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Anne Innis Dagg, Social Behavior of Older Animals, Baltimore: John Hopkins University Press, 2009, 225 pages.
Anne Dagg, who has conducted field research on African ungulates, has laboriously gathered information on older social animals from a huge range of sources. Since this is not a wellresearched topic, she combed through monographs, journals, newspapers and personal accounts to assemble this record based on a wide range of social animals. The approach is much like Elizabeth Thomas' (1993) work on dogs because the animals are named and referred to from the perspective of their value to the social unit, although all the material is meticulously referenced. Birds and humans are also included among the examples of social species, with the result that this book provides a valuable cross-taxonomic evaluation of the importance of older animals in the social sphere, as well as some comparisons of social functions useful when studying humans.
Most theoretical approaches to animal behaviour focus on the adaptive success of the reproductive strategies of males and females. According to Darwin, the differentially successful production of offspring is the most important contribution an animal can make, while sterile or post-reproductive individuals are adaptively useless. However, more modern theories assess the contributions of these individuals to the success of their relatives' offspring and they have thus become the focus of recent work. This book does consider the reproductive contribution of such individuals but mainly focuses on the behavioural and social transition from prime adult to old adult.
Some older animals continue to reproduce, although at a slower rate, and this may be individually adaptive in terms of having the resources and energy to successfully rear these late stage offspring. Older animals also contribute to their groups as repositories of knowledge about the location of resources when conditions become difficult. They can be excellent leaders as is demonstrated by elephant matriarchs who guide their families over hundreds of miles to find water and food. The herds led by the oldest matriarchs seem to be the most successful. The old females seem to know the individual calls of many others sent from long distances and respond...