ICPR Abstracts: Session 3

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Session 3: Symposium

Evolutionary Perspectives on 
Human Social Relationships

In Search of Integration:
The Prospect of Evolutionary Psychology

Douglas T. Kenrick
Arizona State University

The study of human relationships spans a remarkably 
diverse array of topics, ranging from altruism to 
aggression, from interpersonal attraction to intergroup 
conflict, from obedience and conformity to group pressure 
to minority dissent, from how people persuade others to 
how they avoid being persuaded, and from how people 
perceive and think about others to what they actually do in 
different social contexts.  Given this tremendous diversity, 
one might expect that most research on close relationships 
would be organized around and guided by a small number 
of grand theories, perspectives capable of integrating what 
we currently know about relationships and indicating clear 
directions for future research.  Most research on personal 
relationships, however, continues to be structured more 
around research "topics" than by integrative theories.  This 
is unfortunate because a comprehensive theory capable of 
providing considerable theoretical and empirical 
integration to the field of relationships research--the 
Theory of Inclusive Fitness, which has been most cogently 
articulated by William Hamilton (1964) and Robert 
Trivers (1971, 1972, 1974)--currently exists. 
        This paper has three sections:  In the first, I 
present a hierarchical model that depicts the different 
levels at which different evolutionary theories and 
principles reside.  The model reveals that even though 
most evolutionary theories are based on principles derived 
from a single, higher-level theory (Inclusive Fitness 
Theory), most research predictions about social behavior 
are derived from one or more "middle-level" evolutionary 
theories (e.g., mating and sexual selection, reciprocal 
altruism, parent- offspring conflict, host-parasite 
coevolution).  Each middle-level theory deals with 
different adaptive problems that humans recurrently faced 
during evolutionary history (e.g., selecting a good mate, 
deciding when to behave altruistically, resolving conflicts 
with members of different groups).  Thus, there is no 
single theory of evolution; rather, evolutionary theories are 
organized hierarchically, with Inclusive Fitness Theory 
acting as the fundamental theoretical base from which all 
middle-level theories originate. 
        In the second section, I discuss several reasons 
why researchers who study relationships--especially those 
trained in social psychology--have been slow to recognize 
the value of an evolutionary perspective.  The major 
reasons include insufficient graduate training in 
evolutionary principles, a constricted focus on the kinds of 
research questions asked and studied, and the erroneous 
belief that evolution is simply "not relevant" to most forms 
of human social behavior.  I propose that a complete 
understanding of human social behavior cannot be 
achieved without asking, contemplating, and studying 
questions about our evolutionary origins. 
        In the final section, I overview some common 
misconceptions about evolutionary psychology and 
indicate how it differs from traditional sociobiology.  I 
conclude by discussing the kinds of phenomena and social 
behaviors to which evolutionary theories should be most 
applicable. 


Sex Differences in Jealousy:
Sexual vs. Emotional Infidelity

Lee Kirkpatrick, College of William and Mary
David Buss, University of Michigan

One important aspect of close relationships for which an 
evolutionary approach leads to clear and unique 
predictions is the experience of jealousy.  Previous 
research, focusing primarily on individual-difference 
measures of average frequency and/or intensity of jealous 
feelings, has generally neither predicted nor demonstrated 
any reliable sex differences in the experience of jealousy.  
However, an evolutionary approach leads to an 
unambiguous prediction concerning sex differences in the 
kinds of situations that most powerfully evoke jealousy.  
Specifically, men are expected to be particularly concerned 
about sexual infidelities on the part of their partners, due 
to the risk (in terms of inclusive fitness) of investing 
wasted resources in genetically- unrelated offspring.  
Women, on the other hand, should be more concerned 
about their partners' emotional infidelities, which may 
signal a potential loss of resources (especially investment 
in offspring) to a rival. 
        This paper reviews the theoretical basis for this 
prediction, contrasts it with previous (non-evolutionary) 
research findings on jealousy, and reviews a variety of 
published and unpublished studies supporting the 
prediction. Data consistently demonstrate that women are 
far more upset than men by the prospect of partners' 
emotional infidelity (e.g., partner falling in love with or 
becoming emotionally attached to someone else), in 
contrast to the prospect of partners' sexual infidelity (e.g., 
having sexual intercourse with someone else).  This basic 
sex difference has been found (a) across several different 
variations of self-report measures, (b) using 
psychophysiological measures to assess emotional 
reactions, and (c) across a variety of cultures. 
        In addition, a forthcoming critique (DeSteno & 
Salovey, in press) of this research is reviewed, in which 
the authors offer an alternative, non-evolutionary 
explanation--the "double-shot" hypothesis--for these 
findings.  We describe this alternative hypothesis, outline 
a variety of theoretical weaknesses in the position, and 
discuss several additional (unpublished) studies designed 
specifically to pit these competing hypotheses against one 
another.  The evolutionary hypothesis is unambiguously 
supported, and the double-shot hypothesis unambiguously 
falsified, in this series of tests. 


Media and Culture Over the Centuries:
The Interplay of Culture and
 Evolved Psychological Mechanisms

Bram Buunk, University of Groningen
Douglas T. Kenrick and Chondra Lockwood
Arizona State University

Gender differences in mate preferences are often 
attributed to the norms of "American culture" when the 
norms of the culture may themselves simply reflect 
evolved psychological mechanisms.  We report two studies 
of age differences in individuals presented in "the media."  
The first is a study in which university students were 
asked to recall episodes in which sexual affairs were 
reported either in newspapers, magazines, or on television. 
The subjects were asked to estimate the ages of the man 
and the woman in the media account, as well as describing 
features of each person's attractiveness, power, and status.  
Data were also collected on a group of subjects over the 
age of 40.  Both samples showed a similar tendency to 
remember episodes in which the man was, on average, in 
his forties, and the woman was, on average, in her 
twenties.  These estimates suggest an age bias either in 
actual affairs or in the individuals whose affairs are 
considered newsworthy (or memorable to the consumers of 
the media).  In another study, we examined women and 
men presented in over 300 classical works of art in the 
four centuries preceding this one, and had their ages 
estimated by coders.  Age estimates were reliable, and 
again suggested a large age discrepancy--the age 
distribution for women showed a dramatic peak in the 
twenties, whereas that for men was more level over the 
decades, with a peak in the thirties and forties.  These data 
could be taken to demonstrate a centuries old conspiracy 
amongst the creators of media.  However, marriage data 
and singles advertisements from around the world suggest 
that they are better explained in terms of evolved mate 
preferences.  In all cultures and at all times thus far 
examined, women tend to select mates who are on average 
slightly older than them, whereas older men tend to select 
mates considerably younger than them.  These findings fit 
with evolutionary models suggesting different life history 
strategies for men's and women's mate selection criteria. 


The Nature of the Bond in Pair-bonds

Cindy Hazan and Debra Zeifman
Cornell University

Results from several empirical investigations will be 
offered as evidence that stable pair-bonds are regulated by 
the same psychological mechanism that originally evolved 
to ensure that human infants would become emotionally 
attached to their caregivers.  The primary sources of 
evidence are the many fundamental similarities between 
infant-caregiver attachments and pair-bond relationships.  
Specifically, both qualify as a unique type of bond, 
distinguishable from other forms of social connectedness 
by virtue of their common and distinctive components and 
security-promoting function. Both are typified by a similar 
and qualitatively distinct type of physical contact.  The 
time course and processes by which each type of 
relationship develops are essentially the same.  And, both 
are distinctive in their effects on physical and 
psychological well-being. 
        Reproductive fitness is achieved through 
solutions to three adaptive challenges:  surviving to 
reproductive age, successfully mating, and providing 
adequate care to offspring to ensure that they, too, survive 
to reproduce.  It seems clear that attachment is the 
psychological mechanism that evolved as a solution to the 
first problem, of survival through childhood.  Less obvious 
is the role it plays in mate selection.  The goal of mating is 
to identify and attract someone who is fit to serve as a 
reproductive partner.  For both men and women, it forces 
consideration of a potential mate's suitability as an 
attachment figure.  The attachment mechanism also 
contributes to the solution of the third adaptive problem, 
of ensuring the reproductive fitness of offspring.  By 
helping to maintain the pair-bond, it increases the 
probability of long-term paternal investment and the kind 
of family stability that gives progeny an edge in the 
competition for mates, and the skills needed to retain one. 
        Inclusive Fitness Theory has already been 
fruitfully applied to the study of human mating, and the 
resulting research has led to important insights into the 
solutions to such crucial adaptive challenges as how to 
select and attract a mate.  Attachment theory complements 
this growing body of work by providing a different 
evolutionary perspective on human pair-bonds.  Its 
strength lies not so much in explaining strategies of 
selection and attraction as in providing insights into the 
nature of the bond that holds adult partners together.  It 
further supplements existing models by highlighting some 
broad-based similarities between the sexes.