Animal Personalities - Behavior, Physiology and Evolution

Animal Behaviour 87 (2014) 239e241

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Animal Behaviour journal homepage: www.elsevier.com/locate/anbehav

Book Reviews (US) Animal Personalities: Behaviour, Physiology, and Evolution. Edited By Claudio Carere, Dario Maestripieri. Chicago: University of Chicago Press (2013). Pp. ixD507. Price $45.00 paperback. As the editors note in their introduction to this volume, anyone who has spent much time with domesticated animals ‘knows’ that they have personalities. Following a recent upsurge of interest in the topic, we now know that personality is present in species representing a diverse array of other phyla (e.g. nematodes, cnidarians, molluscs, arthropods, and arachnids) as well as in chordates. Personality is usually defined as between-individual variation in behaviour that is consistent across time or situations; at least, this is the definition that I am using in this book review. Where possible I refer to correlations between behaviours used in different contexts as ‘behavioural syndromes’, following Sih, Bell, & Johnson (2004). This volume nicely summarises the current state of play at an exciting time for the field. Recent studies have increasingly asked questions about the mechanistic and developmental underpinnings of personality, the extent to which personality is heritable and about its function. Although animal personality has received much attention from behavioural ecologists over the last decade (e.g. Dall, Houston, & McNamara, 2004), the range of study questions covers a broad range of disciplines, connecting with each of Tinbergen’s original four questions in ethology (Tinbergen, 1963). Both the taxonomic and conceptual breadths are well represented in this book. Section One provides a taxonomic review, the second section deals with genetics, ecology and evolution and the third with proximate mechanisms and development; the final section covers potential applications of animal personality research. While each section has its own particular theme, many chapters are unified by a persistent and fundamental question: what is personality? It might well be the case that we all have an intuitive understanding of personality, but defining it, or at least agreeing on consistent terminologies, remains tricky. It is useful to have in one volume a compilation of different approaches that authors from diverse backgrounds have taken to this. While rarely incompatible, these different ways of describing animal personality surely reflect a field that although large is still maturing. This book will likely be an instrumental contribution to this process. The taxonomic section kicks off with a chapter on personality in invertebrates. As the authors point out, ‘the invertebrates’ represent at least 98% of animal diversity, and studies on species from four phyla are covered in this one chapter. There are in-depth reviews on specific research programmes, but the main messages from this chapter are (a) that, yes, animal personality is present in animals additional to those that belong to one well-studied subphylum and (b) given how convenient many invertebrates are to work with, further work on invertebrate personality could be highly productive. The remaining chapters in Part I, each on a particular vertebrate taxon, illustrate how intensive studies on well-known groups are leading to fundamental insights. In Chapter 2 we learn

about key hypotheses for the maintenance of a boldnessaggression syndrome in sticklebacks. One lesson that jumps out from this chapter is that the best insights come when study systems are well chosen with regard to the biological question. In sticklebacks, comprising both oceanic and freshwater species, the larger number of freshwater populations represents an adaptive radiation from oceanic ancestors. Therefore, behaviour in ancestral and descendent populations can be compared, allowing the mapping of behavioural syndromes onto the new environments into which the freshwater species adapted. Another lesson from this chapter is that, in a field where statistical methods are developing apace, important insights can still be achieved using straightforward experiments and their associated tests. For example, a simple test of correlation shows us how boldness and aggression are associated across populations. Chapter 3 reviews avian personality, describing how complimentary strands of studies conducted in aviaries and in the field provide new insights into the physiology and heritability of personality. The final two taxon-based chapters cover nonhuman primates and humans, respectively. Both raise interesting philosophical questions, but the crux of these is to what extent can and should researchers in the two fields, animal personality and differential psychology, learn from each other? One barrier is the different traditions of scoring behaviour versus the use of personality ratings. While ratings are used in some nonhuman studies, the different approaches both lead to, and possibly arise from, differences in terminology and, more importantly, in study questions. Nevertheless, the overall impression given by the taxon-based section is that analogous consistent between-individual differences in behaviour could be present in a wide range of animals (although admittedly I am not too sure about how a construct such as agreeableness could, for example, be applied to sea anemones). Clearly the taxon-based chapters are not light on conceptual material, but the next two sections get very much stuck in. Many of the advanced statistical ideas currently used in animal personality research were developed in the field of quantitative genetics, and Chapter 6 shows how this approach (e.g. using the animal model) can lead to major advances in our understanding of the heritability of personality traits, and how the expression of these interacts both with the environment that an individual finds itself in and with age. This chapter also raises the exciting prospect that cuttingedge molecular techniques will reveal the loci of personality, as well as discussing the possible roles for life-history trade-offs and the various forms of balancing selection in maintaining variation within populations. Chapter 7 picks up on some of these themes. Having constructed an influential statistical definition of personality, the authors consider how we could identify the key evolutionary mechanisms at play, and they review the empirical studies where this has been attempted. Chapter 8 uses a verbal rather than statistical definition for personality, describing a generalised framework of one-through to multidimensional behavioural syndromes that are consistent between and within individuals. It’s handy to have these two approaches exposited in consecutive

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Book Reviews (US) / Animal Behaviour 87 (2014) 239e241

chapters, because having something explained in more than one way is always of benefit. The key aim of this chapter, though, is to explore the potential for links between personality, mating behaviour and cooperation, in particular how variation in social situation may drive personality variation. Chapter 9 summarises a significant body of recent theoretical work, by explaining current hypotheses about the roles of variation in state and of state-dependent variation in behaviour. Part 3 moves into development and underlying mechanisms. Chapter 10 considers the influence of genes, environment and epigenetic effects (also discussed in chapter 3), with a particular focus on maternal effects and early developmental experiences in rodents. Chapter 11 continues the general theme of parental influence on the behaviour of offspring, this time drawing contrasts between oviparous and placental vertebrates. In Chapter 12, the neuroendocrine correlates of personality in birds and mammals are discussed, along with fascinating insights into the types of mechanism that might constrain behavioural plasticity in these groups. Taken together, these chapters make a convincing argument for homologies in some mechanistic bases for personality across vertebrates (although less is known about the proximate causes of personality in the other 98% of animal diversity). The final chapters provide an invaluable primer on how knowledge about animal personality can be applied to problems such as conservation, animal and human health and animal welfare. Providing exemplars of applied personality research, these chapters will no doubt be essential reading for those attempting to initiate projects in this area. Overall, this book comprises a suite of clearly written, highly informative and extensively referenced chapters that are organised into a logical sequence. The editors seem to have taken a decision not to overly constrain authors into a rigid framework or terminology. Given the abundance of conceptual papers that have been published in recent years, some readers would perhaps have preferred a firmer sense of coherence across the contributions. On the other hand, one might argue that the field is not quite ready for this, and that an imposition of rigid definitions, for example, would stifle an ongoing debate. On balance, I think that the approach taken by the editors is appropriate. Any reader desirous of getting up to speed with this field will want to learn about the diversity of angles from which personality is studied, discussed and described. As an overview of the field in its current state, this book absolutely works. It showcases a rapidly developing subject where study questions are likely to be increasingly influenced by the availability of powerful statistical techniques and perhaps also by molecular biology. We also see that the field has not lost touch with the very basic natural history observation upon which it is based. This is reassuring, because as Tinbergen (1963) argued, while experiments and analysis are key to progress, to neglect the observational and documentary sides of ethology would diminish the field. In Animal Personalities: Behaviour, Physiology, and Evolution, we are presented with a healthy diversity of ideas about the future priorities for personality research in animals. What comes across clearly is that animal personality now intersects with many areas of animal behaviour and may increasingly influence the way that many researchers make observations, ask questions, design experiments and interpret data. This volume effectively encapsulates the current state of the field, and I recommend it highly. It is often a challenge for those interested in animal personality to synthesise a coherent model from the wide range of research questions, terminologies and techniques that they read about. Carere & Maestripieri should be congratulated for marshalling the material in this volume in a way that will encourage readers to do just this, and for this reason I can also recommend this book as a very satisfying and enjoyable read.

Mark Briffa Plymouth University, Drake Circus, Plymouth PL4 8AA, U.K.

References Dall, S. R. X., Houston, A. I., & McNamara, J. M. (2004). The behavioural ecology of personality: consistent individual differences from an adaptive perspective. Ecology Letters, 8, 734e739. Sih, A., Bell, A., & Johnson, J. C. (2004). Behavioral syndromes: an ecological and evolutionary overview. Trends in Ecology & Evolution, 19, 372e378. Tinbergen, N. (1963). On aims and methods in ethology. Zeitschrift für Tierpsychologie, 20, 410e433.

http://dx.doi.org/10.1016/j.anbehav.2013.10.020

Oxytocin, Vasopressin and Related Peptides in the Regulation of Behavior. Edited By Elena Choleris, Donald W. Pfaff, Martin Kavaliers. Cambridge: Cambridge University Press (2013). Pp. xiiiD393. Price $110.00 hardback. The neurohormones oxytocin and vasopressin are members of a closely related family of nonapeptides (peptides with nine amino acids) that are extremely old, dating back hundreds of millions of years, and that serve multiple functions related to reproduction and other fitness-relevant outcomes. One of the most exciting developments in recent times is the discovery that the vertebrate nonapeptides strongly impact social behaviours of great interest to animal behaviourists, including sociality, social recognition and social learning, mating systems, vocal signalling, aggressive behaviour, and avoidance of pathogen-infected conspecifics. Some of these new findings, such as the role of vasopressin in socially monogamous partner preferences of prairie voles, have received a great deal of attention from both the scientific community and the popular media. The published literature on nonapeptides and social behaviour has been increasing rapidly and extending to a more diverse array of vertebrates. Numerous reviews have appeared in multiple journals (e.g. the March 2012 special Issue of Hormones and Behavior, edited by Young & Flanagan-Cato). Animal behaviourists, especially graduate students and younger researchers, who are attracted to the possibility of studying nonapeptide mechanisms in relation to their favourite social behaviour in their favourite animals, need a way to enter into and understand the literature that will guide without overwhelming them. Instructors who teach mechanisms of animal behaviour would also benefit from a clear and up-to-date overview. The time is right for a high-quality comprehensive and accessible book that surveys and evaluates the field with critical and forward directed eyes. Is this that book? The goal as stated by the editors sends mixed signals about the intended audience. On page i we read that ‘this is a valuable resource for graduate students, researchers, and clinicians in this rapidly developing field’. In the editors’ preface (page viii), however, we read that ‘This text is intended by the three of us to serve upper-level undergraduate students and beginning graduate students.’. The first statement seems like the more accurate description. It is very difficult to imagine using this book, or most other multi-authored edited volumes for that matter, as an undergraduate text. Even for an audience of readers at the graduate student or more advanced level, there are challenges to overcome with respect to organization and presentation. The volume begins with a set of four chapters (Part I) on the oxytocin and vasopressin