Rational economics says females largely invest time and money in dating males who are rich, handsome, have big muscles, are sweaty with an average crop of facial hair. (Take these findings with a grain of salt).

Identity economics says females chase those males who have qualities their society praises. So, say your society’s into warriors and you outwit Hannibal Barca, you may have all the women (or men) chasing you.

A new study shows small-brained guppies follow a different type of economics.

October 9, 2018, a team of University College London and Stockholm University professors found that smaller-brained guppies recognize attractive guppies, but show no interest in pursuing them. The researchers photographed gene expression in the brain tissue of the females which showed they processed visual signals and knew who was more attractive than others. At the same time, these small-brained fishes avoided physically attractive guppy males.