The Place of Attachment in Human Matingadultattachmentlab.human.cornell.edu/HazanDiamond2000.pdf · The Place of Attachment in Human Mating Cindy Hazan and Lisa M. Diamond Cornell

Review of General Psychology2000, Vol. 4, No. 2, 186-204

Copyright 2000 by the Educational Publishing Foundation1089-268O/O0/$5.0O DOI: 10.1O37//1089-2680.4.2.186

The Place of Attachment in Human Mating

Cindy Hazan and Lisa M. DiamondCornell University

Application of the principles of evolution and natural selection to the phenomena ofhuman mating does not lead inevitably to a single theoretical model. According to thestandard evolutionary model, formally known as sexual strategies theory (D. M. Buss& D. P. Schmitt, 1993), biologically based sex differences in parental investment haveresulted in hard-wired sex differences in mate preferences and mating strategies. Acritical analysis of the logical and empirical foundations of the theory reveals severalweaknesses and limitations. This article demonstrates how attachment theory (J.Bowlby, 1969/1982, 1973, 1979, 1980, 1988) can be used to integrate a diverse set ofideas and research findings and provide a more grounded account of human mating.

In the past decade, there has been a resur-gence of interest among social scientists in Dar-win's theory of evolution. In the field of psy-chology, this is exemplified by the work ofDavid Buss and colleagues, who have appliedthe theory to human mating. One measure of thesuccess of this effort is the fact that their modelis widely viewed, at least among psychologists,as the definitive evolutionary perspective on thetopic. Put differently, many in our field seem tothink that application of the principles of naturalselection to human mating phenomena inevita-bly results in the Bussian framework. An unfor-tunate result is that those who find fault withthis particular framework tend to reject outrightthe possibility that Darwin's grand and elegant

Cindy Hazan and Lisa M. Diamond, Department of Hu-man Development, Cornell University.

Lisa M. Diamond is now at the Department of Psychol-ogy, University of Utah.

We are grateful to Richard L. Canfield for his thoughtfulcritique of an earlier version of this article, and to EmilyAllen, Jeffrey Ellens, Samantha Goldman, Samara Guzman,Janienne Kondrich, and Shelby Semino for help with theliterature review. Our work also benefited from the supportof a National Science Foundation grant (SJBR-9320364).Many of the ideas and arguments contained herein werepreviously presented by Cindy Hazan in conference papersat the 1997 (Toronto, Ontario, Canada) and 1998 (Lexing-ton, Kentucky) meetings of the Society for ExperimentalSocial Psychology and the 1999 (Denver, Colorado) meet-ing of the American Psychological Society.

Correspondence concerning this article should be ad-dressed to Cindy Hazan, Department of Human Develop-ment, Cornell University, Ithaca, New York 14853-4401.Electronic mail may be sent to [email protected].

theory, which remains one of the most robust inmodern science, has anything of value to con-tribute to the understanding of mating in ourspecies. Although all theories about the ances-tral nature of human mating are necessarilyspeculative, in what follows we hope to dem-onstrate that the available evidence supports avery different evolutionary perspective on howHomo sapiens go about the business of mating.

The Standard Evolutionary Model

The standard evolutionary model is formallyknown as sexual strategies theory (Buss &Schmitt, 1993). It is essentially an extension ofthe theory of parental investment, proposed byTrivers in 1972. He argued that in any species inwhich differences exist in what it costs mem-bers of each sex to reproduce their genes, therewill be corresponding sex differences in matingbehavior. The biological reality in humans isthat males can reproduce their genes with theminimal investment of a few minutes and a fewsperm, whereas the cost to females is usuallyyears of investment in the form of gestation,lactation, and offspring care. In theory, suchasymmetry has resulted in hard-wired sex-spe-cific strategies for achieving reproductive suc-cess. Males "naturally" seek out and take ad-vantage of opportunities to copulate with asmany different females as possible, especiallyones who display the fertility markers of youthand beauty. The female is "by nature" moresexually cautious, preferring one male who has

186

SPECIAL ISSUE: ATTACHMENT AND MATING 187

resources and appears willing to share themwith her and the offspring she will have tonurture. Although sexual strategies theorists ac-knowledge that the mating behavior of men andwomen can be similar in some respects undercertain ecological conditions, above all theyemphasize sex differences. The inescapableconclusion from their writings is that differ-ences between the sexes represent the hallmark;of human mating.

Scores of studies have been conducted to testsexual strategies theory, including one massivesurvey of more than 10,000 individuals in 37different cultures (Buss, 1989). The findingsindicate that males worldwide assign greaterimportance than females to the appearance ofpotential mates, preferring those who are youngand physically attractive. In contrast, femalesgenerally report caring more than males aboutthe social status, ambition, and earning power ofpotential mates. In sum, the sex differences inmate preferences that sexual strategies theorypredicts appear to be both statistically reliableand culturally universal.

As the name implies, a central tenet of sexualstrategies theory is that human mating is inher-ently strategic. In theory, mating behavior isguided by evolved psychological mechanismscompelling men and women not only to desirecertain qualities but to select mates on the basisof these innate desires. However, the methodsused in tests of the theory do not and cannotdirectly test the selection part of the prediction.Participants (often undergraduate students) areasked to generate a list of the qualities on whichthey believe their eventual mate selections willbe based or, sometimes, simply asked to rank orrate the importance of a list of traits provided byresearchers. Lists typically include the fullrange of desirable qualities: a winning person-ality, above-average intelligence, great financialprospects, high social status, and good looks.Although the findings are generally consistentwith theoretical predictions—at least as theypertain to sex differences in the estimated rela-tive future value of certain qualities—they re-veal nothing about whether reported selectioncriteria translate into actual mate choices.Clearly, the validity of sexual strategies theoryhinges on its ability to predict real-world mateselection behavior.

Putting Mate Selection Theories tothe Test

The most straightforward way to identify thecriteria that people use to select actual as op-posed to hypothetical mates would be to study agroup of already-mated individuals and deter-mine the basis on which they chose their part-ners. But simply asking them has obvious lim-itations. For one, respondents might be reluctantto answer honestly, especially if their selectioncriteria included qualities that could be judgedsuperficial, such as money or looks. However,concerns about this possible limitation can beeasily dismissed in light of the fact that largenumbers of respondents in Buss et al.'s studieshave voluntarily mentioned such qualities ontheir lists of mate preferences. A more trouble-some possibility is that the average person lacksawareness of the factors that truly influence hisor her mating decisions (for a similar point, seePietromonaco & Feldman Barrett, 2000).

All theories that regard mate choice as astrategic process presume that choices are sys-tematically guided by characteristics of the in-dividuals making them. That is, whether a re-searcher adopts an assortative mating perspec-tive (one prefers those who are similar), anidiographic view (one's preferences are learnedand idiosyncratic), or a sexual strategies model(one's preferences are determined by biologicalsex), the same prediction would hold: Matechoice is driven primarily by qualities of thosedoing the choosing. A corollary is that individ-uals who have similar qualities should also havesimilar mate preferences. This makes possiblean elegant "natural" test of these theories usingidentical twins. Monozygotic (MZ) twins are assimilar as two people can be. Not surprisingly,they tend to make similar choices in a widerange of domains, including jobs, clothing,friends, cars, hobbies, and vacations, to namejust a few. If mate selection is lawfully guidedby the characteristics of choosers, MZ twinsshould prefer and select mates who are, them-selves, more alike than the mates of less similarpairs of individuals.

Lykken and Tellegen (1993) recently testedthis hypothesis using the Minnesota Twin Reg-istry, which contains a wealth of information,including personality, achievement, IQ, atti-tude, occupation, and physical appearance data,on more than 1,000 twin pairs. Even with this

188 HAZAN AND DIAMOND

large sample size and correspondingly stronganalytic power, no evidence was found to sup-port any strategic model of mate selection. Theunexpected and hugely significant finding wasthat the mates of MZ twins are no more similarto each other than are the mates of randomlyselected pairs.

At first, one might think that this findingdeals a bigger blow to theories of assortative oridiographic models than to sexual strategies the-ory, given that the former attribute mate choiceto the chooser's personal characteristics (inde-pendent of sex), whereas sexual strategies the-ory attributes mate choice to the chooser's sex(independent of personal characteristics). Butpersonal characteristics play just as important arole in sexual strategies theory via their link tomate value. Mate value represents an individu-al's capacity to attract high-quality mates. Inother words, the closer one is to the ideal forone's sex, the better able one is to attract part-ners who are ideal for their sex.

The personal characteristics that factor intothese ideals (most notably, social status for menand physical attractiveness for women) aremore similar in twins than in randomly pairedindividuals. Thus, the genetic similarity be-tween twins equalizes their mate value, givingthem the same range of "attractable" mates. Asa result, twins should end up with mates that aremore similar to one another in physical attrac-tiveness and social status than the mates ofrandomly selected pairs. But it is an empiricalfact that they do not.

Previous tests of sexual strategies theory haverelied exclusively on self-reports from individ-uals who are asked about the qualities theybelieve will influence their eventual mating de-cisions. The twin findings strongly suggest thatthe criteria people think they will use to selecttheir mates are not the factors that ultimatelydetermine their actual mate choices. Equallyimportant is the fact that the twin data challengethe fundamental assumption that mate selectionis a strategic process. It is perhaps ironic thatsocial scientists have taken the premise of stra-tegic selection at face value and devoted muchresearch attention to identifying the criteria onwhich such selections are based. We concurwith the twin researchers' conclusion that hu-man mating may be more "adventitious" than isgenerally assumed.

Overview

If mates are not chosen on the basis of thesex-specific criteria that the standard evolution-ary model posits or according to the criteria ofother strategic mate selection theories, thenwhat determines who ends up with whom? Inthe following sections, we outline an alternativeevolutionary perspective on human mating thatproposes an answer to this burning question.We begin with an overview of mating relation-ships as seen through the lens of attachmenttheory (Bowlby, 1969/1982, 1973, 1979, 1980,1988). It is argued that pair bonding is the normin our species, that this normative mating pat-tern is reflected in male as well as female matepreferences, and that it is advantageous in re-productive fitness terms. Propinquity, familiar-ity, and romantic infatuation are proposed asthe mechanisms that explain how actual mate"choices" are made and how mating relation-ships are established. We conclude by address-ing some of the additional empirical and logicallimitations of sexual strategies theory and byexplicating some of the reasons that pair-bondattachment is an essential component of anytheory purporting to offer a comprehensivemodel of human mating.

Human Mating From an AttachmentTheory Perspective

If one wants to know the most reproductivelyadvantageous mating strategy for any species, asafe bet is simply to observe what the membersof that species normally do. In species in whichconception is all that is needed to achieve re-productive success, sexual partners part ways assoon as a viable pregnancy has been achieved,sometimes after a single copulatory sequence.Yet, this is not the case for our species. Instead,most humans opt to remain with their reproduc-tive partners for an extended period of time(Fisher, 1989, 1992; Lancaster & Kaplan, 1994;Van den Berghe, 1979). This runs counter to theimpression conveyed by sexual strategies the-ory, namely that an enduring relationship be-tween human mates is difficult to achieve andtherefore relatively rare as a result of males'evolved inclination to forgo long-term matingassociations in favor of multiple inseminations.The reality, however, is that human reproduc-tive partners typically remain together for a


minimum of several years, a fact that any theoryof human mating must take into account.

If short-term mating is so advantageous formales, why should this long-term mating pat-tern ever have evolved? It is thought that a trendtoward extended associations between humanmates evolved in response to a birthing crisis inwhich the infant's large head could not easilypass through the birth canal of our bipedal fe-male ancestors (Trevathan, 1987; Washbum,1960). Infants who were born prematurely, withless developed brains and correspondinglysmaller heads, were more likely to survive, aswere their mothers. Immaturity at birth offeredthe additional advantage of a longer period ofpostnatal neural plasticity and potential forlearning, which is important for a highly socialspecies. However, the benefits of prematurebirth would have posed new adaptive chal-lenges. Specifically, the effort required to ade-quately nurture exceptionally dependent off-spring during a protracted period of immaturitymade paternal investment an advantage, if not anecessity (Mellen, 1981; Small, 1993). Helplessand vulnerable offspring would have had littlechance of surviving to reproductive age or de-veloping the skills needed for their own even-tual mating and parenting roles unless fathersparticipated in their protection, care, and social-ization. Thus, a new adaptive problem arose:how to keep males around and involved in thecare of their progeny.

As it happened, our species already had avail-able a specialized but flexible mechanism forfostering an enduring bond between two indi-viduals. The mechanism was attachment, whichhad helped to ensure a survival-enhancing tiebetween infant and mother. Given the generallyconservative tendencies of evolution and natu-ral selection, it is parsimonious to suppose thatthis mechanism was exploited for the (new)purpose of cementing a bond between reproduc-tive partners. This co-opting of an evolvedstructure for a novel purpose is fairly common;such structures are called "exaptations" (Gould& Vrba, 1982). To suggest that the attachmentsystem was exploited to keep adult mates to-gether is to claim that the tie between estab-lished pairs is an attachment bond in the strictand specific sense of the term. There is diverseand abundant evidence that this is so (Hazan &Zeifman, 1999).

Defining Components

Bowlby took care to define the specific typeof relationship to which his theory of attach-ment applied and to distinguish this specialbond from other kinds of social ties. Attach-ments have four defining features, all of whichare evident in the overt behaviors directed to-ward an attachment figure: seeking and main-taining physical proximity (proximity mainte-nance), seeking comfort or aid when needed(safe haven), experiencing distress on unex-pected or prolonged separations (separationdistress), and relying on the attachment figureas a base of security from which to engage inexploratory and other nonattachment activities(secure base).

In infancy, these behaviors are directed al-most exclusively toward primary caregivers.Babies often seek and enjoy contact with manyindividuals and even look for and accept com-fort from them. Yet, usually a much smallernumber of people, not uncommonly one, qual-ify as an attachment figure by being the target ofall four behaviors. Infants are especially dis-criminating in the expression of separation dis-tress. This particular component of attachmenttypically emerges between 6 and 8 months ofage, and its appearance is the accepted markerthat an attachment bond is in place (Ainsworth,Blehar, Waters, & Wall, 1978). This timecourse is universal and, within normal ranges,independent of rearing environment (Kagan,1984).

An explicit prediction of attachment theory isthat, in adulthood, these same behaviors will beredirected toward a mate. Two empirical inves-tigations have confirmed this prediction (Fraley& Davis, 1997; Hazan & Zeifman, 1994). Al-though adults, like infants, seek and enjoy con-tact with a variety of people and sometimes turnto them for comfort or reassurance, most ofthese relationships do not qualify as attachmentbonds. Those that do, by virtue of containing allfour defining components, are almost exclu-sively formed with romantic partners. Thus,by this standard, mate relationships are attach-ments in the technical sense of the term.

Reactions to Separation and Loss

Additional evidence that attachment is an in-tegral part of mate relationships comes from the


literature on bereavement. The original inspira-tion for attachment theory was Bowlby's obser-vations of infants and children separated fromtheir primary caregivers. He found it remark-able that the separations were so distressingeven in situations in which nutritional and hy-gienic needs were being met quite adequatelyby surrogates. More striking was the similarityacross children in how they responded. Bowlbyidentified what appeared to be a universal pat-tern of reactions that he labeled the protest-despair-detachment sequence. The initial reac-tion is characterized by behavioral agitation,hyperactivity, crying, resistance to others' of-fers of comfort, and extreme anxiety, often tothe point of panic. Eventually, active protestsubsides and is followed by a period of lethargy,inactivity, depressed affect, disrupted sleep, andreduced appetite. In time, a degree of emotionaldetachment from the lost attachment figure fa-cilitates the resumption of normal, presepara-tion activities and functioning.

Several studies have documented essentiallythe same sequence in adults grieving the loss ofa long-term partner: initial panic and anxietyfollowed by lethargy and depression and, even-tually, recovery through emotional detachment(Fraley & Shaver, 1999; Hazan & Shaver, 1992;Parkes & Weiss, 1983; Weiss, 1975). This se-quence of reactions is not limited to situationsof permanent loss. Even brief, routine separa-tions are enough to trigger a less intense butessentially identical pattern of responses in mar-ital partners (Vormbrock, 1993).

It is important to note that the protest-de-spair-detachment sequence is observed almostexclusively in two social relational contexts:infant-caregiver relationships and adult pairbonds. The fact that this three-stage reaction isthe norm among adults separated from theirmates, and not the normal reaction to the loss ofother kinds of social ties, is another indicationthat the attachment mechanism is operative inpair bonds. And it is another fact of humanmating that belongs in theories of what suchrelationships are like.

Health Effects

It is well established that human infants, aswell as the young of other primate species,suffer long-term negative health effects if theyare not given an opportunity to bond with an

attachment figure or if an established bond isdisrupted (Harlow & Harlow, 1965; Kraemer,1997; Robertson, 1953; Spitz, 1946; Suomi,1997). Although adults are clearly less depen-dent on an attachment figure for basic survival,there is ample evidence that they incur healthbenefits from having one and are at significantlyincreased risk for numerous physical and mentalhealth problems if they do not. For example,divorce increases the likelihood of admissionto a psychiatric facility, alcoholism and otherforms of substance abuse, accidents, suicide,and impaired functioning of the cardiac, endo-crine, and immune systems (e.g., Bloom, Asher,& White, 1978; Goodwin, Hurt, Key, & Sarret,1987; Lynch, 1977; Uchino, Cacioppo, &Kiecolt-Glaser, 1996). Among the most com-mon life stressors, attachment-related lossescause the most subjective distress. Death ofa spouse is rated as the most stressful event,followed by divorce and marital separation(Holmes & Rahe, 1967). Other losses can bequite painful, but they generally have not beenfound to jeopardize physical or psychologicalwell-being to the same degree as disruption of apair-bond attachment. If separation distress isthe marker of attachment, then bonds betweenmates clearly qualify.

Nature of Physical Contact

Like caregivers and their infants, romanticpartners (at least initially) spend much timeengaged in mutual gazing, cuddling, nuzzling,sucking, and kissing in the context of prolongedface-to-face, skin-to-skin, ventro-ventral con-tact. These most intimate of human interper-sonal exchanges are universally typical of onlytwo types of relationships: those between in-fants and caregivers and those between mates(Eibl-Eibesfeldt, 1975). Not coincidentally, thistype of physical contact is known to fosterattachment.

There is even evidence that the chemical ba-sis for the effects of close physical contact maybe the same for lovers and mother-infant pairs(for a review, see Insel, 2000). Oxytocin is anendogenous hormone that triggers labor in preg-nant women and milk letdown in nursing moth-ers. It is thought to aid infant attachment andmaternal caregiving by inducing a state of calmand contentment and by stimulating a desire forcontinued close bodily contact. Oxytocin is also


present during sexual exchanges between adultlovers. It builds with sexual stimulation andexcitement, is released at climax—in bothmales and females—and has been implicated inthe cuddling or "afterplay" that often followssexual intercourse (Carter, 1992, 1998). Cud-dling or contact comfort, as was famously dem-onstrated by Harlow, is crucial for the establish-ment of attachment bonds. Thus, if sexualorgasm triggers release of a hormone that stim-ulates a desire for bond-promoting contact, iteffectively increases the chances that a matingpair will become emotionally attached.

Sexual Anatomy and Physiology

Many unique features of human sexualityfoster and help maintain an enduring bond be-tween reproductive partners. The most strikingdifference in our reproductive physiology incomparison with that of other mammalian spe-cies is the absence of outward signs of estrus.Most mammals mate only during the short es-trus periods of the female, but human sexualdesire and activity are not so restricted. Womencan be sexually receptive during any phase oftheir reproductive cycle, even though concep-tion is possible only during a small fraction ofit. This physiological adaptation facilitates acontinuous tie between partners on the basis ofsexual reward. Among older couples, in whichthe female's reproductive potential may bepractically nonexistent, nearly half continue tohave sex an average of once per week (Lau-mann, Gagnon, Michael, & Michaels, 1994).All of this suggests that sex in our speciesserves more than a reproductive function.

Hidden ovulation may also serve to diminishthe benefits of straying. Males of many diversespecies guard their mates during periods of sex-ual receptivity so as to ensure paternity. Whenthe fertile period has ended, he can safely moveon to another receptive partner. However, ifovulation is hidden, making it impossible forthe male to determine just when fertilizationwill be possible, his optimal strategy may shifttoward guarding and remaining with the samesexual partner for longer periods of time (Al-cock, 1989).

Genital differences between humans andtheir closest primate relatives also suggest theimportant role of sex in maintaining the humanpair bond. For example, the average length of

the erect human penis is 13 cm, as comparedwith approximately 3 cm for the gorilla, a muchlarger animal in terms of overall body size. Theexceptional length of the human penis, in addi-tion to its unique thickness and flexibility rela-tive to that of all the great apes (Eberhard, 1985,1991), made possible a wide variety of copula-tory positions, including more intimate face-to-face, mutually ventral (i.e., bond-promoting)positions. Distinctive features of the human pe-nis also make female orgasm more likely, whichin turn increases the probability of conceptionby causing her cervix to dip rhythmically intothe semen pool and her uterus to contract in amanner that helps move sperm toward egg(Baker & Bellis, 1995). In addition, it may haveserved to heighten her readiness for engaging insexual activity, thereby strengthening the bondwith her mate (G. F. Miller, 1998).

It deserves noting that penis size alone is notan accurate predictor of monogamous versuspolygamous mating patterns among primates,nor is our species unique in such reproductivecharacteristics as hidden ovulation, female or-gasm, or face-to-face copulation (Blaffer-Hrdy,1988). We do not claim that the presence of anyof these characteristics represents proof that hu-mans are hardwired for monogamy. As manyanthropologists have argued quite convincingly(e.g., Small, 1993), facultative flexibility inmating strategies has been a key component ofour survival as a species. Nevertheless, multiplefeatures of human sexual anatomy and physiol-ogy support the view that we evolved to bondwith our reproductive partners. In addition, thedecrease in sexual dimorphism over the courseof human evolution is another indication ofmovement away from opportunistic mating inthe direction of more enduring pair bonds, notas a culturally prescribed arrangement but as apathway to reproductive success for a specieswhose young fare best with two investing par-ents. If one gives this capacity for bonding andthe reproductive implications of reduced sexualdimorphism their due, one is led to a ratherdifferent evolutionary perspective on humanmating.

Mate Preferences

If natural selection pressures on human mat-ing operated in a manner that is consistent withour pair-bond attachment hypothesis, then at-


tachment considerations ought to be reflected inmate preferences. Moreover, there is no theo-retical basis for predicting that males and fe-males would differ in this respect. The qualitiesthat make one a good attachment figure—beingkind, warm, responsive, and competent—do notvary as a function of sex. In contrast, sexualstrategies theory makes the explicit predictionthat males and females will look for differentqualities in a potential mate owing to differ-ences in parental investment that are presenteven before conception (Trivers, 1972). Earlierwe sketched the basic premises of this argu-ment; here we revisit it in greater depth.

From puberty through late adulthood, malesproduce approximately 500 million tiny spermcells per day (Zimmerman, Maude, & Mold-awar, 1965). Females, on the other hand, pro-duce an average of one large egg per monthfrom puberty until middle adulthood. For males,whose contribution to their progeny can be aslittle as a few cheap sperm, the most effectivestrategy for achieving reproductive success maybe to take advantage of all opportunities for sexwith fertile female partners. The female, forwhom every sexual encounter is potentiallyquite costly, is predicted to be far choosier inaccepting or encouraging copulations. Once heregg is fertilized, she has to forgo other repro-ductive opportunities for a relatively long pe-riod of time. Thus, her most effective strategy isto limit her sexual encounters to males whopossess and appear willing to share valuableresources with her and her offspring.

Previously we cited the 37 cultures study(Buss, 1989) in which it was found that malesand females universally differ in the qualitiesthey seek in a mate. Men assign greater weightto physical attractiveness, and women assigngreater weight to social status. But what getslittle press or theoretical attention is the fact thatneither physical appearance nor social status isgiven top billing by either sex. When men andwomen the world over make their mate wishlists, there are other qualities that they rank asmore important. The top-ranked qualities areidentical for men and women. What are theseuniversally coveted mate traits? The answer iskindness, understanding, and intelligence (Buss& Barnes, 1986), roughly the same qualities thatappeal to infants in potential attachment figures(Bowlby, 1969/1982).

But do people really consider a trait such askindness more important than other qualitieswhen choosing a mate? To address this ques-tipn, Graziano and colleagues (Graziano,Jensen-Campbell, Todd, & Finch, 1997) con-ducted a series of experiments in which hetero-sexual women rated the attractiveness of menwhose hypothetical traits of dominance andagreeableness were systematically manipulated.The experimental conditions represented thevarious combinations of these traits that womenmight encounter in their real-world dating ex-periences. Some men are really nice but notvery dominant, whereas others may have highstatus in the dominance hierarchy but be some-what lacking in agreeableness.

From a sexual strategies perspective, domi-nance should triumph. After all, agreeablenessin a mate is a luxury for females facing years ofparental investment. They should favor the malewho will reliably beat out other males in thecompetition for status and resources. This isnot what Graziano et al. (1997) found. Whenwomen were forced to choose, they consistentlypreferred the nice guy. Apparently, our chim-panzee cousins do too (Sapolsky, 1998). In fact,agreeableness was three times as powerful asdominance in predicting women's attractions.

Further evidence that mate preferences arenot always reducible to sex differences in pa-rental investment comes from studies of maleand female facial attractiveness. In a series ofdetailed analyses involving facial-metric meth-ods and cross-cultural samples, Cunninghamand his collaborators (Cunningham, Druen, &Barbee, 1997) have sought to identify the fea-tures that make potential mates of both sexesmost appealing. The findings vary somewhat asa function of gender, but the overall combina-tion of features judged to be most attractive isessentially the same for men and women. Thewinning configuration combines three types offacial features: expressive, neotenous, and sex-ual maturational. Expressive features (e.g., sizeof smile area) serve as cues of warmth andsensitivity; neotenous features (e.g., large eyes)signal vulnerability; and sexual maturationalfeatures (e.g., prominent cheekbones) functionas cues of reproductive capability. In otherwords, judgments about attractiveness do notboil down to the kinds of sex differences thatsexual strategies theory would predict. Instead,


attachment qualities figure prominently in thejudgments of both sexes.

Such findings demonstrate that human matepreferences are not governed exclusively by aself-contained psychological mechanism cus-tom designed by evolution to propel individualstoward the singular, circumscribed goal of sex-ual intercourse. Not only is such a system in-consistent with the data, we think it makes littlesense in light of the survival problems faced byour ancestors in the environment of evolution-ary adaptation (EEA). Just as Bowlby theorized,human mating involves multiple evolved mech-anisms. Whereas attachments between infantsand caregivers are inherently asymmetric—withinfants seeking the emotional security, protec-tion, and care that parents provide—attach-ments between romantic partners are symmet-rical in that both partners mutually seek andprovide the same social provisions. In the courseof normative development, these evolved psycho-logical mechanisms (attachment and parentalcaregiving) become integrated with the sexualmating system (Hazan & Shaver, 1994a, 1994b;Hazan & Zeifman, 1994; Shaver & Hazan, 1993;Shaver, Hazan, & Bradshaw, 1988). From an at-tachment perspective, it thus comes as no surprisethat the faces judged most appealing by men andwomen alike are those that combine the signalstimuli of all three mechanisms.

The differences between a sexual strategiesperspective on mating and an attachment ap-proach should now be apparent. For sexualstrategies theory, mating is about the reproduc-tion of genes via sexual activity. Emotionalbonds are relevant only insofar as they help orhinder this process. From an attachment per-spective, these bonds belong at the center, ratherthan the periphery, of evolutionary theories ofhuman mating. However, to advance this argu-ment requires more than simply citing evidencethat pair bonding is our species-typical matingpattern, that the attachment mechanism is oper-ative in pair bonds, that numerous features ofhuman sexual anatomy and physiology fostermate attachment, or that attachment consider-ations consistently outweigh physical appear-ance and social status in male and female matepreferences. A case must be made that attach-ment bonds between reproductive partners carryadvantages in terms of reproductive fitness.

Evidence That Pair-Bond Attachment IsReproductively Advantageous

In our species, reproductive success requiresnegotiation of at least three adaptive challenges:surviving to reproductive age, acquiring andretaining a mate, and providing adequate care tooffspring so that they also survive to reproduce.It was argued previously that the emergence ofbipedalism favored premature birth and that theextreme immaturity of human neonates createda situation in the EEA in which survival de-pended not only on infants forming a strongbond to a protector but also on the joint invest-ment of parents. This necessitated a mechanismthat would hold reproductive partners togetherfor an extended period of time. We proposedthat attachment, which had evolved to ensure anenduring bond between infants and caregivers,was exploited for this new purpose (for a dif-ferent view of the adaptive value of pair bond-ing, see Insel, 2000). In what follows, we arguethat the advantages of pair bonding include en-hanced survival and reproductive fitness formates as well as their offspring.

Whether opportunistic, short-term matingstrategies are inferior to stable long-term ap-proaches is the source of much debate (e.g.,Belsky, 1999; Buss, 1997; Chisholm, 1996), butit is important to remember that these are notmutually exclusive strategies. Pair-bond attach-ment is not synonymous with sexual exclusiv-ity. In fact, genetic analyses of offspring pro-vide objective evidence that extrapair copula-tions are common even in species that by allethological criteria qualify as monogamous(Carter et al., 1997; Mendoza & Mason, 1997).The relative value of short-term versus long-term mating strategies will vary depending onenvironmental contingencies. According to lifehistory theory (Stearns, 1992), organisms pos-sess a finite amount of resources that mustbe allocated across various evolutionary chal-lenges, including survival, growth, mating, andparental investment. Local circumstances deter-mine the balance of time and energy an indi-vidual devotes to each. Thus, both long- andshort-term strategies can be viewed as reason-able and comparably adaptive responses, givena particular ecology.

It is clearly advantageous for humans to becapable of adapting their mating strategies tolocal ecological conditions (Daly & Wilson,


1988). This does not necessarily mean thatshort- and long-term mating strategies are dif-ferent but essentially equal solutions to the sameevolutionary challenges (but see Belsky, 1999,for an alternative viewpoint). Adjustments tononoptimal circumstances are sometimes nec-essary, but they may not produce optimal re-sults. Take feeding behavior, for example. Sur-vival depends on the regular intake of food, and,if hungry enough, humans will consume almostanything to stay alive. But garbage is unlikelyto have the same nutritional value as a well-rounded meal, nor would it be expected to sup-port physical development equally well.

Likewise, quick and frequent copulationscoupled with an avoidance of parental invest-ment may be the best available strategy in somecircumstances, but it hardly stands as the bestroute to reproductive success. The clearest ob-jective evidence of this fact is that infant mor-tality rates are significantly higher among chil-dren without an investing father (Hill & Hur-tado, 1995). Even putting aside issues ofoffspring survival, there is other evidence thatlong-term bonds between partners directly en-hance their own reproductive success. For ex-ample, women ovulate more often and moreregularly if they are in a stable sexual relation-ship (Cutler, Garcia, Huggins, & Preti, 1986;Veith, Buck, Getzlaf, Van Dalfsen, & Slade,1983). They also tend to continue ovulatinglonger and reach menopause significantly later.Earlier we cited evidence that partners in long-term relationships enjoy more robust physicaland mental heath. The more fit an individual,the better able he or she is to function in all ofthe various roles adults are required to fill, in-cluding those of mate, parent, and grandparent.A healthy member of any social group is morevalued, more valuable, and more capable ofprotecting the self as well as loved ones. Astable bond with a trusted and reliable compan-ion also promotes the kind of exploration andengagement in constructive activity on whichfamily welfare depends (Hazan & Shaver,1990). Like children, adults benefit from havingsomeone to look out for and keep track of them,someone to initiate a search if they fail to showup at the expected time, to care for them whenthey are sick, dress their wounds, and help de-fend them against external threats.

Other evidence that pair bonding is a superiorreproductive strategy is the finding that the off-

spring of stable pairs are better equipped toattract and retain their own mates. Adolescentsfrom father-absent homes show precocious sex-ual interest, relatively early sexual maturation,more negative attitudes toward potential mates,and less interest in long-term relationships thando their counterparts in father-present homes(Draper & Belsky, 1990; Draper & Harpending,1982; Surbey, 1990). In other words, when re-productive partners do not maintain a long-termbond, their children are more likely to adoptapproaches to mating that emphasize quantityover quality. Parental divorce has also beenfound to affect offspring mating behavior. Fe-male children of divorce tend to fear intimacyand have difficulty establishing committed rela-tionships, whereas the effects for males are ev-idenced in a lack of achievement orientation(Wallerstein, 1994) and lower eventual socio-economic status (Lillard & Gerner, in press).Thus, the failure of reproductive partners tomaintain a long-term bond can negatively affectthe mating appeal and success of their offspring.

Attachment plays an important role in thethree adaptive challenges that our species mustnegotiate to achieve reproductive success: sur-viving to reproductive age, mating, and nurtur-ing offspring to reproductive age. Why, then, isattachment nowhere to be found in the predom-inant evolutionary model of human mating?The (over)emphasis on sex differences has dis-tracted us from the reality that men and womenare basically similar in what they seek in a mate,the processes by which they become attached toa mate, and the benefits that accrue to them as aresult of being in a stable pair bond (Zeifman &Hazan, 1997).

A Mechanism to Foster Mate Attachment

How does one get from attraction to pairbonding? An enduring emotional bond betweenreproductive partners takes time to develop. Theattachment mechanism can maintain the bond,but it would have required a different kind ofpsychological mechanism to hold the pair to-gether long enough for an attachment to form.Ideally, this mechanism would engender a sin-gle-minded focus on the partner at hand, to theexclusion of other potential mates. In addition,it would need to operate at least as strongly, ifnot more so, in males as females. Moreover, itwould have to promote and sustain a strong


desire for the type of close physical contactknown to foster attachment.

In fact, such a mechanism exists; it is calledromantic infatuation. In the largest and mostsystematic investigation of romantic infatua-tion, Tennov (1979) conducted a content anal-ysis of the questionnaire and interview re-sponses of hundreds of men and women. Fromthis database, she was able to identify the com-mon features of this highly common phenome-non. In addition to a reduction in perceived needfor or interest in food and sleep and a paradox-ical increase in energy, the symptoms includemental preoccupation with and idealization ofthe target of infatuation and an intense longingfor intimate physical contact. The overwhelm-ing majority of male and female participants inTennov's study had experienced this constella-tion of feelings. Leibowitz (1983) proposed thatthe physiological arousal and idealization thattypify romantic infatuation are mediated byphenylethylamine, an endogenous amphetaminethat also has mild hallucinogenic effects.

Whatever the source of these symptoms, theavailable empirical evidence indicates that theystrike men and women with equal frequencyand intensity. If sexual strategies theory werecorrect in its postulation of a powerful evolvedmale preference for short-term mating, whywould men be so susceptible to falling in lovewith the female targets of their attraction? Itmakes perfect sense within an attachment modelof mating but is more difficult to explain from asexual strategies theory perspective. Perhapsthis is because sexual strategies theory is arational model of mating, and everyone knowsthat there is nothing rational about romanticinfatuation!

How Specific Mates Are "Chosen"

Although romantic infatuation explains whytwo potential mates would engage in the kindsof intimate interaction that might result in theirbecoming attached to each other, it begs thequestion of how and why one particular indi-vidual becomes the sole focus of attention andpassion. The sexual strategies model impliesspecific triggers for infatuation. In our view, itwould be maladaptive for the triggers to be veryspecific. From an attachment perspective, themental image of a suitable figure is only sche-matic. Imagine how survival would be jeopar-

dized if infants rejected any protector whofailed to match some ideal of the perfect care-giver. And, in actuality, the attachment mecha-nism in human infants can be engaged by al-most any conspecific. Although babies are hap-piest and develop optimally when caregivers areconsistently warm and responsive (Ainsworthet al., 1978), they become fully attached toabusive caregivers (Crittenden, 1995) and evenother children if adult figures are not available(Freud & Dann, 1951). Both Harlow and Lorenzdemonstrated rather dramatically the flexibilityof the attachment mechanism in other species. Itis worth seriously considering the possibilitythat the search image for human mating is alsoinherently flexible.

As noted previously, sexual strategies re-search on mate selection has tended to focus onqualities of the ideal mate, usually assessed byasking people to describe the kind of individualthey would most like to have as their partner.Evolutionary theorists assign special impor-tance to the finding that males and femalesreliably differ in their relative rankings of phys-ical appearance and status-resources. However,rankings and ratings of hypothetical partnerqualities, no matter how consistent within gen-der or across cultures, represent only weak ev-idence that any of these qualities figure into orinfluence mate selection.

In the twin study described earlier, selectioncriteria were examined not by asking peoplewhat they desired in a mate or what theythought influenced their decisions but by ex-ploring the outcomes of actual matings. Thefindings are not consistent with those from stud-ies based on evaluations of hypothetical part-ners, nor do they support predictions derivedfrom sexual strategies theory. In fact, the patternof pairings observed in this large sample ofcouples led the authors to conclude that matingis not lawfully guided by any of the factorsthat relationship researchers have proposed asimportant.

The authors raised the intriguing possibilitythat human mating may be a largely "adventi-tious" process. After all, if our hominid ances-tors lived in relatively small and isolated bands,as many anthropologists contend, there may nothave been many choices available to them. Ifchoice was not an adaptive problem faced byour predecessors in the EEA, then there wouldhave been no need for—and thus no pressure

196 KAZAN AND DIAMOND

for—the development of a mate choice mecha-nism. This possibility questions the corepremise underlying decades of research on mateselection. Have the countless hours spent theo-rizing about and investigating the criteria bywhich humans choose their mates been fornaught because, in the end, there is little or noactive choosing going on?

There are data to support a less extreme con-clusion. After all, logic dictates that matingdecisions cannot be completely random. Ourspecies would have expired long ago had we notsucceeded in choosing mates who were capableof reproducing. Thus, at a minimum, there mustbe some species-typical mechanism for elimi-nating infertile partners from the pool of eligi-bles. An important foundation of sexual strate-gies theory is the claim that this was a problemfaced by men but not women because post-pubescent males are reproductively capablethroughout their lives. This is not actually thecase. Male fertility and reproductive capabilityalso decline with age, albeit not as precipitouslyas for females. For example, the proportion ofmorphologically abnormal sperm increasesstarting at about 35 years of age (Schwartz etal., 1983), and the ability to achieve full erec-tion decreases steadily from middle adulthoodthrough old age (Rowland, Greenleaf, Dorfman,& Davidson, 1993). Needless to say, sperm areof little use in reproductive fitness terms if thedelivery system is nonfunctional. The fact thatlife expectancy for males and females duringthe Pleistocene probably did not extend farbeyond the age of menopause (Mellen, 1981)may render the whole debate somewhat mootanyway.

Putting aside issues of sex differences for themoment, it clearly would have been importantfor members of our species, like all others, tochoose reproductively capable mates. The ques-tion is whether this was, as sexual strategiestheory posits, a problem to be solved. If oneexamines fertility in contemporary hunter-gath-erer societies, the usual comparison group forspeculations about life in the EEA, it does notappear that it was. In such societies, more than90% of postpubescent young people are fertile(Symons, 1979). Thus, it may have sufficed forour ancestors to (a) avoid mating with conspe-cifics who had not yet reached puberty and (b)avoid mating with those who showed signs ofaging or disease. The markers of puberty are

easy enough to recognize to satisfy the firstrequirement; the innate disgust response couldserve to satisfy the second.

There are three important points to be madehere. First, if nearly every postpubescent youngperson is fertile and there is a "natural" aversionto sexual contact with those who display age- ordisease-related cues of infertility, it is doubtfulthat natural selection would have needed toexert pressure for the development of a fertility-detecting mechanism. Second, if our mate se-lection mechanisms evolved in an environmentcharacterized by small and relatively isolatedgroups, the average person would not have hadthe wide range of mate options that typify thecontemporary undergraduate on whose matepreferences sexual strategies theory is largelybased. Thus, it is quite possible that, in the EEA,there was never strong selection pressure for thedevelopment of any highly specific mate choicemechanism. Third, given these considerations,evolution may have equipped us with mate re-jection as opposed to mate selection criteria.That is, our mating system may be designed tosteer us away from fatal choices rather thantoward ideal ones. Everyone can describe his orher ideal mate, but even those who qualify ashigh in mate value often have to compromise.Yet, there are undoubtedly limits to the com-promises that any individual is willing to make.To be in the running, a potential mate mustsimply surpass some threshold of acceptability.

Does this mean that mating decisions (withinthe pool of acceptable partners) are random?No, but neither are they necessarily strategic.We agree with the twin researchers that theremay be an adventitious or chance factor drivingmate choice, and we propose that propinquity isthis factor. In other words, the true pool ofeligibles is not defined as those individuals whoare the best match to one's ideals (even control-ling for one's own mate value), nor does itinclude every fertile person under the sun.Rather, it consists of those individuals who bothexceed one's rejection criteria and happen to beliving or working or playing nearby. This mayseem so commonsensical as to be trivial, but weview it as a critically important point that isroutinely overlooked. A cost-benefit evaluationwould favor mating with one who is adequatelyattractive and readily accessible. It might bepossible to find a marginally more attractive orhigher status mate with a longer and wider


search, but a small incremental change on eitherdimension would probably make little differ-ence in the final (reproductive fitness) analysis.Furthermore, familiarity generally breeds at-traction (Rubin, 1973). Familiarity effects arethemselves thought to reflect an evolved ten-dency to respond favorably to individuals whohave passed the fhend-versus-foe test. Propin-quity affords not only opportunities for matingbut the kind of prolonged association that in-creases familiarity and, in turn, enhances themutual attractiveness of potential mates. As ev-ery zookeeper knows, a nearly sure-fire way toget two members of any species to mate issimply to house them in the same cage. Whymust it be different for Homo sapiens?

The evidence suggests that it is not. Mosthumans end up with a mate who lives withinwalking distance (Eckland, 1968). Yet, ofcourse, "lives within walking distance" wouldnever appear on anyone's wish list of ideal matecharacteristics. This is important for what itreveals about the mate selection process in ourspecies. Specifically, the factors that exert thestrongest influence on humans' mating behaviormay be those that operate outside of their con-scious awareness.

We have yet to address the question of why aparticular pair ends up together. Propinquityand familiarity, along with individual qualitiesand preferences, obviously narrow the pool con-siderably, but what determines the pairing ofspecific mates? Stated differently, what triggersromantic infatuation? What is responsible forthe transition from merely finding another per-son attractive to making him or her the solefocus of intense longing and preoccupation? Inone of only a small number of mating studies touse individuals who were already paired, Aronand his colleagues (Aron, Dutton, Aron, & Iver-son, 1989) discovered a possible answer.

The approach they took was to ask partici-pants to provide detailed accounts of their fall-ing-in-love experiences. According to the find-ings, the factor primarily responsible for theshift from attraction to infatuation is reciprocalliking, or the perception that the person one isinterested in feels the same way. Whether ex-pressed in a warm smile or a prolonged gaze,the message is unmistakable: "It's safe to ap-proach. I like you, too. I'll be nice. You're notin danger of being rejected." Recall that whenpeople are asked to make lists of the qualities

they would ideally like in a mate, the traits mostvalued by both males and females include kind-ness and understanding. In other words, theysay they want a mate who will respond posi-tively to and treat them well. Reciprocal likingcan be interpreted as a signal that one has foundjust such a person, and the fact that this personis acceptably attractive and possesses all of the"right" body parts may be enough to send mostpeople head over heels. For a significant num-ber, this alone is enough to capture and holdtheir interest until a more enduring bond devel-ops. How long does that take? In adult pairs, itrequires approximately 2 years, give or take 6months (Hazan & Zeifman, 1994). Not coinci-dentally, this time frame corresponds to theaverage duration of romantic infatuation (Ten-nov, 1979).

Further evidence that infatuation is morepowerful than strategic choice comes from re-search detailing its effects on social perception.For example, although physical attractivenesscan be defined objectively, how attractive oneperceives a particular individual to be dependsin large part on how one happens to feel abouthim or her. More than 20 years ago, Murstein(1976) conducted a study in which members ofmarried couples were asked to (secretly) ratethe physical attractiveness of their respectivespouses. Eighty-five percent of the husbandsrated their wives as above average on looks,whereas fewer than 25% were judged to beabove average in physical attractiveness by apanel of judges using the same rating scale. It isoften assumed that a woman is desired becauseshe is attractive. This study demonstrates thatthe causal arrow can run in the oppositedirection.

Another example of the influence of romanticinfatuation on social perception comes from astudy conducted by Simpson and colleagues(Simpson, Gangestad, & Lerma, 1990). Hetero-sexual participants with steady dating partnersrated opposite-sex age-mates as less physicallyand sexually attractive than did participantswithout steady partners. The two groups did notdiffer in their ratings of much younger or mucholder opposite-sex individuals, suggesting thatthe effect was specific to potential mates. Alongthe same lines, Murray and Holmes (1993,1994; Murray, Holmes, & Griffin, 1996) have,in numerous studies, documented the benefits ofmutual idealization in couples. Given that the


availability of attractive alternative partnersconstitutes one of the greatest threats to thestability of an existing relationship (Rusbult,1980, 1983), the power of idealization to simul-taneously inflate perceptions of a mate's appealand reduce the appeal of potential rivals under-scores its importance in maintaining the integ-rity of pair bonds. In short, romantic infatuationleaves people with the feeling that they havefound the ideal mate, their "one and only."

More Limitations of Sexual StrategiesTheory

We believe that the empirical evidence re-viewed thus far presents a serious challenge tosexual strategies theory and makes a compellingcase for a very different evolutionary model ofhuman mating. But an obvious question at thispoint is, If the evidence for sexual strategiestheory is so weak, why does it appear to be sostrong? In the remaining sections, we offer apossible explanation,

As previously noted, a major limitation of thesupport for sexual strategies theory is a relianceon self-reports and hypothetical mating scenar-ios. But there are some behavioral data thatBuss and Schmitt (1993) cited to bolster theirtheory. For example, in a study by Clark andHatfield (1989), an attractive male or femaleresearch confederate approached opposite-sexstrangers on a college campus and, after an-nouncing that he or she found the stranger at-tractive, posed one of three randomly selectedinvitations: to go for dinner, to go to the con-federate's apartment, or to have sex. The big-gest sex difference was found for the third con-dition. Fully 75% of the men accepted the in-vitation for sex, whereas none of the womenconsented. The results have been questioned onthe grounds that the risks associated with ac-cepting an invitation to visit the apartment of orhave sex with a complete stranger are quitedifferent for men and women, and thus haveambiguous implications for their respective in-terest in sex per se (Small, 1995). Nevertheless,this finding and others like it are offered asevidence that males have evolved qualitativelydifferent mating tactics than females and thattheir "best" strategy for achieving reproductivesuccess is to have sex with as many fertilefemales as they can.

As in the study just cited, sometimes findingsthat appear to be supportive of sexual strategiestheory have plausible alternative explanations.Another example is a study conducted by De-Steno and Salovey (1996). Sexual strategiestheory predicts sex differences in reactions to apartner's infidelity depending on whether theindiscretion is sexual or emotional. Specifically,men are predicted to show greater concern andupset over a female partner's sexual infidelityfor the reason that it undermines paternity cer-tainty. Women are predicted to be less botheredby a male mate's sexual wanderings than by hisemotional involvement with another woman,because the latter raises the possibility of losinghis valued resources. In a study that involvedmultiple indexes of distress, including heartrate, perspiration, and frowning, these theory-based predictions were confirmed (Buss, Lar-sen, Westen, & Semmelroth, 1992).

DeSteno and Salovey took issue with theauthors' interpretation, arguing that the resultscould be explained in terms of participants'beliefs concerning the covariation between sex-ual and emotional infidelity. Leaving aside fornow questions about whether sex differences insexual behavior reflect evolved mating strate-gies, it is nonetheless true that males are morelikely than females to engage in casual sex.More important, males and females are aware ofthis sex difference. DeSteno and Salovey rea-soned that participants' knowledge of this dif-ference could explain the findings. Specifically,women might reasonably assume that maleemotional infidelities are strongly suggestive ofsexual infidelity as well, and men can safelyassume that female sexual unfaithfulness alsoinvolves emotional infidelity. In other words,maybe Buss et al.'s participants were showingthe greatest distress not to a single type ofinfidelity but instead to the type of infidelity thatimplied both: what DeSteno and Salovey calledthe "double-shot" hypothesis. And when partic-ipant beliefs about the covariation between sex-ual and emotional infidelity were assessed, be-liefs were more powerful in predicting distressthan was biological sex.

Do Men "Naturally" Prefer Short-TermMating ?

There is probably no issue on which sexualstrategies theory depends more, and thus no


issue on which the merits of the theory can bemore critically evaluated, than the sex differ-ence in casual sex, or what has been termedsociosexuality (Simpson & Gangestad, 1992).Accordingly, in their original comprehensiveexposition of the theory, Buss and Schmitt(1993) devoted three separate figures to demon-strating sex differences in sexual promiscuity.Participants were asked about the degree towhich they seek short-term (one-night-stand) asopposed to long-term (marriage) partners, theestimated likelihood of sexual intercourse af-ter acquaintanceships or relationships rangingfrom 1 hr to 5 years, and the ideal number ofsexual partners over periods of time extendingfrom 1 month to 30 years. By all measures,males on average were more interested in andmore willing and eager to pursue casual sexualliaisons.

Arithmetic averages are sometimes informa-tive and sometimes misleading. L. C. Miller andFishkin (1997) set out to replicate one of thesestudies. They asked a large group of undergrad-uates "Ideally, how many sex partners wouldyou like to have in the next 30 years?" Theresults were consistent with those reported byprevious investigators (e.g., Buss & Schmitt,1993). The mean number of ideal future sexualpartners for women was 2; for men, it was 64.The findings appear to support sexual strategiestheory in that reported male desires confirmhypothesized sex differences in "best" repro-ductive strategies, with males preferring largernumbers of sex partners than females. However,another measure of central tendency paints aqualitatively different picture. The median idealnumber of future sexual partners reported bywomen was one; for men, the number was alsoone!

The demographic characteristics of the sam-ple are also informative. The typical male un-dergraduate is young, has yet to commit to along-term relationship, and has access to what isarguably the largest pool of potential mates hewill ever encounter in his lifetime (almost cer-tainly larger than his hominid ancestors hadaccess to in the EEA), and he says that what hewould "ideally" like is one sexual partner overthe next 30 years. It is difficult to imagine anempirical finding more contradictory to the pre-dictions of sexual strategies theory. If humanmales are programmed by evolution to desireand seek out multiple sexual partners, why is

this hard-wired preference not evident in theself-reports of men who are at their sexual peakand living in the midst of extraordinary numbersof young and beautiful potential mates? Couldthe answer be that they have been designed byevolution for pair bonding? As for those fewmen who skewed the distribution by reporting adesire for 100 or more future sexual partners,Miller and Fishkin found that most were inse-curely attached, especially to their fathers, Ageneral theory of human mating must be basedon the behavior of people in general, not aminority of atypical and poorly adjusted youngmen.

Another problem is that in much of the re-search on short- and long-term mating, the twostrategies are presented in a forced-choiceformat (for an exception, see Kenrick, Groth,Trost, & Sadalla, 1993). This approach sets up afalse dichotomy. Although rates of sexual infi-delity vary somewhat across samples and his-torical periods, a significant number of long-term maters of both sexes engage in short-termextrapair copulations (Fisher, 1989). And de-spite the fact that males consistently reporthigher rates of infidelity than females, somemembers of both sexes pursue both strategies intandem, even though the risks for femalessometimes include death (Small, 1993),

This raises a related issue. In line with sexualstrategies theory, one could argue that a manwho has sex with 50 women could conceivablyend up with 50 offspring, whereas a womanwho has sex with 50 men can still get pregnantby only one. Theoretically, then, it never reallypays for her to be sexually promiscuous. But, infact, it can be quite advantageous for women tobe sexually unfaithful to their partners. An es-timated 99% of sperm in each ejaculate func-tions not to fertilize an egg but, rather, to fightoff other men's sperm (Baker, 1996). By havingsex with multiple males, a female can helpensure that her offspring are of the highest pos-sible genetic quality. Not coincidentally, humanfemales are most likely to stray when they areovulating.

Assume, for the sake of argument, that hu-man males are "naturally" more sexually pro-miscuous than human females. This alonewould not constitute proof that high male rela-tive to female sociosexuality reflects an evolvedsex difference in mating strategies. High levelsof androgens are necessary to produce sperm,


and androgens are known to powerfully in-fluence sexual desire in both sexes (Carani,Granata, Fustini, & Marrama, 1996). Male sex-ual promiscuity could be simply a by-product ofhormonal activity as opposed to an adaptive,selected-for mating strategy.

For both empirical and logical reasons, wequestion whether an exclusive short-term mat-ing strategy was ever adaptive for human males.It has been estimated that in contemporary hunt-er-gatherer societies—the model for specula-tions about the EEA—the typical female ispregnant or lactating (and therefore not ovulat-ing) during approximately 24 of the average 26years between puberty and menopause (Sy-mons, 1979). As a result, she would be fertile ononly about 80 of these 8,000 or so days. In otherwords, only 1 of 100 random copulations couldeven potentially result in conception. Normally,it takes several months of unprotected sex toproduce a viable pregnancy. In light of thesefacts, it seems quite improbable mat movingfrom one-night stand to one-night stand wouldhave been an effective strategy for achievingreproductive success or that such a strategywould ever have been selected for.

Why has so much store been placed in the sexdifference in promiscuity? Perhaps the reason isthat it is so salient. What person, male or fe-male, has failed to observe that males are gen-erally more willing and eager than females tohave sex on a moment's notice with a totalstranger? It is a biological fact that men canenjoy sex without concerns about becomingpregnant, and it is a sociological fact that males,relative to females, are more often rewarded andless often punished for their sexual exploits.Surely these facts have some degree of signifi-cance. Whatever its origins, the sex differencein casual sex could be what makes sexual strat-egies theory so intuitively appealing and right-sounding to some. In fact, it may well be thecritical "hook" that leads many to swallow theentire theory, line and sinker.

Do Women "Naturally" Care More AboutStatus and Resources?

There is one additional issue on which sexualstrategies theory appears to have strong support,and that is sex differences in the value of apotential mate's status and resources. In theory,given the reality that the minimal requisite in-

vestment in offspring is so much greater forfemales than males—years versus minutes—females should care more than males about amate's social standing and financial prospects.And worldwide, this appears to be the case(Buss, 1989). The finding that this sex differ-ence is universal is taken as an indication that itis part of an evolved female mating strategy.

There are, however, universal features of theEEA that support an equally plausible accountof this reliable cross-cultural sex difference. AsBern (1993) has pointed out, early humans didnot have access to the modern conveniences ofbirth control or digestible substitutes for moth-er's milk enjoyed today. In addition, much ofthe work of daily survival depended on physicalstrength, which males (then and now) possess toa greater degree than females. It is not improb-able that all human groups would arrive at thesame sex-based division of labor: She wouldstay home with the babies while he and hisfriends took care of the business of hunting andlooking after the group. As human civilizationevolved, males had a power and status advan-tage relative to females that continues today.Even contemporary professional women cannotanticipate financial rewards equal to those oftheir male counterparts.

If this environmental universal, rather than anevolved psychological mechanism, is at theheart of female concern about a potential mate'sstatus and resources, then the degree to whichwomen judge men on the basis of their socialposition and earning capacity should vary asa function of the local financial standing ofwomen. In fact, it does. Eagly and Wood (1999)reanalyzed the 37 cultures data collected byBuss and found exactly this kind of covariation.It is also noteworthy that one female character-istic universally valued by males that was notincluded in the original published report (Buss,1989) is that she be a good housekeeper andcook. Was there selection pressure in the EEAfor female housekeeping skills (before peoplehad houses) or culinary talents (before peopledid any cooking)? The possibility strikes us asunlikely. But the findings are important for whatthey can reveal about human mate preferences.Some may reflect evolved tendencies and somemay simply mirror socially constructed genderroles, and the mere universality of their mentionby research participants cannot settle disputesabout which is which.


Conclusion

A recent American Scientist article on theevolutionary psychology of human mating(Buss, 1994) includes a photograph of business-man Donald Trump and his (then) wife MariaMaples. According to the photo caption, theyrepresent "species-typical mating preferences."We think not. Admittedly, when mating deci-sions are fully conscious and calculated, youthand good looks can be traded for status andresources. But this rule seems also to apply incases in which the one with resources is female.More celebrity examples, this time rich womenwith "boy toys," come to mind: Madonna, Cher,Roseanne, Jackie Collins. But they are no moretypical of mating in our species than are Donaldand Maria. The truly typical human being endsup with a mate who is roughly his or her socio-economic and physical attractiveness equal(Buss, 1984).

An alternative evolutionary model of the pro-cess might go something like this: The physio-logical and psychological changes that accom-pany puberty motivate individuals of both sexesto begin the search for a mate. A natural aver-sion to sexual intimacy with those who arephysically repulsive for any number of reasons(e.g., wrinkled skin, sagging body parts, opensores, or gross asymmetries) helps ensure thatthey avoid mating with anyone who has "bad"genes or is unlikely to be fertile. Most membersof their local group who reached sexual matu-rity before them will already be paired; all re-maining postpubescent members of the desiredsex who exceed their threshold of acceptabilityconstitute the pool of eligibles.

Propinquity and familiarity further narrowthe pool. Potential mates who are encountereddaily at the river's edge have an advantage overthose residing on the other side. Within thispool, they are vigilant for signs of reciprocalinterest, expressed in easily recognized flirta-tion behaviors (the proceptive program; Eibl-Eibesfeldt, 1989). A slightly prolonged gaze, asmile, or a subtle violation of personal spacemay trigger romantic infatuation. If mutual, thepsychological and neurochemical processes thatensue make each person the sole focus of theother's attention and passion and render alter-native potential mates less desirable. The sameprocesses stimulate a seemingly insatiable long-ing for close physical contact. This physical

intimacy in turn triggers a release of hormonesthat boost desire for continued contact In time,their neurobehavioral systems become mutuallyconditioned to the stimulus of the mate such thatshe or he comes to have a uniquely powerfuleffect on physical and psychological well-being. A pair bond is in place. The two areattached.

Admittedly, not all mating relationships turnout this way. As many as half may dissolvebefore an attachment bond is fully formed. Evenso, most endure long enough to see at least oneinfant through the most vulnerable early years(Fisher, 1992).

If the goal is to understand human mating,one must go beyond self-reported ideals andhypothetical scenarios to a thorough investiga-tion of the processes by which mating relation-ships are actually established and what suchrelationships are really like. There can be nocomprehensive evolutionary theory of humanmating without a full accounting of our species-typical mating pattern. Moreover, given the ir-refutable necessity for successful negotiation ofthe adaptive challenges associated with infantsurvival, mate acquisition, and offspring care—and the central place of attachment in allthree—we contend that an evolutionary theoryof human mating that does not include attach-ment is hollow at its core. Bowlby's grand andelegant theory complements Darwin's by pro-viding the foundations of a new and more ac-curate model of mating in our species.

References

Ainsworth, M. D. S., Blehar, M. C , Waters, E., &Wall, S. (1978). Patterns of attachment. Hillsdale,NJ: Erlbaum.

Alcock, J. (1989). Animal behavior: An evolutionaryapproach. Boston: Sinauer.

Aron, A., Dutton, D. G., Aron, E. N., & Iverson, A.(1989). Experiences of falling in love. Journal ofSocial and Personal Relationships, 6, 243-257.

Baker, R. R. (1996). Sperm wars: The evolutionarylogic of love and lust. London: Basic Books.

Baker, R. R., & Bellis, M. A. (1995). Human spermcompetition. London: Chapman & Hall.

Belsky, J. (1999). Modern evolutionary theory andpatterns of attachment. In J. Cassidy & P. R.Shaver (Eds.), Handbook of attachment: Theory,research, and clinical applications (pp. 141-161).New York: Guilford Press.


Bern, S. L. (1993). The lenses of gender. New Haven,CT: Yale University Press.

Blaffer-Hrdy, S. (1988). The primate origins of hu-man sexuality. In R. Bellig & G. Stevens (Eds.),The evolution of sex (pp. 101-131). San Francisco:Harper & Row.

Bloom, B. L., Asher, S. J., & White, S. W. (1978).Marital disruption as a stressor: A review andanalysis. Psychological Bulletin, 85, 867-894.

Bowlby, J. (1973). Attachment and loss: Vol. 2. Sepa-ration: Anxiety and anger. New York: Basic Books.

Bowlby, J. (1979). The making and breaking of af-fectional bonds. London: Tavistock.

Bowlby, J. (1980). Attachment and loss: Vol. 3. Loss:Sadness and depression. New York: Basic Books.

Bowlby, J. (1982). Attachment and loss: Vol. 1. At-tachment (2nd ed.). New York: Basic Books.(Original work published 1969)

Bowlby, J. (1988). A secure base: Parent-child at-tachment and healthy human development. NewYork: Basic Books.

Buss, D. M. (1984). Toward a psychology of person-environment (PE) correlation: The role of spouseselection. Journal of Personality and Social Psy-chology, 47, 361-377.

Buss, D. M. (1989). Sex differences in human matepreferences: Evolutionary hypotheses tested in 37cultures. Behavioral and Brain Sciences, 12, 1-49.

Buss, D. M. (1994). The strategies of human mating.American Scientist, 82, 238-249.

Buss, D. M. (1997). The emergence of evolutionarysocial psychology. In J. A. Simpson & D. T. Ken-rick (Eds.), Evolutionary social psychology (pp.387-400). Mahwah, NJ: Erlbaum.

Buss, D. M., & Barnes, M. (1986). Preferences inhuman mate selection. Journal of Personality andSocial Psychology, 50, 559-570.

Buss, D. M., Larsen, R. J., Westen, D., & Semmel-roth, J. (1992). Sex differences in jealousy: Evo-lution, physiology, and psychology. PsychologicalScience, 3, 251-255.

Buss, D. M , & Schmitt, D. P. (1993). Sexual strat-egies theory: An evolutionary perspective on hu-man mating. Psychological Review, 100, 204-232.

Carani, C , Granata, A. R., Fustini, M. F., & Mar-rama, P. (1996). Prolactin and testosterone: Theirrole in male sexual function. International JournalofAndrology, 19, 48-54.

Carter, C. S. (1992). Oxytocin and sexual behavior. Neu-roscience and Bhbehavhral Reviews, 16, 131-144.

Carter, C. S. (1998). Neuroendocrine perspectives onattachment and love. Psychoneuroendocrinol-ogy, 23, 779-818.

Carter, C. S., DeVries, A. C , Taymans, S. E., Rob-erts, R. L., Williams, J. R., & Getz, L. L. (1997).Peptides, steroids, and pair bonding. Annals of theNew York Academy of Sciences, 807, 260-272.

Chisholm, J. S. (1996). The evolutionary ecology ofattachment organization. Human Nature, 7, 1-38.

Clark, R. D., & Hatfield, E. (1989). Gender differ-ences in receptivity to sexual offers. Journal ofPsychology and Human Sexuality, 2, 39-55.

Crittenden, P. M. (1995). Attachment and psychopa-thology. In S. Goldberg, R. Muir, & J. Kerr (Eds.),Attachment theory: Social, developmental, andclinical perspectives (pp. 367-406). Hillsdale, NJ:Analytic Press.

Cunningham, M. R., Druen, P. B., & Barbee, A. P.(1997). Angels, mentors, and friends: Trade-offsamong evolutionary, social, and individual vari-ables in physical appearance. In J. A. Simpson &D. T. Kenrick (Eds.), Evolutionary social psychol-ogy (pp- 109-140). Mahwah, NJ: Erlbaum.

Cutler, W. B., Garcia, C. R., Huggins, G. R., & Preti,G. (1986). Sexual behavior and steroid levelsamong gynecologically mature premenopausalwomen. Fertility and Sterility, 45, 496-502.

Daly, M., & Wilson, M. (1988). Homicide. NewYork: Aldine de Gruyter.

DeSteno, D. A., & Salovey, P. (1996). Genes, jeal-ousy, and the replication of misspecifled models.Psychological Science, 7, 376-377.

Draper, P., & Belsky, J. (1990). Personality develop-ment in evolutionary perspective. Journal of Per-sonality, 58, 141-161.

Draper, P., & Harpending, H. (1982). A sociobiologi-cal perspective on the development of human re-productive strategies. In K. MacDonald (Ed.), So-ciobiological perspectives on human development(pp. 340-372). New York: Springer-Verlag.

Eagly, A. H., & Wood, W. (1999). The origins of sexdifferences in human behavior: Evolved dispositionsversus social roles. American Psychologist, 54, 408-423.

Eberhard, W. G. (1985). Sexual selection and animalgenitalia. Cambridge, MA: Harvard UniversityPress.

Eberhard, W. G. (1991). Copulatory courtship andcryptic female choice in insects. Biological Re-view, 66, 1-31.

Eckland, B. K. (1968). Theories of mate selection.Eugenics Quarterly, 15, 71-84.

Eibl-Eibesfeldt, I. (1975). Ethology: The biology ofbehavior. New York: Holt, Rinehart & Winston.

Eibl-Eibesfeldt, I. (1989). Human ethology. NewYork: Aldine de Gruyter.

Fisher, H. E. (1989). Evolution in human serial pairbonding. American Journal of Physical Anthropol-ogy, 73, 331-354.

Fisher, H. E. (1992). Anatomy of love. New York:Norton.

Fraley, R. C , & Davis, K. E. (1997). Attachmentformation and transfer in young adults' closefriendships and romantic relationships. PersonalRelationships, 4, 131-144.


Fraley, R. C , & Shaver, P. R. (1999). Loss andbereavement: Attachment theory and recent con-troversies concerning "grief work" and the natureof detachment. In J. Cassidy & P. R. Shaver (Eds.),Handbook of attachment: Theory, research, andclinical applications (pp. 735-759). New York:Guilford Press.

Freud, A., & Dann, S. (1951). An experiment ingroup upbringing. In R. Eisler, A. Freud, H. Hart-mann, & E. Kris (Eds.), The psychoanalytic studyof the child (Vol. 6). New York: InternationalUniversities Press.

Goodwin, J. S., Hurt, W. C , Key, C. R., & Sarret, J. M.(1987). The effect of marital status on stage, treat-ment and survival of cancer patients. Journal of theAmerican Medical Association, 258, 3125-3130.

Gould, S. J., & Vrba, E. S. (1982). Exaptation—Amissing term in the science of form. Paleobiol-ogy, 8, 4-15.

Graziano, W. G., Jensen-Campbell, L. A., Todd, M., &Finch, J. F. (1997). Interpersonal attraction from anevolutionary psychology perspective: Women's re-actions to dominant and prosocial men. In J. A.Simpson & D. T. Kenrick (Eds.), Evolutionary socialpsychology (pp. 141-167). Mahwah, NJ: Erlbaum.

Harlow, H., & Harlow, M. K. (1965). The affectionalsystems. In A. M. Schrier, H. F. Harlow, & F.Stollnitz (Eds.), Behavior of nonhuman pritnates(Vol. 2, pp. 287-334). New York: Academic Press.

Hazan, C , & Shaver, P. R. (1990). Love and work:An attachment theoretical perspective. Journal ofPersonality and Social Psychology, 59, 270-280.

Hazan, C , & Shaver, P. R. (1992). Broken attach-ments. In T. L. Orbuch (Ed.), Close relationshiploss: Theoretical approaches (pp. 90-108). Hills-dale, NJ: Erlbaum.

Hazan, C , & Shaver, P. R. (1994a). Attachment as anorganizational framework for research on closerelationships. Psychological Inquiry, 5, 1-22.

Hazan, C, & Shaver, P. R. (1994b). Deeper into attach-ment theory. Psychological Inquiry, 5, 68-79.

Hazan, C , & Zeifman, D. (1994). Sex and the psy-chological tether. Advances in Personal Relation-ships, 5, 151-177.

Hazan, C , & Zeifman, D. (1999). Pair bonds asattachments: Evaluating the evidence. In J.Cassidy & P. R. Shaver (Eds.)T Handbook of at-tachment: Theory, research, and clinical applica-tions (pp. 336-354). New York: Guilford Press.

Hill, K., & Hurtado, M. (1995). Demographic/life his-tory of Ache foragers. New York: Aldine de Gruyter.

Holmes, T. H., & Rahe, R. H. (1967). The SocialReadjustment Rating Scale. Journal of Psychoso-matic Research, II, 213-218.

Insel, T. R. (2000). Toward a neurobiology of attach-ment. Review of General Psychology, 4, 176-185.

Kagan, J. (1984). The nature of the child. New York:Basic Books.

Kenrick, D. T., Groth, G. E., Trost, M. R., & Sadalla,E, K. (1993). Integrating evolutionary and socialexchange perspectives on relationships: Effects ofgender, self-appraisal, and involvement level onmate selection criteria. Journal of Personality andSocial Psychology, 64, 951-969.

Kraemer, G. W. (1997). Psychobiology of early so-cial attachment in rhesus monkeys. Annals of theNew York Academy of Sciences, 807, 401-418.

Lancaster, J. B., & Kaplan, H. (1994). Human matingand family formation strategies: The effects ofvariability among males in quality and the alloca-tion of mating effort and parental investment. In T.Nishida, W. C. McGrew, P. Marler, M. Pickford,& F. B. M. de Waal (Eds.), Topics in primatology,vol. 1: Human origins (pp. 21-33). Tokyo: Uni-versity of Tokyo Press.

Laumann, E. O., Gagnon, J. H., Michael, R. T., &Michaels, S. (1994). The social organization ofsexuality. Chicago: University of Chicago Press.

Leibowitz, M. (1983). The chemistry of love. NewYork: Berkeley Books.

Lillard, D., & Gerner, J. (in press). Getting to the IvyLeague: How family composition affects collegechoice. Journal of Higher Education.

Lykken, D. T., & Tellegen, A. (1993). Is humanmating adventitious or the result of lawful choice?A twin study of mate selection. Journal of Person-ality and Social Psychology, 65, 56-68.

Lynch, J. J. (1977). The broken heart: The medicalconsequences of loneliness. New York: Basic Books.

Mellen, S. L. W. (1981). The evolution of love. Ox-ford, England: Freeman.

Mendoza, S. P., & Mason, W. A. (1997). Attachmentrelationships in new world primates. Annals of theNew York Academy of Sciences, 807, 203-209.

Miller, G. F. (1998). How mate choice shaped humannature: A review of sexual selection and human evo-lution. In C. Crawford & D. L. Krebs (Eds.), Hand-book of evolutionary psychology: Ideas, issues, andapplications (pp. 87-129). Mahwah, NJ: Erlbaum.

Miller, L. C , & Fishkin, S. A. (1997). On the dy-namics of human bonding and reproductive suc-cess: Seeking windows on the adapted-for human-environment interface. In J. A. Simpson & D. T.Kenrick (Eds.), Evolutionary social psychology(pp. 197-235). Mahwah, NJ: Erlbaum.

Murray, S. L., & Holmes, J. G. (1993). Seeing virtues infaults: Negativity and the transformation of interper-sonal narratives in close relationships. Journal ofPersonality and Social Psychology, 65, 707-722.

Murray, S. L., & Holmes, J. G. (1994). Story-tellingin close relationships: The construction of confi-dence. Personality and Social Psychology Bulle-tin, 20, 663-676.

Murray, S. L., Holmes, J. G., & Griffin, D. W.(1996). The benefits of positive illusions: Idealiza-tion and the construction of satisfaction in close


relationships. Journal of Personality and SocialPsychology, 70, 79-98.

Murstein, B. I. (1976). Who will marry whom? The-ories and research in marital choice. New York:Springer.

Parkes, C. M., & Weiss, R. S. (1983). Recovery frombereavement. New York: Basic Books.

Pietromonaco, P. R., & Feldman Barrett, L. (2000).The internal working models concept: What do wereally know about the self in relation to others?Review of General Psychology, 4, 155-175.

Robertson, J. (1953). Some responses of young chil-dren to the loss of maternal care. NursingTimes, 49, 382-386.

Rowland, D. L., Greenleaf, W. J., Dorrman, L. J., &Davidson, J. M. (1993). Aging and sexual functionin men. Archives of Sexual Behavior, 22, 545-557.

Rubin, Z. (1973). Liking and loving. New York: Holt,Rinehart & Winston.

Rusbult, C. E. (1980). A longitudinal test of theinvestment model: The development (and deterio-ration) of satisfaction and commitment in hetero-sexual involvements. Journal of Personality andSocial Psychology, 45, 101-117.

Rusbult, C. E. (1983). Commitment and satisfactionin romantic associations: A test of the investmentmodel. Journal of Experimental Social Psychol-ogy, 16, 172-186.

Sapolsky, R. M. (1998, July-August). Sex and thesingle monkey. The Sciences, pp. 10-11.

Schwartz, D., Mayauz, M. J., Spira, A., Moscato, J. L.,Jouannet, P., DzygJik, F., & David, G. (1983). Semencharacteristics as a function of age in 833 fertile men.Fertility and Sterility, 39, 530-535.

Shaver, P. R., & Hazan, C. (1993). Adult romanticattachment: Theory and empirical evidence. In D.Perlman & W. Jones (Eds.), Advances in personalrelationships (Vol. 4, pp. 29-70). Greenwich, CT:JAI Press.

Shaver, P. R., Hazan, C, & Bradshaw, D. (1988).Love as attachment: The integration of three be-havioral systems. In R. J. Sternberg & M. L. Bar-nes (Eds.), The psychology of love (pp. 68-99).New Haven, CT: Yale University Press.

Simpson, J. A., & Gangestad, S. W. (1992). Socio-sexuality and romantic partner choice. Journal ofPersonality, 60, 31-52.

Simpson, J. A., Gangestad, S. W., & Lerma, M.(1990). Perception of physical attractiveness:Mechanisms involved in the maintenance of ro-mantic relationships. Journal of Personality andSocial Psychology, 59, 1192-1201.

Small, M. F. (1993), Female choices; Sexual behav-ior of female primates. Ithaca, NY: Cornell Uni-versity Press.

Small, M. F. (1995). What's love got to do with it?The evolution of human mating. New York: An-chor Books.

Spitz, R. A. (1946). Anaclitic depression. Psychoan-alytic Study of the Child, 2, 313-342.

Stearns, S. (1992). The evolution of life histories.New York: Oxford University Press.

Suomi, S. J. (1997). Early determinants of behaviour:Evidence from primate studies. British MedicalBulletin, 53, 170-184.

Surbey, M. (1990). Family composition, stress, andhuman menarche. In F. Bercovitch & T. Zeigler(Eds.), The socioendocrinology of primate repro-duction (pp. 71-97). New York: Liss.

Symons, D. (1979). The evolution of human sexual-ity. New York: Oxford University Press.

Tennov, D. (1979). Love and limerence: The experi-ence of being in love. New York: Stein & Day.

Trevathan, W. (1987). Human birth. New York: Al-dine de Gruyter.

Trivers, R. L. (1972). Parental investment and sexualselection. In B. Campbell (Ed.), Sexual selectionand the descent of man (pp. 1871-1971). Chicago:Aldine.

Uchino, B. N., Cacioppo, J. T., & Kiecolt-Glaser, J. K.(1996). The relationship between social support andphysiological processes: A review with emphasis onunderlying mechanisms and implications for health.Psychological Bulletin, 119, 488-531.

Van den Berghe, P. L. (1979). Human family sys-tems: An evolutionary view. Westpott, CT: Green-wood Press.

Veith, J. L., Buck, M., Getzlaf, S., Van Dalfsen, P., &Slade, S. (1983). Exposure to men influences theoccurrence of ovulation in women. Physiology andBehavior, 31, 313-315.

Vormbrock, J. K. (1993). Attachment theory as ap-plied to war-time and job-related marital separa-tion. Psychological Bulletin, 114, 122-144.

Wallerstein, J. S. (1994). Children after divorce:Wounds that don't heal. In L. Fenson & J. Fenson(Eds.), Human development 94/95 (pp. 160-165).Guilford, CT: Dushkin.

Washbum, S. L. (1960). Tools and human evolution.Scientific American, 203, 3-15.

Weiss, R. S. (1975). Marital separation. New York:Basic Books.

Zeifinan, D., & Hazan, C. (1997). Attachment: Thebond in pair-bonds. In J. A. Simpson & D. T.Kenrick (Eds.), Evolutionary social psychology(pp. 237-263). Mahwah, NJ: Erlbaum.

Zimmerman, S. J., Maude, M. B., & Moldawar, M.(1965). Frequent ejaculation and total sperm count,motility and forms in humans. Fertility and Steril-ity, 16, 342-345.

Received March 18, 1999Revision received September 8, 1999

Accepted September 8, 1999 •

Documents

The Place of Attachment in Human Matingadultattachmentlab.human.cornell.edu/HazanDiamond2000.pdf · The Place of Attachment in Human Mating Cindy Hazan and Lisa M. Diamond Cornell