The new psychology of love by robert j sternberg

Hendrick 8 Searching for the Meaning of “Love” 171 Part III Implicit Theories of Love 11 A PrototypeApproach to Studying Love 225 Beverley Fehr Part IVCultural Theories of Love 12 Evolut

A N D K A R I N W E I S

The New Psychology

of Love

Yale University Press

New Haven &

London

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This book may not be reproduced, in whole or in part, including illustrations,

in any form (beyond that copying permitted by Sections 107 and 108 of the U.S Copyright Law and except by reviewers for the public press), without written permission from the publishers.

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Printed in the United States ofAmerica by

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Preface vii

1 Introduction 1

Karin Weis

Part I Biological Theories

2 A Dynamical Evolutionary View of Love 15

Douglas T Kenrick

3 A Behavioral Systems Approach to Romantic LoveRelationships: Attachment, Caregiving, and Sex 35Phillip R Shaver and Mario Mikulincer

Part II Taxonomies of Love

7 Styles of Romantic Love 149

Clyde Hendrick and Susan S Hendrick

8 Searching for the Meaning of “Love” 171

Part III Implicit Theories of Love

11 A PrototypeApproach to Studying Love 225

Beverley Fehr

Part IVCultural Theories of Love

12 Evolutionary and Cross-Cultural Perspectives on Love:

The Influence of Gender, Personality, and Local Ecology

on Emotional Investment in Romantic Relationships 249David P Schmitt

13 PassionateLove: Cross-Cultural and Evolutionary

Perspectives 274

Debra Lieberman and Elaine Hatfield

14 Individualism, Collectivism, and the Psychology of Love 298Karen K Dion and Kenneth L Dion

15 Conclusion: The Nature and Interrelations of Theories

of Love313

Karin Weis

Contributors 327

Index 329

In the mid-1980s, the senior editor of this volume, Robert J Sternberg,thought that the field of love had become sufficiently advanced that therewas room for an edited volume to be published on the psychology of love.

In 1988, The Psychology of Love was published by Yale University Press.The volume was edited by Robert J Sternberg and Michael Barnes It hadsixteen chapters, representing pretty much the full range of theories of loveavailable at the time The volume has sold extremely well over the years,and has been a useful reference for those readers wanting an overview ofthe range of theories that attempt to capture the nature of love The chapterswere written to provide not only theories but also the data that had beencollected to support them

By the beginning of the twenty-first century, The Psychology of Love wasout of date New theories had been proposed, and some of the theories thathad existed in 1988 had been modified Some of the old theories were nolonger attracting the same level of attention they once had And the theoriesthat were attracting attention had been bolstered by new data that were notavailable in 1988 Michael Barnes, who was a graduate student when ThePsychology of Love was conceived, has left the field of psychology, so Stern-berg teamed up with a current graduate student at the University of Hei-delberg, Karin Weis, to launch The New Psychology of Love Together, they

decided on a plan for the book, selected authors for the various chapters,and edited the chapters.

The editors are pleased to present The New Psychology of Love Eachchapter addresses the following questions:

1 How would you define love?

2 What theory of love do you propose or utilize?

3 What evidence is there

a favoring this theory?

b disfavoring thetheory?

4 How is your approach to love similar to and different from related proaches?

ap-5 What do you view as the practical implications of your theory?

Becausethequestions areuniform, it is possibleto comparethevarioustheories and the data that have been collected to test them

Part I of the book, on biological theories, examines a “dynamical tionary view of love” (Douglas T Kenrick), a behavioral systems approach

evolu-to romantic love relationships (Phillip R Shaver and Mario Mikulincer), theevolution of love (David M Buss), the drive to love (Helen Fisher), and abiobehavioral model of attachment and bonding (James F Leckman, Sarah

B Hrdy, Eric B Keverne, and C Sue Carter) Part II, on taxonomies of love,considers styles of romantic love (Clyde Hendrick and Susan S Hendrick),searching for the meaning of “love” (Ellen Berscheid), a duplex theory oflove (Robert J Sternberg), and giving and receiving communal responsive-ness as love (Margaret S Clark and Joan K Monin) Part III, on implicittheories of love, has a single chapter, which presents a prototype approach

to studying love (Beverley Fehr) Part IV, on cultural theories of love, dealswith evolutionary and cross-cultural perspectives on love in terms of emo-tional investment (David P Schmitt), cross-cultural and evolutionary per-spectives on passionate love (Debra Lieberman and Elaine Hatfield), andindividualism, collectivism, and the psychology of love (Karen K Dion andKenneth L Dion) The conclusion, by Karin Weis, provides a discussion oftheentirebook

We are grateful to Jonathan Brent for contracting the book, to Keith don for his support in seeing the book through the publication process, and

Con-to Cheri Stahl for her ediCon-torial assistance throughout the project

When the United States did not yet exist, and Columbus had not yetarrived in the Americas, people on the North American continent were al-ready trying to make sense of their everyday lives and of the phenomenathey encountered Such phenomena included thunderstorms, droughts, thespectacular settings of their homes in the canyons of the Southwest, andtheir relationships to each other, both within their tribe and with othernations They tried to organize their lives around construals of places andevents that gave them meaning This is why, from the earliest age on, chil-dren of the Pueblo Indians learned about the world in terms of contrasts.They learned about pairings such as day and night, sun and moon, men andwomen Their world was ordered around such divisions (Iverson, 1992).This book is also about pairs, in that it is concerned with the relationships

of humans to each other, and in particular with the dyadic relationships thattwo humans form It is about a special kind of relationship involving thesepairs of humans that in English is labeled with one word, love

Let us return to the present and look at three different relationships tween humans Consider the following examples.

be-Maria and Linda have been friends for six years, ever since they started

to study together and both were new in town Usually they see one anotheronce or twice a week to chat or go out at night Maria has had problemswith depression for a long time Sometimes during the past few years shehas had difficulties completing school assignments She has always beenafraid of exams, but in general she has done well Now it is time for finalexams, and Maria, confronted not only with the stress of showing her learn-ing but also with the prospect of having to search for a job and move to atown where she does not know anybody, feels severe depression coming onagain She cannot sleep, has trouble preparing scripts for learning, and isterribly afraid of failing the oral exam She has already missed one exam,because she was too panicked to show up Although Linda has to learn thematerial for her own exams, she helps Maria prepare her scripts, simulatestaking the exam with her, and goes to see her friend every day The weekendbefore the exam, Maria’s situation deteriorates; she is panicky and frightened

to be alone Linda moves in with Maria for the weekend and stays until thefollowing Tuesday, when the exam is scheduled To make sure Maria ac-tually takes the exam, Linda goes there with her and waits until the exam

is over Maria passes the exam with a B

Jonnie, while playing, ran after his ball and did not see a car coming downthe street The car hit him, and his right leg is broken; he needs to stay inthe hospital for a few days He is a shy child and very frightened of the newenvironment His mother takes off from work while he is in the hospitaland remains with him more or less continually during his waking hours Shemakes sure he has his favorite toys to play with and that he gets somedistraction during the short time she spends at home While she is at home,she cooks his favorite meals, then takes them to the hospital so he does nothave to eat the food served there

Martin and Julia attend the same college They first meet during rations for a student council meeting Martin is immediately enchanted Heloves Julia’s long black hair and could just sink into her dark brown eyes.She has the most beautiful voice he has ever heard, and always makes smartand entertaining contributions to their conversations He starts inviting her

prepa-to go out with him and his friends Martin spends a lot of time dreaming

of the life he wants to build with Julia and of the family they will have.Julia, however, does not respond to his love She finds he is increasinglyintrusive, and finally tries to avoid him whenever she can

Thus, as we have seen, love is not a uniform phenomenon There are

countless variations on the forms these relationships can take: the love themother feels for her child as she spends all the time possible with him in thehospital, the love friends feel for one another that makes them go out oftheir way to help in times of need, and the passionate love people feel whenthey fall in love There is also altruistic love, in which people help otherswith whom they do not have a close relationship or whom they may noteven know Just as diverse as the appearances of love are the theories oflove that try to fathom it Some of them deal mainly with one aspect oflove, most often romantic love Some of them expand their focus to kinds

of love that include eldercare or the affection between parents and theirchildren Others deal with sexual behavior and with why most people donot feel sexually attracted to close relatives

There is one thing all these theories have in common: they have come along way When The Psychology of Love was published in 1988, it was thefirst book of its kind, in that it covered a broad spectrum of psychologicaltheories on love At that time, the study of love was relatively new to thefield of psychology In earlier times, psychologists had surrendered the study

of love to poets, songwriters, philosophers, and the like Only recently hadthe study of love begun to make its way from the status of a frivolous topic

to that of a suitable topic for behavioral-scientific study One of the mainreasons for its having been largely ignored was that love was considered to

be too elusive for psychologists to study It did not seem as though it could

be subjected to systematic measurement and analysis (Berscheid, 1988).Since then, much has changed in the study of love Researchers now have

a much broader spectrum of theories and the methods for assessing them.New scales have been developed, such as the Perceptions of Love and SexScale (Hendrick and Hendrick, 2002), the Love Stories Scale (Sternberg,Hojjat, and Barnes, 2001), and the “Sexy Seven Measure” (Schmitt et al.,2003) Biological methods of assessment also have greatly improved As thescientific study of love has become much more accepted, the number ofresearchers and the number of studies conducted have increased many timesover As a result, today there is much more empirical evidence at hand thanthere was a decade or two ago New aspects of love have been studied, andthe focus has shifted Intercultural research and topics such as sexual desireand mate selection have taken center stage As a result, the time has comefor The New Psychology of Love, which keeps pace with the latest research

in the field of love

This book consists of four parts that deal with the different theories oflove: biological theories, taxonomies, implicit theories, and cultural theories.Part I, “Biological Theories,” concerns five theories that look at love on the

basis of biology and evolutionary theory Part II, “Taxonomies of Love,”consists of four theories that attempt to group the phenomenon of love intodifferent styles Part III, “Implicit Theories of Love,” contains only one chap-ter, which deals with laypeople’s conceptions of love Part IV, “CulturalTheories of Love,” puts love in the context of culture Finally, the conclusionintegrates the theories of love introduced in the previous chapters.

Part I: Biological Theories

The biological theories constitute the largest group In chapter 2, “ADynamical Evolutionary View of Love,” Douglas T Kenrick proposes thatlove is a set of decision biases that evolved to serve genetic interests, that is,

to facilitate reproduction These biases influence people’s attention, memory,and decision-making For example, when one interacts with a stranger, al-truistic behavior is less likely than when one interacts with relatives withwhom one shares genes Kenrick emphasizes the dynamic aspect of love thatarises out of continual bidirectional interactions between partners that shapethe responses to each person’s actions and subsequent reactions Therefore,romantic love is an instinctive part of human nature Humans encounter avariety of different problems related to survival and reproduction such asmate-seeking, mate retention, and parental care—and these problems requirevarious solutions, with different decision biases evolved for every goal sys-tem There are different kinds of love that are relevant to these variousdomains The love one feels for one’s partner is different from the love onefeels for one’s offspring Kenrick acknowledges the existence of cultural dif-ferences in love and corresponding behaviors They arise, he believes, be-cause of social variations and variations in the physical ecology Behaviorsthat are adaptive in one environment are not necessarily adaptive in a dif-ferent environment

In chapter 3, “ABehavioral Systems Approach to Romantic Love tionships: Attachment, Caregiving, and Sex,” Phillip R Shaver and MarioMikulincer assume that there are three behavioral systems: attachment, care-giving, and sex The goal of the attachment system is to ensure a person’ssafety by making him or her stay close to others who can provide supportand care The attachment system is activated, for example, when proximity

Rela-is not maintained and threats are encountered In thRela-is case, the proximity

of the caregiving person is sought again The goals of the caregiving systemare altruistic in that it provides support and care to others in need Thefocus of this system is on another person’s well-being and development Thesexual system has as its primary goal the passing on of genes to the next

generation Therefore, one must be sensitive to signals of fertility and interest

in people of the opposite sex, be able to increase one’s own attractiveness

to these others, and have available strategies to arouse the interest of thepotential partner These behavioral systems involve specific goals and a set

of strategies that include several behaviors that serve to attain the sponding goal If goals repeatedly cannot be achieved, secondary strategies(hyperactivation and deactivation) can come into play to cope with the re-sulting distress They enable the individual to try to reach the goal in anotherway “Hyperactivating strategies” consist of an intensification of the primarystrategy to force the partner to behave according to one’s own goals Forexample, if the partner does not do what one wishes, one can protest andtry to make the partner take care of one’s needs “Deactivating strategies,”

corre-on the ccorre-ontrary, ccorre-onsist of turning off the entire system to avoid frustraticorre-onand distress because one cannot reach one’s goals One stops trying to makethe partner behave as one wishes These strategies are used when a partnerdoes not respond, or even punishes the system’s primary strategy For ex-ample, if one partner frequently is rejected when seeking his or her partner’sproximity, then at some point he or she no longer even tries to get close tothe partner, in order to avoid being rejected

Chapter 4, “The Evolution of Love,” by David M Buss, states that love

is an adaptation that evolved in the course of evolution to solve problems

of reproduction It provides sexual access, signals sexual fidelity, and cates commitment, for example Therefore, it is universal and not limited toWestern cultures Experiences of love can differ, however, depending on thecircumstances For example, a person never has to experience jealousy if his

indi-or her partner never gives cause findi-or it Buss suggests that love is a devicefor achieving commitment and appears primarily in the context of long-termmating Love is associated with several developments in human evolution.Since males cannot detect female ovulation, they tend to stay with onewoman and to have sex with her throughout the menstrual cycle Also,males at some point started to invest intensely in their offspring and to guardtheir partners from rivals, while females concentrated their reproductive re-sources on only one man According to Buss’s theory, men are more likelythan women to fall in love at first sight, and they are also more likely toexpress themselves violently when they lose the love of their beloved one.Women, on the contrary, are more likely to be jealous and to dismiss thepossibility of having sex without love

Chapter 5, “The Drive to Love: The Neural Mechanism for Mate tion,” by Helen Fisher, suggests that there are three interrelated motivationsystems: attachment, attraction (romantic love), and the sex drive The sex

Selec-drive is associated with the desire to have sexual contact with others It can

be directed at a number of potential partners Attraction in mammals responds to what we label “romantic love” in humans It is associated withfocusing on one particular mate, showing him or her one’s affiliation, andtrying to guard the partner from rivals Attachment is characterized by feel-ings of security and comfort as well as by seeking proximity In humans, it

cor-is also known as companionate love Fcor-isher puts the three systems into thecontext of their neural correlates The sex drive is related in particular totestosterone; romantic love is related to norepinephrine and serotonin; andattachment is related to oxytocin and vasopressin There may even be ageneral arousal component underlying all drives (involving the neurotrans-mitters dopamine, norepinephrine, and serotonin) that produces motivation,and a more specific constellation of brain systems that evokes the specificthoughts, feelings, and behaviors that are connected with every biologicalneed related to love This view implies that rejection, as well as monogamyand adultery, for example, is associated with specific neural correlates Ro-mantic love is a mating drive similar to many other basic drives

In Chapter 6, “ABiobehavioral Model of Attachment and Bonding,”James F Leckman, Sarah B Hrdy, Eric B Keverne, and C Sue Carter refer

to the conscious subjective experience that arises from bonding and ment, and that also exerts an influence on them, rather than to the termlove By observing various species of mammals, they find that humans ex-hibit comparatively few universal fixed behaviors They point out that there

attach-is evidence of romantic love in most cultures and that parental love andromantic love have many features in common For example, both kinds oflove lead to an increased sense of responsibility for the well-being of thebeloved one and to the urge to behave according to the other person’s needs.Furthermore, the importance of oxytocin and opioids for bonding in mam-mals has been illustrated in various studies Early life experiences are im-portant for interactions between parents and their offspring; however, infantresponsiveness is also influenced by genetic determinants The behaviortherefore is a result of the interaction of both genes and environmental in-fluences As a result, it is possible to design intervention programs to enhanceparental sensitivity and security of attachment in children

Part II: Taxonomies of Love

Three of the theories presented in this volume are taxonomies thatcategorize the various phenomena associated with love into different styles

or kinds of love In chapter 7, “Styles of Romantic Love,” Clyde Hendrick

and Susan S Hendrick follow the categorization of Lee (1973), who gested six types of love: eros (passionate love), ludus (game-playing, uncom-mitted love), storge (friendship love), pragma (calculating love), agape (al-truistic love), and mania (obsessional love) Each style consists of a certaincombination of attitudes and beliefs It is possible to generate a profile of aspecific love style for any person at any given time, thereby making it pos-sible to assess the extent to which the person exhibits each of the six lovestyles The love styles moderate the experience of falling in love and loving,

sug-in that they sug-influence, for example, how quickly or passionately someonefalls in love They are related to several personality traits Eros, for example,

is positively related to agreeableness, extraversion, and conscientiousness,and negatively related to neuroticism, whereas ludus is positively related toneuroticism and negatively related to agreeableness and conscientiousness.Furthermore, the love styles are also related to sexual attitudes such as per-missiveness (ludus) and responsible sexuality (eros) Gender differences inregard to the various love styles also were found, in that men seem to en-dorse game-playing, uncommitted love more than women, who instead seelove as friendship or calculating love The taxonomy can be used in couplestherapy to help people understand themselves and their partners by means

of their personal love styles

Chapter 8, “Searching for the Meaning of ‘Love,’ ” by Ellen Berscheid,suggests classifying love into four different kinds: attachment love, compas-sionate love, companionate love/liking, and romantic love Attachment loveseems to be unlearned, and serves the need for protection The experience

of a threat causes the individual to seek proximity to another individual.Attachment can then provide shelter Compassionate love is concernedabout the other’s welfare and can also be labeled altruistic love Bowlby’scaregiving system is the basis of this kind of love Companionate love canalso be labeled affection, liking, or pragmatic love It is based on principles

of reward and punishment That means that people who are rewarding areliked, and people who are punishing are disliked The fourth kind of love,romantic love, incorporates sexual desire, and therefore also has been la-beled passionate love or erotic love It is proposed that each of these differenttypes of love is activated for different reasons and has different conse-quences It is possible to experience more than one type of love in an indi-vidual relationship Berscheid also elaborates on the difference between

“love” and “being in love.” To “be in love” refers to only one type of love,and for a person to “be in love” with someone, that someone has to be bothliked and sexually attractive The term love, on the contrary, is more uni-versal and seems to refer to many different types of love

Chapter 9, “ADuplex Theory of Love,” by Robert J Sternberg, consists

of two subtheories, the triangular theory of love and the theory of love as

a story The triangular theory suggests that love comprises three nents: intimacy, commitment, and passion, which together constitute thevertices of a triangle The geometry of a love triangle then depends on boththe amount of love (size of the triangle) and the balance of love (form ofthe triangle) As a function of the existence of one or more of these com-ponents in a specific relationship, one can distinguish eight different kinds

compo-of love For example, passionate love involves intimacy plus passion,whereas companionate love involves intimacy plus commitment There arevarious kinds of love triangles, such as real triangles and ideal triangles, andaction and feeling triangles The theory of love as a story suggests that theinteraction of our personal attributes with the environment gives rise tostories about love Every person has his or her own story of love, and seeks

to fulfill it in his or her life Some examples of stories are the fairy tale,involving a prince and a princess; the horror story, involving a terrorizerand a victim; and the business story, involving two business partners Thesuccess of a relationship depends in part on the similarity or compatibility

of the stories of the two partners

Chapter 10, “Giving and Receiving Communal Responsiveness as Love,”

by Margaret S Clark and Joan K Monin, centers on communal siveness, an unconditional reaction that focuses on the welfare of the part-ner; attends to his or her expressed needs, desires, or goals; and does notexploit his or her vulnerabilities There are five forms of responsiveness: (1)helping (for example, when a person is injured or is in need of a particularobject or action); (2) support for reaching future goals (for example, listen-ing or providing advice); (3) creating something in collaboration with an-other person (for example, dancing or playing a game together); (4) exhib-iting caring behaviors when the other person has transgressed (for example,being forgiving when the partner has forgotten a lunch appointment because

respon-he or srespon-he is so busy); (5) symbolic, wrespon-hen trespon-here is no clear need apparentand one nevertheless shows that one cares for the other The processesrelated to communal responsiveness are the same ones that are often men-tioned when people describe a loving relationship Communal responsive-ness provides individuals with a feeling of security and comfort Commu-nicating needs and disclosing oneself contribute to the sense of being in aloving relationship At the same time, even seemingly acceptable behaviorshave the potential to undermine communal responsiveness Communal re-sponsiveness is not the only way in which love can be defined, but it is thekind of love that can be distinguished from other kinds, in that it is not

associated with the anxiety and distress that arise, for example, from feelings

of intense passion

Part III: Implicit Theories of Love

There is only one theory in this book that belongs to the category ofimplicit theories: “APrototype Approach to Studying Love” (chapter 11),

by Beverley Fehr Fehr examines not how she, as a scientist, views love, butwhat ordinary people believe love to be She finds that companionate kinds

of love are considered a central part of love There also seem to be somegender differences as to how love is seen Women in general subscribe to amore companionate conception of love, whereas men hold a passionate con-cept Women have more of a friendship orientation in love and are alsomore pragmatic; men report having fallen in love at first sight more oftenand foster romantic beliefs, such as that true love lasts forever These pro-totypes—how people think love typically is—have implications for their re-lationships Studies have shown that when features of love that are veryprototypical are violated, love is perceived as more subverted than when lessprototypical features are violated Couples who view love in a very proto-typical way report greater relationship satisfaction and greater love for oneanother Prototypes are also used to analyze different kinds of love, sug-gesting that all kinds of love have some core features in common

Part IV: Cultural Theories of Love

Three more theories emphasize cultural aspects of love In chapter 12,

“Evolutionary and Cross-Cultural Perspectives on Love: The Influence ofGender, Personality, and Local Ecology on Emotional Investment in Ro-mantic Relationships,” David P Schmitt introduces a general love dimensionlabeled “emotional investment.” It comprises many core features of love,including the intimacy, passion, and commitment components of Sternberg’sduplex theory of love The construct of emotional investment is positivelyrelated to both extraversion and agreeableness, meaning that higher scores

on one dimension are associated with higher scores on the other dimension.However, kinds of love differ in their degree of relatedness to personalitytraits Schmitt reports a study he and his colleageus conducted with fifteenthousand participants from forty-eight nations They found that the concept

of love is relatively similar across cultures Emotional investment in a tionship is positively correlated with the level of development of a country,secure attachment, and individualism, but also with short-term mating in-

rela-terests and divorce rates In cultures in which children are exposed to highlevels of stress, such as result from economic difficulties or a harsh physicalenvironment, the children tend to express lower levels of emotional invest-ment Another finding is that in most countries, there are gender differences

in emotional investment, with men usually scoring lower than women

In Chapter 13, “Passionate Love: Cross-Cultural and Evolutionary spectives,” Debra Lieberman and Elaine Hatfield suggest that although pas-sionate love is a cultural universal, cultural values influence the exact mean-ing that is attributed to the term love They state that the concept ofromantic love, for example, fits in well in individualistic American culture,but less well in collectivistic Chinese culture, where people are expected toconsider not only their own feelings but also their obligations to other peo-ple, such as their parents For some traits, such as the importance of goodlooks in mate preferences, however, gender has an even greater impact thanculture The authors observe that the differences between Western and East-ern cultures are diminishing because young people increasingly adopt pat-terns typical of the West, such as endorsing gender equality in love and sex,and marrying for love rather than entering into arranged marriages Theyalso deal with mechanisms that serve to avoid inbreeding In this context it

Per-is important to be able to recognize who Per-is related to oneself and who Per-isnot (kin detection), in order to judge who is an appropriate sexual partner.Furthermore, the emotion of disgust serves to avoid situations in which sex-ual contact with close relatives could occur

In chapter 14, “Individualism, Collectivism, and the Psychology of Love,”Karen K Dion and Kenneth L Dion argue that the beliefs people of a givenculture have about the relation of the individual and the group influence theunderstanding of love In individualistic societies, marriage is based on love.Individualism is associated with a relatively permissive view of love as well

as a lower likelihood of ever having been in love and a lower sense ofperceived success in one’s family life Collectivist cultures view love as based

on friendship and altruistic goals, and emphasize caregiving rather than tense affect There are also cultural differences as to how intimacy in rela-tionships develops Couples in the United States try to maintain a high level

in-of intimacy during their marriage while at the same time trying to keep somespace for themselves to develop autonomously In Japan, couples in the firstyears of their marriage have to attend to the needs of others in their extendedfamily, and tend to develop greater intimacy later in their marriage Theseobservations are expanded to eldercare People in collectivist cultures seeaffection and attachment as main reasons for the care of their elders Inindividualistic cultures, duty and the perception of eldercare as a burden

prevail However, in individualistic cultures, parents try to maintain a higherdegree of independence from their adult children.

Conclusion

In chapter 15, “Conclusion: The Nature and Interrelations of Theories

of Love,” Karin Weis discusses the theories that are introduced in this bookand integrates them in various ways For example, the chapter exploreswhether the different kinds of love have a common denominator, or at leastwhether parts of them do Furthermore, it summarizes some of the findings

on the influence of context, personality, time, and culture on love It alsotakes another look at the various mechanisms proposed in this book toachieve goals that are associated with love and relationship issues Last,some more open questions are pointed out and areas in which further re-search is needed are described

References

Berscheid, E (1988) Some comments on love’s anatomy In R J Sternberg and M L Barnes (eds.), The Psychology of Love New Haven, Conn.: Yale University Press Hendrick, S S., and Hendrick, C (2002) Linking romantic love with sex: Development

of the Perceptions of Love and Sex Scale Journal of Social and Personal ships, 19, 361–378.

Relation-Iverson, P (1992) Taking care of the earth and sky In A M Josephy, Jr (ed.), America in 1492: The World of the Indian Peoples Before the Arrival of Columbus New York: Vintage Books.

Lee, J A (1973) The Colours of Love: An Exploration of the Ways of Loving ronto: New Press.

To-Schmitt, D P., Alcalay, L., Allik, J., Ault, L., Austers, I., Bennett, K L., et al (2003) Universal sex differences in the desire for sexual variety: Tests from 52 nations, 6 continents, and 13 islands Journal of Personality and Social Psychology, 85, 85– 104.

Sternberg, R J., Hojjat, M., and Barnes, M L (2001) Empirical tests of aspects of a theory of love as a story European Journal of Personality, 15(3): 199–218.

P A R T I

Biological Theories

phenom-Psychologists working to empirically and theoretically nail down exactlywhat love is have come up with some consensus that it is more than onething, and may be half a dozen or more (e.g., Fehr and Russell, 1991; Hen-drick and Hendrick, 1986; Sternberg, 1986) Most of the empirical workhas focused on the phenomenology of love, trying to dissect the inner feel-ings that make up the experience of love For example, some researchershave asked how many different facets make up the feeling of love (e.g., Aronand Westbay, 1996; Sternberg, 1986), and others have explored how thosevarious facets might combine into different kinds of love for different people(e.g., Fehr and Russell, 1991; Sprecher and Regan, 1998) Some researchers

have tried to determine whether there are different physiological systemsundergirding different facets of love (e.g., Diamond, 2003).

In this chapter I will consider the different types of love from a dynamicevolutionary perspective The central assumptions of the dynamical evolu-tionary model are the following:

1 Love is at base a set of evolved decision biases This assumption porates a network of other assumptions based on the modern integration

incor-of cognitive science and evolutionary psychology (e.g., Kenrick, 2001;Kenrick, Sadalla, and Keefe, 1998; Lumsden and Wilson, 1981; Toobyand Cosmides, 1992) The mind, on this view, is composed of a set ofinnate biases that affect what we pay attention to, how we interpretevents, what we retrieve from memory, and how we make decisions.Those biases are designed to promote behaviors that, on average, wouldhave served to enhance reproduction Because powerful social bonds wereessential to our ancestors’ survival and reproduction, decision biases de-signed to facilitate those bonds would have been highly adaptive

2 The decision biases that drive loving relationships differ for men andwomen Female mammals are required to make a very high minimuminvestment, whereas males are not, a very simple fact that makes themating game very different for men and women (Geary, 1998; Trivers,1972) Although research on the phenomenology of love suggests similarexperiences for men and women, general evolutionary principles lead us

to expect key differences in the determinants and consequences of intensesocial bonds in women as compared with men

3 The mind is modular, with very different decision biases operating indifferent domains of social life Different problems need solving in dif-ferent types of strongly bonded relationships Finding a lover and keepingthat lover are two different problem sets involving very different decisionbiases The same can be said about caring for offspring and keepingfriendships Thus, although different types of love have the surface sim-ilarity of serving to promote social bonds, they may, from a functionalperspective, involve motivations as distinct and specialized as those dis-tinguishing hunger, thirst, or fear

4 Decision biases in one individual interact in a dynamic way with those

in other individuals Each decision bias affecting loving bonds involves

an “if-then” contingency rule in which inputs from other people mine whether the actor picks one option or another Any given person’sresponses change the inputs for other individuals, each operating on his

deter-or her own decision rules, which in turn play out in the context of

de-cisions made by many others Not only does it take two to tango, buttwo rarely tango alone in a dark basement; instead, their carefully co-ordinated maneuvers are typically executed within a larger ballroomcrowd who often change partners as they move in time to the samerhythms.

5 Cultural norms surrounding love emerge out of interactions between namically connected individuals and features of the nonsocial environ-ment There is considerable cross-cultural variation in the expression ofpowerful social bonds, with some societies being relatively more polyg-ynous (multiple wives marrying the same man), some being somewhatpolyandrous (same woman, multiple husbands), and so on (e.g., Crookand Crook, 1988) Cross-cultural variations are neither infinite nor ar-bitrary, however, because our individual decision biases are ultimatelybased on evolved mechanisms that were designed to solve recurrent prob-lems faced by our ancestors On this view, the human mind is a coloringbook rather than a blank slate—there is flexibility in the choice of pal-ettes, but the overall pattern is constrained by some strongly suggestivelines (Kenrick, Becker, Butner, Li, and Maner, 2003)

dy-Instincts, Mental Modules, and Domain Specificity

Because loving relationships often involve powerful emotions, some ofwhich seem to override conscious decision-making, feelings of love seem like

an intuitively reasonable place to search for human instincts Of course,social scientists are rather suspicious of intuition as a form of scientific ev-idence If anything, psychologists favor viewpoints that violate intuition(Krueger and Funder, 2004) Directly contradicting the intuition that ro-mantic love might be an instinctive part of human nature, a popular view

in the social sciences held that love was a historically and culturally eral construction Many social scientists in fact believed that the particularlypowerful and consuming feelings of romantic love found in modern Westernsocieties were absent in other societies and other periods of history (seeJankowiak and Fisher, 1992) Although that position was appealingly coun-terintuitive to social scientists, cross-cultural research has combined withphysiological research to indicate that it was also quite wrong (Diamond,2003; Jankowiak and Fischer, 1992) Feelings of love are universal acrossour species, and they are based at least partly in innate mechanisms Are wetherefore justified in calling them instinctive?

ephem-The word instinct historically had several meanings, with different cations for thinking about the varieties of love William James (1890) viewed

impli-an instinct as impli-an innate capacity to act “to produce certain ends, withoutforesight of the ends, and without previous education in the performance”(vol 2, p 383) The prototypical Jamesian instinct would be a sneeze—areflexive impulse automatically triggered by particular sensory inputs (nasalirritation, in this case) James did expand his concept of instinct to includemore complex and cognitively involving social inclinations, as in his famousquery: “Why does the maiden interest the youth so that everything abouther seems more important and significant than anything else in the world?”(vol 2, p 386).

William McDougall’s (1908) view of instinct was more similar to modernconcepts of emotion: “an inherited or innate psycho-physical dispositionwhich determines its possessor to perceive, and to pay attention to, objects

of a certain class, to experience an emotional excitement of a particularquality upon perceiving such an object, and to act in regard to it in a par-ticular manner, or, at least, to experience an impulse to such action” (p 29).McDougall viewed instincts as linked to seven powerful emotions: (1) fear,(2) disgust, (3) wonder (linked to curiosity), (4) anger, (5) subjection (hu-miliation or embarrassment), (6) elation (pride), and (7) parental instinct(tenderness, empathy) To these seven, McDougall added two social moti-vations without distinct emotions—the reproductive instinct and the gregar-ious instinct

Instincts were never presumed to be inflexible and/or insensitive to ronmental inputs On the contrary, James believed that instincts are “notalways blind or invariable” (vol 2, p 389) and that, indeed, “every instinc-tive act, in an animal with memory, must cease to be ‘blind’ after being oncerepeated.” Indeed, an innate response system that operated without envi-ronmental inputs, and without environmental calibration, would hardly befunctional So, although many twentieth-century social scientists miscon-ceived instinct as incompatible with learning, this was always a bad rap,whether applied to humans or to other animals (Alcock, 2001)

envi-Instinctive behavioral programs often involve more than a simple step, stimulus-emotion-response link: rather, they involve a complex se-quence that unfolds over time For example, Lehrman (1965) noted thatring dove courtship involved a series of stages, with one set of stimuli trig-gering certain hormonal and behavioral responses early in courtship, fol-lowed by physiological changes that led the birds to attend to differentstimuli and act in different ways later Morris (1958) observed a similarsequential series of lockstep behavioral escalations in the mating ritual of asmall fish called the stickleback The view of instinctive behavior as involv-ing multiple stages calibrated to responses by the opposite sex may better

one-represent the sequential complexities of courtship in humans as well as otheranimals (Kenrick and Trost, 1987).

MODERN VIEWS OF MODULARITY

Many modern evolutionary psychologists share with James the notionthat the human mind is composed of relatively independent modules Ex-amples include different memory systems for food location versus songlearning in birds, special mechanisms for different features of human lan-guage, specialized learning mechanisms governing food aversion and fear asopposed to other types of learning, and particularized logical abilities fordetecting cheaters on social contracts (e.g., O¨ hman and Mineka, 2001;Pinker, 1994; Rozin and Kalat, 1971; Sherry and Schacter, 1987; Sugiyama,Tooby, and Cosmides, 2002) McDougall’s view of instinct also persists inmodern evolutionary conceptions of emotions or motivations as goal-oriented systems designed to facilitate adaptive responses to particular clas-ses of recurring threats or opportunities faced by humans (e.g., Cottrell andNeuberg, 2005; Plutchik, 1980)

Modern psychologists have come a long way since James and McDougall

in our understanding of innate behavioral mechanisms, but we have a longway to go toward specifying the particulars An especially interesting set ofquestions concerns how many different sets of recurrent human problemsare governed by different evolved modules These issues have particular rel-evance to questions about the different forms of love

DOMAINS OF SOCIAL LIFE

The dynamical evolutionary model posits a set of domains passing the various problems regularly confronted in human social life (Ken-rick, Li, and Butner, 2003; Kenrick, Maner, and Li, 2005) Humans every-where have repeatedly confronted several sets of problems involving thefollowing:

encom-• Affiliation: Our ancestors always lived in small, highly interdependent

groups (Sedikides and Skowronski, 1997) To survive and eventually produce, each individual human needed to cooperate with a group offriends

re-• Status: Humans everywhere want to know where their fellows stand in

the local dominance hierarchy (Goldberg, 1981) For both sexes, statusdirectly increases access to resources For males, there are additional bio-logical payoffs for attaining status, because females use status cues to helpdecide which males they will select as mates (Li, Bailey, Kenrick, and Lin-senmeier, 2002; Sadalla, Kenrick, and Vershure, 1987)

• Self-protection: Ancestral humans frequently faced threats from members

of other groups (Baer and McEachron, 1982), as well as occasional harshcompetition from members of their own group (Daly and Wilson, 1988).Any ability or inclination to recognize cues associated with such threatswould have been highly adaptive

• Mate-seeking: Natural selection is centrally linked to differential

repro-duction, and we are here today not because our ancestors all lived longand happy lives, but because they managed to reproduce Because ancestralmales and females contributed different resources to their offspring, thetwo sexes are presumed to use slightly different criteria to select mates(e.g., Li et al., 2002)

• Mate retention: In most mammals, courtship is all over after mate

selec-tion, which usually involves males displaying and females choosing Butbecause human offspring are helpless at birth and require substantial re-sources to survive, modern humans are the descendants of ancestral pairs

in which males cooperated with females (Geary, 1998) Indeed, althoughthere are cultural variations in the shape and number of pair bonds, allhuman societies have some form of long-term marital bonds betweenmales and females (Daly and Wilson, 1983)

• Parental care: The ultimate function of human parental bonds is offspring

care Parents and children tend to bond to each other, but the constraints

on parent-to-parent and parent-to-child bonds, and the rules of exchangeassociated with each, are very different

Because solutions to problems in one domain are often inconsistent withsolutions to problems in another, humans are presumed to have a modular-ized set of executive goal systems designed to deal with the separate problemsets in particular ways A domain-general model (e.g., do what is rewarding,

or what results in equitable benefit-to-cost ratios) is not specific enough towork across different social domains (e.g., a passionate kiss is rewardingfrom a lover, but may be punishing from a friend; a man might expect afriend to share the bill in a restaurant [or pick up the next one], but bedisappointed if a woman did so in the early stages of courtship)

At the base of each social goal system is a set of evolved decision biases.For example, inclusive fitness considerations lead to the assumption that therules for sharing resources differ for unrelated affiliates as opposed to off-spring Because a child shares half of one’s genes, whereas an unrelatedacquaintance does not, the costs of providing any resource for one’s childare accordingly discounted An abundance of evidence suggests that humandecision-making, just like decision-making in other species, is indeed highly

influenced by kinship considerations (Alcock, 2001; Laham, Gonsalkorale,and Von Hippel, 2005; Smith, Kish, and Crawford, 1987).

The model also assumes that decision rules vary predictably as a function

of interactions between particular individual differences and environmentalinputs For example, because developing offspring are always highly costlyfor a female to carry, deliver, and nurse, ancestral females, as comparedwith ancestral males, were selected to have higher thresholds for consideringcourtship offers from potential mates There is abundant evidence consistentwith this assumption (e.g., Buss and Schmitt, 1993; Clark and Hatfield,1989; Kenrick and Luce, 2000)

Where Does Love Fit into the Social Domains?

Webster’s ninth New Collegiate Dictionary offers the following as itsfirst three definitions of love: (1) “strong affection for another arising out

of kinship or personal ties” (e.g., maternal love); (2) “attraction based onsexual desire”; and (3) “affection based on admiration, benevolence, or com-mon interests.” This multiplicity of meanings is consistent with subsequentresearch on the experience of love (e.g., Fehr and Russell, 1991; Sternberg,1986) The different types of love may be more relevant to one social domainthan to another Passionate love based on sexual desire is most likely toarise in the mate search domain, for example, whereas the less intense af-fection based on admiration, benevolence, or common interests is more rel-evant to mate retention, the strong affection arising out of kinship comesinto play in the parental care domain, and love between friends fits nicelyinto the coalitional domain

Does some common underlying physiological or phenomenological ponent tie together the different types of love? This is an interesting question,and possible answers have focused on hormones such as oxytocin and onfeelings of attachment (e.g., Zeifman and Hazan, 1997) Yet the differencesmay be functionally more important than the similarities For example, oncetestosterone comes into play in romantic passion, the experience and itsbehavioral consequences are entirely different from the pure effects ofoxytocin-induced attachment

com-Is each type of love a separate emotion, in the sense of anger or fear, thatcomes into play whenever a particular domain of problems is activated? Forexample, is passionate love the motivational component of the mate searchexecutive system? This is an interesting question, but I am inclined to thinkany such mapping will be inexact at best For example, although passionatelove is largely confined to the mate search domain, the feelings (and under-

lying hormonal states) associated with love of a child and love of a term mate, and even love of a friend, may overlap considerably (thoughperhaps less than perfectly) Furthermore, although testosterone-driven sex-ual arousal plays a central motivational role in some of the most salientphases of early courtship, it probably plays a minor role in many others(e.g., the longing for a new lover during periods of separation; the intenseinterest in everything the lover has to say at 3 a.m., after sexual urges havebeen fully satisfied).

long-Finally, although psychological research, like the dictionary, has focused

on the positive affective experiences associated with love, negative affectmay also play an occasional role in maintaining strong social bonds Forexample, some behaviors associated with the maintenance of long-termbonds may be motivated by the nasty and selfish emotion of sexual jealousy.And besides the positive awe one feels in gazing on one’s infant, parentallove is defined perhaps as much by incessant worrying about the child’swelfare as by feelings of parental rapture Furthermore, an interesting fea-ture of various types of love is the relative suppression of negative emotions.Imagine if a friend or a lover spit out half the food you offered, then wokeyou up by screaming in your ear at midnight, and kept up this barrage ofmaltreatment for several months on end Unless you are a candidate forcanonization, you would be inclined to scream back, and you might soonterminate the relationship However, most infants act the same way, yetsurprisingly few are left on the doorsteps of orphanages Instead, their one-sided and high-volume demands are more typically met with sympatheticand cooing reassurances

Thus the different social domains and the various affective and emotionalcomponents of love do not map precisely onto one another, and such map-ping may not provide the best way to understand the diverse functions en-compassed by the various meanings of the term love

LOVE AS AN ARRAY OF DECISION BIASES

From the perspective offered here, a fuller understanding of love in allits forms can come from considering the decision biases that underlie strongsocial bonds across the different domains Table 2-1 suggests a set of pos-sible biases that would serve to smooth interactions with closely bondedothers (aka the people we love) Note that the mechanisms underlying thesebiases in social decision-making are not necessarily conscious, “rational,” orcomplex Instead, they are often based in simple predispositions to be selec-tively attentive to certain features of the social environment (akin to theinclination to rapidly notice emotion in other people’s faces), and to expe-

accompanying cognitive biases

Social Domain

Functions ofStrong Bonds

Examples ofCognitive BiasesCoalition

formation

To cement reciprocalalliances

To gain benefits ofgroup cooperation

Attention to commonalities over ferences

dif-Dampened attention to short-term equity

successful associates

To share benefits ofbacking the winningteam

To inspire followers tofollow

Dampened critical thinking for spected authorities

re-Informational biases favoring owngroup, disfavoring other groupsAttention to commonalities with win-ners, distance self from losers

re-sources to, and injury

by, out-group bers or treacherous in-group members

mem-Biased perceptions of infractions by group vs out-group membersLowered thresholds for seeing nega-tive inclinations in out-group mem-bers

de-sirable reproductivepartners

Males relatively more attentive tophysical attractiveness and youthFemales more attentive to statusMales have lower thresholds for per-ceiving interest by potential mates,and for feeling passionate loveFemales have higher thresholds fortrusting potential suitors

Retaining mates Maintain reproductive

in families as opposed to other tionships

rela-Hyperattention to offspring’s being

well-rience certain feelings in response to those features (e.g., to feel fear when

we see an angry face on a large man who is walking toward us)

The biases suggested in table 2-1 have not all been empirically verified,but there is some support for most of them For example, subjects in onestudy got feedback that their team had done quite well on a trivia game,and were asked to assign relative responsibility for their success to them-selves and their partner When playing with strangers, people demonstratedthe typical “self-serving bias,” giving themselves the majority of the credit.When playing with a close relative, on the other hand, they tended toward

an “other-serving bias,” giving relatively more credit to the other man, Ledlow, and Kenrick, 2003) In other studies, participants have playedvarious resource dilemma games with strangers, friends, or relatives (e.g.,Ledlow and Linder, 2003) People who believe they are playing with kin aremore generous and cooperative than those playing with strangers Friendsare generally treated less well than kin, but better than strangers Given itstheoretical importance, there is surprisingly little social psychological re-search on kin relationships (Daly, Salmon, and Wilson, 1997) However,that picture is beginning to change (e.g., Laham et al., 2005; Park andSchaller, 2003)

(Acker-There is much more research examining how men and women think aboutpotential mates For example, one series of studies explored responses toattractive males and females at various levels of cognitive processing Un-surprisingly, attention measured via an eye tracker indicated that men lookmore at beautiful women Also unsurprisingly, men dedicate greater “down-stream” processing to those women, as indicated by biased estimates of thefrequency of good-looking women in rapidly presented arrays (Maner, Ken-rick, Becker, Robertson, Hofer, Neuberg, Delton, Butner, and Schaller,2003) In a Concentration-type game, men show especially good abilities toremember the locations of beautiful women (Becker, Kenrick, Guerin, andManer, 2005) Women also favor beautiful women at all levels of processing,but show an interesting “disjunction” in processing handsome men Womenvisually attend to handsome male strangers for a few seconds, but seem toquickly terminate further processing downstream (failing to remember hand-some men any better than average-looking men, and failing to show thefrequency estimation bias that men show toward beautiful women).Men asked to judge whether neutral faces are showing subtle signs ofemotion tend to project sexual arousal onto neutral facial expressions, butonly if the faces are attractive women and if the men have had a matingmotive activated (Maner et al., 2005) Another series of studies foundwomen to be more suspicious of a man’s professions of love, and men to be

more likely to attribute sexual motivation to women—except in the case oftheir own sisters (Haselton and Buss, 2000) These findings are all consistentwith a differential parental investment model, which posits that females havemore to lose from an ill-chosen mating decision than do males (e.g., Kenrick,Groth, Trost, and Sadalla, 1993; Kenrick, Sadalla, Groth, and Trost, 1990).

We thus far have only a rough idea of the qualitative nature of several ofthese decision biases Additional research and theory could allow us to con-vert those qualitative biases into quantitative decision weights This wouldallow more precise theory-driven predictions, as well as a better understand-ing of how those biases play out in complex social dynamics, where smalldifferences in individual biases can have large effects at the group level (Ken-rick, Becker, et al., 2003)

These decision biases are at base cold, hard economic rules designed toserve selfish genetic interests Yet they are accompanied by affective statesthat may be warm and fuzzy or even hot and steamy Why feelings some-times accompany otherwise cold decision rules is an interesting question.Presumably the experienced feeling is accompanied by hormonal changes,which perhaps help keep attention on task until a goal is reached Consider,for example, that the central nervous system operates very rapidly and canchange the direction of conscious processing in milliseconds, whereas theautonomic nervous system involves the secretion of hormones that linger for

a while despite momentary attentional shifts Once sexual hormones enterthe bloodstream in sufficient quantities, for example, they will dissipateslowly until copulation signals the release of other hormones, which termi-nate that goal state (and the next higher executive priority can take over).LOVE AND INTERPERSONAL DYNAMICS

Understanding the inner experience of any one actor will not be ficient if we want to understand how love works This is because all socialbonds involve a continual dynamic interaction Consider parental love As

suf-I write this, my fifteen-month-old son has been playing in a nearby roomwith his babysitter When I pass by and hear his voice, I am strongly mo-tivated to pick him up and play with him (his smile provides a reward whosepower I would not have predicted before I had children) If I try to return

to work on my overdue chapter, he becomes obviously and loudly upset.His agony motivates me to stay and settle him with the babysitter beforesneaking out of his field of view He prefers my company to that of hisbabysitters, but if his mother is around, I take second priority He prefersthe company of his grandmother over that of the babysitters, but not asmuch as that of his parents All of this, I would argue, is a function of

interactions between evolved psychological decision rules and experience.Experience is clearly critical—he did not know his grandmother until heinteracted with her, for example But many of these experiences are them-selves a function of decision biases built into the human species and leading

to reliable social dynamics Grandma has been more motivated to win hisaffections than are his babysitters, but not as motivated as his mother, whocannot bear to be separated for more than a few hours

Are these family dynamics merely a function of American culture? Evenassuming the remote possibility of an arbitrary culture unbiased by the pref-erences of the biological organisms who constructed it, such an explanationseems unlikely in this case For one thing, cross-cultural research finds sim-ilar family dynamics the world over (e.g., Geary, 1998; Hrdy, 1999) Foranother, grandparental fondness follows the rules of inclusive fitness in waysvery likely invisible to the grandparents themselves (Laham et al., 2005).Grandparental investment tends to go along more “certain” kinship lines.That is, a mother’s mother is closer to her grandchildren than is a father’smother, and a father’s father is least likely to invest in the grandchildren.Certainty in this case refers to the fact that, because of internal fertilization,the mother is virtually always sure the baby has half her genes, whereas thefather cannot be completely sure There are two steps at which paternity isuncertain for a father’s father, but none for a mother’s mother Most im-portant, people were less close to their mother’s father and their father’sfather only when those grandparents had more “genetically certain” grand-children (e.g., through daughters rather than sons) If they have no daugh-ters, grandparents seem to invest more resources in their son’s children, tak-ing the next best bet from an inclusive fitness standpoint

The individual decision rules (as in table 2-1) take the form of “if-then”statements contingent on inputs from other people In turn, any individual’sdecisions become contingencies for the other people around him or her Thedifferent decision rules thus have important consequences for understandinghow social dynamics vary across different relationships Consider the verysimple case of how interacting with kin versus non-kin might change thedynamics of the classic prisoner’s dilemma (figure 2-1) The prisoner’s di-lemma is a classic economic game modeled on the conflict of interest faced

by two prisoners being interrogated by the police If the prisoners cooperatewith one another by remaining silent, they share a better outcome than ifboth agree to testify for the prosecution (compare the upper left box in theleft figure with the lower right box in the same figure) The dilemma arisesbecause if prisoner A testifies, while B does not, A wins a bigger reward and

B gets the worse outcome, and vice versa Thus, each will be inclined totestify against the other to avoid this worst-case scenario The same set of

5.5A

Figure 2-1 Considerations of inclusive fitness lead to

more positive outcomes in situations that would pose

dilemmas for unrelated associates When the payoffs for

each player in a traditional prisoner’s dilemma (left) are

recalculated to be his own plus half of his brother’s,

cooperation (C) replaces defection (D) as the dominant

strategy (Kenrick and Sundie, in press) Reprinted by

permission of Guilford Press.

payoffs creating a difficult dilemma for a pair of unrelated individuals, ever, may have a different outcome if the two players are first-degree kin(who share, on average, 50 percent of their genes) (Kenrick and Sundie, inpress) Thus, from a genetic perspective, each brother gets to share in halfthe other’s rewards, and the payoff matrix on the right reflects that eachnow benefits from cooperation, regardless of what the other one does.Hence, the temptation to testify, and the consequent dilemma, evaporate.The fact that one person’s decision biases interact with those of the people

how-in his or her social network adds complexity to social life, but may also helporganize our relationships into meaningful patterns Because I am makingdecisions with you in mind, and vice versa, our interactions can harmonize

Of course, both of us are interacting with many other people as well, andthose people all have their own decision biases Rather than leading to ahopelessly complex disorder, the result is often “self-organization”—theemergence of order out of initial randomness Computer simulations dem-onstrate why this self-organization is likely to be found for cooperation, suchthat some neighborhoods will become highly cooperative, and others highlycompetitive, as people try to match the behaviors of their neighbors (Ken-rick, Li, and Butner, 2003) The same kind of normative self-organizationcan emerge for mating strategies It will be difficult to behave in a sexuallyunrestricted way if the majority of one’s neighbors are faithfully married,and it will be harder to settle down into a monogamous marriage if most

of one’s neighbors are promiscuous partygoers Although a neighborhoodmay start out with a mix of mating strategies, small random variations infrequencies may throw it slightly in one direction or the other, with theeventual result being strong local norms that tend to become self-maintaining (Kenrick, Li, and Butner, 2003).

Another consequence of the different decision rules used in the variousdomains is that there will be different social geometries associated with eachdomain For example, long-term mateships tend to be more dyadic thanaffiliative networks (a new friend may bring more benefits than costs foryour current friends, but a new mating partner usually brings more coststhan benefits for your current long-term mate)

SOCIAL DYNAMICS AND CULTURAL NORMS

The decision rules underlying behaviors in each domain are “if-then”statements in which the “if” is provided by inputs from the social environ-ment, and the “then” is presumed to be a variable strategic response de-signed to result in behaviors better adapted to one contingency than another.Regular variations in the social and physical ecology determine whether oneresponse or another will be adaptive For example, when there is a relativelyhigh ratio of women to men, men are in a position to engage in more un-restricted behaviors, and societal norms tend to become more promiscuous(Guttentag and Secord, 1983) When the reverse occurs and there are rela-tively many men competing for the attentions of relatively few mating-agewomen, men are required to be more committal, and societal norms favorlong-term monogamous commitments

There is evidence that such ecological factors have direct and immediateimpact on psychological judgments about relationships For example, menexposed to a large number of available and beautiful females report lesscommitment to their current partner (Kenrick, Gutierres, and Goldberg,1989; Kenrick, Neuberg, Zierk, and Krones, 1994) On the other hand,women are unaffected by exposure to good-looking men, but do decreasecommitment to current partners after they are exposed to available success-ful men (Kenrick, Neuberg, et al., 1994) Self-evaluations, on the other hand,seem calibrated to information about one’s same-sex competitors Menlower their self-appraised mate value after exposure to highly successfulrather than attractive men, whereas women do the opposite, lowering theirself-assessments after exposure to other women who are beautiful ratherthan successful (Gutierres, Kenrick, and Partch, 1999)

Cross-cultural variations in the norms surrounding love are often simpleextensions of these dynamic links between variable strategies and features

of the physical and social environment For example, polyandry in animals

is rare, but is more likely to be found when resources are scarce Polyandryoften involves cooperation between brothers, who have less to lose by raisingone another’s offspring (unrelated males in a polyandrous arrangement mayhave no genetic relationship at all to the offspring) In humans, polyandry

is likewise rare, but also is found under circumstances of resource scarcity,and also is likely to involve brothers as the polyandrous mates of the samefemale (Crook and Crook, 1988) On the other hand, polygyny is morecommon in animals, but tends to be correlated with different ecologicalconditions than is polyandry, in this case variable distribution in the quality

of male resources (with some males controlling much richer territories thanothers, for example) (Orians, 1969) In humans, polygyny is also associatedwith high variance in male resources, and high-status wealthy males aremuch more likely to attract multiple wives (Crook and Crook, 1988).Cross-cultural variations in age differences between women and their hus-bands are consistent with assumptions of an evolutionary life history modelthat considers the interactions between human social ecology and sex dif-ferences in resources contributed to offspring In North American society,women in their late teens and twenties commonly marry older men Thishas often been attributed to the particular norms of American society, butthis theory has difficulty explaining why the same pattern is found not only

in Germany and Holland but also in India, the Philippines, Africa, SouthAmerica, and small islands around the world (Harpending, 1992; Kenrickand Keefe, 1992; Otta, Queiroz, Campos, Da Silva, and Silveira, 1998) Theevolutionary life history model suggests that this pattern is so widespreadbecause of the basic biological difference in resources invested in offspring.Human females contribute bodily resources directly, but this ability lessens

in their mid-thirties, and terminates completely at menopause Males, on theother hand, contribute other resources, which generally continue to accu-mulate as the male’s age increases

The Tiwi of Australia provide a rare exception to this general pattern,with young Tiwi men usually marrying much older women (often womenpast menopause) This arrangement at first seems to go against any biolog-ical model, evolutionary or otherwise, raising a question of how the mem-bers of this society manage to reproduce themselves The answer is that Tiwisociety actually shows hypertrophied versions of several other human ten-dencies The society is polygynous, so the first (older) wife is not usually thewoman who produces a man’s children By marrying an older woman, ayoung man cements alliances with powerful older men who control the mar-riages of all their younger daughters The control of Tiwi patriarchs is so

total that all young women are married to one of them (indeed, they arebetrothed at birth) The norms require that all women be married, includingthe older widows, but older patriarchs with younger wives are not interested

in marrying widows Instead, a young man who marries a patriarch’s agingfemale relative puts himself in line to be given a young wife (Hart and Pillig,1960) Thus, rather than canceling all the rules of human reproduction, Tiwisociety is one in which the normative rules have been shuffled slightly Nev-ertheless, the usual human sex differences manifest themselves, though inanother form Most of the cultural variations in romantic relationships, for-merly believed to be completely arbitrary, may instead involve biologicallysensible interactions of basic human evolved tendencies with local social andphysical ecological factors

Conclusion

The dynamic evolutionary model of love presumes that powerfulbonds serve several distinct functions for human beings The bonds withlovers, friends, long-term mates, and family members are consequently as-sociated with very different evolved decision biases The effects of thosedecision biases unfold in a dynamic way because the other players possessdecision biases of their own Consequently, there are different social dynam-ics and social geometries associated with the various kinds of love objects.Because those decision biases are flexibly calibrated to recurrent ecologicalfactors, there will be biologically meaningful variations within and acrosssocieties that are linked to features of the prevailing social and physicalenvironment From this perspective, the key question is what the differentforms of love do, not what they feel like Most of the key questions raised

by this perspective remain to be answered Foremost among these are two:What is the precise nature of the decision biases associated with each type

of social bond? Which features of the social and physical environment teract with those biases to create the various forms of social relationshipsfound across human societies?

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