Smart Female Guppies With Bigger Brains Choose More Attractive Mates


Stephen Luntz

Stephen has a science degree with a major in physics, an arts degree with majors in English Literature and History and Philosophy of Science and a Graduate Diploma in Science Communication.

Freelance Writer

guppy tail

Look, that tail is all very well but it takes a certain amount of brain power to see its worth. Napat/Shutterstock

Men, we can't promise the way to a smart woman's heart is to dress in flashy colors, but it'd probably work if she was a guppy. Female guppies with large brains show a preference for brightly colored males, while those with small brains do not. 

One of the theories for why humans evolved such big brains is that they impressed potential mates. But what about the other side? It takes a certain amount of processing power to decide who you want to get it on with. Does brain power matter in choosing a mate? Let's face it, we all know very smart people who make dumb decisions about love.


It's easier to study such things in a relatively simple animal than in humans, and few species have had their sex lives as closely examined as guppies (Poecilia reticulata). Dr Alberto Corral-Lopez of Stockholm University compared the mating decisions of big and small brained female guppies, using previous research showing that for guppies at least, (brain) size does matter.

Male guppies are colorful, and females are known to prefer the most highly ornamented blokes. In part, this is because bright colors strongly correlate with foraging ability and good health, desirable traits to pass on to children. There is also a self-reinforcing component. Even if colorful males were no healthier, it is in a female's evolutionary interest to breed with a male whose traits will be attractive to future generations.

In Science Advances, Corral-Lopez reports he used two strains of female guppies, respectively bred for big and small brains, along with a third group resembling those found in the wild. The most and least colorful male guppies Corral-Lopez found find were placed in separate tanks. The female was put in a third tank where she could see either male, but not both simultaneously.

Both the large-brained and wild-type female guppies showed a strong preference for spending time where they could gaze on the better-looking suitor. Wild-type guppies actually showed a somewhat stronger preference in this regard than the big-brained variety, but the difference was not statistically significant.


On the other hand, small-brained female guppies spent the same time mooning over potential mates irrespective of coloring. Corral-Lopex and colleagues tested, and rejected, the theory that there was something wrong with some of the guppies' color perception. Since all the guppies showed a similar capacity to respond to colors the authors were left with one conclusion: If you're as stupid as a small-brained guppy, telling the difference between hot and not overloads the brain cells. It's easier to just flip a coin.

It's getting easier to see why bigger brains, despite all the extra energy they use, have proven an evolutionary benefit.

  • tag
  • brain development,

  • guppies,

  • mate selection