Mate-choice copying is a sex-general heuristic among humans
– by Robert Bowers
There is a large ground bird from the American plains whose mating system could not be more convenient for studying sexual selection. Over a conveniently short mating season, male sage grouse gather in a conveniently compact space, within a few miles of each other, and there they all perform their best mating displays. The hens of this species browse the performances at their leisure and choose a mate. This event attracts not only competing cocks and broody hens, but also biologists keen on showing how the striking sexual dimorphisms expressed in this species relate to female choice and intersexual sexual selection. Unsurprisingly, mating variance among male sage grouse is large, and optimism was high that with enough clipboards, the exaggerated waddles and dances and girth of these males would all have a clear explanation. But the mating variance was too great. Even with all the elaborate male characters of these birds, there were still insufficient bases to explain the extent that some hens chose the most successful males. In apparent exasperation, there is a remark in the middle of a 1960’s doctoral thesis that the females might be copying each others’ choices.
The subsequent area within sexual selection research, initially termed “female copying”, grew in several ways. Theoreticians showed its relation to reproductive variance and sexual selection. Experimentalists demonstrated it empirically in laboratory demonstrations. And phylogenetically, it grew in the breadth of species that were shown to be affected. However, even with all these advances, it remained within the theoretical context of female choice, and continued to be studied as if it were an exclusively female phenomenon. Even among humans, a species in which both sexes choose, a large majority of “mate-choice copying” (what the phenomenon is now called) studies focused exclusively on females choosing males.
Among humans, however, the earliest documented recognition of mate-choice copying (in a dating advice column from 1928, predating the sage grouse observation by decades), was actually about men copying the choices of other men. Indeed, studies that have included both men and women have most often found that both sexes are affected by the choices of others. Despite this, it remains common to find mate-choice copying presented as a specifically female phenomenon. Typically, this sentiment is accompanied with reference to Parental Investment Theory, the popular view that the sex that suffers greater costs in reproduction will have greater use for any means of choosing better mates. The received view is that women should engage in social mate choice heuristics more than men.
But mate choice is complicated, and harnessing information about mates from attending to others’ choices is no less so. When one considers mate-choice copying more closely, several features of social mate-choice information (as well as of human parental care) muddy the theoretical waters that motivate looking for a sex difference. Mate-choice information is readily accessible, relevant to both sexes, indicative of characters not visible on the surface, and fallible. Copying others’ choices heightens competition. Paternal care among humans is long and extensive. All of these features push expectations in various directions about what kind of sex difference should or should not express in how people attend to others’ choices when choosing a mate.
Not long ago, we decided to address this question directly. One problem in assessing sex difference claims from previous data was that male and female participants are typically presented with different stimuli. Male mate choice is assessed with images or videos of women, and female mate choice is assessed with images or videos of men. And one point that has been clear from the earliest human mate-choice copying studies is that the specific stimuli matter; the strength of the effect depends heavily on such features as the relative attractiveness of the stimuli employed.
To address whether the sexes differ in the extent that they rely on social mate-choice heuristics, we removed all sex-specific stimuli so that we could present the very same stimuli to male and female participants. Profiles furthermore included only accurate information about real daters making sincere choices in the context of a speed-dating event.
Our results did not support the kind of sex difference expected by the received view. We did find evidence of human mate-choice copying, but both male and female participants changed their ratings in the direction of others’ choices, and to comparable extents.
This matters because mate-choice copying is both a cause and a consequence of sexual selection. As a consequence, it being sex-general implies that there is substantial pressure on both sexes to be selective. As a cause, the sex-generality of mate-choice copying is expected to have the effect of increasing reproductive variance, and so of intensifying selection on sex-specific characters in both sexes.
These results add human mate-choice copying to the growing list of phenomena that do not abide expectations of the still dominant set of views related to Parental Investment Theory, Sexual Strategies Theory, and Bateman’s Principle. These views satisfy aesthetically but are increasingly found to falter empirically, not necessarily because they are wrong, but because mate choice is complicated, and because human mate choice and parenting are not so one-sided as in the comparatively extreme mating systems amid which these ideas were developed. The good news is that with attention to the specific features of the structure of the problem mate seekers face, there are fine grounds for refining understanding of sexual selection in the context of how copying others’ choices allows mate seekers to harness social information about mate quality.
Read the original article: Bowers, R.I., Pinar, V., Sariyildiz, S.S., & Parlak, D. (2025) Is mate-choice copying a female phenomenon? Evolution & Human Behavior, 46(1), 106653.