Food Transfer in Sichuan Snub-nosed Monkeys (<Emphasis Type="Italic">Rhinopithecus roxellana</Emphasis>)

Food transfer behavior provides a way to distribute food resources among individuals. It is not confined to kin, but also occurs among genetically unrelated individuals. Food transfer among nonkin may result from byproduct mutualism, reciprocal altruism (RA), or tolerated scrounging (TS). Sichuan snub-nosed monkeys (Rhinopithecus roxellana) exhibit a high level of social tolerance, and researchers have observed food transfer behavior in the wild. However, little is known about how tolerant social relations influence food transfer in this species. We recorded food-related interactions and social behavior in a group of captive Sichuan snub-nosed monkeys. Our findings suggest that the monkeys develop partner preference in food transfer behaviors. Moreover, individuals rely primarily on nonharassed approaches to claim food, suggesting that the TS model alone cannot explain their food transfer. Food transfer in this species may be a form of mutualism, in which an individual benefits on an immediate basis by fostering a preferred and tolerant relationship. However, we cannot rule out the possibility of reciprocal altruism. Future studies should record the temporal delay of social exchange to distinguish between mutualism and reciprocal altruism.     

Cultural transmission and the evolution of cooperative behavior

Sociobiological theory predicts that humans should not cooperate with large groups of unrelated individuals. This prediction is based on genetic models that show that selection acting on variation between large unrelated groups will generally be much weaker than selection acting on variation between individuals. Recently, several authors have presented related models of human evolution that integrate cultural and genetic transmission of behavior. We show that in such models group selection is potentially a strong force. Data on ethnocentrism is examined in the context of these results.     

An evolutionary theory of moral injury with insight from Turkana warriors

Clinicians in Western, Educated, Industrialized, Rich, and Democratic (WEIRD) societies are rethinking whether Post-traumatic Stress Disorder (PTSD) is caused solely by exposure to life-threatening experiences, or also by moral injury—witnessing or participating in acts that violate moral beliefs. However, while there are evolutionary hypotheses explaining PTSD as a response to physical danger, the evolutionary roots of moral injury lack an explanation. We posit that a subset of symptoms of combat-related PTSD is associated with moral injury and that these symptoms evolved in tandem with human's norm-psychology. We can examine this hypothesis by comparing societies with different moral beliefs about warfare, norm enforcement mechanisms, and spheres of moral concern. To illustrate the utility of this framework, we describe combat trauma, war norms, and norm enforcement among Turkana pastoralist warriors in Kenya who participate in highly lethal raids of neighboring ethnic groups. We previously showed that depressive PTSD symptoms in Turkana warriors are more strongly associated with experiencing moral violations in combat, and that Turkana warriors with comparably high overall PTSD symptom-severity experience lower rates of depressive symptoms than US combat veterans. Here we detail aspects of Turkana warfare, moral beliefs, and post-battle rituals that differ from WEIRD societies, and that may ameliorate the symptoms of moral injury in Turkana warriors. Our findings highlight how further studies of combat trauma outside of WEIRD militaries can help evaluate this theory and illustrate the importance of cross-cultural research for identifying the evolutionary roots of combat stress and best practices for prevention and recovery.     

The co-evolution of individual behaviors and social institutions

We present agent-based simulations of a model of a deme-structured population in which group differences in social institutions are culturally transmitted and individual behaviors are genetically transmitted. We use a standard extended fitness accounting framework to identify the parameter space for which this co-evolutionary process generates high levels of group-beneficial behaviors. We show that intergroup conflicts may explain the evolutionary success of both: (a) altruistic forms of human sociality towards unrelated members of one's group; and (b) group-level institutional structures such as food sharing which have emerged and diffused repeatedly in a wide variety of ecologies during the course of human history. Group-beneficial behaviors may evolve if (a) they inflict sufficient fitness costs on outgroup individuals and (b) group-level institutions limit the individual fitness costs of these behaviors and thereby attenuate within-group selection against these behaviors. Thus, the evolutionary success of individually costly but group-beneficial behaviors in the relevant environments during the first 90,000 years of anatomically modern human existence may have been a consequence of distinctive human capacities in social institution building.     

Successful same-sex pairing in Laysan albatross

Unrelated same-sex individuals pairing together and cooperating to raise offspring over many years is a rare occurrence in the animal kingdom. Cooperative breeding, in which animals help raise offspring that are not their own, is often attributed to kin selection when individuals are related, or altruism when individuals are unrelated. Here we document long-term pairing of unrelated female Laysan albatross (Phoebastria immutabilis) and show how cooperation may have arisen as a result of a skewed sex ratio in this species. Thirty-one per cent of Laysan albatross pairs on Oahu were female-female, and the overall sex ratio was 59% females as a result of female-biased immigration. Female-female pairs fledged fewer offspring than male-female pairs, but this was a better alternative than not breeding. In most female-female pairs that raised a chick in more than 1 year, at least one offspring was genetically related to each female, indicating that both females had opportunities to reproduce. These results demonstrate how changes in the sex ratio of a population can shift the social structure and cause cooperative behaviour to arise in a monogamous species, and they also underscore the importance of genetically sexing monomorphic species.     

Viral adaptation to host: a proteome‐based analysis of codon usage and amino acid preferences

Viruses differ markedly in their specificity toward host organisms. Here, we test the level of general sequence adaptation that viruses display toward their hosts. We compiled a representative data set of viruses that infect hosts ranging from bacteria to humans. We consider their respective amino acid and codon usages and compare them among the viruses and their hosts. We show that bacteria‐infecting viruses are strongly adapted to their specific hosts, but that they differ from other unrelated bacterial hosts. Viruses that infect humans, but not those that infect other mammals or aves, show a strong resemblance to most mammalian and avian hosts, in terms of both amino acid and codon preferences. In groups of viruses that infect humans or other mammals, the highest observed level of adaptation of viral proteins to host codon usages is for those proteins that appear abundantly in the virion. In contrast, proteins that are known to participate in host‐specific recognition do not necessarily adapt to their respective hosts. The implication for the potential of viral infectivity is discussed.     

Assessing the impact of hunting pressure on population structure of Guinea baboons (Papio papio) in Guinea-Bissau

Guinea baboons are heavily hunted for bushmeat consumption in Guinea-Bissau. We investigated whether hunting-driven mortality has affected population structure in this generalist primate using two genetic markers. Sampling was conducted in protected areas separated by anthropogenic landscape features. We predicted significant genetic differentiation between samples and investigated whether genetic discontinuities in the data were concordant with the location of human infrastructures. Genetic diversity was not significantly reduced when compared with a neighbouring population in Senegal and we inferred historically female-biased dispersal and recent contact between localities. Evidence was found for a contact zone between genetically differentiated populations where gene-flow is unidirectional, admixed individuals are at a higher proportion and individuals differentiated for both genetic markers co-exist within the same social units. Genetic discontinuities were, however, unrelated to anthropogenic dispersal barriers and we could not explain the existence of a contact zone by geographic distance, habitat type or the effect of social structure. We propose that hunting practices have affected the population structure by increasing dispersal distances, facilitating contact between previously separated gene pools within social groups. We suggest that hunting-related density sinks found in areas where the quality of the habitat remains adequate could precipitate the immigration of genetically distinct individuals from distant populations. Alternatively, migrants found in protected areas might be avoiding hunters, in locations they may perceive as less disturbed. This study suggests that hunting practices must be considered when investigating genetic patterns in primates and underlines the utility of molecular approaches to detect population perturbations due to bushmeat hunting.     

Genetic differentiation and the evolution of cooperation in chimpanzees and humans

It has been proposed that human cooperation is unique among animals for its scale and complexity, its altruistic nature and its occurrence among large groups of individuals that are not closely related or are even strangers. One potential solution to this puzzle is that the unique aspects of human cooperation evolved as a result of high levels of lethal competition (i.e. warfare) between genetically differentiated groups. Although between-group migration would seem to make this scenario unlikely, the plausibility of the between-group competition model has recently been supported by analyses using estimates of genetic differentiation derived from contemporary human groups hypothesized to be representative of those that existed during the time period when human cooperation evolved. Here, we examine levels of between-group genetic differentiation in a large sample of contemporary human groups selected to overcome some of the problems with earlier estimates, and compare them with those of chimpanzees. We find that our estimates of between-group genetic differentiation in contemporary humans are lower than those used in previous tests, and not higher than those of chimpanzees. Because levels of between-group competition in contemporary humans and chimpanzees are also similar, these findings suggest that the identification of other factors that differ between chimpanzees and humans may be needed to provide a compelling explanation of why humans, but not chimpanzees, display the unique features of human cooperation.     

Reproductive skew, costs, and benefits of cooperative breeding in female wood mice (Apodemus sylvaticus)

Two current models seek to explain reproduction of subordinatesin social groups: incentives given by dominants for peacefullyremaining in the group (reproductive skew model) or incompletecontrol by dominants. These models make different predictionsconcerning genetic relatedness between individuals for thedistribution of reproduction and the stability of cooperativebreeding associations. To test these models and to furtherexplore the relationships between reproductive skew, geneticrelatedness, and investment of each participant, we performedbehavioral observations of female wood mice (Apodemus sylvaticus)raising pups communally. Our results do not support previousmodels. Differences in lifetime reproductive success were significantlygreater within mother—daughter pairs than within pairsof sisters or unrelated females. Subordinate females of eitherbreeding unit did not differ in their direct reproduction.Calculations of inclusive fitness based on our results leadto the following predictions: (1) Communal nests should occuronly when ecological circumstances prevent solitary breeding.(2) Subordinate females gain the highest inclusive fitnessjoining their mothers; they also show the highest nursing investment.(3) Mothers should accept daughters, who have no opportunityfor solitary breeding. (4) Dominant sisters and unrelated femalesshould reject subordinate females because cooperative breedingreduces their reproductive success. However, breeding unitsof dominant sisters and unrelated females nevertheless occurand can be explained by our finding that such females significantlyreduce nursing time, which may help them save energy for futurebreeding cycles. Our data demonstrate that both genetic relatednessand investment skew are important in the complex evolutionof reproductive skew in cooperative breeding.     

Female Bechstein's Bats Share Foraging Sites with Maternal Kin but do not Forage Together with them – Results from a Long‐Term Study

In many social animals, group members exchange information about where to feed. Thereby, they may gain direct benefits, for example, if social hunting enhances individual foraging success. Alternatively, individuals may receive indirect fitness benefits by preferentially sharing information about suitable feeding sites with kin. Indeed, in some species, a positive correlation between the degree of relatedness among individuals and the overlap among their foraging areas was found. However, sharing foraging sites with kin can also have costs if it increases food competition, which is not compensated by direct benefits. The goal of this study was to investigate whether sharing of individual foraging areas in female Bechstein's bats is best explained by kin selection or by direct benefits through social foraging. To assess their individual foraging behaviour, we analysed radio‐tracking data of 22 members of one maternity colony, including nine mother–daughter pairs, seven pairs of less closely related individuals and six pairs of unrelated bats. We examined the bats' fidelity to specific foraging areas during several years and quantified the influence of kinship on the overlap among individual foraging areas. By measuring how close to each other the bats foraged, we assessed whether individuals with overlapping areas are likely to forage together. Our study confirms previous findings that Bechstein's bats show high fidelity to foraging areas across years. Moreover, we found that relatives share foraging areas significantly more often compared with unrelated colony members. Finally, our data reveal for the first time that most colony members that share foraging areas are unlikely to forage together. This suggests that female Bechstein's bats gain no direct benefits from sharing foraging areas with members of the same maternal lineage. Our findings also have implications for conservation as habitat loss within a colony's home range might expose entire matrilines to high risks.     

Genotypic‐specific variance in Caenorhabditis elegans lifetime fecundity

Organisms live in heterogeneous environments, so strategies that maximze fitness in such environments will evolve. Variation in traits is important because it is the raw material on which natural selection acts during evolution. Phenotypic variation is usually thought to be due to genetic variation and/or environmentally induced effects. Therefore, genetically identical individuals in a constant environment should have invariant traits. Clearly, genetically identical individuals do differ phenotypically, usually thought to be due to stochastic processes. It is now becoming clear, especially from studies of unicellular species, that phenotypic variance among genetically identical individuals in a constant environment can be genetically controlled and that therefore, in principle, this can be subject to selection. However, there has been little investigation of these phenomena in multicellular species. Here, we have studied the mean lifetime fecundity (thus a trait likely to be relevant to reproductive success), and variance in lifetime fecundity, in recently‐wild isolates of the model nematode Caenorhabditis elegans. We found that these genotypes differed in their variance in lifetime fecundity: some had high variance in fecundity, others very low variance. We find that this variance in lifetime fecundity was negatively related to the mean lifetime fecundity of the lines, and that the variance of the lines was positively correlated between environments. We suggest that the variance in lifetime fecundity may be a bet‐hedging strategy used by this species.     

Lanchester's attrition models and fights among social animals

Lanchester's models of attrition during warfare have servedas the basis for several predictions about conflicts betweengroups of animals. These models and their extensions describerates of mortality during battles as functions of the numberand fighting abilities of individuals in each group, allowinganalysis of the determinants of group strength and of the cumulativenumbers of casualties. We propose modifications to Lanchester'smodels to improve their applicability to social animals. Inparticular, we suggest that the per-capita mortality rate ofa group is a decreasing function of the fighting abilities ofits members, that the mortality rate is an increasing functionof the number of individuals in both groups, and that therewill often be diminishing returns for increasing numerical advantage.Models incorporating these assumptions predict that the abilityof social animals to win fights depends less on group size andmore on individual prowess than under Lanchester's originalmodels. We discuss how data on casualties can be used to distinguishamong alternative attrition models.     

A Y‐chromosomal comparison of the Madjars (Kazakhstan) and the Magyars (Hungary)

The Madjars are a previously unstudied population from Kazakhstan who practice a form of local exogamy in which wives are brought in from neighboring tribes, but husbands are not, so the paternal lineages remain genetically isolated within the population. Their name bears a striking resemblance to the Magyars who have inhabited Hungary for over a millennium, but whose previous history is poorly understood. We have now carried out a genetic analysis of the population structure and relationships of the Madjars, and in particular have sought to test whether or not they show a genetic link with the Magyars. We concentrated on paternal lineages because of their isolation within the Madjars and sampled males representing all extant male lineages unrelated for more than eight generations (n = 45) in the Torgay area of Kazakhstan. The Madjars show evidence of extensive genetic drift, with 24/45 carrying the same 12‐STR haplotype within haplogroup G. Genetic distances based on haplogroup frequencies were used to compare the Madjars with 37 other populations and showed that they were closest to the Hungarian population rather than their geographical neighbors. Although this finding could result from chance, it is striking and suggests that there could have been genetic contact between the ancestors of the Madjars and Magyars, and thus that modern Hungarians may trace their ancestry to Central Asia, instead of the Eastern Uralic region as previously thought. Am J Phys Anthropol 2009. © 2009 Wiley‐Liss, Inc.     

The cost of cowardice: punitive sentiments towards free riders in Turkana raids

Models indicate that large-scale cooperation can be sustained by indirect reciprocity or direct punishment, but the relative importance of these mechanisms is unresolved. Unlike direct punishment, indirect sanctions can be meted out without cost to the sanctioner, but direct punishment is advantageous when the scale of cooperation exceeds the network size of individuals. It is of great interest to assess the importance of these mechanisms in small-scale acephalous groups in which people have lived for most of our evolutionary history. Here we evaluate sentiments towards free riders in combat among the Turkana, an acephalous nomadic pastoral society in East Africa who periodically mobilize for cattle-raids against neighboring ethnic groups. Using vignette studies, we probed participants’ motivation to sanction fictitious warriors who were cowards or deserters in a raid and compared it respectively to their reactions to an unskilled warrior or a warrior who turns back due to illness. Our results indicate that the Turkana are motivated to impose both indirect and direct sanctions on cowards consistent with indirect reciprocity and punishment models of cooperation. Our findings imply that both these mechanisms have shaped human cooperative psychology, and sheds light on how prestate societies solve the collective action problem in warfare.     

The sentineling—Foraging trade‐off in dominant and subordinate Arabian babblers

Many cooperative breeders forage under predation risks, sentineling is a central activity, and groupmates have to balance between sentineling and foraging. The optimal balance between sentinel activity and foraging may differ among dominant and subordinate individuals, as dominants are more efficient foragers. Two theoretical models pertain to this balance and predict when individuals with different foraging abilities should switch between the two activities on the basis of their energetic state. In one of these models, individuals must attain a critical energetic level by dusk to pass the night, and in the second model fitness is monotonically increasing with the energetic state. We tested these models in the cooperatively breeding Arabian babbler, Turdoides squamiceps. We measured the length of sentinel bouts and the gaps between them both in natural conditions and following experimental feeding. Following feeding ad libitum, subordinates expanded their sentinel bouts significantly more than dominants in comparison with natural conditions. These findings are consistent with the first model, but not with the second. In the experiment, we measured the mass of mealworms consumed by each individual following a sentinel bout relative to its body mass. This ratio was larger for subordinates, indicating that they ended their sentinel bouts at a lower energetic state than dominants. This finding is consistent with the second model, but not with the first. Immediately after eating ad libitum, in 62% of the cases the first behavior performed by the babblers was a new sentinel bout, but in 17% it was a mutual interaction with a groupmate, indicating that social interactions also play a role in the trade‐off vis‐à‐vis sentinel activity.     

Scale‐dependent strategies for coexistence of mesocarnivores in human‐dominated landscapes

Identifying factors influencing the distribution of and interactions within carnivore communities is important for understanding how they are affected by human activities. Species differ in their ability to adapt to humans depending on their degree of specialization in habitat use and feeding habits. This results in asymmetric changes in the ecology of co‐occurring species that can influence their interactions. We investigated whether human infrastructures and free‐ranging domestic dogs (a species typically associated with humans) influenced the co‐occurrence and habitat use of mesocarnivores in a landscape of high human population density in Maharashtra, India. We used 40 camera trap locations during 233 trapping nights and used Bayesian co‐occurrence occupancy models to investigate the habitat use and coexistence of species at different spatial scales. Additionally, we investigated their temporal overlap in space use. Indian foxes altered their habitat use both spatially and temporally in order to avoid free‐ranging domestic dogs and other larger competitors. The use of human infrastructure by jackals and jungle cats was limited by the presence of dogs. Our results illustrate how habitat use of smaller carnivore species changes both spatially and temporally in order to avoid larger competitors. We also show that the presence of species associated with humans mediates the influence of human infrastructures on the habitat use of mesocarnivores. We highlight the importance of acknowledging the potential impact of urbanization not only on single species, but also on the interactions within the community.     

The evolution of intergroup tolerance in nonhuman primates and humans

Primate individuals use a variety of strategies in intergroup encounters, from aggression to tolerance; however, recent focus on the evolution of either warfare or peace has come at the cost of characterizing this variability. We identify evolutionary advantages that may incentivize tolerance toward extra‐group individuals in humans and nonhuman primates, including enhanced benefits in the domains of transfer, mating, and food acquisition. We highlight the role these factors play in the flexibility of gorilla, chimpanzee, bonobo, and human behavior. Given humans have an especially broad range of intergroup behavior, we explore how the human foraging ecology, especially large spatial and temporal fluctuations in resource availability, may have selected for a greater reliance on tolerant between‐community relationships—relationships reinforced by status acquisition and cultural institutions. We conclude by urging careful, theoretically motivated study of behavioral flexibility in intergroup encounters in humans and the nonhuman great apes.     

毒素战剂的生防疫苗简

毒素战剂是重要的生物战剂之一,其最大的威胁来自它的高毒性和缺乏有效的防治手段。在毒素战剂中,肉毒毒素、志贺毒素、蓖麻毒素、相思子毒素等属于致死性生物战剂,葡萄球菌肠毒素B属于失能性生物战剂。生防疫苗作为毒素战剂的一种重要的有效预防手段,一直备受关注,但目前绝大部分毒素战剂的疫苗都还在研制中,随着分子生物学技术的快速发展,几种重要毒素战剂的重组疫苗研究已获得重要突破。我们重点介绍肉毒毒素、志贺毒素、蓖麻毒素、相思子毒素、葡萄球菌肠毒素B等毒素战剂生防疫苗的研究与发展。     

Phylogenies support out‐of‐equilibrium models of biodiversity

There is a long tradition in ecology of studying models of biodiversity at equilibrium. These models, including the influential Neutral Theory of Biodiversity, have been successful at predicting major macroecological patterns, such as species abundance distributions. But they have failed to predict macroevolutionary patterns, such as those captured in phylogenetic trees. Here, we develop a model of biodiversity in which all individuals have identical demographic rates, metacommunity size is allowed to vary stochastically according to population dynamics, and speciation arises naturally from the accumulation of point mutations. We show that this model generates phylogenies matching those observed in nature if the metacommunity is out of equilibrium. We develop a likelihood inference framework that allows fitting our model to empirical phylogenies, and apply this framework to various mammalian families. Our results corroborate the hypothesis that biodiversity dynamics are out of equilibrium.     

The early‐life environment and individual plasticity in life‐history traits

We tested whether the early‐life environment can influence the extent of individual plasticity in a life‐history trait. We asked: can the early‐life environment explain why, in response to the same adult environmental cue, some individuals invest more than others in current reproduction? Moreover, can it additionally explain why investment in current reproduction trades off against survival in some individuals, but is positively correlated with survival in others? We addressed these questions using the burying beetle, which breeds on small carcasses and sometimes carries phoretic mites. These mites breed alongside the beetle, on the same resource, and are a key component of the beetle's early‐life environment. We exposed female beetles to mites twice during their lives: during their development as larvae and again as adults during their first reproductive event. We measured investment in current reproduction by quantifying average larval mass and recorded the female's life span after breeding to quantify survival. We found no effect of either developing or breeding alongside mites on female reproductive investment, nor on her life span, nor did developing alongside mites influence her size. In post hoc analyses, where we considered the effect of mite number (rather than their mere presence/absence) during the female's adult breeding event, we found that females invested more in current reproduction when exposed to greater mite densities during reproduction, but only if they had been exposed to mites during development as well. Otherwise, they invested less in larvae at greater mite densities. Furthermore, females that had developed with mites exhibited a trade‐off between investment in current reproduction and future survival, whereas these traits were positively correlated in females that had developed without mites. The early‐life environment thus generates individual variation in life‐history plasticity. We discuss whether this is because mites influence the resources available to developing young or serve as important environmental cues.