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.


The researchers think it’s brain size.

“One of the biggest decisions a female guppy has to make in its life is choosing who to mate with,” said Professor Judith Mank of UCL Genetics, Evolution & Environment.

Long tails and bright orange fins would give guppy kids a hoist in life. Such fish are more beautiful than their stocky gray colleagues.

“You might think female guppies would all prefer a single most attractive male,” Mank added.

For the moment, all the UCL researchers have to hop on is the guess that the smaller the guppy’s brain-size, the less attraction matters.

Indeed, “…we found,” Professor Judith Mank said, “that it takes a certain amount of brain-power to size up an attractive mate.”

So, does that mean that in the human species, it’s our larger brain size that, allegedly, tends to make females more attracted to certain males?


Unless fish have different choices.

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Research paper in Nature Ecology & Evolution

Professor Judith Mank’s academic profile

UCL Genetics, Evolution & Environment