Review of General Psychology Copyright 2000 by the Educational Publishing Foundation 2000, Vol. 4, No. 2, 186-204 1089-268O/O0/$5.0O DOI: 10.1O37//1089-2680.4.2.186 The Place of Attachment in Human Mating Cindy Hazan and Lisa M. Diamond Cornell University Application of the principles of evolution and natural selection to the phenomena of human mating does not lead inevitably to a single theoretical model. According to the standard evolutionary model, formally known as sexual strategies theory (D. M. Buss & D. P. Schmitt, 1993), biologically based sex differences in parental investment have resulted in hard-wired sex differences in mate preferences and mating strategies. A critical analysis of the logical and empirical foundations of the theory reveals several weaknesses and limitations. This article demonstrates how attachment theory (J. Bowlby, 1969/1982, 1973, 1979, 1980, 1988) can be used to integrate a diverse set of ideas and research findings and provide a more grounded account of human mating. In the past decade, there has been a resur- theory, which remains one of the most robust in gence of interest among social scientists in Dar- modern science, has anything of value to con- win's theory of evolution. In the field of psy- tribute to the understanding of mating in our chology, this is exemplified by the work of species. Although all theories about the ances- David Buss and colleagues, who have applied tral nature of human mating are necessarily the theory to human mating. One measure of the speculative, in what follows we hope to dem- success of this effort is the fact that their model onstrate that the available evidence supports a is widely viewed, at least among psychologists, very different evolutionary perspective on how as the definitive evolutionary perspective on the Homo sapiens go about the business of mating. topic. Put differently, many in our field seem to think that application of the principles of natural selection to human mating phenomena inevita- The Standard Evolutionary Model bly results in the Bussian framework. An unfor- tunate result is that those who find fault with The standard evolutionary model is formally this particular framework tend to reject outright known as sexual strategies theory (Buss & the possibility that Darwin's grand and elegant Schmitt, 1993). It is essentially an extension of the theory of parental investment, proposed by Trivers in 1972. He argued that in any species in which differences exist in what it costs mem- Cindy Hazan and Lisa M. Diamond, Department of Hu- bers of each sex to reproduce their genes, there man Development, Cornell University. Lisa M. Diamond is now at the Department of Psychol- will be corresponding sex differences in mating ogy, University of Utah. behavior. The biological reality in humans is We are grateful to Richard L. Canfield for his thoughtful that males can reproduce their genes with the critique of an earlier version of this article, and to Emily minimal investment of a few minutes and a few Allen, Jeffrey Ellens, Samantha Goldman, Samara Guzman, Janienne Kondrich, and Shelby Semino for help with the sperm, whereas the cost to females is usually literature review. Our work also benefited from the support years of investment in the form of gestation, of a National Science Foundation grant (SJBR-9320364). lactation, and offspring care. In theory, such Many of the ideas and arguments contained herein were asymmetry has resulted in hard-wired sex-spe- previously presented by Cindy Hazan in conference papers at the 1997 (Toronto, Ontario, Canada) and 1998 (Lexing- cific strategies for achieving reproductive suc- ton, Kentucky) meetings of the Society for Experimental cess. Males "naturally" seek out and take ad- Social Psychology and the 1999 (Denver, Colorado) meet- vantage of opportunities to copulate with as ing of the American Psychological Society. many different females as possible, especially Correspondence concerning this article should be ad- ones who display the fertility markers of youth dressed to Cindy Hazan, Department of Human Develop- and beauty. The female is "by nature" more ment, Cornell University, Ithaca, New York 14853-4401. Electronic mail may be sent to [email protected]. sexually cautious, preferring one male who has 186 SPECIAL ISSUE: ATTACHMENT AND MATING 187 resources and appears willing to share them Putting Mate Selection Theories to with her and the offspring she will have to the Test nurture. Although sexual strategies theorists ac- knowledge that the mating behavior of men and The most straightforward way to identify the women can be similar in some respects under criteria that people use to select actual as op- certain ecological conditions, above all they posed to hypothetical mates would be to study a emphasize sex differences. The inescapable group of already-mated individuals and deter- conclusion from their writings is that differ- mine the basis on which they chose their part- ences between the sexes represent the hallmark; ners. But simply asking them has obvious lim- of human mating. itations. For one, respondents might be reluctant Scores of studies have been conducted to test to answer honestly, especially if their selection criteria included qualities that could be judged sexual strategies theory, including one massive superficial, such as money or looks. However, survey of more than 10,000 individuals in 37 concerns about this possible limitation can be different cultures (Buss, 1989). The findings easily dismissed in light of the fact that large indicate that males worldwide assign greater numbers of respondents in Buss et al.'s studies importance than females to the appearance of have voluntarily mentioned such qualities on potential mates, preferring those who are young their lists of mate preferences. A more trouble- and physically attractive. In contrast, females some possibility is that the average person lacks generally report caring more than males about awareness of the factors that truly influence his the social status, ambition, and earning power of or her mating decisions (for a similar point, see potential mates. In sum, the sex differences in Pietromonaco & Feldman Barrett, 2000). mate preferences that sexual strategies theory All theories that regard mate choice as a predicts appear to be both statistically reliable strategic process presume that choices are sys- and culturally universal. tematically guided by characteristics of the in- As the name implies, a central tenet of sexual dividuals making them. That is, whether a re- strategies theory is that human mating is inher- searcher adopts an assortative mating perspec- ently strategic. In theory, mating behavior is tive (one prefers those who are similar), an guided by evolved psychological mechanisms idiographic view (one's preferences are learned compelling men and women not only to desire and idiosyncratic), or a sexual strategies model certain qualities but to select mates on the basis (one's preferences are determined by biological of these innate desires. However, the methods sex), the same prediction would hold: Mate used in tests of the theory do not and cannot choice is driven primarily by qualities of those directly test the selection part of the prediction. doing the choosing. A corollary is that individ- Participants (often undergraduate students) are uals who have similar qualities should also have asked to generate a list of the qualities on which similar mate preferences. This makes possible they believe their eventual mate selections will an elegant "natural" test of these theories using be based or, sometimes, simply asked to rank or identical twins. Monozygotic (MZ) twins are as rate the importance of a list of traits provided by similar as two people can be. Not surprisingly, researchers. Lists typically include the full they tend to make similar choices in a wide range of desirable qualities: a winning person- range of domains, including jobs, clothing, ality, above-average intelligence, great financial friends, cars, hobbies, and vacations, to name just a few. If mate selection is lawfully guided prospects, high social status, and good looks. by the characteristics of choosers, MZ twins Although the findings are generally consistent should prefer and select mates who are, them- with theoretical predictions—at least as they selves, more alike than the mates of less similar pertain to sex differences in the estimated rela- pairs of individuals. tive future value of certain qualities—they re- veal nothing about whether reported selection Lykken and Tellegen (1993) recently tested criteria translate into actual mate choices. this hypothesis using the Minnesota Twin Reg- Clearly, the validity of sexual strategies theory istry, which contains a wealth of information, hinges on its ability to predict real-world mate including personality, achievement, IQ, atti- tude, occupation, and physical appearance data, selection behavior. on more than 1,000 twin pairs. Even with this 188 HAZAN AND DIAMOND large sample size and correspondingly strong Overview analytic power, no evidence was found to sup- port any strategic model of mate selection. The If mates are not chosen on the basis of the unexpected and hugely significant finding was sex-specific criteria that the standard evolution- that the mates of MZ twins are no more similar ary model posits or according to the criteria of to each other than are the mates of randomly other strategic mate selection theories, then selected pairs. what determines who ends up with whom? In At first, one might think that this finding the following sections, we outline an alternative deals a bigger blow to theories of assortative or evolutionary perspective on human mating that idiographic models than to sexual strategies the- proposes an answer to this burning question. ory, given that the former attribute mate choice We begin with an overview of mating relation- ships as seen through the lens of attachment to the chooser's personal characteristics (inde- theory (Bowlby, 1969/1982, 1973, 1979, 1980, pendent of sex), whereas sexual strategies the- 1988).