--- title: "Guppies, black grouse and humans all practice mate choice copying, picking partners others already chose" url: https://badiyaa.com/mate-choice-copying-guppies-grouse-humans/ published: 2026-11-11T07:06:00+00:00 modified: 2026-11-11T07:06:00+00:00 section: Pets & Animals publisher: Badiyaa --- # Guppies, black grouse and humans all practice mate choice copying, picking partners others already chose Mate choice copying, picking a partner because others chose him, is seen in guppies, black grouse, rats and humans, studies show. A female guppy watching another female court a male will often decide she wants him too, and she is choosier about whom she copies: she is more likely to follow the pick of a bigger fish than one her own size or smaller. Biologists call this mate choice copying, and it turns up from fruit flies to people. Some researchers describe it as mate choice shaped by onlookers. Instead of judging every suitor from scratch, an animal lets the choices of others steer its own. It is a form of social learning, and researchers suspect it helps drive sexual selection, the process that shapes showy male traits. ## Who copies whom The list of known copiers is long and strange: - **Insects:** the common fruit fly, Drosophila melanogaster. - **Fish:** guppies and the ocellated wrasse. In sailfin mollies, it is the males that copy. - **Birds:** black grouse, Japanese quail and zebra finches. - **Mammals:** Norway rats, mice and humans. Black grouse show the strategy at work. Young females in their first breeding season tend to mate later than older females, which gives them time to watch the experienced birds and copy their pick. ## Copying by sight and by smell Guppies copy by watching. A female has to recognize the female doing the choosing, judge her quality, then recognize the chosen male later. Location matters too: a copier may repeat the choice where she saw the courtship but be less keen if the same male turns up somewhere else. Rodents do not need to watch. A female rat or mouse can sniff a male’s urine, and if it carries the scent of other females, she reads that as a recommendation. In mice, the hormone oxytocin is central. Females bred without the oxytocin gene failed to recognize either the female doing the choosing or the male she picked. ## The human version People do it too, with a twist. In a 2007 experiment at the University of Aberdeen’s Face Research Laboratory, 28 women and 28 men rated pairs of male faces, then watched a short slideshow in which a woman looked at one man in each pair, either smiling or with a neutral face. When the participants rated the pairs again, [women warmed to the men who had been smiled at](https://pmc.ncbi.nlm.nih.gov/articles/PMC2093971/) more than to the men who got a neutral look. Men reacted the opposite way. They rated the smiled-at men lower and the neutrally regarded men higher, which the authors linked to competition between men. An earlier test found that a wedding ring alone did not make men more attractive to women, suggesting human copying runs on subtler cues than a simple “taken” label. ## Why copy at all Here is the logic in one line: judging a mate costs time and energy, and copying an expert is cheap. That trade-off explains the patterns biologists see. Inexperienced females copy more. Females copy more when the breeding season is nearly over and there is no time to shop around. The strategy has costs. If the first chooser got it wrong, every copier repeats the error. Atlantic molly males can even exploit copiers: a male may court an unattractive female while a rival watches, steering the rival toward a poor match. Some apparent copying may not be copying at all, since females might pick the same male because they share genes, live in the same patch or want to join a harem. Badiyaa covers more animal behavior in the [Pets & Animals section](https://badiyaa.com/category/pets-animals/), including how [a narwhal and a beluga produced the only known narluga](https://badiyaa.com/narluga-narwhal-beluga-hybrid-skull-dna/). The full review is on the [mate choice copying page](https://en.wikipedia.org/wiki/Mate_choice_copying). ## Further reading - [Wikipedia: Mate choice copying](https://en.wikipedia.org/wiki/Mate_choice_copying) - [Social transmission of face preferences among humans (2007)](https://pmc.ncbi.nlm.nih.gov/articles/PMC2093971/) *Image: Bouke ten Cate, CC BY 4.0 via Wikimedia Commons* *This article was produced with AI assistance and reviewed by our Editorial Desk. [How we work](https://badiyaa.com/editorial-policy/).*