Abstract: Linear hierarchies, the classical pecking-order structures, are formed readily in both nature and the laboratory in a great range of species including humans. However, the probability of getting linear structures by chance alone is quite low. In this paper we investigate the two hypotheses that are proposed most often to explain linear hierarchies: they are predetermined by differences in the attributes of animals, or they are produced by the dynamics of social interaction, i.e., they are self-organizing. We evaluate these hypotheses using cichlid fish as model animals, and although differences in attributes play a significant part, we find that social interaction is necessary for high proportions of groups with linear hierarchies. Our results suggest that dominance hierarchy formation is a much richer and more complex phenomenon than previously thought, and we explore the implications of these results for evolutionary biology, the social sciences, and the use of animal models in understanding human social organization.

Abstract: There has been relatively little research on the psychological mechanisms of social learning. This may be due, in part, to the practice of distinguishing categories of social learning in relation to ill-defined mechanisms (Davis, 1973; Galef, 1988). This practice both makes it difficult to identify empirically examples of different types of social learning, and gives the false impression that the mechanisms responsible for social learning are clearly understood. It has been proposed that social learning phenomena be subsumed within the categorization scheme currently used by investigators of asocial learning. This scheme distinguishes categories of learning according to observable conditions, namely, the type of experience that gives rise to a change in an animal (single stimulus vs. stimulus-stimulus relationship vs. response-reinforcer relationship), and the type of behaviour in which this change is detected (response evocation vs. learnability) (Rescorla, 1988). Specifically, three alignments have been proposed: (i) stimulus enhancement with single stimulus learning, (ii) observational conditioning with stimulus-stimulus learning, or Pavlovian conditioning, and (iii) observational learning with response-reinforcer learning, or instrumental conditioning. If, as the proposed alignments suggest, the conditions of social and asocial learning are the same, there is some reason to believe that the mechanisms underlying the two sets of phenomena are also the same. This is so if one makes the relatively uncontroversial assumption that phenomena which occur under similar conditions tend to be controlled by similar mechanisms. However, the proposed alignments are intended to be a set of hypotheses, rather than conclusions, about the mechanisms of social learning; as a basis for further research in which animal learning theory is applied to social learning. A concerted attempt to apply animal learning theory to social learning, to find out whether the same mechanisms are responsible for social and asocial learning, could lead both to refinements of the general theory, and to a better understanding of the mechanisms of social learning. There are precedents for these positive developments in research applying animal learning theory to food aversion learning (e.g. Domjan, 1983; Rozin & Schull, 1988) and imprinting (e.g. Bolhuis, de Vox & Kruit, 1990; Hollis, ten Cate & Bateson, 1991). Like social learning, these phenomena almost certainly play distinctive roles in the antogeny of adaptive behaviour, and they are customarily regarded as 'special kinds' of learning (Shettleworth, 1993).(ABSTRACT TRUNCATED AT 400 WORDS)

Abstract: In this paper some considerations on the environment of the 42 Kmq of the volcanic-basaltic Giara tableland are discussed. Conditioning by the environment and its effect on the distribution of a population of 712 horses is illustrated in view of their social and behavioural organization.

Abstract: A consistent conclusion in reconciliation research is that animals that reconcile are likely to have strong social bonds. This has led to the hypothesis that reconciliation occurs most often between valuable social partners. We tested this hypothesis in a group of Assamese macaques (Macaca assamensis) living near a temple in Assam, India. Using focal sample and ad libitum data collection, we recorded the occurrence of reconciliation, grooming, and agonistic aiding, and the outcomes of approach. We used matrix association methods (TauKr correlation) to correlate reconciliation with grooming, aiding, and approach outcome. Females reconciled more often with females with which they had stronger grooming and aiding relationships. The correlation between reconciliation and aiding was significant for support to the aggressor and the victim. In contrast, no such correlations with reconciliation were found for males. This study provides evidence that females reconcile most often with valuable and compatible social partners. The results do not support the relationship-quality hypothesis for males, and we suggest that future studies give more consideration to the possibility that males reconcile for reasons other than to repair relationships with valuable partners.

Abstract: Although reconciliation in bonobos (Pan paniscus) has previously been described, it has not been analyzed heretofore by the postconflict (PC) match-control (MC) method. Furthermore, although reconciliation has been investigated before in this species, consolation has not. In this study we analyzed agonistic and affiliative contacts in all sex-class combinations to clarify and reevaluate the occurrence of reconciliation in bonobos via the PC-MC method. We also investigated the occurrence of consolation by analyzing the victims' triadic contact tendency (TCT), the influence of the sex of victims, and the relative occurrence of consolation and reconciliation. We collected 167 pairs of PC-MC observations in a captive group of bonobos (in Apeldoorn, The Netherlands). The conciliatory tendency (CCT) we obtained was tendentially lower than the mean value previously found for Yerkes captive chimpanzees. Close relationships, which were present in all female-female (FF) and some male-female (MF) dyads, positively affected reconciliation rates. When only adult PC-MC pairs (157) were considered, the mean TCTs and CCTs did not differ significantly. When we focused on types of PC affiliative contact, in the case of consolation we found a striking preference for sociosexual patterns. As to the relative occurrence of consolation and reconciliation, the highest level of the former was found in the absence of the latter. When reconciliation took place, consolation generally preceded it, suggesting that consolation may be a substitutive behavior. Our findings suggest that even if reconciliation remains the best option, consolation may be an alternative substitute for reconciliation that is used to buffer the tension originating from an unresolved conflict. Reconciliation and consolation are complex phenomena that are probably related to the life history of a group. Given that few studies have been conducted on this subject, we can not at this time make any generalizations regarding conflict resolution in certain species by comparing results among studies.