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No matter what we do, however kind or generous our deeds may seem, a hidden motive of selfishness lurks--or so science has claimed for years. This book, whose publication promises to be a major scientific event, tells us differently. In Unto Others philosopher Elliott Sober and biologist David Sloan Wilson demonstrate once and for all that unselfish behavior is in fact an important feature of both biological and human nature. Their book provides a panoramic view of altruism throughout the animal kingdom--from self-sacrificing parasites to insects that subsume themselves in the superorganism of a colony to the human capacity for selflessness--even as it explains the evolutionary sense of such behavior. Explaining how altruistic behavior can evolve by natural selection, this book finally gives credence to the idea of group selection that was originally proposed by Darwin but denounced as heretical in the 1960s. With their account of this controversy, Sober and Wilson offer a detailed case study of scientific change as well as an indisputable argument for group selection as a legitimate theory in evolutionary biology. Unto Others also takes a novel evolutionary approach in explaining the ultimate psychological motives behind unselfish human behavior. Developing a theory of the proximate mechanisms that most likely evolved to motivate adaptive helping behavior, Sober and Wilson show how people and perhaps other species evolved the capacity to care for others as a goal in itself. A truly interdisciplinary work that blends biology, philosophy, psychology, and anthropology, this book will permanently change not just our view of selfless behavior but also our understanding of many issues in evolutionary biology and the social sciences.
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Ii l( Unto Others Unto Others The E�oLution and PdychoLogy of Unde/foih Beha�ior Elliott Soher David Sloan Wilson Harvard University Press Cambridge, Massachusetts London, England 1 998 Copyright © 1998 by the President and Fellows of Harvard College All rights reserved Printed in the United States of America Library of Congress Cataloging-in-Publication Data Sober, Elliott. Unto others: the evolution and psychology of unselfish behavior I Elliott Sober, David Sloan Wilson. p. cm. Includes bibliographical references and index. ISBN 0-674-93046-0 (hardcover) 1. Altruism. BF637.H4S65 2. Helping behavior. 1998 171'.8- ni and p; < pi.="" the="" ratio="" si="n;" lni="" serves="" as="" a="" measure="" of="" group="" benefit.="" to="" find="" the="" frequency="" p="" of="" the="" gene="" in="" the="" global="" population,="" we="" need="" to="" add="" the="" total="" number="" of="" altruistic="" genes="" across="" all="" groups="" and="" divide="" by="" the="" total="" number="" of="" genes="" in="" all="" groups.="" the="" frequency="" of="" the="" altruistic="" gene="" before="" selection="" is:="" p="(''l.niPi)/('l.ni)" =="" p="" +=""> (2.4) The terms P and n denote the average gene frequency and the size of the average group. The covariance term, cov(n,p), measures the 74 A Unified EvoLutionary Theory of SociaL Behavior Evolutionary Altruism association between group size and gene frequency before selection. Suppose that 50 groups have size n 10 and that each member possesses the gene for altruism (p 1). Another 50 groups are of size 20 and contain no members with the gene for altruism (p = 0). The frequency of the gene in the global population of individuals is � = 50011500 = .333, while the average gene frequency in a group IS .5(0) + .5(1) = 0.5 (that is, half the groups have the gene). These two numbers don't match because of a negative correlation between group size and gene frequency. The covariance term accounts for this association, suc