Group-structured cultural selection can explain both war and peace.

Glowacki recognizes the importance of norms in enabling war and peace, but does not focus on the cultural evolutionary mechanisms by which these norms are maintained. We highlight how group-structured cultural selection shapes the scale and nature of peaceful intergroup interactions. The mechanistic perspective reveals that there are many more cases of peaceful intergroup relations than the current account implies.

Gods are watching and so what? Moralistic supernatural punishment across 15 cultures.

Psychological and cultural evolutionary accounts of human sociality propose that beliefs in punitive and monitoring gods that care about moral norms facilitate cooperation. While there is some evidence to suggest that belief in supernatural punishment and monitoring generally induce cooperative behaviour, the effect of a deity's explicitly postulated moral concerns on cooperation remains unclear. Here, we report a pre-registered set of analyses to assess whether perceiving a locally relevant deity as moralistic predicts cooperative play in two permutations of two economic games using data from up to 15 diverse field sites. Across games, results suggest that gods' moral concerns do not play a direct, cross-culturally reliable role in motivating cooperative behaviour. The study contributes substantially to the current literature by testing a central hypothesis in the evolutionary and cognitive science of religion with a large and culturally diverse dataset using behavioural and ethnographically rich methods.

Moving the needle on time to resuscitation: An EAST prospective multicenter study of vascular access in hypotensive injured patients using trauma video review.

BACKGROUND: Vascular access in hypotensive trauma patients is challenging. Little evidence exists on the time required and success rates of vascular access types. We hypothesized that intraosseous (IO) access would be faster and more successful than peripheral intravenous (PIV) and central venous catheter (CVC) access in hypotensive patients. METHODS: An EAST prospective multicenter trial was performed; 19 centers provided data. Trauma video review was used to evaluate the resuscitations of hypotensive (systolic blood pressure ≤90 mm Hg) trauma patients. Highly granular data from video recordings were abstracted. Data collected included vascular access attempt type, location, success rate, and procedural time. Demographic and injury-specific variables were obtained from the medical record. Success rates, procedural durations, and time to resuscitation were compared among access strategies (IO vs. PIV vs. CVC). RESULTS: There were 1,410 access attempts that occurred in 581 patients with a median age of 40 years (27-59 years) and an Injury Severity Score of 22 [10-34]. Nine hundred thirty-two PIV, 204 IO, and 249 CVC were attempted. Seventy percent of access attempts were successful but were significantly less likely to be successful in females (64% vs. 71%, p = 0.01). Median time to any access was 5.0 minutes (3.2-8.0 minutes). Intraosseous had higher success rates than PIV or CVC (93% vs. 67% vs. 59%, p < 0.001) and remained higher after subsequent failures (second attempt, 85% vs. 59% vs. 69%, p = 0.08; third attempt, 100% vs. 33% vs. 67%, p = 0.002). Duration varied by access type (IO, 36 [23-60] seconds; PIV, 44 [31-61] seconds; CVC 171 [105-298]seconds) and was significantly different between IO versus CVC ( p < 0.001) and PIV versus CVC ( p < 0.001) but not PIV versus IO. Time to resuscitation initiation was shorter in patients whose initial access attempt was IO, 5.8 minutes versus 6.7 minutes ( p = 0.015). This was more pronounced in patients arriving to the hospital with no established access (5.7 minutes vs. 7.5 minutes, p = 0.001). CONCLUSION: Intraosseous is as fast as PIV and more likely to be successful compared with other access strategies in hypotensive trauma patients. Patients whose initial access attempt was IO were resuscitated more expeditiously. Intraosseous access should be considered a first line therapy in hypotensive trauma patients. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level II.

"Doing what others do" does not stabilize continuous norms.

Differences in social norms are a key source of behavioral variation among human populations. It is widely assumed that a vast range of behaviors, even deleterious ones, can persist as long as they are locally common because deviants suffer coordination failures and social sanctions. Previous models have confirmed this intuition, showing that different populations may exhibit different norms even if they face similar environmental pressures or are linked by migration. Crucially, these studies have modeled norms as having a few discrete variants. Many norms, however, have a continuous range of variants. Here we present a mathematical model of the evolutionary dynamics of continuously varying norms and show that when the social payoffs of the behavioral options vary continuously the pressure to do what others do does not result in multiple stable equilibria. Instead, factors such as environmental pressure, individual preferences, moral beliefs, and cognitive attractors determine the outcome even if their effects are weak, and absent such factors populations linked by migration converge to the same norm. The results suggest that the content of norms across human societies is less arbitrary or historically constrained than previously assumed. Instead, there is greater scope for norms to evolve towards optimal individual or group-level solutions. Our findings also suggest that cooperative norms such as those that increase contributions to public goods might require evolved moral preferences, and not just social sanctions on deviants, to be stable.

Turkana warriors' call to arms: how an egalitarian society mobilizes for cattle raids.

Humans are able to overcome coordination and collective action problems to mobilize for large-scale intergroup conflict even without formal hierarchical political institutions. To better understand how people rally together for warfare, I examine how the politically decentralized Turkana pastoralists in Kenya assemble raiding parties. Based on accounts of 54 Turkana battles obtained from semi-structured interviews with Turkana warriors, I describe the precipitating factors, recruitment process, exhortations and leadership involved in marshalling a raiding party. Details of this ethnographic case shed light on how voluntary informal armies are mobilized, and illustrate how culturally evolved institutions harness our cooperative dispositions at multiple scales to produce large-scale warfare. This article is part of the theme issue 'Intergroup conflict across taxa'.

Genomic analysis reveals geography rather than culture as the predominant factor shaping genetic variation in northern Kenyan human populations.

OBJECTIVES: The aim of this study was to characterize the genetic relationships within and among four neighboring ethnolinguistic groups in northern Kenya in light of cultural relationships to understand the extent to which geography and culture shape patterns of genetic variation. MATERIALS AND METHODS: We collected DNA and demographic information pertaining to aspects of social identity and heritage from 572 individuals across the Turkana, Samburu, Waso Borana, and Rendille of northern Kenya. We sampled individuals across a total of nine clans from these four groups and, additionally, three territorial sections within the Turkana and successfully genotyped 376 individuals. RESULTS: Here we report that geography predominately shapes genetic variation within and among human groups in northern Kenya. We observed a clinal pattern of genetic variation that mirrors the overall geographic distribution of the individuals we sampled. We also found relatively higher rates of intermarriage between the Rendille and Samburu and evidence of gene flow between them that reflect these higher rates of intermarriage. Among the Turkana, we observed strong recent genetic substructuring based on territorial section affiliation. Within ethnolinguistic groups, we found that Y chromosome haplotypes do not consistently cluster by natal clan affiliation. Finally, we found that sampled populations that are geographically closer have lower genetic differentiation, and that cultural similarity does not predict genetic similarity as a whole across these northern Kenyan populations. DISCUSSION: Overall, the results from this study highlight the importance of geography, even on a local geographic scale, in shaping observed patterns of genetic variation in human populations.

Combat stress in a small-scale society suggests divergent evolutionary roots for posttraumatic stress disorder symptoms.

Military personnel in industrialized societies often develop posttraumatic stress disorder (PTSD) during combat. It is unclear whether combat-related PTSD is a universal evolutionary response to danger or a culture-specific syndrome of industrialized societies. We interviewed 218 Turkana pastoralist warriors in Kenya, who engage in lethal cattle raids, about their combat experiences and PTSD symptoms. Turkana in our sample had a high prevalence of PTSD symptoms, but Turkana with high symptom severity had lower prevalence of depression-like symptoms than American service members with high symptom severity. Symptoms that facilitate responding to danger were better predicted by combat exposure, whereas depressive symptoms were better predicted by exposure to combat-related moral violations. The findings suggest that some PTSD symptoms stem from an evolved response to danger, while depressive PTSD symptoms may be caused by culturally specific moral norm violations.

Arbitration supports reciprocity when there are frequent perception errors.

Reciprocity is undermined by perception errors, mistakes that cause disagreement between interacting individuals about past behaviour. Strategies such as win-stay-lose-shift and generous tit-for-tat can re-establish cooperation following a perception error, but only when errors arise infrequently. We introduce arbitration tit-for-tat (ATFT), a strategy that uses third-party arbitration to align players' beliefs about what transpired when they disagree. We show that, when arbitration is moderately accurate, ATFT is a strong subgame-perfect equilibrium and is evolutionarily stable against a range of strategies that defect, cooperate, ignore arbitration or invoke arbitration unnecessarily. ATFT can persist when perception errors are frequent, arbitration is costly or arbitration is biased. The need for third parties to resolve perception errors could explain why reciprocity is rare in other animals despite opportunities for repeated interactions and why human reciprocity is embedded within culturally transmitted moral norms in which community monitoring plays a role.

Human large-scale cooperation as a product of competition between cultural groups.

A fundamental puzzle of human evolution is how we evolved to cooperate with genetically unrelated strangers in transient interactions. Group-level selection on culturally differentiated populations is one proposed explanation. We evaluate a central untested prediction of Cultural Group Selection theory, by assessing whether readiness to cooperate between individuals from different groups corresponds to the degree of cultural similarity between those groups. We documented the normative beliefs and cooperative dispositions of 759 individuals spanning nine clans nested within four pastoral ethnic groups of Kenya-the Turkana, Samburu, Rendille and Borana. We find that cooperation between groups is predicted by how culturally similar they are, suggesting that norms of cooperation in these societies have evolved under the influence of group-level selection on cultural variation. Such selection acting over human evolutionary history may explain why we cooperate readily with unrelated and unfamiliar individuals, and why humans' unprecedented cooperative flexibility is nevertheless culturally parochial.

Moralizing gods, impartiality and religious parochialism across 15 societies.

The emergence of large-scale cooperation during the Holocene remains a central problem in the evolutionary literature. One hypothesis points to culturally evolved beliefs in punishing, interventionist gods that facilitate the extension of cooperative behaviour toward geographically distant co-religionists. Furthermore, another hypothesis points to such mechanisms being constrained to the religious ingroup, possibly at the expense of religious outgroups. To test these hypotheses, we administered two behavioural experiments and a set of interviews to a sample of 2228 participants from 15 diverse populations. These populations included foragers, pastoralists, horticulturalists, and wage labourers, practicing Buddhism, Christianity, and Hinduism, but also forms of animism and ancestor worship. Using the Random Allocation Game (RAG) and the Dictator Game (DG) in which individuals allocated money between themselves, local and geographically distant co-religionists, and religious outgroups, we found that higher ratings of gods as monitoring and punishing predicted decreased local favouritism (RAGs) and increased resource-sharing with distant co-religionists (DGs). The effects of punishing and monitoring gods on outgroup allocations revealed between-site variability, suggesting that in the absence of intergroup hostility, moralizing gods may be implicated in cooperative behaviour toward outgroups. These results provide support for the hypothesis that beliefs in monitoring and punitive gods help expand the circle of sustainable social interaction, and open questions about the treatment of religious outgroups.

Facile synthesis, growth process, characterisation of a nanourchin-structured α-MnO2 and their application on ultrasonic-assisted adsorptive removal of cationic dyes: A half-life and half-capacity concentration approach.

Textile dyes pose a serious threat in terms of water pollution due to its complex aromatic structures and poor degradability. In order to reduce the toxic effects of Crystal Violet (CV) and Methylene Blue (MB), an ultrasonic-assisted dye adsorption using urchin like α-MnO2 nanostructures was studied. The adsorbent was synthesised by hydrothermal method at low-temperature. The crystallinity and morphology were determined to investigate the growth mechanism of α-MnO2 nanourchins which consists of two main stages. The initial stage includes the formation of α-MnO2 microspheres followed by the epitaxial growth of nanoneedles on to the surface of them. The α-MnO2 was characterised by BET, XRD, FT-IR, XPS, SEM, TEM and TGA. At 5.6, the point of zero charge of α-MnO2 nanostructures was determined. The total pore volume and average pore radius were confirmed to be 4.751 × 10-2 cc/g and 10.99 Šrespectively from the BET analysis. Batch adsorption experiments were performed to investigate the effect of pH, adsorbent dosage, sonication time, initial dye concentration, temperature, ultrasonic frequency and power. The adsorption mechanism was studied using several isotherm and kinetic models. The adsorption data of CV and MB at equilibrium was observed to adopt the Langmuir isotherm model and pseudo-second order kinetic model. The maximum adsorption capacities for CV and MB were found to be 5882.3 and 5000 mg/g respectively. The thermodynamic study predicted that the process was exothermic for CV and endothermic for MB. The effects of competitive ions, ionic strength and humic acid on the uptake of both the dyes were also investigated. And finally, the reusability of recovered α-MnO2 after dye adsorption was studied up to five cycles for its potential industrial applications.

Temporary arterial shunts in damage control: Experience and outcomes.

BACKGROUND: Arterial shunting is a well-described method to control hemorrhage and rapidly reestablish flow, but optimal shunt dwell times remain controversial. We hypothesized that prolonged shunt dwell times of more than 6 hours are related to adverse outcomes after major arterial injury. METHODS: A review (2005-2013) of all patients with arterial shunts placed after traumatic injury at our urban Level I trauma center was undertaken. Patients who died prior to shunt removal (n = 7) were excluded. Shunt complications were defined as dislodgement, thrombosis, and distal ischemia. Patients were compared on the basis of shunt complications with respect to clinical parameters. RESULTS: The 42 patients who underwent arterial shunting after major vascular injury were primarily young (median, 26 years; interquartile range [IQR], 22-31 years) males (97.6%), severely injured (Injury Severity Score, 17.5 [IQR, 14-29]; shunted vessel Abbreviated Injury Scale score, 4 [IQR, 3-4]) by gunshot (85.7%) requiring neck/torso (33.3%) or upper-extremity (19.1%) or lower-extremity (47.6%) shunts. Thirty-five patients survived until shunt removal, and 5 (14.3%) of 35 developed shunt complications. Demographics and clinical characteristics were compared between those with shunt dwell times of less than 6 hours (n = 19) and more than 6 hours (n = 16). While patients appeared to have a greater injury burden overall in the group with dwell times of more than 6 hours, there were no statistical differences between groups with respect to age, gender, initial systolic blood pressure or hemodynamics during the shunt dwell period, use of vasopressors, Abbreviated Injury Scale score of the shunted vessel, Injury Severity Score, or outcomes including limb amputation or mortality. No patients (0/19) with shunt dwell times of less than 6 hours developed complications, whereas 5 (31.3%) of 16 patients with dwell times of more than 6 hours developed shunt complications (p = 0.05). CONCLUSIONS: In this civilian series, 14% of patients with arterial shunts developed shunt complications. Our data suggest that limiting shunt dwell times to less than 6 hours when clinically feasible may decrease adverse outcomes. LEVEL OF EVIDENCE: Therapeutic/care management study, level IV.

Cultural group selection follows Darwin's classic syllogism for the operation of selection.

The main objective of our target article was to sketch the empirical case for the importance of selection at the level of groups on cultural variation. Such variation is massive in humans, but modest or absent in other species. Group selection processes acting on this variation is a framework for developing explanations of the unusual level of cooperation between non-relatives found in our species. Our case for cultural group selection (CGS) followed Darwin's classic syllogism regarding natural selection: If variation exists at the level of groups, if this variation is heritable, and if it plays a role in the success or failure of competing groups, then selection will operate at the level of groups. We outlined the relevant domains where such evidence can be sought and characterized the main conclusions of work in those domains. Most commentators agree that CGS plays some role in human evolution, although some were considerably more skeptical. Some contributed additional empirical cases. Some raised issues of the scope of CGS explanations versus competing ones.

Cultural group selection plays an essential role in explaining human cooperation: A sketch of the evidence.

Human cooperation is highly unusual. We live in large groups composed mostly of non-relatives. Evolutionists have proposed a number of explanations for this pattern, including cultural group selection and extensions of more general processes such as reciprocity, kin selection, and multi-level selection acting on genes. Evolutionary processes are consilient; they affect several different empirical domains, such as patterns of behavior and the proximal drivers of that behavior. In this target article, we sketch the evidence from five domains that bear on the explanatory adequacy of cultural group selection and competing hypotheses to explain human cooperation. Does cultural transmission constitute an inheritance system that can evolve in a Darwinian fashion? Are the norms that underpin institutions among the cultural traits so transmitted? Do we observe sufficient variation at the level of groups of considerable size for group selection to be a plausible process? Do human groups compete, and do success and failure in competition depend upon cultural variation? Do we observe adaptations for cooperation in humans that most plausibly arose by cultural group selection? If the answer to one of these questions is "no," then we must look to other hypotheses. We present evidence, including quantitative evidence, that the answer to all of the questions is "yes" and argue that we must take the cultural group selection hypothesis seriously. If culturally transmitted systems of rules (institutions) that limit individual deviance organize cooperation in human societies, then it is not clear that any extant alternative to cultural group selection can be a complete explanation.

Behavioural variation in 172 small-scale societies indicates that social learning is the main mode of human adaptation.

The behavioural variation among human societies is vast and unmatched in the animal world. It is unclear whether this variation is due to variation in the ecological environment or to differences in cultural traditions. Underlying this debate is a more fundamental question: is the richness of humans' behavioural repertoire due to non-cultural mechanisms, such as causal reasoning, inventiveness, reaction norms, trial-and-error learning and evoked culture, or is it due to the population-level dynamics of cultural transmission? Here, we measure the relative contribution of environment and cultural history in explaining the behavioural variation of 172 Native American tribes at the time of European contact. We find that the effect of cultural history is typically larger than that of environment. Behaviours also persist over millennia within cultural lineages. This indicates that human behaviour is not predominantly determined by single-generation adaptive responses, contra theories that emphasize non-cultural mechanisms as determinants of human behaviour. Rather, the main mode of human adaptation is social learning mechanisms that operate over multiple generations.

An evolutionary theory of large-scale human warfare: Group-structured cultural selection.

When humans wage war, it is not unusual for battlefields to be strewn with dead warriors. These warriors typically were men in their reproductive prime who, had they not died in battle, might have gone on to father more children. Typically, they are also genetically unrelated to one another. We know of no other animal species in which reproductively capable, genetically unrelated individuals risk their lives in this manner. Because the immense private costs borne by individual warriors create benefits that are shared widely by others in their group, warfare is a stark evolutionary puzzle that is difficult to explain. Although several scholars have posited models of the evolution of human warfare, these models do not adequately explain how humans solve the problem of collective action in warfare at the evolutionarily novel scale of hundreds of genetically unrelated individuals. We propose that group-structured cultural selection explains this phenomenon.