uppose that dissenting Justice Antonin Scalia was right when he fulminated recently that, by overturning the Texas antisodomy law, the Supreme Court was paving the way for "same-sex marriage." What's the big deal about gay nuptials, besides the fact that Canada got there first?

After all, when two people with matching sex chromosomes select each other as long-term partners, they're being only slightly more emphatic in a strategy that scientists say may explain mate choice among a great majority of heterosexuals, too.

As a new report demonstrates with the no-nonsense zing of the phrase "I do," humans often seek in a spouse the sort of person they know best: themselves. Beautiful people want beautiful partners. The well-heeled covet Prada-clad companions. Those who are devoted to kith, kids and unabridged Passover seders expect no less from the person who adorably snores beside them each night.

And while the notion that like-seeks-like may not surprise anybody who has scanned the newspaper wedding announcements and wondered if a few of the couples weren't inadvertently committing incest, the new results contradict some important claims about male-female differences in mating strategies that lately have emanated from the niche of neo-Darwinism called evolutionary psychology.

According to one widely touted premise of the field, men are comparatively more concerned with the physical appearance of their partners, while women tend to fixate on the relative wealth and ambitiousness of their suitors. This disparity in mate-choice modules, the story goes, can result in a rich if homely financier in Scarsdale married to the gorgeous waitress from the Bronx: he has the material resources that she is evolutionarily predisposed to desire, while she gives evidence, through her cinched waist, symmetric cheekbones and fetching décolletage, of youthful fecundity and genetic quality.

Yet the new report, by Dr. Stephen T. Emlen, a professor in the department of neurobiology and behavior at Cornell, and his former student Dr. Peter M. Buston, now at the National Center for Ecological Analysis and Synthesis at the University of California at Santa Barbara, offers scant support for the chasmic divide between the romantic algorithms of men and women.

Instead, in analyzing the results of a questionnaire about who wants what in a long-term relationship, the researchers found that the men who were most likely to seek beauty in a woman were not the trust-fund sons, but those men who considered themselves quite handsome; while men who rated themselves as wealthy and ambitious were much likelier to focus on the wealth and status of a prospective mate than on her physical charms.

Similarly, women who viewed themselves as attractive ranked the toothsomeness of a potential husband above the particulars of his stock portfolio; while women from privileged backgrounds wanted a groom who knew the purpose and position of all four forks in a formal table setting.

The same "Why not make more of me?" principle held for each of the 10 traits that were listed on the survey, including devotedness, faithfulness, strength of family bonds, health, desire for children and qualities for raising children. The biggest predictor of whether a person rated the characteristic low or high on a partner-picking scale depended above all on where the respondent placed himself or herself on the same gradient from one to nine.

The findings, which are to be published this month in The Proceedings of the National Academy of Sciences, were based on a survey of 978 residents of Ithaca, aged 18 to 24, most of them students, and all, for reasons of analytic simplicity, declared heterosexuals.

"People seem to be looking for soul mates on many levels, and that makes adaptive sense," said Dr. Emlen in a telephone interview. "Peter and I are evolutionary biologists, so we're both interested in why people would have rules that essentially say, seek someone who is like yourself on many of the things you value. Well, if you do, you'll end up with a compatible mate, and less conflict in the relationship, and a better chance of a long-term bond and successful child rearing."

In a species like Homo sapiens, where babies take a decade or longer to rear, the relative strength of a pair bond can spell the difference between dynasties that linger and a stint on Jerry Springer.

When asked why they hadn't included salient characteristics like intelligence, Dr. Emlen replied that they wanted to keep the survey streamlined and to focus on traits that others have seen as relevant to a person's putative "reproductive potential." In any event, he added, Ivy League students would sooner put themselves on the Lizzie Borden end of the family-ties scale than to self-assess their intelligence as, oh, a five or six.

Dr. Robin Dunbar, a professor of evolutionary psychology at the University of Liverpool, calls it "a good study with good results," although he quarrels with some of their interpretations and says that the authors overlook the differences between what people may truly want in a mate — the ideal — and what they realize they will have to settle for.

Dr. David M. Buss, a professor of psychology at the University of Texas famed for his studies of human mate choices of more than 10,000 people in 37 cultures worldwide, said by e-mail of the new report, "The authors present many things that are new, and many things that are true; unfortunately, the things that are true are not new; and the things that are new are not true." As Dr. Buss sees it, the idea that "likes attract" is familiar fare, which he discusses at length in his 1994 book, "The Evolution of Desire."

Despite the general tendency for people to seek mates with whom they share many characteristics, Dr. Buss added, he and others have shown significant differences in the relative value that men and women place on a mate's appearance and financial resources. "The authors choose not to analyze their data for sex differences in mate preferences," he said, adding that if such differences had been explored, "you can bet that they would be found in their data, just as they have in dozens of studies conducted worldwide."

Dr. Emlen replied that, yes, Dr. Buss and others had talked about likes attracting likes, but they nonetheless had highlighted the sex differences in mate preference over the concordances, a perspective made clear by the titles of the second and third chapters in Dr. Buss's book: "What Women Want" and "Men Want Something Else."

By contrast, Dr. Emlen said, the new paper emphasizes similarities: between one's self-perception and one's preferences in a long-term partner, and between men and women in their reliance on the mirror-image method of mate mapping. And this shift in emphasis, he said, "is very new."

As for analyzing their data with sex differences in mind, Dr. Buston said in a telephone interview that, yes, there were minor discrepancies based on sex, and, yes, pretty women were a bit more likely to be interested in a man's money than a handsome man was in a woman's money; and the well-to-do young men were slightly more concerned over a potential mate's appearance than the financially endowed women.

"But these effects were very weak compared to the likelihood of women who score themselves highly in physical appearance choosing males with the same," said Dr. Buston, "and for both men and women with lots of resources to choose mates with resources."

To give a sense of the strength of the likes-attract rule, the authors said that, while only 5 percent of the variation in women's mate-preference scores for wealth, status and family commitment (traits assumed to be indicators of a man's mate quality) could be explained by the women's perception of their physical appeal and sexual fidelity (the items correspondingly thought to signify a woman's reproductive value) more than 35 percent of the variation could be attributed to how the women rated themselves for wealth, status and family commitment.

How replicable the new results are, and whether they will hold up in studies of other cultures remains unknown. The authors of the paper are careful to stress in the title of the paper that they are talking about mate preferences "in Western society." Tastes and needs may be very different in polygamous cultures, said Dr. Buston, where the ideals of a well-harmonized "pair bond" don't quite apply.

"At the end of the day, humans are very complex creatures," Dr. Dunbar said. "Nonhuman primates are bad enough, but people are even worse."

As for affairs of the heart, who knows what lies on the other side of the Looking Glass?