Neuroactive hormones and interpersonal trust: International evidence

Social attachment is vital for human health and welfare. Recent experimental evidence in humans has identified the role of neuroactive hormones, especially the peptide oxytocin, in mediating trusting behaviors. Herein, we test if the endocrinological basis for trust between humans scales up to the country level. Trust pervades nearly every aspect of our daily lives, yet survey data on trust show substantial variation across countries. Using 31 measures of biological, social, and environmental factors associated with hormone levels for a sample of 41 countries, we find that two classes of factors are related to trust: consumption of plant-based estrogens (phytoestrogens), and the presence of environmental conditions that include measures of estrogen-like molecules. Our findings provide preliminary evidence that interpersonal trust at the country level may be related to the intake of neuroactive hormones.     

Dominance competition through affiliation and support in Japanese macaques: An experimental study

It has been proposed that monkeys direct grooming to high-ranking individuals in an attempt to obtain agonistic support in return. But whether these two categories of interactions are causally related has proven difficult to establish. Part of the problem stems from the fact that in stable groups social relationships reflect an equilibrium state and that behaviors need only be performed at low rates and long intervals to maintain the current social structure. In theory, however, if affiliative and supportive interactions are indeed causally related, it should be possible to accentuate their temporal relation, hence their causal dynamics. For example, destabilizing dominance relations can be expected to induce competition for status and force individuals to deploy behavioral tactics for settling new rank relations. We experimentally induced rank reversals in a captive group of Japanese macaques (Macaca fuscata) composed of three matrilines (A-B-C rank order). A reversed C-A-B order composed of three individuals per matriline was maintained for 2 weeks. The results show the close temporal relation among (i) asserting one’s rank, (ii) competing for access to dominants through affiliation and interferences in affiliation, (iii) receiving support from dominants against lower-ranking individuals, and (iv) supporting dominants against subordinates. These findings are compatible with one version of the affiliation-for-support hypothesis, namely that monkeys affiliate with dominants as a way to assert their position in the hierarchy. In a functional perspective, mutual selfishness provides a better explanation than reciprocal altruism because the possibility that both groomers and supporters derive immediate net benefits cannot be excluded.     

Phylogenetic evidence for an animal pathogen origin of ergot and the grass endophytes

Grass-associated fungi (grass symbionts) in the family Clavicipitaceae (Ascomycota, Hypocreales) are species whose host range is restricted to the plant family Poaceae and rarely Cyperaceae. The best-characterized species include Claviceps purpurea (ergot of rye) and Neotyphodium coenophialum (endophyte of tall fescue). They have been the focus of considerable research due to their importance in agricultural and grassland ecosystems and the diversity of their bioactive secondary metabolites. Here we show through multigene phylogenetic analyses and ancestral character state reconstruction that the grass symbionts in Clavicipitaceae are a derived group that originated from an animal pathogen through a dynamic process of interkingdom host jumping. The closest relatives of the grass symbionts include the genera Hypocrella, a pathogen of scale insects and white flies, and Metarhizium, a generalist arthropod pathogen. These data do not support the monophyly of Clavicipitaceae, but place it as part of a larger clade that includes Hypocreaceae, a family that contains mainly parasites of other fungi. A minimum of 5-8 independent and unidirectional interkingdom host jumps has occurred among clavicipitaceous fungi, including 3-5 to fungi, 1-2 to animals, and 1 to plants. These findings provide a new evolutionary context for studying the biology of the grass symbionts, their role in plant ecology, and the evolution of host affiliation in fungal symbioses.     

陕南早寒武世ANABARITES壳体内部结构及亲缘关系探讨

陕南灯影组宽川铺段的小壳化石具完好的三维保存方式。Anabarites是三辐射对称、单管底栖群居生物,亲缘关系不明。作者通过对陕南宁强下寒武统宽川铺段进行数次系统采样,经过对样品的醋酸溶蚀处理和电子扫描电镜照像后,发现Anabarites壳体内部具螺旋状微结构;经测试分析后认为该结构可能与中槽的深浅成正相关,两者的形成可能与微环境中水体的变化有关。探讨其可能的亲缘关系及其演化序列。     

Response to social challenge in young bonnet (Macaca radiata) and pigtail (Macaca nemestrina) macaques is related to early maternal experiences

Previous experience affects how young primates respond to challenging social situations. The present retrospective study looked at one aspect of early experience, the quality of the mother-infant relationship, to determine its relationship to young bonnet and pigtail macaques' responses to two social challenges: temporary maternal separation at 5-6 months and permanent transfer to an unfamiliar peer group at 16-17 months. Relationship quality was measured quantitatively on 30 macaque mother-infant pairs with the Relationship Quality Index (RQI), the ratio of relative affiliation to relative agonism as previously applied to capuchin monkeys. Infants with high RQI values had amicable mother-infant relationships and infants with low RQI values had agonistic mother-infant relationships. Young monkeys with amicable and agonistic relationships showed consistent differences in behavior before, during, and after each social challenge, supporting the hypothesis that juveniles from amicable mother-infant relationships based on the RQI coped more effectively with social challenges than did juveniles from agonistic mother-infant relationships. Results suggest 1) characteristic amicability or agonism in early mother-offspring macaque relationships has the potential to influence offspring behavior in tense social contexts and 2) the RQI is useful as one of a coordinated suite of methods for studying the development of social skills.     

Reconciliation and third‐party affiliation in carrion crows

Conflicts are costly because they can damage social relationships. To buffer conflicts, various species use post‐conflict behaviour, such as reconciliation or third‐party affiliation. Both behaviours have predominantly been studied in non‐human primates. However, recently, studies revealed post‐conflict behaviour in other mammalian and some bird species (e.g., corvids). While third‐party affiliation has been reported in several corvid species, reconciliation has only rarely been observed. The social structure of the studied groups has been postulated as a reason for the absence of reconciliation. Here, we investigated whether post‐conflict behaviours in corvids indeed mirror the relationship structure. We studied the behaviour of a newly established group of juvenile carrion crows (Corvus corone corone), where pair bonds had not yet been established. We applied a combination of observations and food monopolisation experiments to quantify the use of post‐conflict behaviours. Provisioning food in one or two pieces induced different patterns of aggression during feeding and differently affected the affiliation patterns after feeding. Specifically, victims of severe aggression affiliated with third parties after conflicts in the two‐piece condition, while aggressors affiliated with victims of mild aggression in the one‐piece condition. We thus provide the first evidence that a corvid species, crows, flexibly engage in both third‐party affiliation and reconciliation.     

Abundance and site fidelity of bottlenose dolphins off a remote oceanic island (Reunion Island,southwest Indian Ocean)

This study represents the first comprehensive assessment of the population dynamics and residency of common bottlenose dolphin around Reunion Island (southwest Indian Ocean). Understanding dynamics and movement patterns of this local population is essential to guide effective conservation efforts, notably in a context of growing dolphin-watching activities. Dedicated surveys based on photo-identification methods were conducted over 6 years (2010–2015). The species was present year-round, in groups of 25 individuals on average (1–150). Jolly-Seber mark-recapture models resulted in a population estimate of 254 individuals (95% CI = 191–337) and an apparent annual survival rate of 0.83. The population was almost equally split into three residency patterns: residents (33.1%), long-term visitors (32.6%), and short-term visitors (34.3%, including transients, i.e., individuals only seen once [14.9%]), suggesting that the majority of the population showed a moderate-to-high level of residency in the study area. Individuals from the three residency patterns associated randomly, mixing together and forming a single community. Models based on the lagged identification rate indicated emigration and reimmigration to the survey area, with some individuals occupying the study area for about 2 years (832 days), and remaining outside for an average of 276 days, probably exhibiting larger home ranges and extensive movement behavior.