1,721,046 research outputs found
Maintaining homeostasis in the group: a possible role of agonistic support in geladas
No full textAgonistic support occurs when a bystander intervenes in an ongoing conflict to help one of the two participants. In addition to the clear benefit to the recipient, agonistic support can provide benefits to the bystander who intervenes (e.g. help gain access to resources or maintain hierarchical status). However, the consequences of agonistic support provided to the victim might be different from that given to the aggressor. We hypothesized that agonistic support for the victim may not only provide a protective function for the supported subject, but also have a homeostatic role limiting the escalation of aggression among group members. To test this hypothesis, we selected Theropithecus gelada , a highly social species well equipped with behavioural mechanisms aimed at maintaining cohesion in the group. Our results show that agonistic support was preferentially directed towards the victim rather than towards the aggressor. The best supporters for the victim were high-ranking individuals. Supporting victims significantly reduced the frequency of subsequent aggression both towards the victim and further aggression in the group. In contrast, support for aggressors increased the probability of further aggression. Further, the highest levels of support were provided to the victims who were unrelated and without strong social bonds to aggressors. Agonistic support may be a social tool which comes into play when affiliative post-conflict mechanisms are less likely to occur, for instance, when the two participants are not kin or friends. This peacekeeping role (both at individual and at group level) of agonistic support in geladas could be favoured by natural selection on the basis of the self-interest and motivation of the supporter. However, we cannot exclude other selective forces, especially those that are not mutually exclusive, such as kin selection or reciprocal altruism, in the evolution of this complex and variable behaviour
Post-conflict emotional variation in bystanders: the case of Tonkean Macaques
No full textThe perception of emotions in others regulates many aspect of social life. Consolation, a post-conflict mechanism aimed at reducing distress of the victim, relies on the victim and the consoler sharing emotions. One hypothesis is that consolation depends on a mirroring effect. Mirroring permits an exchange of representations between the victim, who experiences an emotional variation, and the consoler, who is affected by the emotional variation of the victim. From this perspective, consolation is considered an empathy-rooted phenomenon, activated by a perception-action mechanism. If consolation relies on the perception of the victim’s distress, the occurrence of a conflict and the following consolatory contact should produce an emotional variation in the consoler as well as in the victim. As a model species we selected Macaca tonkeana , a primate characterized by high levels of tolerance, which allows individuals to reveal their social relationships through many different behaviours including consolation. Data were collected on a colony of 54 macaques housed at the Parc zoologique de Thoiry (France). Behaviour of both the victim and the bystander was recorded at the same time with a video camera. Our results showed that victims and bystanders increased their anxiety rate after the end of a conflict. Consolation decreased anxiety in the receiver and in the actor of the affiliative contact, but not in bystanders who did not actively participate in the consolatory event. Moreover, in the absence of consolation, a correlation between the anxiety rate of the victim and the bystander was found. These findings, taken together, strongly indicate the sensitivity of the subjects to react empathically according to the affective state variation of the victims
Yawning in the forest: a comparative study on wild Propithecus verreauxi and Lemur catta
No full textYawning is an involuntary behaviour common to all vertebrates. Although easily recognizable, its adaptive significance is not yet fully understood. In the past, several physiological hypotheses have been tested to explain yawning including oxygenation, circulation and thermoregulation. More recently, researchers have begun to focus on the behavioural meaning of yawning, especially in primates. This is the first study to test hypotheses on yawning in natural populations of primates. We selected two sympatric species, Lemur catta and Propithecus verreauxi, of the Ankoba forest (24.99°S, 46.29°E, Berenty Reserve) in southern Madagascar that differ in ecological and behavioural characteristics. Their low sexual dimorphism and high sexual competition may have reduced the differences between sexes in both species. As predicted from the Dimorphism Hypothesis , males and females yawned with similar frequencies. As in other primate species, yawning was linked to the sleep-wake cycle and punctuated the transitions from one behavioural pattern to another ( State Changing Hypothesis supported). Finally, we tested the Anxiety Hypothesis, which predicts that yawning should increase after stressful, anxiogenic events. We found a significant increase in yawning after both predatory attacks and aggression. Clearly, primate yawning is associated with behavioural state changes within different contexts (e.g. threat, anxious or rest). Yet it is not known if yawning is a single, unitary behaviour that varies only with respect to the context in which it is performed. We cannot exclude that yawning in lemurs can be elicited by certain type of stressors; further data in clearly defined contexts will be necessary to demonstrate this hypothesis
Triadic post-conflict behaviour in wild and captive ring-tailed lemurs
No full textThe escalation of conflicts may reduce the benefits of group living. To reduce such risks, social species have developed mechanisms to repair the damage caused by aggression (post-conflict strategies). Affiliation between former opponents of a conflict (reconciliation) and triadic affiliation (defined as a friendly gesture provided by a bystander to the victim) can function as post-conflict strategies. Triadic contacts spontaneously offered to the victim by a bystander seem to lower victims’ distress (measured by self-directed behaviours, e.g. scratching). This phenomenon has been found in hominoids, monkeys and in some non-primate mammals, but it has never been described in lemurs. Here, for the first time, we investigated the post-conflict strategies used by Lemur catta by analysing data collected in the wild (383.5 h of observation; Berenty Reserve, Madagascar) and in captivity (1,138 h of observation; Pistoia Zoo, Italy). The data analysis revealed the presence of unsolicited post-conflict triadic affiliation in both settings, but failed to reveal solicited affiliation. Our analyses also showed that whenever social conditions do not favour reconciliation, unsolicited triadic contacts can substitute for it, thus lowering the risk of further aggression. The anxiety levels experienced by the victims after an aggressive event and in the absence of any kind of post-conflict affiliation did not vary compared to controls. Therefore, triadic spontaneous affiliation does not have a key role in buffering distress after conflicts. GLMM analyses revealed that the tendency of a bystander to approach and interact with a victim was affected by the sex of the aggressor. When the previous aggressor was a female, the probability of spontaneous triadic post-conflict affiliation was higher. This is an interesting result for a despotic species characterized by a strict dominance hierarchy led by females, which frequently reiterate aggression, not only towards the previous victim, but also towards other group members
Reciprocal painting and Fission Breakpoints to analyse the phylogenetic relationshi among Titi monkeys.
No full textVariazioni recenti nella struttura genetica e nelle caratteristiche antropometriche dei coscritti delle leve militari nazionali
No full textImplicazioni dietetiche di un possibile caso di brucellosi in Australopithecus africanus Stw 431 (Pliocene Superiore, Sterkfontein, Sud Africa).
No full textStudio etnolinguistico ed antropogenetico di una popolazione residuale dell’Asia Centrale: gli Yaghnobi del Tajikistan. Studio preliminare
No full textEvolutionary dynamics of mammalian karyotypes
No full textThis special volume of Cytogenetic and Genome Research (edited by Roscoe Stanyon, University of Florence and Alexander Graphodatsky, Siberian division of the Russian Academy of Sciences) is dedicated to the fascinating long search of the forces behind the evolutionary dynamics of mammalian karyotypes, revealed after the hypotonic miracle of the 1950s...
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