Elsevier

Psychoneuroendocrinology

Volume 23, Issue 8, November 1998, Pages 891-904
Psychoneuroendocrinology

SOCIAL RELATIONSHIPS AND THE MANAGEMENT OF STRESS

https://doi.org/10.1016/S0306-4530(98)00059-6Get rights and content

Abstract

Two different types of social relationships exist in mammalian social systems: dominance relationships and social bondings. This article shows that both are crucial for the management of stress. The following general conclusions are derived: (1) In stable social systems, established dominance relationships result in predictable behaviour. As a consequence, low positions in the hierarchy do not necessarily lead to enhanced endocrine stress responses. Under conditions of instability, however, distinct increases in the activities of the pituitary-adrenocortical- and the sympathetic-adrenomedullary systems are found; (2) The ability to establish and to respect dominance relationships is a prerequisite to build up stable social systems. Whether this ability is realized, however, depends on social experiences made during behavioural development. The time around puberty seems to be essential for the acquisition of those social skills needed to adapt to unfamiliar conspecifics in a non-stressful and non-aggressive way; (3) Stress responses can be ameliorated by the presence of members of the same species. This phenomenon is called social support. In general, social support cannot be provided by any conspecific, but the ability to give social support is restricted to bonding partners. In most mammalian species mothers are important bonding partners for their infants. In some species bondings also occur between adult individuals; and (4) On a physiological level the bonding partner reduces the activities of the pituitary-adrenocortical- and the sympathetic-adrenomedullary systems. On a psychological level he/she can be regarded as a ‘security-giving and arousal-reducing structure’. This is true irrespective of whether the bonding partner is the mother, in the case of an infant, or a male or a female in the case of an adult individual. © 1998 Elsevier Science Ltd. All rights reserved.

Section snippets

INTRODUCTION

Two different types of social relationships can be found in mammalian social systems. On the one hand dominance relationships exist which are established and maintained by agonistic behaviours. As a consequence, the members of a social system are characterized by differences in social status. Dominant animals mainly display aggressive behavior, the subordinate individuals display defensive and submissive behaviours. The dominants possess priority of access to the necessities of life (e.g. food)

METHODS

The guinea pigs (Cavia aperea f. porcellus) used were descendants of a heterogeneous stock of 40 animals obtained from a breeder in 1975. They were kept under constant conditions (12:12 light:dark cycle; photoperiod 0700–1900h; temperature 20±2°C; relative humidity ≈60%). Commercial guinea pig diet and water were available ad lib. This diet was supplemented regularly with hay.

The animals were kept under different housing conditions: mainly in colonies, in pairs and individually. Colonies of 24

Social organization and stress

The effects of increasing population density on behaviour were studied in a first experiment. We placed a small number of guinea pigs (four males and two females) in a 16 m2 enclosure. The animals lived and reproduced in a rather peaceful way and after 20 months there were about 50 individuals in the colony. However, the astonishing point was that even at such high individual numbers no indications of increased social stress were found: the reproductive success of the females (that is the

GENERAL CONCLUSIONS

Which general conclusions can be drawn from these findings? When we look at the relevant literature in a comparative way five points emerge which obviously apply to most mammals:

(1) Social stratification seems to be a general phenomenon in all mammals studied so far in their natural habitats as well as in captivity. Even in species where close cooperation, social tolerance and amicable relations predominate, distinct differences in social status have been described among the adult individuals

Acknowledgements

We are grateful to Professor Dr Dietrich von Holst and to Professor Dr Elisabeth Spinelli de Oliveira for valuable comments on the manuscript. This research was supported by the Deutsche Forschungsgemeinschaft.

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