Relatedness and Social Behaviors in <Emphasis Type="Italic">Cercopithecus solatus</Emphasis>

Inclusive fitness and kin selection theories predict that organisms will evolve biased behavior toward kin when the inclusive fitness benefits outweigh the costs of such behaviors. Researchers have long observed that primates bias their behavior toward relatives, particularly maternal kin. We examined the effect of kinship on social behaviors in a semifree-ranging colony of Cercopithecus solatus, a poorly studied forest guenon species. We used microsatellite loci and paternity analyses to determine the degree of relatedness between individuals, as well as kinship. Individuals biased some of their behavior according to relatedness. Specifically, related individuals are more spatially associated and less aggressive toward each other. When we replaced the relatedness coefficients with defined kin categories, Cercopithecus solatus seemed to behave preferentially toward maternal kin versus paternal kin. Even though the setting of the colony and the small sample size limit our conclusions, we discuss the potential implications of our finding for the study of the impact of kin selection in primate social relationships.     

Memory in the grip of emotions and stress: a necessarily harmful impact?

While intense negative events are vividly recalled, information learned during stressful situations is poorly remembered. These differential effects of emotions and stress on memory have been attributed to the physiological manifestations generated during those affective states. Intense emotional and stressful events trigger the secretion of catecholamines and of glucocorticoids, in particular. These hormones would be modulatory agents of memory functions. In the first part of this paper, we review the specific effects emotions and stress have on memory. We then summarize the psychological and biological determinants responsible for these effects. Finally, we discuss different methodological issues that could explain the discrepancy found between the impact of emotions and stress on memory. Defining more precisely the effects emotion and stress have on memory will lead to a better comprehension of the cognitive problems that characterize patients dealing with emotional turmoil, such as patients suffering from depression or post-traumatic stress disorder.     

Bonds of bros and brothers: Kinship and social bonding in postdispersal male macaques

Group‐living animals often maintain a few very close affiliative relationships—social bonds—that can buffer them against many of the inevitable costs of gregariousness. Kinship plays a central role in the development of such social bonds. The bulk of research on kin biases in sociality has focused on philopatric females, who typically live in deeply kin‐structured systems, with matrilineal dominance rank inheritance and life‐long familiarity between kin. Closely related males, in contrast, are usually not close in rank or familiar, which offers the opportunity to test the importance of kinship per se in the formation of social bonds. So far, however, kin biases in male social bonding have only been tested in philopatric males, where familiarity remains a confounding factor. Here, we studied bonds between male Assamese macaques, a species in which males disperse from their natal groups and in which male bonds are known to affect fitness. Combining extensive behavioural data on 43 adult males over a 10‐year period with DNA microsatellite relatedness analyses, we find that postdispersal males form stronger relationships with the few close kin available in the group than with the average nonkin. However, males form the majority of their bonds with nonkin and may choose nonkin over available close kin to bond with. Our results show that kinship facilitates bond formation, but is not a prerequisite for it, which suggests that strong bonds are not restricted to kin in male mammals and that animals cooperate for both direct and indirect fitness benefits.     

Kinship,association, and social relationships in rhesus monkeys (Macaca mulatta)

Data on social interactions with matrilineal kin were collected from two groups of rhesus monkeys for 6 years. All behavioral states, including time within one meter of another, involved kin more often than would be expected by chance. Significant associations were also found between kinship and the frequencies of various forms of agonistic as well as affiliative acts. Frequency of social interaction, however, was not a simple function of time in proximity. Although animals spent more time with kin than nonkin they had more aggressive interactions with kin. Moreover, aggression was biased toward the more serious forms of expression in interactions with kin. Time spent in association was neither predictive of the rate of aggressive interaction nor reduced by high rates of aggressive interaction. Rather than association time influencing rates of interaction, association time may be the consequence of a history of aggressive and affiliative exchanges. Preferential association and high rates of aggressive interaction with kin may be possible due to the existence of compensating social mechanisms nullifying the negative influence of specific aggressive encounters. © 1993 Wiley-Liss, Inc.     

Influences on communication about reproduction: the cultural evolution of low fertility

The cultural norms of traditional societies encourage behavior that is consistent with maximizing reproductive success but those of modern post-demographic transition societies do not. Newson et al (2005) proposed that this might be because interaction between kin is relatively less frequent in modern social networks. Assuming that people's evaluations of reproductive decisions are influenced by a desire to increase their inclusive fitness, they will be inclined to prefer their kin to make fitness-enhancing choices. Such a preference will encourage the emergence of pronatal cultural norms if social networks are dense with kin. Less pronatal norms will emerge if contact between kin makes up a small proportion of social interactions. This article reports evidence based on role-play studies that supports the assumption of the kin influence hypothesis that evaluations of reproductive decisions are influenced by a desire to increase inclusive fitness. It also presents a cultural evolutionary model demonstrating the long-term effect of declining kin interaction if people are more likely to encourage fitness-enhancing choices when interacting with their kin than with nonrelatives.     

Consequences of group fission for the patterns of relatedness among rhesus macaques

When mammalian social groups exceed their optimal size, they often tend to split. In view of the potential evolutionary benefits, it should be more advantageous for animals to stay with kin, rather than nonkin, during such fission events. In the present study, the spontaneous fission of two social groups, R and S, of rhesus macaques living on Cayo Santiago, Puerto Rico, provided the opportunity to compare the kinship structure of the corresponding parent and daughter groups, using information on both maternal and paternal relatedness. In both instances, maternal half-siblings and pairs of animals from the same family were significantly more prevalent in the fission products than in the parent group. During the split of group R, significantly more paternal half-siblings stayed in the remnants of the parent group than joined the seceding group. Our findings are compatible with previous behavioural studies demonstrating that female primates bias their social behaviour more to maternal than to paternal kin, but that both types of half-siblings prefer each other more than unrelated animals. It remains to be clarified by future research, however, whether the observed co-segregation of paternal half-sibs in our study reflects active choice or is a by-product of the group-specific kin structures, prior to fission.     

Infant Handling and Maternal Response in Japanese Macaques

We focused on the social interactions of infant Japanese macaques (Macaca fuscata) and on the protective response of their mothers to such interactions. Infant social interactions included: received allomaternal behavior (positive infant handling), hand touch and inspection (neutral handling), and aggression (negative handling) as well as social play. Maternal protective responses included aggression to the infant's interactant and restraining or retrieving the infant. All types of social interactions as well as the maternal response to such interactions showed clear developmental variations. Frequency of infant social interactions and maternal protective responses also showed large interindividual variability. Juvenile and subadult females without maternal experience were the most frequent infant handlers. Infants received positive handling primarily from their kin, while mothers were equally protective in response to positive handling received by kin and by non-kin. Conversely, kin showed higher levels of neutral handling and their interest was more easily tolerated by mothers compared to that of non-kin.     

非人灵长类的亲缘选择

亲缘选择是动物进化的重要研究领域之一,非人灵长类因具有丰富的社会网络,是亲缘选择研究领域的重要类群。动物进行亲缘选择的前提是亲缘识别,并常通过社会行为的亲缘偏向表现。因此,本文从非人灵长类的亲缘识别机制和亲缘关系对其社会行为的影响两方面进行了综述:熟悉性和表现型匹配是目前普遍认同的非人灵长类亲缘识别机制,同时这两种机制并不相互排斥,它们可能共同在灵长类的亲缘识别中起作用;在非人灵长类中,亲缘关系是影响社会行为模式的主导因子,它影响着多种灵长类个体的友好行为、攻击行为和性行为的选择,同时亲缘偏向行为在不同物种中表现不尽相同,说明亲缘选择理论可以部分解释灵长类的行为,但存在一定的局限性。本文分析了两种亲缘识别机制的异同以及在实际研究中利用亲缘选择理论解释非人灵长
类社会行为的局限及可能原因。目前,对非人灵长类社会中的亲缘选择研究正逐步深入,其中分子遗传学技术的应用是重要的推动力量。同时,依然存在诸如汉密尔顿规则参数估计和新大陆猴的亲缘选择研究案例的难点,有待研究者进一步探究。     

OF MICE AND KIN: THE FUNCTIONAL SIGNIFICANCE OF KIN BIAS IN SOCIAL BEHAVIOUR

1. Sharing recent ancestry (kinship) increases the degree of genetic similarity between individuals, where genetic similarity could mean anything from sharing a particular allele to sharing an entire genome. 2. Genetic similarity can influence behavioural and other responses between individuals in a number of ways, discriminatory and non-discriminatory. All are likely to result in kin bias, because of the correlation between genetic similarity and kinship, but only some should be regarded as involving kin discrimination. 3. Non-discriminatory kin bias could arise through close relatives sharing, for instance, physical characteristics (such as those influencing competitive ability), thresholds of behavioural response or requirements for particular resources. 4. Discriminatory kin bias could arise through the direct perception of genetic similarity between individuals (direct similarity discrimination) or the use of cues likely to correlate with genetic similarity (indirect similarity discrimination--of which kin discrimination is one form). Alternatively, it could arise incidentally through mistaken identity or discrimination at some other level, such as species identification. 5. Experiments with laboratory and wild house mice have revealed kin bias in a number of contexts, including (a) parental and infanticidal behaviour, (b) sexual development and behaviour and (c) investigatory behaviour and passive body contact among juveniles and adults. 6. While kin bias in mice has been interpreted as evidence for kin discrimination, there are several problems with such an interpretation. These include (a) pronounced and complex effects of familiarity on discrimination, (b) a high risk of error-proneness in the indirect cues used in apparent kin discrimination and (c) weak and easily disrupted kin bias effects in certain contexts. 7. Consideration of social structure and discriminatory responses within populations of wild house mice leads to an alternative explanation for some kin bias in terms of incidental discrimination based on social group membership. 8. Several results from laboratory experiments suggest incidental discrimination is a more parsimonious explanation than kin discrimination for some intrasexual kin bias in behaviour. However, kin or direct similarity discrimination appears to be the most likely explanation for other aspects of intrasexual kin bias and for intersexual kin bias.     

Lévi-Strauss on the Oedipus Myth: A Reconsideration

The first half of the article presents a critique of Lévi-Strauss' well-known analysis of the Oedipus myth. A consideration of Greek beliefs suggests that Lévi-Strauss is incorrect in tying certain events in that myth to the "overvaluation of blood relations" and in asserting that the myth is concerned with the "affirmation/denial of man's autochthonous origins." The second half of the article presents a different structural analysis of the entire Theban Saga, of which the Oedipus myth is but a part. It concludes (1) that Lévi-Strauss is correct in identifying a series of events in the myth which indicate the devaluation of blood relations, but that these events specifically refer to the devaluation of patrilineal kin ties and that the range of events indicating the devaluation of patrilineal ties is broader than his analysis would suggest, and (2) there is another series of repeated events (unmentioned by Lévi-Strauss) which indicates the affirmation of patrilineal kin ties. The final hypothesis— that the opposition between the devaluation/affirmation of patrilineal kin ties underlies the Theban Saga— "makes sense" in terms of Greek history, as the period in which the Olympian myths look their present form is also the period in which the Greeks moved from a society organized along patrilineal kin ties to one organized around allegiance to the polis. [structuralism, Oedipus myth, myth and social structure, Lévi-Strauss, anthropological theory]     

Kin and Child Survival in Rural Malawi

This paper investigates the impact of kin on child survival in a matrilineal society in Malawi. Women usually live in close proximity to their matrilineal kin in this agricultural community, allowing opportunities for helping behavior between matrilineal relatives. However, there is little evidence that matrilineal kin are beneficial to children. On the contrary, child mortality rates appear to be higher in the presence of maternal grandmothers and maternal aunts. These effects are modified by the sex of child and resource ownership: female children and children in households where women, rather than men, own land suffer higher mortality rates in the presence of maternal kin. These modifiers suggest the detrimental effects of matrilineal kin may result from competition between such kin for resources. There are some positive effects of kin on child survival: the presence of elder siblings of both sexes is correlated with higher survival rates, and there is some weak evidence that paternal grandmothers may be beneficial to a child’s survival chances. There is little evidence that any male kin, whether matrilineal or patrilineal, and including fathers, affect child mortality rates. This study highlights the importance of taking social and ecological context into account when investigating relationships between kin.     

Yawn contagion and empathy in Homo sapiens

The ability to share others' emotions, or empathy, is crucial for complex social interactions. Clinical, psychological, and neurobiological clues suggest a link between yawn contagion and empathy in humans (Homo sapiens). However, no behavioral evidence has been provided so far. We tested the effect of different variables (e.g., country of origin, sex, yawn characteristics) on yawn contagion by running mixed models applied to observational data collected over 1 year on adult (>16 years old) human subjects. Only social bonding predicted the occurrence, frequency, and latency of yawn contagion. As with other measures of empathy, the rate of contagion was greatest in response to kin, then friends, then acquaintances, and lastly strangers. Related individuals (r≥0.25) showed the greatest contagion, in terms of both occurrence of yawning and frequency of yawns. Strangers and acquaintances showed a longer delay in the yawn response (latency) compared to friends and kin. This outcome suggests that the neuronal activation magnitude related to yawn contagion can differ as a function of subject familiarity. In conclusion, our results demonstrate that yawn contagion is primarily driven by the emotional closeness between individuals and not by other variables, such as gender and nationality.     

Adaptive responses and disruptive effects: how major wildfire influences kinship-based social interactions in a forest marsupial

Environmental disturbance is predicted to play a key role in the evolution of animal social behaviour. This is because disturbance affects key factors underlying social systems, such as demography, resource availability and genetic structure. However, because natural disturbances are unpredictable there is little information on their effects on social behaviour in wild populations. Here, we investigated how a major wildfire affected cooperation (sharing of hollow trees) by a hollow-dependent marsupial. We based two alternative social predictions on the impacts of fire on population density, genetic structure and resources. We predicted an adaptive social response from previous work showing that kin selection in den-sharing develops as competition for den resources increases. Thus, kin selection should occur in burnt areas because the fire caused loss of the majority of hollow-bearing trees, but no detectable mortality. Alternatively, fire may have a disruptive social effect, whereby postfire home range-shifts 'neutralize' fine-scale genetic structure, thereby removing opportunities for kin selection between neighbours. Both predictions occurred: the disruptive social effect in burnt habitat and the adaptive social response in adjacent unburnt habitat. The latter followed a massive demographic influx to unburnt 'refuge' habitat that increased competition for dens, leading to a density-related kin selection response. Our results show remarkable short-term plasticity of animal social behaviour and demonstrate how the social effects of disturbance extend into undisturbed habitat owing to landscape-scale demographic shifts. We predicted long-term changes in kinship-based cooperative behaviour resulting from the genetic and resource impacts of forecast changes to fire regimes in these forests.     

Society, demography and genetic structure in the spotted hyena

Spotted hyenas (Crocuta crocuta) are large mammalian carnivores, but their societies, called 'clans', resemble those of such cercopithecine primates as baboons and macaques with respect to their size, hierarchical structure, and frequency of social interaction among both kin and unrelated group-mates. However, in contrast to cercopithecine primates, spotted hyenas regularly hunt antelope and compete with group-mates for access to kills, which are extremely rich food sources, but also rare and ephemeral. This unique occurrence of baboon-like sociality among top-level predators has favoured the evolution of many unusual traits in this species. We briefly review the relevant socio-ecology of spotted hyenas, document great demographic variation but little variation in social structure across the species' range, and describe the long-term fitness consequences of rank-related variation in resource access among clan-mates. We then summarize patterns of genetic relatedness within and between clans, including some from a population that had recently gone through a population bottleneck, and consider the roles of sexually dimorphic dispersal and female mate choice in the generation of these patterns. Finally, we apply social network theory under varying regimes of resource availability to analyse the effects of kinship on the stability of social relationships among members of one large hyena clan in Kenya. Although social bonds among both kin and non-kin are weakest when resource competition is most intense, hyenas sustain strong social relationships with kin year-round, despite constraints imposed by resource limitation. Our analyses suggest that selection might act on both individuals and matrilineal kin groups within clans containing multiple matrilines.     

Paternal Relatedness Predicts the Strength of Social Bonds among Female Rhesus Macaques

Forming strong, equitable, and enduring social bonds with a few individuals in a group carries adaptive benefits in terms of increased longevity, offspring survival and paternity success in birds and mammals, including humans. These recent insights generated a new interest in the factors creating variation in the strength of social relationships. Whether and how animals discriminate paternal kin from non-kin and bias their social behavior accordingly is being debated. This study explores the relative importance of dominance rank, age, maternal and paternal relatedness in shaping dyadic affiliative relationships in a group of 30 captive rhesus macaque females. The strength of social relationships, measured by the composite sociality index from observational data, was independently predicted in GLMMs by both maternal and paternal relatedness as well as rank similarity. In addition, social bonds between paternal half-sisters were stronger than between distantly related kin suggesting that females biased their affiliative effort towards paternal relatives. Despite identical relatedness coefficients bonds between mothers and their daughters were three times as strong as those between full sisters. Together these results add to the growing body of evidence for paternal kin biases in affiliative behavior and highlight that females prefer descendent over lateral kin.     

The role of social cognition in decision making

Successful decision making in a social setting depends on our ability to understand the intentions, emotions and beliefs of others. The mirror system allows us to understand other people's motor actions and action intentions. 'Empathy' allows us to understand and share emotions and sensations with others. 'Theory of mind' allows us to understand more abstract concepts such as beliefs or wishes in others. In all these cases, evidence has accumulated that we use the specific neural networks engaged in processing mental states in ourselves to understand the same mental states in others. However, the magnitude of the brain activity in these shared networks is modulated by contextual appraisal of the situation or the other person. An important feature of decision making in a social setting concerns the interaction of reason and emotion. We consider four domains where such interactions occur: our sense of fairness, altruistic punishment, trust and framing effects. In these cases, social motivations and emotions compete with each other, while higher-level control processes modulate the interactions of these low-level biases.     

近缘细菌细胞间的相互识别与相互作用

亲缘识别是细菌细胞间竞争与合作的前提和基础。细菌通过亲缘识别分辨自我细胞和非自我细胞;非同类的细菌细胞相互分离或被排除,而亲缘种群内的细菌细胞进行群体运动、生物膜和子实体形成等社会性合作行为。细菌的自我识别机制可能有助于不同亲缘类群在混杂的自然系统中的共存。近些年来,细菌亲缘识别及相互作用的机制研究工作成为热点,本文总结了近缘细菌细胞间相互识别和作用机制的研究进展。     

Paternal kin discrimination: the evidence and likely mechanisms

One of the most important assumptions of kin selection theory is that individuals behave differently towards kin than non-kin. In mammals, there is strong evidence that maternal kin are distinguished from non-kin via familiarity. However, little is known about whether or not mammals can also recognize paternal kin as many female mammals, including primates, mate with multiple males near the time of conception, potentially concealing paternal kinship. Genetic data in several mammalian species with a promiscuous mating system and male-biased dispersal reveal a high skew in male reproduction which leads to co-residing paternal half-siblings. In most primates, individuals also form stable bisexual groups creating opportunities for males to interact with their offspring. Here I consider close paternal kin co-resident in the same social group, such as father-offspring and paternal half-siblings (i.e. animals sharing the same father but who were born to different mothers) and review mammalian studies of paternal kin discrimination. Furthermore, I summarize the most likely mechanisms of paternal kin discrimination (familiarity and phenotype matching). When familiarity is the underlying mechanism, mothers and/or the sire could mediate familiarity among paternal half-siblings as well as between fathers and offspring assuming mothers and/or fathers can assess paternity. When animals use phenotype matching, they might use their fathers' template (when the father is present) or self (when the father is absent) to assess paternal kinship in others. Available evidence suggests that familiarity and phenotype matching might be used for paternal kin discrimination and that both mechanisms might apply to a wide range of social mammals characterized by a high skew in male reproduction and co-residence of paternal kin. Among primates, suggested evidence for phenotype matching can often have an alternative explanation, which emphasizes the crucial importance of controlling for familiarity as a potential confounding variable. However, the mechanism/s used to identify paternal kin might differ within a species (as a function of each individual's specific circumstances) as well as among species (depending upon the key sensory modalities of the species considered). Finally, I discuss the possible cues used in paternal kin discrimination and offer suggestions for future studies.     

Inheritance of wealth as human kin investment

Like many other animals, humans appear to have evolved to invest time and energy in their relatives in order to maximize inclusive fitness. Inheritance of material wealth may be a uniquely human form of kin investment. If fitness-maximizing dispositions do influence will-makers, beneficiaries may be favored according to their relatedness and reproductive value. An analysis of 1000 probated wills showed that this was the case. Close relatives were favored over distant kin, as were kin of higher reproductive value. Wealthier decedents favored male kin, while poorer decedents favored females. This pattern might reflect a facultative shifting of resources toward males when the family's resources are sufficient to ensure reproductive competitiveness, and toward the safer option of females when resources are less abundant. The results support the possibility that fitness-maximizing dispositions do influence will-makers. It is likely that such dispositions are flexible and responsive to the physical and social environment.     

Affiliation Between Aggressors and Third Parties Following Conflicts in Long-Tailed Macaques (Macaca fascicularis)

Studies on cercopithecine monkeys have shown that soon after an agonistic conflict, victims have increased rates of affiliation with the agressor—reconciliation—but not with other group members. Postconflict affiliation is thought to function to restore disturbed relationships and to reduce social tension. This study on a captive group of long-tailed macaques (Macaca fascicularis) is focused on postconflict affiliative behavior of the aggressor. Increased rates of contact between female aggressors and kin of the victim occurred, as well as between female aggressors and their own kin. Furthermore, there were increased rates of contact between aggressors—males and females—and other group members. The increase in contacts with the victim's kin was selective, i.e., it could not be ascribed to the increased contact tendency with group members in general, and was not a side effect of the aggressor's proximity to the victim due to reconciliation. The increase in contacts with own kin was not selective. The fact that male aggressors do not have increased postconflict contacts with their kin or with kin of the victim is in agreement with the notion that males are less integrated in the nepotistic matrilineal network than females are. The fact that studies by others that focused on the victim evidence no increase in postconflict contacts with kin of the opponent or with other group members may be explained by the aggressor's larger influence over the postconflict situation: to reduce social tension, it might be more effective to affiliate with the aggressor than with the victim. Our findings emphasize that conflicts influence the behavior of other monkeys besides the direct contestants and, thus, indicate that the disturbance of social homeostasis is a matter of concern for all group members.