key requirement is that helping behaviours and punishing behaviours form one single conjoined trait (strong reciprocity). Previous economics experiments have provided support for the hypothesis that punishment and cooperation form one conjoined, altruistically motivated, trait. However, such a conjoined trait may be evolutionarily unstable, and previous experiments have confounded a fear of being punished with being surrounded by cooperators, two factors that could favour cooperation. Here, we experimentally decouple the fear of punishment from a cooperative environment and allow cooperation and punishment behaviour to freely separate (420 participants). We show, that if a minority of individuals is made immune to punishment, they (i) learn to stop cooperating on average despite being surrounded by high levels of cooperation, contradicting the idea of conditional cooperation and (ii) often continue to punish, 'hypocritically', showing that cooperation and punishment do not form one, altruistically motivated, linked trait.

The elderly's physiological and perceptual responses to cooling during simulated activities of daily living in UK summer climatic conditions.

OBJECTIVES: The elderly are the most at-risk population for heat-related illness and mortality during the periods of hot weather. However, evidence-based elderly-specific cooling strategies to prevent heat-illness are limited. The aim of this investigation was to quantify the elderly's physiological and perceptual responses to cooling through cold water ingestion (COLD) or an L-menthol mouth rinse (MENT) during simulated activities of daily living in UK summer climatic conditions. STUDY DESIGN: Randomised, controlled repeated measures research design. METHODS: A total of ten participants (men n = 7, women n = 3: age; 69 ± 3 yrs, height; 168 ± 10 cm, body mass; 68.88 ± 13.72 kg) completed one preliminary and three experimental trials; control (CON), COLD and MENT. Experimental trials consisted of 40 min rest followed by 30 min of cycling exercise at 6 metabolic equivalents and a 6-min walk test (6MWT), within a 35 °C, 50% relative humidity environment. Experimental interventions (every 10 min); cold water (4 °C) ingestion (total of 1.5L) or menthol (5 ml mouth swill for 5 s, menthol concentration of 0.01%). RESULTS: Peak rectal temperature (Tre) was significantly (P < 0.05) lower in COLD compared with CON (-0.34 ± 0.16 °C) and MENT (-0.36 ± 0.20 °C). End exercise heart rate (HR) decreased in COLD compared with CON (-7 ± 9 b min-1) and MENT (-6 ± 7 b min-1). There was no difference in end exercise thermal sensation (TS) (CON; 6.1 ± 0.4, COLD; 6.0 ± 0.4, MENT; 6.4 ± 0.6) or thermal comfort (TC) (CON; 4 ± 1, COLD; 4 ± 1, MENT; 4 ± 1) between trials. The participants walked significantly further during the COLD 6MWT compared with CON (40 m ± 40 m) and MENT (40 m ± 30 m). There was reduced physiological strain in the COLD 6MWT compared with CON (Tre; -0.21 ± 0.24 °C, HR; -7 ± 8 b min-1) and MENT (Tre; -0.23 ± 0.24 °C, HR; -4 ± 7 b min-1). CONCLUSION: The elderly have reduced physiological strain (Tre and HR) during activities of daily living and a 6MWT in hot UK climatic conditions, when they drink cold water. Furthermore, the elderly's perception (TS and TC) of the hot environment did not differ from CON at the end of exercise with COLD or MENT interventions. Menthol provided neither perceptual benefit to exercise in the heat nor functional gain. The TS data indicate that elderly may be at increased risk of heat illness, due to not feeling hot and uncomfortable enough to implement physiological strain reducing strategies such as cold-water ingestion.

Conditional cooperation and confusion in public-goods experiments.

Economic experiments are often used to study if humans altruistically value the welfare of others. A canonical result from public-good games is that humans vary in how they value the welfare of others, dividing into fair-minded conditional cooperators, who match the cooperation of others, and selfish noncooperators. However, an alternative explanation for the data are that individuals vary in their understanding of how to maximize income, with misunderstanding leading to the appearance of cooperation. We show that (i) individuals divide into the same behavioral types when playing with computers, whom they cannot be concerned with the welfare of; (ii) behavior across games with computers and humans is correlated and can be explained by variation in understanding of how to maximize income; (iii) misunderstanding correlates with higher levels of cooperation; and (iv) standard control questions do not guarantee understanding. These results cast doubt on certain experimental methods and demonstrate that a common assumption in behavioral economics experiments, that choices reveal motivations, will not necessarily hold.

UDiTaS™, a genome editing detection method for indels and genome rearrangements.

BACKGROUND: Understanding the diversity of repair outcomes after introducing a genomic cut is essential for realizing the therapeutic potential of genomic editing technologies. Targeted PCR amplification combined with Next Generation Sequencing (NGS) or enzymatic digestion, while broadly used in the genome editing field, has critical limitations for detecting and quantifying structural variants such as large deletions (greater than approximately 100 base pairs), inversions, and translocations. RESULTS: To overcome these limitations, we have developed a Uni-Directional Targeted Sequencing methodology, UDiTaS, that is quantitative, removes biases associated with variable-length PCR amplification, and can measure structural changes in addition to small insertion and deletion events (indels), all in a single reaction. We have applied UDiTaS to a variety of samples, including those treated with a clinically relevant pair of S. aureus Cas9 single guide RNAs (sgRNAs) targeting CEP290, and a pair of S. pyogenes Cas9 sgRNAs at T-cell relevant loci. In both cases, we have simultaneously measured small and large edits, including inversions and translocations, exemplifying UDiTaS as a valuable tool for the analysis of genome editing outcomes. CONCLUSIONS: UDiTaS is a robust and streamlined sequencing method useful for measuring small indels as well as structural rearrangements, like translocations, in a single reaction. UDiTaS is especially useful for pre-clinical and clinical application of gene editing to measure on- and off-target editing, large and small.

Physiological and perceptual responses in the elderly to simulated daily living activities in UK summer climatic conditions.

OBJECTIVES: The elderly population is at an increasingly significant health risk to heat-related illnesses and mortality when compared with younger people in the same conditions. This is due to an increased frequency and severity of heatwaves, attributed to climate change, and reduced ability of elderly individuals to dissipate excess heat. Consequently, most excess deaths and emergency visits during heatwaves occur in people aged more than 65 years. The aim of this investigation was to assess the physiological and perceptual responses of elderly people during exercise sessions equating to activities of daily living in UK summer climatic conditions. STUDY DESIGN: Mixed-method, randomised research design. METHODS: Twenty-eight participants (17 males, 10 females and 1 transgender female) were randomly assigned into three experimental groups; 15°C, 25°C or 35°C, with 50% relative humidity. Participants completed one preliminary and three experimental trials within their assigned environment. The data from the preliminary incremental recumbent cycling test was used to calculate participant's individual exercise intensities equating to 2, 4 and 6 metabolic equivalents (METs) for the subsequent trials. During experimental trials, participants completed 30-min seated rest and 30-min cycling. RESULTS: No change was observed in thermal comfort ([TC] just uncomfortable in both trials), and only modest changes in ratings of perceived exertion (14 ± 2 vs 15 ± 2) at 6 METs in 25°C compared with those in 35°C were observed. In contrast, thermal strain markers did significantly increase (P < 0.05) across the same conditions, including change in rectal temperature (ΔTre) during exercise (0.27 ± 0.17°C vs 0.64 ± 0.18°C) and peak skin temperature ([Tskin] 32.94 ± 1.15°C vs 36.11 ± 0.44°C). CONCLUSION: When completing exercise that equates to activities of daily living, elderly people could have a decreased perceptual awareness of the environment even though physiological markers of thermal strain are elevated. Consequently, the elderly could be less likely to implement behavioural thermoregulation interventions (i.e. seek shade and/or remove excess layers) due to a decreased awareness of an increasingly thermally challenging environment.

Trends and Characteristics of Pediatric Dentistry Patients Treated under General Anesthesia.

PURPOSE: The aims of this study were to describe the demographic characteristics of pediatric dentistry patients undergoing dental rehabilitation under general anesthesia (DRGA) at UNC-Chapel Hill during the last 13 years and identify factors associated with multiple (1 versus 2 or more) DRGA visits during that timeframe. STUDY DESIGN: Administrative claims data were used to identify children and adolescents (age <18 years) who underwent DRGA between 1/1/2002 and 12/31/2014 at the UNC Hospitals system. Information on children's age, sex and all treatment-associated CDT codes were collected. Descriptive statistics and bivariate tests of association were used for data analyses. RESULTS: There were 4,413 DRGAs among 3,973 children (median age=4 years 8 months, males=55%) during the study period. The annual rate of DRGAs increased over time, peaking (n=447) in 2013. Overall, 9% of children had ≥2 visits with repeat rates up to 18%. There was no association between children's sex and receipt of one versus multiple DRGAs; however, craniofacial cases were more likely (p<0.0005) to have multiple DRGAs compared to non-craniofacial ones. CONCLUSION: DRGAs are on the increase-with the exception of craniofacial and special health care needs patients, multiple DRGAs may be reflective of sub-optimal adherence to preventive and continuing care recommendations.

Social learning and the demise of costly cooperation in humans.

Humans have a sophisticated ability to learn from others, termed social learning, which has allowed us to spread over the planet, construct complex societies, and travel to the moon. It has been hypothesized that social learning has played a pivotal role in making human societies cooperative, by favouring cooperation even when it is not favoured by genetical selection. However, this hypothesis lacks direct experimental testing, and the opposite prediction has also been made, that social learning disfavours cooperation. We experimentally tested how different aspects of social learning affect the level of cooperation in public-goods games. We found that: (i) social information never increased cooperation and usually led to decreased cooperation; (ii) cooperation was lowest when individuals could observe how successful individuals behaved; and (iii) cooperation declined because individuals preferred to copy successful individuals, who cooperated less, rather than copy common behaviours. Overall, these results suggest that individuals use social information to try and improve their own success, and that this can lead to lower levels of cooperation.

Evidence for strategic cooperation in humans.

Humans may cooperate strategically, cooperating at higher levels than expected from their short-term interests, to try and stimulate others to cooperate. To test this hypothesis, we experimentally manipulated the extent an individual's behaviour is known to others, and hence whether or not strategic cooperation is possible. In contrast with many previous studies, we avoided confounding factors by preventing individuals from learning during the game about either pay-offs or about how other individuals behave. We found clear evidence for strategic cooperators-just telling some individuals that their groupmates would be informed about their behaviour led to them tripling their initial level of cooperation, from 17 to 50%. We also found that many individuals play as if they do not understand the game, and their presence obscures the detection of strategic cooperation. Identifying such players allowed us to detect and study strategic motives for cooperation in novel, more powerful, ways.

Evolutionary changes in symbiont community structure in ticks.

Ecological specialization to restricted diet niches is driven by obligate, and often maternally inherited, symbionts in many arthropod lineages. These heritable symbionts typically form evolutionarily stable associations with arthropods that can last for millions of years. Ticks were recently found to harbour such an obligate symbiont, Coxiella-LE, that synthesizes B vitamins and cofactors not obtained in sufficient quantities from blood diet. In this study, the examination of 81 tick species shows that some Coxiella-LE symbioses are evolutionarily stable with an ancient acquisition followed by codiversification as observed in ticks belonging to the Rhipicephalus genus. However, many other Coxiella-LE symbioses are characterized by low evolutionary stability with frequent host shifts and extinction events. Further examination revealed the presence of nine other genera of maternally inherited bacteria in ticks. Although these nine symbionts were primarily thought to be facultative, their distribution among tick species rather suggests that at least four may have independently replaced Coxiella-LE and likely represent alternative obligate symbionts. Phylogenetic evidence otherwise indicates that cocladogenesis is globally rare in these symbioses as most originate via horizontal transfer of an existing symbiont between unrelated tick species. As a result, the structure of these symbiont communities is not fixed and stable across the tick phylogeny. Most importantly, the symbiont communities commonly reach high levels of diversity with up to six unrelated maternally inherited bacteria coexisting within host species. We further conjecture that interactions among coexisting symbionts are pivotal drivers of community structure both among and within tick species.

The time course of endogenous erythropoietin, IL-6, and TNFα in response to acute hypoxic exposures.

Erythropoietin (EPO) rapidly decreases on return to sea level (SL) after chronic altitude exposure. Acute hypoxia may provide an additional stimulus to prevent the decline in EPO. Proinflammatory cytokines, interleukin-6 (IL-6), and tumor necrosis factor alpha (TNFα) have been shown to inhibit EPO production. Optimal normobaric hypoxic exposure has not been established; therefore, investigation of methods eliciting the greatest response in EPO to limit physiological stress is required. Eight men (age 27 ± 4 years, body mass 77.5 ± 9.0 kg, height 179 ± 6 cm) performed four passive exposures to different normobaric hypoxic severities [FiO2 : 0.209 (SL), FiO2 : ~0.135 (3600 m), FiO2 : ~0.125 (4200 m) and FiO2 : ~0.115 (4800 m)] in a hypoxic chamber for 2 h. Venous blood was drawn pre-exposure and then at 1, 2, 4, 6, and 8 h to determine EPO concentration ([EPO]), IL-6, and TNFα. During 4200 and 4800 m, [EPO] increased from 5.9 ± 1.5 to 8.1 ± 1.5 mU/mL (P = 0.009) and 6.0 ± 1.4 to 8.9 ± 2.0 mU/mL (P = 0.037), respectively, with [EPO] increase peaking at 4 h (2 h post-exposure). There were no differences in IL-6 or TNFα during or post-exposure. Increased [EPO] was found 2 h post hypoxic exposure as result of 2 h of normobaric hypoxia ≥4200 m. There was no dose-response relationship in [EPO] between simulated hypoxia severities.

Measured body composition and geometrical data of four "virtual family" members for thermoregulatory modeling.

The purpose of this paper is to develop a database of tissue composition, distribution, volume, surface area, and skin thickness from anatomically correct human models, the virtual family. These models were based on high-resolution magnetic resonance imaging (MRI) of human volunteers, including two adults (male and female) and two children (boy and girl). In the segmented image dataset, each voxel is associated with a label which refers to a tissue type that occupies up that specific cubic millimeter of the body. The tissue volume was calculated from the number of the voxels with the same label. Volumes of 24 organs in body and volumes of 7 tissues in 10 specific body regions were calculated. Surface area was calculated from the collection of voxels that are touching the exterior air. Skin thicknesses were estimated from its volume and surface area. The differences between the calculated and original masses were about 3 % or less for tissues or organs that are important to thermoregulatory modeling, e.g., muscle, skin, and fat. This accurate database of body tissue distributions and geometry is essential for the development of human thermoregulatory models. Data derived from medical imaging provide new effective tools to enhance thermal physiology research and gain deeper insight into the mechanisms of how the human body maintains heat balance.

The evolution of altruism in humans.

Humans are an intensely social species, frequently performing costly behaviors that benefit others. Efforts to solve the evolutionary puzzle of altruism have a lengthy history, and recent years have seen many important advances across a range of disciplines. Here we bring together this interdisciplinary body of research and review the main theories that have been proposed to explain human prosociality, with an emphasis on kinship, reciprocity, indirect reciprocity, punishment, and morality. We highlight recent methodological advances that are stimulating research and point to some areas that either remain controversial or merit more attention.

Prosocial preferences do not explain human cooperation in public-goods games.

It has become an accepted paradigm that humans have "prosocial preferences" that lead to higher levels of cooperation than those that would maximize their personal financial gain. However, the existence of prosocial preferences has been inferred post hoc from the results of economic games, rather than with direct experimental tests. Here, we test how behavior in a public-goods game is influenced by knowledge of the consequences of actions for other players. We found that (i) individuals cooperate at similar levels, even when they are not informed that their behavior benefits others; (ii) an increased awareness of how cooperation benefits others leads to a reduction, rather than an increase, in the level of cooperation; and (iii) cooperation can be either lower or higher than expected, depending on experimental design. Overall, these results contradict the suggested role of the prosocial preferences hypothesis and show how the complexity of human behavior can lead to misleading conclusions from controlled laboratory experiments.