The Cambridge Handbook of Play

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Edited by Peter K. Smith , Jaipaul L. Roopnarine Frontmatter

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Play takes up much of the time budget of young children, and many animals, but its importance in development remains contested. This comprehensive collection brings together multidisciplinary and developmental perspectives on the forms and functions of play in animals, in children in different societies, and through the lifespan.

The Cambridge Handbook of Playcovers the evolution of play in animals, especially mammals; the development of play from infancy through childhood and into adulthood; historical and anthropological perspectives on play; theories and methodologies; the role of play in children’s learning; play in special groups such as children with impairments or those suffering political violence; and the practical applications of playwork and play therapy. Written by an international team of scholars from diverse disciplines such as psychology, education, neuroscience, sociology, evolutionary biology, and anthropology, this essential reference presents the current state of theﬁeld in play research.

peter k. smith is Emeritus Professor of Psychology at the Unit for School and Family Studies, Department of Psychology at Gold- smiths, University of London. He has published thirty books, and more than 200 refereed journal articles. He is author ofUnderstanding School Bullying(2014), co-author ofUnderstanding Children's Devel- opment(sixth edition, 2015) and co-editor of theHandbook of Child- hood Social Development(second edition, 2010).

jaipaul l. roopnarine is the Pearl S. Falk Professor of Human Development at Syracuse University, New York, and Professor of Developmental Psychology at Anton de Kom University of Suri- name. He has co-edited several notable volumes on culture and development and is the editor of theCaribbean Journal of Psychology.

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978-1-107-19251-5 — The Cambridge Handbook of Play Edited by Peter K. Smith , Jaipaul L. Roopnarine Frontmatter

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The Cambridge Handbook of Play

Developmental and Disciplinary Perspectives

Edited by

Peter K. Smith

Goldsmiths College, University of London

Jaipaul L. Roopnarine

Syracuse University

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University Printing House, Cambridge CB2 8BS, United Kingdom One Liberty Plaza, 20th Floor, New York, NY 10006, USA 477 Williamstown Road, Port Melbourne, VIC 3207, Australia 314–321, 3rd Floor, Plot 3, Splendor Forum, Jasola District Centre, New Delhi–110025, India

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Information on this title: www.cambridge.org/9781107192515 DOI: 10.1017/9781108131384

This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press.

First published 2019

Printed and bound in Great Britain by Clays Ltd, Elcograf S.p.A.

A catalogue record for this publication is available from the British Library.

Library of Congress Cataloging-in-Publication Data Names: Smith, Peter K., editor.

Title: The Cambridge handbook of play : developmental and disciplinary perspectives / edited by Peter K. Smith, Goldsmiths College, University of London, Jaipaul L.

Roopnarine, Syracuse University, New York.

Description: Cambridge, United Kingdom ; New York, NY : Cambridge University Press, 2019. | Includes bibliographical references and index.

Identiﬁers: LCCN 2018024260 | ISBN 9781107192515 (hardback : alk. paper) | ISBN 9781316640906 (paperback : alk. paper)

Subjects: LCSH: Play. | Child development.

Classiﬁcation: LCC GV1200 .C365 2019 | DDC 649/.5–dc23 LC record available at https://lccn.loc.gov/2018024260 ISBN 978-1-107-19251-5 Hardback

ISBN 978-1-316-64090-6 Paperback

Cambridge University Press has no responsibility for the persistence or accuracy of URLs for external or third-party internet websites referred to in this publication and does not guarantee that any content on such websites is, or will remain, accurate or appropriate.

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Figures

2.1 Topographic landscape illustrating how the more complex behavioural and cognitive repertoire in endothermic vertebrates, especially mammals, may have resulted from a reorganization of the ontogeny of some response systems

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2.2 A cladogram for rodents, spanning the three major divisions of the order

18 2.3 A sequence of playﬁghting for a pair of juvenile deer mice 21 2.4 A cladogram for murid rodents, on which is mapped the

degree of complexity of playﬁghting

22 9.1 Percentages of mothers and fathers who played with children

in Caribbean and Latin American countries

147 9.2 Percentages of mothers and fathers who played with children

in African countries

148 16.1 Pieter Bruegel the Elder,Kinderspiele, 1560 283 16.2 Courtyard of the Dutch abbey of Middelburg in Zeeland 283 16.3 In the street near the city hall.Children’s Games, by Adriaen

Pietersz van de Venne, 1625

284 16.4 Cornelius Ketel,Double Portrait of a Brother and Sister,

circa 1600

288 16.5 Isaac van Swanenburg,Portrait of Catharina van

Warmondt, 1596

291 16.6 Jakob Seisenegger,Portrait of a Mother with Her Eight

Children, 1565

291

18.1 Biomes and political divisions 323

24.1 An action prompt card for make-believe play 451 24.2 A role prompt card for make-believe play 452 24.3 Example of a play plan made by a pre-school child 452

28.1 Example of a playworld 515

39.1 Compoundﬂexibility: a positive spiral 709

39.2 The BRAWGS continuum 712

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Tables

12.1 Differentiating serious aggression from rough play page205

12.2 Beneﬁts of sociodramatic rough play 209

12.3 Strategies for supporting rough play 214

18.1 Location of indigenous groups in the South American territory 324

18.2 Play artefacts 328

23.1 Analytical frame 426

24.1 Mature play observation tool descriptions 446

25.1 Adult guided beginning role-play 465

26.1 Different ways that‘pedagogues’(preschool teachers and leisure-time personnel) relate to children’s play

484 29.1 Variables representing early literacy skills 535

29.2 Language and literacy curricula 537

39.1 The Playwork Principles 706

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Contributors

e. j. marijke achterberg, Department of Animals in Science and Society, Faculty of Veterinary Medicine, Utrecht University, the Netherlands

colleen baish cameron, Department of Human Development and Family Science, Syracuse University, Syracuse, NY, USA

doris bergen, Educational Psychology, University of Miami, Oxford, OH, USA

carol berman, Department of Anthropology, The State University of New York, NY, USA

anna beresin, University of the Arts, Philadelphia, PA, USA elena bodrova, Tools of the Mind, Lakewood, CO, USA anna bortoli, RMIT University, Melbourne, Australia

adam howell boyette, Writing Program, Duke University, Durham, NC, USA

milda bredikyte, Vilnius, Lithuania

fraser brown, Childhood Development and Playwork Team, Leeds Beckett University, Leeds, UK

p. margaret brown, Melbourne Graduate School of Education, University of Melbourne, Parkville, Australia

gordon m. burghardt, Department of Psychology, University of Tennessee, Knoxville, TN, USA

anam.a.carvalho, Institute of Psychology, University of Sao Paulo, Sao Paulo, Brazil

esther cohen, Baruch Ivcher School of Psychology Interdisciplinary Center (IDC), Hebrew University of Jerusalem, Herzliya, Israel

cynthia j. cress, Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, NE, USA

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elise cuschieri, Arts and Play Therapies, Department of Psychology, University of Roehampton, Surrey, UK

kimberly l. davidson, Human Development and Family Studies, Central Michigan University, Mount Pleasant, MI, USA

crystal day-hess, Marsico Institute for Early Learning, University of Denver, Denver, CO, USA

elif dede yildirim, Department of Human Development and Family Studies, Auburn University, Auburn, AL, USA

pool ip dong, Department of Curriculum and Instruction, College of Education, Pennsylvania State University, State College, PA, USA susan engel, Williams College, Williamstown, MA, USA

beth ferholt, Early Childhood Education, Brooklyn College, Brooklyn, NY, USA

marilyn fleer, Foundation Chair of Early Childhood Education and Development, Monash University, Frankston Victoria, Australia carrie germeroth, Marzano Research, Centennial, CO, USA

artin go¨ ncu¨, Educational Psychology, University of Illinois at Chicago, Chicago, IL, USA

yumi gosso, Institute of Psychology, University of Sao Paulo, Sao Paulo, Brazil peter gray, Department of Psychology, Boston College, Chestnut Hill, MA, USA

pentti hakkarainen, Vilnius, Lithuania

sophia han, College of Education, University of South Florida, Tampa, FL, USA

maritta ha¨ nnika¨ inen, Department of Education, University of Jyväskylä, Jyväskylä, Finland

jennifer l. hart, School of Education, University of the Sunshine Coast, Queensland, Australia

thomas s. henricks, Department of Sociology, Elon University, Elon, NC, USA

james e. johnson, Department of Curriculum and Instruction, College of Education, Pennsylvania State University, State College, PA, USA eunjoo jung, Department of Human Development and Family Science, Syracuse University, Syracuse, NY, USA

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lila kossyvaki, Department of Disability Inclusion and Special Needs, School of Education, University of Birmingham, Birmingham, UK anne kultti, Department of Education, Communication and Learning, University of Gothenburg, Göteborg, Sweden

robert lecusay, School of Education and Communication, Jönköping University, Jönköping, Sweden

deborah j. leong, Tools of the Mind, Golden, CO , USA

alexandra long, Childhood Development and Playwork Team, Leeds Beckett University, Leeds, UK

lauren mcnamara, Department of Child and Youth Studies, Brock University, St. Catharines, Canada

gail f. melson, Department of Human Development and Family Studies, Purdue University, West Lafayette, IN, USA

hilkka munter, Kajaani, Finland

ageliki nicolopoulou, Psychology Department, Lehigh University, Bethlehem, PA, USA

monica nilsson, Stockholm, Sweden

despina papoudi, Department of Disability Inclusion and Special Needs, School of Education, University of Birmingham, Birmingham, UK michael m. patte, Department of Elementary Education, Bloomsburg University, Bloomsburg, PA, USA

anthony d. pellegrini, Bloomington, MN, USA

sergio m. pellis, Department of Neuroscience, University of Lethbridge, Canada

lacey e. peters, School of Education, Hunter College, CUNY, New York, NY, USA

linda pollock, Department of History, Tulane University, New Orleans, LA, USA

niklas pramling, Department of Education, Communication and Learning, University of Gothenburg, Göteborg, Sweden

briseida d. resende, Institute of Psychology, University of Sao Paulo, Sao Paulo, Brazil

jaipaul l. roopnarine, Department of Human Development and Family Science, Syracuse University, Syracuse, NY, USA, and Department of

Contributors xiii

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Psychology and IGSR, Anton de Kom University of Suriname, Paramaribo, Suriname

kathleen roskos, Department of Education and School Psychology, John Carrol University, University Heights, OH, USA

ingrid pramling samuelsson, Department of Education, Communication and Learning, University of Gothenburg, Göteborg, Sweden

fiona scott, School of Education, University of Sheffield, Sheffield, UK lynda l. sharpe, Research School of Biology, Australian National University, Canberra, Australia

peter k. smith, Department of Psychology, Goldsmiths, University of London, UK

john a. sutterby, College of Education and Human Development, University of Texas-San Antonio, San Antonio TX, USA

beth blue swadener, School of Social Transformation, Arizona State University, Tempe, AZ, USA

michelle t. tannock, Child, Family and Community Studies, Douglas College, Vancouver, Canada

viviana trezza, Department of Science, Roma Tre University, Rome, Italy jennifer a. vadeboncoeur, Educational Psychology, University of Illinois at Chicago, Chicago, IL, USA

louk j. m. j. vanderschuren, Department of Animals in Science and Society, Faculty of Veterinary Medicine, Utrecht University, the Netherlands ditte winther-lindqvist, Aarhus University, Tuborgvej, Denmark mike wragg, Childhood Development and Playwork Team, Leeds Beckett University, Leeds, UK

akie yanagi, Department of Anthropology, The State University of New York, NY USA

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1 Editorial Introduction

Peter K. Smith and Jaipaul L. Roopnarine

Play remains a topic of continuing interest and fascination, for parents, teachers, researchers, and anyone interested in human nature. Play takes up much of the time budget of young children and many animals. Yet its nature and function remain contested. This book brings together a comprehensive collection of disciplinary and developmental perspectives on the topic. Differ- ent sections cover the evolution of play in animals, especially mammals including monkeys and apes; the development of play from infancy through childhood and into the lifespan; historical and anthropological perspectives on play; theories of play and methods of studying its different dimensions; the role of play in children’s learning and development; play in special groups such as children with impairments; and play spaces and the rights of children.

There are of course classical theories of play (see Chapter 20), and for children’s play the work of Lev Vygotsky from the 1930s remains inﬂuential, as is apparent in many chapters in Part V on play and learning. However, the modern study of play, in both animals and humans, became active again in the 1970s and 1980s. After a quieter period in the 1990s and early 2000s, recent years have seen a resurgence of interest in theorizing and research on play. With international contributors from thirteen countries and a range of disciplinary perspectives from evolutionary biology, neuroscience, developmental psychology, early childhood education, special education, anthropology, sociology, cultural and media studies, and history, we have aimed to provide a comprehensive collection of chapters on play, so that readers will get a clear picture of state-of-the-art thinking on the topic.

Part I of this Handbook focuses on the evolution of play. Gordon Burghardt and Sergio Pellis (Chapter 2) discuss five criteria for recognising and defining play, and consider the evolution of play in animal species, distinguishing primary, secondary, and tertiary process play in terms of function. This chapter emphasises the heterogeneity of play and indicates the use of computer simulations for modelling the costs and benefits of play. Neuro- science and particularly neurochemistry has also taken great strides in the study of play, as reviewed by Viviana Trezza, Marijke Achterberg, and Louk Vanderschuren (Chapter 3). Focusing on the proverbial laboratory rat, they make clear how sophisticated experimental techniques have given much insight into the neural underpinnings of social play in this species. Drawing

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on more naturalistic observations and experimental studies in a range of mammalian species, Lynda Sharpe (Chapter 4) takes a critical look at a range of hypotheses advanced to explain the functions of play, and the evidence for costs and benefits in various domains. It is clear that the evidence for benefits is mixed at best, and this chapter concludes with a plea for more focused hypothesis-testing experiments. Akie Yanagi and Carol Berman (Chapter 5) consider social play in non-human primates (monkeys and apes) and document the costs of such play (mostly play fighting, which can be risky); they argue that there are likely social skills benefits to balance such costs. They discuss how such costs can be reduced by use of play signals and appropriate choice of play partners. In considering human play, Peter Gray (Chapter 6) also opens with considerations of definition. He mentionsfive characteristics of human play (these may be compared with the five criteria in Chapter 2;

there is some overlap but also some differences). Reviewing the pioneering work of Groos, as well as more recent work on animal play, Gray moves on to consider play in hunter-gatherer groups (as best representing the kind of societal structure that humans evolved in). He considers hypotheses such as the role of play in learning and innovation and in promoting cooperation and egalitarianism. Humans also play with animals; indeed, the domestication of dogs from wolf-like ancestors, as well as later partial domestication of many other species, probably played a crucial role in human evolution. In Chapter 7, Gail Melson describes human-animal play, particularly focusing on the contemporary phenomenon of play with pets, raising interesting issues around the role of play in attachment, and the scaffolding of play (also picked up in discussions in the next section on parent-infant/child play).

Part II examines various types of human play from a developmental perspective. Building on the work of Piaget, Bruner, Gibson, and Thelen, as well as what we know from more recent work on brain development, Doris Bergen (Chapter 8) discusses infant sensorimotor play. She describes this as a dynamic systems process, ending by considering how such sensorimotor play is affected by recent technological developments (see also Chapter 14). In Chapter 9, Jaipaul Roopnarine, Elif Dede Yildirim, and Kimberly Davidson summarize a considerable amount of research on mother-child and father-child play in the early years. They pay particular attention to cultural and gender differences, and what may explain these. Possible links to developmental outcomes are considered. Much parent-child play is social, but Anthony Pellegrini (Chapter 10) discusses the development of play with objects. He carefully considers how play with objects can be distinguished from exploration, construction, and tool use and tool making. Much object play can be solitary, but Pellegrini also considers the role of object play in social learning and innovation. In Chapter 11, Ageliki Nicolopoulou examines pretend and social pretend play–the most distinctive kind of childhood play.

She considers its development and possible cultural universality and discusses how Lillard and colleagues have critiqued the evidence on the functional

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significance of pretend play, in part countering this with ideas from Vygotsky and Harris. Play fighting shows much more continuity with social play in mammals, and Jennifer Hart and Michelle Tannock (Chapter 12) survey the research on what they call rough play. They distinguish parent-child and peer- peer rough play, describing it as mainly a male phenomenon and emphasizing positive aspects of such play for learning and skill development. They end with important comments on how educators may sometimes misperceive such kinds of play, and how they can best support it. These different forms of play (object, pretend, rough) overlap, but also by middle childhood tend to mutate into rule-governed, game-like activities. Ditte Winther-Lindqvist (Chapter 13) contrasts the positions of Piaget and Vygotsky in the development of games with rules, and illustrates the developmental origins of this with extensivefield notes based on his own observations. Once beyond early childhood, however (and increasingly even in early childhood, Chapter 8), modern digital tech- nologies are an increasingly salient aspect of the sociocultural environment, with important ramifications on children’s play. Fiona Scott (Chapter 14) describes the developmental course of this, drawing especially on research in the cultural and media studies tradition. In Chapter 15, Jennifer Vadeboncoeur and Artin Göncü discuss playing and imagining in a lifespan perspective.

They draw specially on Vygotsky and the sociocultural perspective and discuss how playing and imagining can contribute to, for example, abstract thinking and self-direction.

Most research on human play is on contemporary children in Western societies, but in Part III several chapters foreground historical and anthropological perspectives. In Chapter 16, Linda Pollock looks at the historical evidence on play in early modern Europe. She documents how play was often seen as a distraction from learning, but how attitudes to play also changed over the centuries, partly inﬂuenced by philosophical and educational writings. In Chapter 17, Adam Boyette considers play in foraging societies;

although the evidence is from contemporary societies, they may provide insight into the kind of selection pressures affecting play through much of human evolution. He reviews different kinds of play and points out how play and work contexts may intermingle. Boyette also critiques Gray’s view (Chapter 6) that play in forager societies promotes egalitarianism but does consider what lessons may be learnt from the characteristics of forager play.

Yumi Gosso, Briseida Resende, and Ana Carvalho (Chapter 18) document studies of play in various South American indigenous communities, who also live by hunting and foraging but also small-scale agriculture. They too com- ment on how work activities for children (such as washing dishes or looking after younger siblings) can be used as play opportunities. Eunjoo Jung and Sophia Han (Chapter 19) examine play in societies, such as China, Japan, and Korea, inﬂuenced by Confucian values. They summarise six main aspects of Confucian values and how these may impact adult-child relationships and play, including ritual-based play and gendered play. They also consider

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the impact of Western inﬂuences and culture change in these societies on engagement in play.

Three chapters in Part IV are on theories of play and on research method- ology. Some contemporary theories of play are considered in many other chapters, but Thomas Henricks (Chapter 20) overviews the classic theories of play, from Schiller, Spencer, and Groos onward through the nineteenth and twentieth centuries. His chapter provides a roll-call of important theorists, many very well known but some less so. Among contemporary theorists, especially of human play, Brian Sutton-Smith has had a preeminent position.

In Chapter 21, Anna Beresin, Fraser Brown, and Michael Patte provide an account of Sutton-Smith’s early children’s books, his critique of Piaget, and his work on children’s folklore, ending with his theorising on play generally, including his posthumous book on play as emotional survival. Turning to methods of studying play, James Johnson and Pool Ip Dong (Chapter 22) start with conceptual issues, and then review a range of quantitative and qualitative methodologies. They conclude with examples of innovative methods being used in some contemporary play research.

An enduring topic of discussion and debate has been the role of play in young children’s learning. Part V provides an extensive examination of this topic. Throughout, the inﬂuence of Vygotsky’s thinking, even more than 80 years after his death in 1934, remains a key inspiration for many researchers in this area. Marilyn Fleer (Chapter 23) considers play and learning in family contexts. She provides an in-depth discussion of this, drawing on observations of various forms of play, and how they are structured, in an Australian family. In Chapter 24, Elena Bodrova, Deborah Leong, Carrie Germeroth, and Crystal Day-Hess draw very speciﬁcally on Vygotsky’s ideas, describing levels of pretend or make-believe play. They discuss how such play can be scaffolded inTools of the Mind, an early childhood curriculum based on these ideas. In Chapter 25, Pentti Hakkarainen and Milda Bredikyte similarly draw on Vygotsky’s levels of play, but especially emphasise his concept of the zone of proximal development (ZPD). They use this concept to consider in detail the role of the adult as a mediator of development in children’s play, for example, in structuring imaginative storytelling. Such themes are developed further by Niklas Pramling, Anne Kultti and Ingrid Pramling Samuelsson (Chapter 26). In particular, they discuss what is meant by concepts such as learning, and teaching, in the early child curriculum, how play relates to these, and how skilful adults can enhance this through socially responsive actions. In Chapter 27, Maritta Hännikäinen and Hilkka Munter develop similar themes, referring not only to the ZPD but to Vygotsky’s notion of the social situation of development–the changing relations between a child and his or her social reality. The ways in which teachers can enhance, but also sometimes hinder, children’s play are considered in detail.

In Chapter 28, Beth Ferholt, Robert Lecusay, and Monica Nilsson describe the concept of playworlds, in which creative play is developed between adults

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and children, based on Vygotsky’s theories. Besides picking up familiar themes around children’s play and learning, these authors highlight how adults too are learning and developing, illustrating this with a case study of a discussion among three preschool teachers. Pretend play, especially in its narrative or sociodramatic forms, is often linked to literacy development, and in Chapter 29, Kathleen Roskos (echoing Donald Rumsfeld) discusses the known knowns, the known unknowns, and the unknown unknowns in what is a considerable area of research. She covers many aspects of this, including recent digital developments such as use of apps and robotic puppets. In Chapter 30, Susan Engel discusses how gathering information, inquiry, and invention contributes to play, and how play in turn contributes to developing ideas. This is illustrated by four examples of play observed in 3- to 7-year-olds.

While much research on children’s play has described its educational implications in mainstream settings, there has also been interest in how play may be relevant for special groups of children and/or have more therapeutic implications. The chapters in Part VI consider such issues. One such special group comprises children with autism or autism spectrum disorders (ASD). It is known that these children have some delay or lack of interest in the full range of pretend play behaviours. Despina Papoudi and Lila Kossyvaki (Chapter 31) discuss the research on this and the educational implications, including how such play can be scaffolded by various kinds of social inter- action and technological support. In Chapter 32, Margaret Brown and Anna Bortoli consider play in children with sensory impairments, in particular visual and hearing impairments. Depending on context, there can be delays in social pretend play with peers, for example, and the authors discuss the role of adults and the risks and beneﬁts of inclusive education in this respect.

Another category of disability, physical impairments, covers primary conditions such as cerebral palsy and traumatic brain injury, and secondary outcomes of conditions such as Down syndrome or premature birth. In Chapter 33, Cynthia Cress describes how such conditions can affect object play and coordination, and interactions with parents and peers. She discusses how accurate assessment of difficulties, direct treatment, and specific skill training or coaching for parents can be helpful interventions. Play can also have diagnostic and therapeutic benefits for those with a range of medical conditions. Colleen Baish Cameron and Michael Patte (Chapter 34) review the provision of play facilities and opportunities for children in hospital, and how in the United States, for example, this can be facilitated by trained child life specialists. They end with a range of practical suggestions for improving play practices in health care settings. The psychoanalytic tradition has contributed to the development of play therapy for emotionally disturbed children, and in Chapter 35 Elise Cuschieri describes how ideas of play therapy have developed. She discusses the space, materials, therapeutic relationship, and the research evidence for effectiveness, drawing on a detailed case study of therapy with one child to illustrate the processes involved. Political violence

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and terrorism can be sources of trauma for any child unfortunate enough to witness these, and in Chapter 36, Esther Cohen describes the impact of this on children’s development and mental health. She enumerates four ways in which play can function to help children cope with these situations. She considers the phenomenon of post-traumatic play, often serious and morbid, and draws practical implications for ways of helping children in these circumstances.

Part VII concludes this Handbook by bringing together four chapters on play spaces and the rights of children. In Chapter 37, John Sutterby gives a comprehensive overview of play spaces, both indoors and outdoors. Heﬁrst considers space and materials in indoor classrooms, and then the design of outdoor play spaces. These raise considerations of accessibility and safety.

He considers community and adventure playgrounds, and the concepts of democratic, commercial, and virtual play spaces. For school-aged children, recess provides an opportunity for play, and this is the topic of Chapter 38 by Lauren McNamara. She provides a historical account of how attitudes and practice regarding recess breaks have changed, and the arguments for and against it in an educational context. She discusses the available research and gives a thorough account of the various aspects to be considered in optimising the social and play potential of recess. For older children, outdoor and adventure playgrounds provide opportunities for play, and the discipline of playwork has evolved in connection with the supervision of playgrounds and the facilitation of such play opportunities. This is described in Chapter 39, by Fraser Brown, Alexandra Long, and Mike Wragg, as a unique way of working with children. They enunciate the principles of playwork, and it is clear that while adult supervision and facilitation is important, the playwork movement generally places great emphasis on children’s freedom and the right to play as they wish (within broad constraints of safety and respect for others).

In this context they cite the UN Convention on the Rights of the Child (CRC).

This theme of children’s rights and the implications of the CRC are elaborated in Chapter 40 by Lacey Peters and Beth Swadener. They discuss how theories of play and attitudes to play can impact on the kinds of play opportunities provided for children. Giving examples from several countries, they strongly emphasise the rights of children, not only to be consulted but to be active participants in research and decision making.

As researchers in theﬁeld for more than several decades, we have enjoyed bringing together a wide range of scholars to contribute to this Handbook.

Some have been in theﬁeld a long time; others are earlier in their careers and bringing fresh perspectives on the topic. However, on a sadder note, while this Handbook was in preparation, several notable play scholars died. These include Brian Sutton-Smith, whose seminal work starting in folklore and moving into diverse areas of play is reviewed in Chapter 21. Another loss in the folklore area was Iona Opie, who with her husband Peter pioneered publications on observations of children’s games. Jaak Panksepp pioneered work in the neuroscience of emotions and was originally scheduled to write

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Chapter 3; the present authors of this chapter dedicate it to him. Panksepp is also a dedicatee of Chapter 2, as is Stan Kuczaj, one of theﬁrst psycholo- gists to write on language play. Another sad loss is Jim Christie, who wrote extensively on play and literacy. The work in this Handbook is in part a tribute to these recent scholars, and to those of earlier generations, who have helped take forward our understanding of an activity that is both enjoyable and valuable, that of play behaviour.

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2 New Directions in Studying the Evolution of Play

Gordon M. Burghardt and Sergio M. Pellis

Historically, theories and ﬁndings on the evolution of play have focused on identifying possible positive consequences or adaptive functions of play behaviour. This approach concentrated on play in the most playful species, primarily mammals, with special emphasis on non-human primates and humans. Today, we have a much greater comparative database on play and have more descriptive details on play in many species, not only within mammals but also in all other vertebrate classes as well as some invertebrates, and experimental support for some functions of play is accumulating. We now have some theories, such as surplus resource theory, that help to characterize the settings that facilitate play and its evolution. However, play is also a heterogeneous category and speciﬁc examples are better evaluated with narrower‘micro’theories that utilize more focused ethological, developmental, and life history data. In other words, global overarching theories for play are no longer viable in terms of prediction, even in humans, and thus evolutionary studies must take a more comparative and phylogenetic approach. By them- selves, studies of selected species such as laboratory rodents, rhesus monkeys, dogs, horses, chimpanzees, and children are not useful in addressing the evolution of play. This chapter will review new comparative research on diverse types of play in a wide range of species, computer simulation and modelling studies, neurophysiological substrates of play, and other areas to identify possible scenarios for play evolution, their implications for play researchers generally, and, most importantly, how they can be tested.

Our understanding of the evolution of play has had a controversial history.

In this chapter, we characterize play in animals and brieﬂy discuss its diversity.

We then give a brief overview of this history, citing sources reviewing these views in more depth than is possible here. We then present a few recent

* We dedicate this chapter to two recently deceased colleagues, Jaak Panksepp and Stan Kuczaj, who contributed so much to the study of play. We thank the many students and colleagues who have enriched our research and thinking about play over several decades, numerous granting agencies, and the participants in the Play, Evolution, and Sociality Working Group at the National Institute for Mathematical and Biological Synthesis at the University of Tennessee sponsored by the National Science Foundation, the US Department of Homeland Security, and the US Department of Agriculture through NSF Awards EF-0832858 and DBI-1300426, with additional support from the University of Tennessee, Knoxville. We also thank Vivien Pellis for her comments.

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theories that revisit the origin and evolution issue, giving most attention to current empirical and theoretical treatments on the phylogeny of play and some implications for studies of play in humans. Some of this material overlaps another recent chapter we wrote (Pellis & Burghardt, 2017) and we cite other sources for more details on the topics we introduce. We hope to whet the reader’s appetite for exploring this fascinating topic in more detail, as progress is coming fast after decades of relative stasis, especially since the publication of Fagen’s major review (Fagen, 1981) and the edited volume by Smith (1984).

Questions of origins and evolution address different, though related, processes. Recall that in On the Origin of SpeciesDarwin (1859) never actually discussed the origin of species (or life from non-life), instead devoting his efforts to the transmutation process of one (or groups of ) species to a different one. Here he famously championed natural selection as a primary, but not sole, underlying process, or mechanism, for such changes. Similarly, but even more pertinently, we address the origin of play from non-playful behaviour, as well as the course of play evolution among species once play has evolved. Our task is complicated by the fact that we now know that play is a heterogeneous category and that while all play shares some basic properties, or criteria by which we recognize instances of play, the evolutionary, developmental, functional, causal, and experiential aspects may differ considerably (Burghardt, 2005;

Pellis & Pellis, 2009). Here we will only discuss other aspects of play insofar as they help explicate issues of origins and evolution. Just as issues of origin and evolution need to be differentiated, so too the function of play has often been conﬂated with its origins and evolution (e.g., Müller-Schwarze, 1978), also leading to confusion that has bedevilled research and that we address elsewhere (Pellis et al., 2015).

What Is Play?

We recognize as play any behaviour in any animal that satisfies all five play criteria set forth by Burghardt (2005, 2011), which have been used by many authors to identify play in species and contexts where it has not formally been recognized, as well as accommodating all generally accepted traditional examples of play (Burghardt, 2014). These criteria are also helpful in focusing research on species for which preliminary descriptive observations or natural history reports suggest that at least some of the criteria are met, but the jury is out on others due to insufficient data. These problematic examples are called “play at the margins” in Burghardt’s survey of play throughout the animal kingdom and are particularly seen in invertebrates (Burghardt, 2005).

Theﬁve play criteria, all of which need to be satisﬁed in at least one respect, can be summarized as behaviour that

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1. appears incompletely functional in the context expressed 2. is voluntary, rewarding, pleasurable, or done for its own sake

3. is in some ways modiﬁed structurally or developmentally as compared with its functional counterpart

4. is repeated in recognizable but not necessarily invariant form

5. is initiated when the animal is not under more than mild stress due to poor health, bad environmental conditions, social upheaval, or intense conﬂict- ing motivational states such as hunger, thirst, wariness of enemies or predators, and so on.

These criteria have allowed identiﬁcation of behaviour meeting the play criteria in some members of all vertebrate classes as well as in octopus, insects, spiders, and crustaceans (Burghardt, 2005, 2014; Graham & Burghardt, 2010;

Pellis & Burghardt, 2017; also see the special issue ofCurrent Biology,25(1), 2015, on the Biology of Fun).

Play, of course, as in humans, can take many forms in diverse species.

Traditionally, animal play has been divided into three types: locomotor/rotational, object/predatory, and social, with the latter including play ﬁghting, chasing, and sexual/courtship play. In humans, many other types of play are recognized such as circular reactions (infants shaking a rattle), babbling, joking/teasing, sociodramatic, pretence, construction, games, and imaginary/

mental play. As many instances, albeit rudimentary, of virtually all types of human play occur in non-humans, it is reasonable to assume that they derived from the more basic forms of play observed in other species (Burghardt, 2005).

The task for students of play evolution is not only to trace the phylogeny of different types of play in extant, and perhaps ancestral, species but also to formulate and test hypotheses as to how the various types of play both originated and evolved from one another. Does the behaviour, for example, of animals pretending that a rubber mouse is prey or a Cuban crocodile blowing courtship bubbles at a red ball contain precursors to the elaborate pretend or make-believe play found in young children (Russ, 2015; Russ et al., 1999)? As physically vigorous social playﬁghting is most commonly studied in animals, our examples focus on this type of social play. Note that such rough- and-tumble play is often neglected in humans, especially children (Pellegrini &

Smith, 1998). Social playﬁghting in animals is, in fact, highly complex and involves many features usually shown in social play such as play signals, metacommunication, role reversals, and self-handicapping (Bekoff, 1972, 1975, 1995; Fagen, 1981; Pellis & Pellis, 2017).

The diverse signals used in mammalian play involving facial expressions, vocalizations, and body postures (such as the play bow in dogs) have been recently reviewed (Palagi et al., 2016). Controversy exists, however, on the communicatory function of many of these putative signals, as many of them involve movements and postures that occur during play ﬁghting. Conse- quently, it is often indeterminate whether a particular action is performed

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for a combat function rather than a communicatory one (Pellis & Pellis, 2015).

For example, although rolling over to supine during play in dogs has been subsumed as part of the behavioural measures thought to signify dominance asymmetries (Bauer & Smuts, 2007), detailed analysis of the correlated actions by both participants suggests that rolling over is mostly used as a defensive tactic. However, rolling over on the back can also be used as an invitation to play in dogs (Norman et al., 2015) and a number of other species, such as in black bear cubs (Burghardt & Burghardt, 1972) and juvenile vervet monkeys (Pellis et al., 2014b). In this way, such an action can have multiple functions during play (Smuts et al., 2015), suggesting that commonly recognized ‘signals’, such as the play bow in dogs, need to be evaluated empirically (Byosiere et al., 2016) to ensure that the different functional uses can be discerned.

The main lesson from these controversies regarding overt behavioural actions during play is that the communicatory functions of presumed play signals need to be empirically assessed rather than uncritically accepted (Pellis

& Pellis, 2015). Signals that are not essential to combat, such as adding facial gestures beyond the opening of the mouth, which is necessary to bite the partner during playﬁghting in some primates (e.g., Pellis & Pellis, 2011; Scopa

& Palagi, 2016), or vocal signals that are independent of combat actions (e.g., Kipper & Todt, 2002; Kisko et al., 2017), may be useful for understanding the contexts in which communication is critical.

Thus, even with a common type of play in a species that virtually everyone, of all ages and cultures, has observed, the nature of some essential elements has only recently been scrutinized. What we conclude about the mechanisms and function of speciﬁc play types and components does impact our analysis of their origin and evolution. Play indeed comprises a complicated set of phenomena. We will focus on the general origins of play and then selected phylogenetic approaches to the diversity of play observed in closely related species dealing primarily with changes within play of a given type.

Origins

The play bow in dogs is a specific component of play, as is play fighting generally, be it in dogs, monkeys, or rats. How did such play originate? Of course, we were not there when the first animals played, but can we gain some plausible ideas? Today we recognize that given the heterogeneous nature of play, the diverse types of play, and the observation that play seems to have evolved multiple times, no encompassing hypothesis or theory can adequately specify the origins, function, or causal mechanisms underlying all kinds of play. Historically, however, there are several views that have tried to do so. Three of these views, originating in the nineteenth century, are particularly associated with animal play and have been described in detail elsewhere (e.g., Burghardt, 2005; Henricks, 2015a; Müller-Schwarze, 1978) and briefly

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highlighted here. We will not, in this chapter, discuss the many subsequent views, theories, and viewpoints on play largely limited to human play by scholars such as Freud, Piaget, Huizinga, Vygotsky, Bakhtin, Turner, Caillois, Fein, Geertz, Sutton-Smith, Henricks, Smith, Pellegrini, and others that are covered in other chapters in this handbook and other sources (e.g., Henricks, 2015b; Johnson et al., 2015; Pellegrini, 2011). All theories of play, of course, ultimately depend on evolutionary support: biological, cultural, or both (Boyd & Richerson, 1985; Richerson & Boyd, 2005).

The earliest of these three classic views is by Herbert Spencer (1872), who, building on Schiller, provided a causal theory for play by positing that only

‘advanced’animals such as mammals with extended parental care would have the surplus metabolic energetic reserves enabling them to be able to blow off, as it were, excess energy through apparently useless behaviour that resembled their serious instinctive repertoire. This became known as surplus energy theory. Groos (1898) also focused on the importance of parental care by claiming that relatively carefree youth allowed animals to perfect the skills they would later need for survival in a relatively safe context. This became known as the instinct practice theory. Hall (1904) argued that play, especially in humans, could be explained as recapitulation of behaviour from ancestral stages, building on Haeckel’s views of species evolution. For example, adults often engage in hunting andfishing even when not needed for survival andfind these activities enjoyable and rewarding for their own sake. Similarly, most active competitive games involve activities formerly essential in warfare or otherfighting contexts involving hitting, tackling, throwing, chasing, etc., and this was no accident. Developmentally, recapitulation was seen in children playing with objects prior to engaging with them seriously, for example, girls with dolls and boys with toy weapons, and so on.

All these theories have been amended, critiqued, dismissed, and ridiculed, but all capture some truths about play. In an ecumenical approach to the work of these thoughtful pioneers and other early scholars, Burghardt (1984, 1988, 2005) combined their insights into a broad-scale theoretical approach, surplus resource theory to target the physiological, behavioural, ecological, social, and developmental factors that seem to underlie, in diverse ways, the appearance of play in many groups of animals. Surplus resource theory posits that surpluses of time and energy, along with a diverse behavioural repertoire and parental care that buffers animals from the necessity of protecting them- selves and acquiring all their resources on their own, accompany and facilitate play. This helps explain, for example, why play is much more common in endothermic (warm-blooded) animals born in an altricial state or necessitating extended parental care (Figure 2.1).

Furthermore, play can differ in its functional evolution. Some play may have no function, as play, at all (primary process play).Secondary process play serves to maintain functions, such as physical ﬁtness or sensory and motor abilities. Tertiary process play truly increases an animal’s competence in

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various domains (foraging, defensive, social among others) and may even produce evolutionarily and culturally important novel and innovative behaviour. These processes have been summarized in a ﬁgure available in Burghardt (2005), Pellis et al. (2015), Pellis et al. (2014a), and Pellis and Burghardt (2017).

What is very helpful in looking at the origins of play, unlike seeking ancestral conditions for the origins of life or key morphological and physiological innovations, is that all three processes of play can be observed in many species, including humans. Incipient play–play that appears prior to any functional consequences and thus is termed primary process play, may result from many factors including the need or drive to be active (boredom), developmental precursors of adult-like behaviour (precocious behaviour), motivational con- ﬂicts, lowered thresholds to stimuli, and intention movements. Such primary process play is not done for any speciﬁc adaptive function but may, through individual experiences and both genetic and cultural evolutionary processes, gain both secondary and tertiary functions. Indeed, the social play in rats (Pellis et al., 2014a), ground squirrels (Marks et al., 2017), and several species

Young Reptile

Young Mammal

Increasing Behavioral Complexity

Adult Reptile

Adult Mammal

Figure 2.1Topographic landscape illustrating how the more complex behavioural and cognitive repertoire in endothermic vertebrates, especially mammals, may have resulted from a reorganization of the ontogeny of some response systems. Changes in neonatal behaviour and its experiential basis derive from a more effective metabolism, extended parental care, and the consequent deterioration of precocial response systems that allowed play to evolve in response to the motivational and stimulus needs of the young animals and to provide an avenue for secondary and tertiary play processes.Reprinted from Burghardt, 1988.

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of primates (Palagi, 2011) has been shown to have tertiary properties. Tertiary process play may also undergird creativity and innovation (Bateson & Martin, 2013; Burghardt, 2015; Kuczaj, 2017), the transition from behavioural to mental imagination and planning, and the pace of evolution itself. But play can also evolve into apparently non-playful behaviour such as rituals (Burghardt, 2017).

Besides comparative observations on extant species, hypotheses on play origins can also be tested by mathematical and computer modelling. Auerbach et al. (2015) used a very simple model to show that play could originate from non-play in animals and become established in a population, albeit at low rates, even though it was costly and non-functional (“frivolous”). When play was made functional by aiding foraging success, the play genes increased, but eventually collapsed if the animals were living withﬁnite resources. If the play allowed new resources to become available, then play might continue to expand, though not in an unlimited fashion. The irony of the model’sﬁndings is that costly play behaviour may result in greater costs to the nonplayers.

A recent study on male macaque monkeys (Macaca assamensis) showed that while vigorous play facilitated rapid acquisition of motor skills, the cost was somewhat slower growth (Berghänel et al., 2015). A life history dynamic state- dependent model based on social play enhancing foraging success also has appeared (Grunloh & Mangel, 2015) but did not address nonfunctional play, yet was more realistic than the Auerbach model in that sexual reproduction was incorporated. Other types of mathematical models and simulations are also needed and now possible, especially individual agent-based ones (Schank, Burghardt, & Pellis, 2018) that can test both the role of various costs and beneﬁts of play such as predation risk, energy depletion, skill acquisition, and so on, and how actions used during play are constructed (Bell et al., 2015).

Social play models necessitate more complex modelling. For example, Durand and Schank (2015) published an intriguing agent-based model in which juvenile play facilitated cooperation, and individuals with social play experiences were more successful in the stag hunt game. In this game, both cooperating and not cooperating produces a beneﬁcial payoff, but the payoff associated with cooperating is larger. The model found that if cooperators and non-cooperators selectively congregated together into small groups, the players would be more successful. The authors view this as a way in which cooperation could have evolved through learning indirectly via playful interactions early in life. The model has similarities to the ﬁnding that learning facilitates the evolution of communication (MacLennan & Burghardt, 1993).

Evolutionary Transformations of Play

The diversity of social play in rodents provides a detailed example of how evolutionary transformation in play may occur and offers insights on the mechanisms involved and the novel functions that may arise (Pellis & Pellis,

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Figure 2.2A cladogram, a tree diagram that reveals the pattern of relatedness across a group of species, for rodents, spanning the three major divisions of the order. The clade that includes the rat (Rattus), the domestic mouse (Mus), the deer mouse (Peromyscus), the grasshopper mouse (Onychomys), the fat sand rat (Psammomys), the Syrian golden hamster (Mesocricetus), the Djungarian hamster (Phodopus), voles (montane vole,Microtus montanus; prairie vole,M. ochrogaster; and European vole,M. agrestis) represents murid (mouse-like) rodents. The clade that includes the North American ground squirrels (Spermophilus) and the grey tree squirrel

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2009; Pellis et al., 2014a). There are two major dimensions along which the organization of play fighting in this order can vary. First, play fighting can involve competition for body targets that are derived from several different functional contexts. Playfighting can involve competition for access to body targets otherwise competed over during aggressive encounters, sexual encounters, greeting and grooming encounters, or, in some cases for obligate carni- vores, such as the grasshopper mouse, predatory encounters (Pellis & Pellis, 2017). Comparison of the distribution of sex-derived playful competition with aggression-derived playful competition across the order shows that some lineages predominantly engage in the sexual version, others the aggressive version, and others combine both to varying degrees, with the ancestral condition being a state in which the two co-occur (Figure 2.2).

Why different lineages engage in one type of playfighting more than another remains unresolved, but some clues are suggestive. In ground squirrels, there is a marked variation even among closely related species, with some mostly competing for sexual targets and some mostly for aggressive targets. Those mostly engaging in the sexual version live in social systems in which males live separ- ately from females, whereas those that predominantly engage in the aggressive version tend to live in relatively stable mixed sex groups. It is possible that in the former, the primary pathway to reproductive success for males is to access receptive females as quickly as possible, whereas in the latter, reproductive success may depend more on the ability of males within a group to gain dominance (Pellis & Iwaniuk, 2004). In this regard, it is interesting that in some social marmots it has been shown that juvenile playfighting influences dominance status in adulthood (Blumstein et al., 2013). That is, the social or mating systems of different species may influence which traits are more salient and so which are more likely to be engaged in as play, and this, in turn, may have differential selective advantages. Larger datasets, not only for rodents but also for other taxa, such as primates, are needed, to test these possibilities using modern comparative statistical methods (O’Meara et al., 2015).

Second, within a more limited clade of rodents – the murid (mouse-like rodents) – which predominantly engage in the same form of play ﬁghting, competing for targets otherwise contacted during precopulatory behaviour, there is a marked variation in the complexity involved (Pellis et al., 2014a).

Figure 2.2(cont.)(Sciurus) represents squirrel-like rodents. The third clade that includes the guinea pig (Cavia) and the degu (Octodon)

represents the guinea pig–like rodents. Whether the playﬁghting is mostly aggressive, mostly sexual, or some combination of both is mapped onto the cladogram. The degree of complexity in the form of play performed is not indicated, which will be discussed for murid rodents below. Legend: dotted, sexual play only; dashed, mostly sexual play; grey, about equal amounts of sexual and aggressive play; black, mostly aggressive play.Reprinted from Pellis

& Iwaniuk (2004), with permission of the authors.

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For example, while renowned for their acrobatic locomotor/rotational play, house mice do occasionally launch attacks toward the nape of the neck. This is like the targeting of the nape present during adult sexual encounters but is unlike the biting attacks directed at the lowerflanks and dorsum during seriousfighting, so akin to other murid rodents with regard to social play, mimicking sex not aggression (see Figure 2.2). Moreover, when one mouse jumps or runs toward the neck of another, the recipient evades contact by jumping andfleeing away.

Thus, the playﬁghting evident in this species is rare and relatively simple, but it can be even simpler in some species (Pellis & Pellis, 2009). In some, such as the European vole, there is nape attack, but no attempt to defend the nape, and in others, such as some species of Australian hopping mice, there is neither attack nor defence. Complexity is added when the recipient of an attack actively defends against contact, which then leads to playful wrestling. As shown in a sequence in deer mice (Figure 2.3), playﬁghting involves one animal attacking another as it reaches to contact the play target (in this case, the nape of the neck) (panels a–c), which is then accompanied by the recipient defending itself and so blocking access to the target (b–e). Once the target is successfully defended, the defending animal may launch a counterattack (f–h), which can lead to a successful role reversal (i and j). As shown in deer mice, the defending animal rolls over onto its back (see panels c–e in Figure 2.3) and by doing so maximizes bodily contact. Different species, even closely related ones, use such tactics to varying degrees–for example, prairie voles do so much more than do montane voles. Of those species that engage in defence that leads to wrestling, some follow this up with counterattacks, as seen in Figure 2.3, that not only prolong further wrestling, but also lead to role reversals, and some do not.

Even among species that engage in all three subcomponents leading to the most complex forms of playﬁghting–attack, wrestling defence, and counterattack–there are quantitative differences as well. In deer mice, for example, encounters that include counterattacks constitute less than 10% of interactions, whereas in rats, it is more than 40%. Importantly, in this subclade of rodents, the playﬁghting mostly involves competition for targets otherwise contacted during precopulatory behaviour, thus behaviour from the same functional system is being compared during play (Pellis & Pellis, 2009).

Coalescing these different aspects of playﬁghting into an index of complexity and then mapping this onto a cladogram reveals several important features of how play may evolve (Figure 2.4). First, the base of the tree shows that the ancestral condition involves species that have moderate degrees of complexity in their play; second, the most complex forms can emerge independently in different branches of the clade; third, some terminal branches show that play can be reduced in complexity over evolution. As will be detailed below, the most complex forms of playﬁghting constitute tertiary process play, and the tree shows that it is built on by transformations from secondary process (i.e., intermediate levels of complexity). That play can regress to primary process play, or even to no play, suggests that complex forms of play are sustained by

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adaptive functions, so that in the absence of such functions, play is eliminated (i.e., the costs exceed the beneﬁts).

In studying the subcomponents of play ﬁghting in a diverse range of rodents, it becomes evident that changes in the frequency of attack and in the likelihood of defence, or in the type of defence tactics most often used, vary across species independently of one another. Moreover, developmental studies

Figure 2.3A sequence of playﬁghting for a pair of juvenile deer mice.

As detailed in the text, the sequence includes attack, defence, and

counterattack. Reprinted from Pellis et al. (1989), with permission from Wiley.

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Figure 2.4A cladogram for murid rodents (see Figure 2.2), on which is mapped the degree of complexity of playﬁghting. Legend: white or light stippling for absent or simple play; dark stippling for moderately complex play; grey or black for complex play. Note that the position of some species has been altered in this cladogram to that shown in Figure 2.2. Especially evident is the changed clustering of the hamsters (Mesocricetusand Phodopus), which arose from the use of more recent consensus about

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within some of these species similarly reveal that the frequency of attack, likelihood of defence, and differential use of different defensive tactics wax and wane independently of one another. Rats, with one of the most complex patterns of play ﬁghting in murid rodents (seeRattusin Figure 2.4), having been domesticated for well over 100 years and selectively bred to produce diverse strains, provide further insights into how play may evolve.

Domesticated laboratory rats are all derived from wild Norwegian brown rats, with different strains having different selection histories. There are many different strains, but for current purposes we will focus on strains that have been used extensively for research on play. For example, one of theﬁrst strains selected from wild rats is the pure albino Wistar strain; then with a backcross with a wild rat, a hooded line (pigmented eyes, black head, and hood extending down the shoulders) was developed, the Long–Evans hooded strain.

Further selective breeding of Wistar rats led to the Sprague Dawley strain. As an independent lineage to consider, the domesticated brown rat was derived more recently, directly from wild congeners. A systematic comparison of the play of wild rats with that of Wistar, Long–Evans, Sprague Dawley, and brown rats revealed that all domesticated strains initiate more playful attacks– consistent with the view that domestication leads to increased playfulness (Burghardt, 1984). However, with regard to defence tactics, all differed from the wild type in some ways, although differently across strains (see Himmler et al., 2016, for a summary of this comparative work). That is, playful attack and playful defence can be selected for change in different ways. This conclu- sion is supported by comparisons involving specially selected lines of rats derived from these and other strains (for primary sources, see references in Himmler et al., 2016; Pellis & Pellis, 2009).

Comparisons across closely related species of murid rodents and across strains of domesticated rats show that playﬁghting is comprised of independent subcomponents, suggesting that evolutionary change in playﬁghting may be mosaic in form. Identifying the genetic and neural substrates of these different subcomponents and how they are transformed during evolution would be a major step forward in understanding the phylogeny of play. Again, a clue into such mechanisms is afforded by focusing on the tertiary process play of rats.

Starting with the pioneering work by Jaak Panksepp (1998), a network of neural structures from the hindbrain, midbrain, and forebrain has been shown to be engaged in the playﬁghting of rats (Siviy, 2016; Vanderschuren et al.,

Figure 2.4(cont.)phylogenetic relationships. These changes do not affect the main take-home messages from bothﬁgures–the relative simulation of sex and aggression varies markedly across lineages (Figure 2.2) and changes in complexity occur independently across lineages (Figure 2.3).Reprinted from Whishaw et al. (2001), with permission by Wiley.

The Cambridge Handbook of Play

The Cambridge Handbook of Play

Developmental and Disciplinary Perspectives

Peter K. Smith

Jaipaul L. Roopnarine

Contents

Figures

Tables

Contributors

1 Editorial Introduction

2 New Directions in Studying the Evolution of Play