Intergenerational Family Relations This book offers a synthesis of social science and evolutionary approaches to the study of intergenerational relations, using biological, psychological and socio- logical factors to develop a single framework for understanding why kin help one another across generations. With attention to both biological family relations and in-law and step-relations, it provides an overview of existing studies cen- tred on intergenerational relations – particularly grandparenting – that incorporate social science and evolutionary family theories. This evolutionary social science approach to intergenerational family relations goes well beyond the traditional nature versus nurture distinction. As such, it will appeal to scholars across a range of disciplines with interests in relations of kinship, the lifecourse and the sociol- ogy of the family. Antti O. Tanskanen is Senior Researcher in the Department of Social Research at the University of Turku, Finland. Mirkka Danielsbacka is Senior Researcher in the Department of Social Research at the University of Turku, Finland. “This book is of interest to all family scholars but in particular those scientists seeking to understand better the complexities of intergenerational relations. The real pleasure in reading this book is that it challenges one’s traditional thinking about intergenerational relations. I strongly recommend it to all family scholars but particularly those seeking new ideas.” – Ann Buchanan, Professor Emeritus, Department of Social Policy and Intervention, University of Oxford, UK “In a rapidly ageing world, the contributions that grandparents make to children, and the pleasures that they derive from making those contributions, are hot topics of research and discussion in the social sciences. In this timely review and syn- thesis of what anthropologists, demographers, evolutionary biologists, historians, psychologists and sociologists have separately discovered about grandparents, Tanskanen and Danielsbacka provide an invaluable resource for workers in all these fields, as well as for those struggling to bring evidence-based practice to social work and other applied areas.” – Martin Daly, Professor Emeritus, Department of Psychology, Neuroscience and Behaviour, McMaster University, Canada “It is only fitting that social scientists from the homeland of Westermarck should be the first to blend biological and social science approaches to the study of inter- generational relations and the family. Tanskanen and Danielsbacka show how theories from social science and biology are complementary and can be seam- lessly blended together to organize and explain findings from the study of inter- generational relations, plus generate new hypotheses for further studies. A must read for anyone with an interest in the study of intergenerational relations and the family.” – Rosemary L. Hopcroft, Professor, Department of Sociology, University of North Carolina, USA “This ambitious book provides an inclusive synthesis concerning studies on inter- generational relations among humans. Reading this book will strongly benefit all biologists and social scientists working with family relations.” – Virpi Lummaa, Professor, Department of Biology, University of Turku, Finland Routledge Advances in Sociology For a full list of titles in this series, please visit www.routledge.com/series/SE0511 Social Generativity A Relational Paradigm for Social Change Edited by Mauro Magatti The Live Art of Sociology Cath Lambert Video Games as Culture Considering the Role and Importance of Video Games in Contemporary Society Daniel Muriel and Garry Crawford The Sociology of Central Asian Youth Choice, Constraint, Risk Mohd. Aslam Bhat Indigenous Knowledge Production Navigating Humanity within a Western World Marcus Woolombi Waters Time and Temporality in Transitional and Post-Conflict Societies Edited by Natascha Mueller-Hirth, Sandra Rios Oyola Practicing Art/Science Experiments in an Emerging Field Edited by Philippe Sormani, Guelfo Carbone and Priska Gisler The Dark Side of Podemos? Carl Schmitt’s Shadow in Progressive Populism Josh Booth and Patrick Baert Intergenerational Family Relations An Evolutionary Social Science Approach Antti O. Tanskanen and Mirkka Danielsbacka Performing Fantasy and Reality in Contemporary Culture Anastasia Seregina Intergenerational Family Relations An Evolutionary Social Science Approach Antti O. Tanskanen and Mirkka Danielsbacka First published 2019 by Routledge 2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN and by Routledge 711 Third Avenue, New York, NY 10017 Routledge is an imprint of the Taylor & Francis Group, an informa business © 2019 Antti O. Tanskanen and Mirkka Danielsbacka The right of Antti O. Tanskanen and Mirkka Danielsbacka to be identified as authors of this work has been asserted by them in accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988. The Open Access version of this book, available at www.taylorfrancis.com, has been made available under a Creative Commons Attribution-Non Commercial-No Derivatives 4.0 license. Trademark notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data A catalog record has been requested for this book ISBN: 978-1-138-09187-0 (hbk) ISBN: 978-1-315-10780-6 (ebk) Typeset in Times New Roman by Deanta Global Publishing Services, Chennai, India Contents List of figures viii List of tables ix List of boxes x Foreword xi Preface xiv 1 Cooperative breeding species 1 2 Theories on intergenerational relations 12 3 Structure of intergenerational relations 49 4 Factors related to intergenerational relations 63 5 Grandparents and parental childbearing 87 6 Grandparents and child wellbeing 100 7 Grandparent wellbeing 120 8 What about aunts and uncles? 135 9 An evolutionary social science approach 147 Index 159 Figures 3.1 Life expectancy in selected countries 52 3.2 Child–parent–grandparent relationships from the child’s perspective 54 3.3 Grandparent–child–grandchild relationships from grandparents’ perspective 55 3.4 Biological and non-biological intergenerational family relationships 56 3.5 (a) Family types in which mothers have children with different partners. (b) Family types in which fathers have children with different partners 58 3.6 Family types when mothers have a stepparent (example in the figure considers maternal grandfather’s step-relatedness to a grandchild) 59 3.7 Family types when mothers have foster or adoptive parents (example in the figure considers maternal grandparents’ relatedness to a grandchild) 59 3.8 Family types when children have foster or adoptive parents 60 8.1 Relatedness among aunts, uncles, parents and niece/nephew 136 8.2 Relatedness among aunt, uncle, parents and niece/nephew when maternal aunt and paternal uncle are monozygotic twins to mother and father 137 8.3 Relatedness among aunts, uncles, parents and niece/nephew when aunts and uncles are half-siblings to mother and father 138 Tables 2.1 Degree of genetic relatedness between the self and kin 19 2.2 Key evolutionary predictions for biased grandparental investment 22 2.3 Key social science predictions for biased intergenerational relations 28 Boxes 1.1 Intergenerational relations 2 1.2 Grandparental investment 4 1.3 Naturalistic fallacy 6 2.1 Ultimate reasons and proximate mechanisms 13 2.2 Conscious and unconscious motives behind human behaviour 15 2.3 Inclusive fitness theory 18 2.4 Parental investment theory 20 2.5 Grandparental endowment 35 Foreword Intergenerational family relations: An evolutionary social science approach covers a gambit of hot topics across the social and natural sciences that have direct implications for understanding family function, relationships and out- comes. In recent decades, dramatic demographic changes have pushed the issues of intergenerational exchange and intergenerational relations to centre stage in policy, service and academic debate. Increased shared lifespans between genera- tions, reduced birth rate, and increased individual wealth and investment per child mean that generations have more opportunities to influence each other than ever before in human history. Simultaneously, recent reductions in state investment, increased rates of divorce and gender biases in rates of remarriage mean families are increasingly diverse. These times of change have seen the value of families and their relationships increase. Intergenerational family relations makes a valu- able contribution to this burgeoning field of enquiry. Crucial to a comprehensive view of the myriad factors that impact on and are consequences of family relations is a multi-level, interdisciplinary approach. Intergenerational family relations successfully achieves this by introducing the reader to an interdisciplinary perspective that takes them from broad population, historical and evolutionary level analyses to detailed differences in dyadic rela- tionships between family members. This enables the authors to critically explore questions related to why grandparenting exists, and the health impact grandparent- ing may or may not have on family members, parental birth rates and grandchild development, the influence of the welfare state, and the roles of aunts and uncles. It is a privilege for me to write this foreword as I have known