Conflicts over food, access to mates, or other limited resources can sometimes escalate into aggression. In species that form social groups, these aggressive conflicts can jeopardize the benefits of group living, such as enhanced access to valued resources, necessitating the development of behavioural mechanisms that either mitigate conflicts, prevent aggressive escalation or resolve disputes. Two important mechanisms for managing the effects of disputes involve postconflict (PC) affiliative behaviour, either between the former opponents (called ‘reconciliation’) or between one opponent and a third party. Even though numerous studies have tested reconciliatory and third‐party affiliation tendencies in primates, for non‐primate animals little systematic data are available. We performed behavioural observations on three groups of captive domestic dogs (Canis familiaris) and used a PC/MC method to test the existence of reconciliation and third‐party affiliation in this species. The results of this study clearly indicate that both reconciliation and third‐party PC interactions are present in the domestic dog, and form important social mechanisms of the domestic dog. Furthermore, familiar individuals showed a significantly higher proportion of reconciled conflicts than did unfamiliar individuals, and also displayed fewer conflicts. Finally, we show that most of the third‐party affiliations involve the victim of a conflict and that victim‐directed affiliation outweighs victim‐initiated third‐party affiliation in these PC interactions.

In a mixed-sex, captive group of hamadryas baboons (Papio hamadryas hamadryas) we investigated whether female grooming relationships are affected by their dominance ranks. Seyfarth's [1977] grooming for support model and Barrett et al. 's [1999] biological market model both predict that in primate groups where competition for monopolizable resources is high, grooming among females is based, at least partly, on the interchange of grooming for rank-related benefits, and that rank thus influences the distribution of grooming in females. Contrary to this prediction, our results show that despite the existence of a linear dominance hierarchy, rather strict dominance relationships, and high food-related aggression rates, grooming among female hamadryas baboons is not affected by rank and is only exchanged for itself. This is understandable since rank differences in our study group only result in differential access to limited, preferred food items that are not actively shared. Although some females are more likely to tolerate one another at the food pile, this tolerance is not determined by their grooming efforts and interchange of grooming for rank-related benefits does not occur. We conclude that female hamadryas baboons groom others in order to be groomed by them, which is supported by our observation that grooming reciprocity within a dyad increases when more grooming occurs in this dyad. Our results indicate that grooming is indeed a valuable commodity in itself, probably because of its stress-and tension-reducing effect. Based on our findings, the existing groom trade model is extended to include circumstances in which monopolizable resources are available but are not traded for grooming. Am. J. Primatol. 55:25-42, 2001.

Several studies conducted from an evolutionary perspective have documented differential investment in grandchildren by lineage. The majority of these studies have used retrospective ratings by grandchildren, but only a fraction of these studies have examined actual grandparental behavior. Here we focus on the interaction between distance and lineage on face-to-face contact with a (random) grandchild in a large scale sample. Our main prediction is that maternal grandparents are significantly more willing to travel in order to see their grandchild. While controlling for initiative of contact, urbanization, sex and age of the grandchild, educational attainment, marital status and age we found a significant interaction between distance and grandparent type on frequency of contact with a grandchild. Maternal grandmothers were significantly more inclined than paternal grandfathers and grandmothers to maintain frequent face-to-face contact, as distance between grandparent and grandchild increased. The results are discussed with reference to evolutionary theories of grandparental investment.

Evolutionary theory suggests that maternal grandparents will invest more in their grandchildren than paternal grandparents, due to the difference between the certainty of maternity and the uncertainty of paternity. Most tests of this prediction have tended to use retrospective ratings by grandchildren rather than examining grandparental behaviour. Using a large-scale data set from the UK (n>7000), significant differences are shown between maternal and paternal grandparents in terms of frequencies of contact with their newborn grandchildren, while controlling for a wide range of other variables. Maternal grandparents also provided a significantly wider range of financial benefits than paternal grandparents. Maternal grandparents were also more likely to provide essentials and gifts and extras for the baby. Multiple correspondence analysis showed that contact frequencies systematically related to other measures of grandparental investment, indicating that contact frequencies are a useful proxy measure to examine overall investment. Findings are discussed with reference to the paternity uncertainty hypothesis.

Abstract. Evolutionary theory suggests that maternal grandparents will invest more in their grandchildren than paternal grandparents, due to the difference between the certainty of maternity and the uncertainty of paternity. Tests of this prediction have tended to use retrospective ratings by grandchildren rather than self-reported behaviour by grandparents. Using a large-scale dataset from the Netherlands, we show significant differences between maternal and paternal grandparents in terms of frequencies of contact with their grandchildren, while controlling for a wide range of other variables. Our results show biases consistent with the paternity uncertainty hypothesis.

In this paper we present two compatible hypotheses to explain interest in celebrity gossip. The Learning Hypothesis explains interest in celebrity gossip as a by-product of an evolved mechanism useful for acquiring fitness-relevant survival information. The Parasocial Hypothesis sees celebrity gossip as a diversion of this mechanism, which leads individuals to misperceive celebrities as people who are part of their social network. Using two preliminary studies, we tested our predictions. In a survey with 838 respondents and in-depth interviews with 103 individuals, we investigated how interest in celebrity gossip was related to several dimensions of the participants' social lives. In support of the Learning Hypothesis, age proved to be a strong predictor of interest in celebrities. In partial support of the Parasocial Hypothesis, media exposure, but not social isolation, was a strong predictor of interest in celebrities. The preliminary results support both theories, indicate that across our life span celebrities move from being teachers to being friends, and open up a list of future research opportunities.

Two questions are asked: (1) Which relation is there between the dominance hierarchy and communication? (2) Which are the dominance determining factors that are a result of group life ("group factors") and that cannot be found in pairs of animals? Melanochromis auratus, a cichlid fish from Lake Malawi, is studied under laboratory conditions as a representative model. Dominance relations in pairs of animals differ from those (between the same fishes) in groups of conspecifics. In groups M. auratus establishes and maintains a linear dominance hierarchy, of which the communicative structure is described and discussed. The number of aggressive interactions between two group members, is determined by the rank number of the actor and the reactor. Most interactions occur between rank neighbours. "Group factors" are looked for by analysing the clustering of all possible chase-interactions. Four categories of such clusterings are discussed: a preceding aggressive interaction can have an influence on high-ranked animals, the effect of such an influence is directed towards low-ranked animals. The stable hierarchy can be changed by successive circle fights. The highest-ranked group members always intervene in circle fights in order to stabilize the hierarchy, for their own benefit. This is another "group factor". An alpha animal has to spend all its energy in obtaining and maintaining its rank status. When it looses this position, it drops down the hierarchy. The benefit of the alpha place could be the reproductive succes.

Iconic representations (i.e., figurative imagery and realistic art) only started to appear consistently some 45,000 years ago, although humans have been anatomically modern since 200,000-160,000 years ago. What explains this? Some authors have suggested a neurocognitive change took place, leading to a creative explosion, although this has been contested. Here, we examine the hypothesis that demographic changes caused cultural "cumulative adaptive evolution" and as such the emergence of modern symbolic behavior. This approach usefully explains the evolution of utilitarian skills and tools, and the creation of symbols to identify groups. However, it does not equally effectively explain the evolution of behaviors that may not be directly adaptive, such as the production of iconic representations like figurines and rock art. In order to shed light on their emergence, we propose to combine the above-mentioned cultural hypothesis with the concept of sensory exploitation. The concept essentially states that behavioral traits (in this case iconic art production) which exploit pre-existing sensory sensitivities will evolve if not hindered by costs (i.e., natural selection). In this view, iconic art traditions are evolved by piggy-backing on cumulative adaptive evolution. Since it is to date uncertain whether art has served any adaptive function in human evolution, parsimony demands paying more attention to the primary and a functional mechanism of sensory exploitation as opposed to mechanisms of models based exclusively on secondary benefits (such as Miller's, for instance, in which art is proposed to evolve as a sexual display of fitness).