Abstract: Although positive reciprocity (reciprocal altruism) has been a focus of interest in evolutionary biology, negative reciprocity (retaliatory infliction of fitness reduction) has been largely ignored. In social animals, retaliatory aggression is common, individuals often punish other group members that infringe their interests, and punishment can cause subordinates to desist from behaviour likely to reduce the fitness of dominant animals. Punishing strategies are used to establish and maintain dominance relationships, to discourage parasites and cheats, to discipline offspring or prospective sexual partners and to maintain cooperative behaviour.

Abstract: Appleby (1983, Anim. Behav., 31, 600-608) described a statistical test, based on the work of Kendall (1962, Rank Correlation Methods), for the significance of linearity in dominance hierarchies. He suggested that unknown relationships should be assigned the value 1/2 and that subsequently the same test procedure can be used. In this paper it is shown that incorrect results are obtained by this method whenever there are unknown relationships. Values of the linearity index are systematically too low. P-values can be too high (underestimating the significance) or too low (overestimating), and seem to differ by not much more than a factor two (respectively a half) from the correct P-value. An improved method is developed for testing linearity in a set of dominance relationships containing unknown relationships. Furthermore, it is argued that, if one admits the possibility of tied dominance relationships, which should indeed be assigned the value 1/2, Landau's linearity index is to be preferred to Kendall's index. A randomization test is developed for assessing the significance of linearity or non-linearity in a set of dominance relationships containing unknown or tied relationships. The test statistic employed in this testing procedure is based on Landau's linearity index, but takes the unknown and tied relationships into account.

Abstract: In mirror mark tests dolphins twist, posture, and engage in open-mouth and head movements, often repetitive. Because postures and an open mouth are also dolphin social behaviors, we used self-view television as a manipulatable mirror to distinguish between self-examination and social behavior. Two dolphins were exposed to alternating real-time self-view (“mirror mode”) and playback of the same to determine if they distinguished between them. The adult male engaged in elaborate open-mouth behaviors in mirror mode, but usually just watched when played back the same material. Mirror mode behavior was also compared to interacting with real dolphins (controls). Mark tests were conducted, as well as switches from front to side self-views to see if the dolphins turned. They presented marked areas to the self-view television and turned. The results suggest self-examination over social behavior.

Abstract: Marten and Psarakos have presented some evidence which suggests that objective self-awareness and possibly representations of self may characterize the dolphins' experience of self. Their research demonstrates the possibility of similarities in the sense of self between primate species and dolphins, although whether dolphins have subjective self-awareness, personal memories, and theories of self--all important facets of the sense of self in humans--was not examined. Clearly, even this limited evidence was difficult to achieve; the difficulties in adapting methods and coding behavior are quite apparent in their report. Future progress, however, may depend upon clarification of what are the necessary components for a sense of self and an explication of how these might be reflected in dolphin behavior. We are mindful of the authors' point (pp. 219 and 220) that the dolphin lives more in an acoustic than a visual environment. Thus, while tasks relying upon vision may reveal the presence or absence of the sense of self in primates, it might well be the case that in dolphins self-related experiences might be better revealed in auditory tasks. But then, what is the nature of human self-awareness in terms of audition? While both conceptual and methodological hurdles remain, Marten and Psarakos have demonstrated that important questions can be asked about the minds and phenomenal worlds of nonanthropoid species.