The human life span continues to increase even in already low-mortality C L a i r f James R. Carey populations—with major implications for societies and economies. e e y Classical evolutionary theory accounts for survival only through the / S T age of reproduction. A more elaborate theory, integrating biological p u Shripad Tuljapurkar a l and demographic perspectives, is required to explain these current j a n trends in longevity and to gauge their future course. The papers col- p Editors u lected in this volume contribute to the development of such a theo- r ry. The authors are leading scientists from demography, evolutionary k a biology, and field ecology, equipped to draw insights not only from r human populations but also from the comparative mortality pat- terns and environmental circumstances of many other species: mam- mals, birds, fish, and insects. The opening chapter presents an overview of the evolutionary and genetic bases of aging and senes- cence, within and between species, and of the additional role of social evolution. Subsequent chapters explore the selective forces that shape Life Span life span patterns in various species—not least, in fruit flies; present an economic optimization model of the evolution of life span; and analyze the surprising phenomenon of the apparent slowing of the rate of increase in human mortality with age at the oldest ages. A final chapter attempts a synthesis of the various approaches to Evolutionary, Ecological, explaining and predicting age patterns of mortality. and Demographic About the Editors James R. Carey is Professor, Department of Entomology, University of California at Davis; and Senior Scholar, Center for the Economics and Demography of Aging, University of California at Berkeley. Shripad Perspectives Tuljapurkar is Morrison Professor of Population Studies and Professor of Biological Sciences, Stanford University. P o p u l a t i o n A Supplement to Vol. 29, 2003 C o u POPULATION n c AND i l DEVELOPMENT REVIEW Cover design by Charles & Ruth Kaplan Population and Development Review seeks to advance knowledge of the interrelationships between population and socioeconomic development and provides a forum for discussion of related issues of public policy. EDITOR Paul Demeny MANAGING EDITOR Ethel P. Churchill EDITORIAL COMMITTEE Paul Demeny, Chair Geoffrey McNicoll Ethel P. Churchill Michael P. Todaro Susan Greenhalgh EDITORIAL STAFF Robert Heidel, Production Editor Y. Christina Tse, Production/Design Margaret A. Knoll, Circulation Sura Rosenthal / Mike Vosika, Production ADVISORY BOARD John C. Caldwell Milos˘ Macura Mercedes B. Concepción Carmen A. Miró Richard A. Easterlin Asok Mitra Akin L. Mabogunje Samuel H. 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Individuals and institutions wishing to apply for complimentary subscriptions should send requests on letterhead stationery to the above address stating the nature of professional involvement in development- and population-related issues. Volumes are available on microfilm from Xerox University Microfilms, 300 North Zeeb Road, Ann Arbor, Michigan 48106. PDR 29 Supp inside front cover 1 7/6/06, 3:11 PM LIFE SPAN: EVOLUTIONARY, ECOLOGICAL, AND DEMOGRAPHIC PERSPECTIVES LIFE SPAN: EVOLUTIONARY, ECOLOGICAL, AND DEMOGRAPHIC PERSPECTIVES James R. Carey Shripad Tuljapurkar Editors POPULATION AND DEVELOPMENT REVIEW A Supplement to Volume 29, 2003 POPULATION COUNCIL New York ©2003 by The Population Council, Inc. All rights reserved. Library of Congress Cataloging-in-Publication Data Life span : evolutionary, ecological, and demographic perspectives / James R. Carey, Shripad Tuljapurkar, editors. p. cm. Includes bibliographical references. ISBN 0-87834-111-0 (pbk. : alk. paper) 1. Life spans (Biology) 2. Longevity. 3. Population biology. 4. Demography. I. Carey, James R. II. Tuljapurkar, Shripad, 1951- QP85 .L583 2003 612.6’8—dc21 2003042903 ISSN 0098-7921 ISBN 0-87834-111-0 Printed in the United States of America. CONTENTS Preface vii Acknowledgments xi Life Span: A Conceptual Overview 1 JAMES R. CAREY How and Why Do Aging and Life Span Evolve? 19 STEVEN HECHT ORZACK Ecological Correlates of Life Span in Populations 39 of Large Herbivorous Mammals JEAN-MICHEL GAILLARD ANNE LOISON MARCO FESTA-BIANCHET NIGEL GILLES YOCCOZ ERLING SOLBERG Environment and Longevity: The Demography of the Growth Rate 57 MARC MANGEL Life Span in the Light of Avian Life Histories 71 ROBERT E. RICKLEFS ALEX SCHEUERLEIN Life Span Extension of Drosophila melanogaster: Genetic and Population Studies 99 LAWRENCE G. HARSHMAN Interspecies Differences in the Life Span Distribution: Humans versus Invertebrates 127 SHIRO HORIUCHI Embodied Capital and the Evolutionary Economics of the Human Life Span 152 HILLARD KAPLAN JANE LANCASTER ARTHUR ROBSON Rescaling the Life Cycle: Longevity and Proportionality 183 RONALD LEE JOSHUA R. GOLDSTEIN Survival Beyond Age 100: The Case of Japan 208 JEAN-MARIE ROBINE YASUHIKO SAITO Life Course, Environmental Change, and Life Span 229 JEAN-MARIE ROBINE The World Trend in Maximum Life Span 239 JOHN R. WILMOTH JEAN-MARIE ROBINE Post-Darwinian Longevity 258 JAMES W. VAUPEL Hazard Curves and Life Span Prospects 270 KENNETH W. WACHTER AUTHORS 292 PREFACE This volume is based on a series of papers presented at the workshop “Life span: Evolutionary, ecological, and demographic perspectives,” held 14–18 May 2001 at the Petros M. Nomikos Conference Centre on the Greek island of Santorini. The specific aims of the Santorini workshop were threefold: first, to bring to- gether leading scientists from demography, evolutionary biology, and field ecol- ogy to integrate and synthesize concepts in gerontology, demography, ecology, and evolution as they pertain to aging and longevity at the level of the organ- ism; second, to foster greater interaction between biologists and demographers, including the development of collaborative research on the biodemography of aging and longevity; third, to assemble a set of papers written to be accessible to a wide audience and designed to have lasting value to readers. To this end the chapters in this volume have been substantially developed beyond the con- ference presentations and rigorously reviewed. The volume is concerned with the biodemography of life span, a subject that has recently emerged at the confluence of demography and biology. Over the twentieth century, human life span measured as period life expectancy has increased by more than 50 percent in most industrialized countries, driving concern about the benefits and costs of longer life and raising keen interest in whether we can maintain the past rate of increase in life span. Biodemography brings together methods, materials, theories, and analyses from both biology and demography with the aim of understanding the past and anticipating the future of life span. Traditionally, demographers have focused on the age pattern of death within populations and on the consequences of mortality change for popula- tions, societies, and economies. Biologists have studied aging in terms of its ultimate (i.e., evolutionary) and proximate (i.e., mechanistic and genetic) causes within species and in terms of variability within and between populations and species. To set the stage, the first chapter, by James Carey, presents a broad overview of these viewpoints and their contribution to understanding the na- ture and determinants of life span. Carey also discusses the role of social evolu- tion as a potential accelerator of increase in life span. The thirteen chapters that follow fall in four broad groups: those con- cerned primarily with biological mechanisms, observations, or theories of ag- ing; those that develop new theories of aging that are not biologically based but use economic or statistical arguments; those that analyze old-age mortality among humans; and, finally, a synthesis. The first group begins with a theoretical overview by Steven Orzack. He uses an explicitly evolutionary approach, based on allele frequencies and de- mographic theory, to examine the significance of environmental variability as a selective