We're herd animals… especially the female members of our species when it comes to their dating instincts. That's the conclusion one might reasonably draw from the results of a new study in press at the journal Human Nature. In it, psychologists Ryan Anderson and Michele Surbey from James Cook University in Australia showcase a common—but oddly enough, a theoretically underappreciated—reproductive strategy in human females known as “mate copying.” This involves women copying the mating choices of other women as a sort of thoughtless romantic heuristic, which of course doesn’t sound very romantic at all.

Evolutionary biologists, the authors point out, have in the past tended to characterize female mate selection (essentially, which individual man a woman chooses to have sex with, given the realistic ancestral prospect of being impregnated by and dependent on him for the care of their mutual offspring) as occurring in a sort of solitary vacuum. Is his face symmetrical? Check. Does he have a masculine voice? Check. Is he the right height? Check. Is his penis formidable enough to scoop out a rival’s sperm? Check. And so on. But in reality, Anderson and Surbey surmise, men aren’t mere asocial stimuli floating around out there in women’s environments, with their physical traits being processed via blind cognitive algorithms. Instead, just like women, men are complex social creatures who are routinely interacting with other people—most notably in this case, with females. And you can learn a lot about a man, or more specifically, about his genetic quality, by how other women regard him.

“Mate copying,” reason the authors, “is a means by which individuals gain information about potential partners without incurring the substantial costs of selecting a mate.” In other words, it’s a quick-and-dirty shortcut for a woman to decide which guy to spend the rest of her life with—and which to take a pass on. If another woman, particularly another woman who’s attractive and can therefore afford to be picky about their baby’s daddy, previously saw something appealing in your average Joe Blow over there, well, maybe Joe Blow has some genetic je ne sais quoi that isn’t immediately apparent on the surface. The authors posit, in line with standard evolutionary theory, that while a woman’s reproductive value can be rapidly gauged by her physical features (curvy hips, signs of youth, big mammary glands, that sort of thing), a man’s reproductive value lies more in what you can’t always see at first glance, such as his social status, his resources, his political savvy, and other ethereal traits that would give your shared progeny a leg up in the evolutionary arms race. The simple fact that another woman was willing to gamble with her own genetic interests by dating a particular man makes him more attractive in the unconscious minds of female observers.

Or does it? It’s an empirical question, and Anderson and Surbey came up with an admittedly modest but quite reasonable way of answering it. The authors asked 123 heterosexual female undergrads ranging in age from 17 to 40 to judge the sex appeal of five average-looking male strangers based on their face-only photographs. (These men had been previously matched for attractiveness as part of an unrelated earlier study, all receiving a handsomeness quotient of about 3.5 out of 7. They weren’t hideous, in other words, but neither were these guys likely to grace the cover of GQ anytime soon). The men’s faces were presented randomly to the female participants, either alone against a plain background, or juxtaposed with 1, 2, or 5 silhouettes. The silhouettes were of women, of men, or of neutral “distracter arrays” such as pets or television sets. Under each such visual array was a brief description. This included the man’s name (fictitious, of course), his current relationship status (whether he was single or seeing someone), and the number of romantic relationships that he’d had within the past four years. So for example, one female participant might be shown the photo of Male #5 alongside silhouettes of two attractive women, and she’d be told something like this: “This is Mike. He’s presently single. Mike has been in two romantic relationships within the past four years but he’s not currently seeing anyone.” Another female judge, meanwhile, would see this same face but with the silhouettes of two TV sets and something like: “This is Mike. He’s single. Mike has owned two television sets the last four years. He’s not dating anyone.”

Sounds a bit odd, yes, but there’s logic to it, because the experiment was meant to test a specific hypothesis: Do women see men who are surrounded by other women, and who have a recent history of romantic relationships, as being more desirable partners than men without such a sexual backstory? If so, this would offer at least preliminary support for the authors’ mate-copying interpretation. But proper experimentalists—as these researchers are, of course—realise that one must rule out simpler accounts before celebrating the discovery of their preferred one. In the case of the present study, perhaps women simply favour men who are more social in general (i.e., hence the reason for including other male silhouettes with the male target) or who can afford to own expensive items (i.e., television sets), or more parsimonious interpretations of the data still, such as a preference for superficial features of the visual stimuli used. And, indeed, with a couple of caveats, no matter which male face they saw, the female judges rated those shown with the silhouettes of women as being more appealing than those shown alone, with men, with pets, or with inanimate objects.

Now, about those caveats… they’re important, and I must say, intuitive even to those without such an evolutionary bent. (That doesn’t mean the experiment shouldn’t have been done, I should add; in hindsight, many important findings in social psychology seem “obvious” to us now, but at the time of the study, they were anything but). First, having some past history with women does make a man more attractive in the eyes of a prospective girlfriend or wife, but it seems there’s a “tipping point” (in the authors’ words) between two prior partners and five where it all falls apart. The guy presented with five female silhouettes (with the accompanying text that he’d been in so many relationships in the past four years) was judged as being even less desirable than the lonely guy without any silhouettes who’d been in none. The authors suspect that there’s a fuzzy line at which the number of a man’s prior partners crosses into the range of promiscuity, a red alert for women seeking long-term relationships because male promiscuity is “strategically inconsistent with exclusive investment”. So this tipping point, they reason, “is where mate copying ends and mate avoidance begins.”

Another caveat is that the mate-copying effect was more pronounced in the younger than in the older female participants, presumably because naively copying other women’s mating choices becomes less adaptive over time than decisions based on one’s firsthand experiences with men, including mistakes. And here’s another important point to emerge from the study: men depicted as currently in a romantic relationship weren’t particularly attractive to the female judges, even if these men also had a (less-than-promiscuous but more than absent) precedent with other women. To the authors, this was evidence that mate copying is different from mate poaching (basically, stealing another woman’s man—think “homewrecker”). “Men currently in a romantic relationship may be simultaneously seen as desirable, because of the approval they have been given by at least one female partner (mate copying), and undesirable because of the difficulty in securing them as a partner (mate poaching). The latter effect could negate the former,” suggest the authors.

A final caveat is that female mate copying didn’t seem to play a role for women with high “self-perceived mate value” (or “SPMV”). Women who are convinced—wrongly or rightly—that they’re especially hot aren’t so easily swayed by other women’s views of a man when rating that man’s desirability. “Women with high mate value may be less likely to copy the choices of other women,” speculate the authors, “if those women have lower mate values than themselves, and thus lower standards.”

Meow. That sounds a bit harsh, but natural selection can be that way, I suppose.