According to scientists, what might be considered the most suitable mate does not always mean it’s the best fit. For frogs, that is.

Natural selection leads us to believe that the most suitable males will be chosen by the females in order to ensure evolution. For example, the most prolific peacock dance attracts the peahens wile the most profound bullfrog croak attracts the female, according to Pioneer News.

But to indirectly debunk this evolutionary theory, researchers have found that the túngara frog does not always match up to its most suitable female partner. The co-author of the study, Amanda Lea, says, “People are really interested in this because it’s such a common thing for people.”

The University of Texas, Austin evolutionary biologist added, “This is the first time we’ve found evidence for irrational mating behavior. If they aren’t making rational decisions, then these models don’t hold up.”

A previous study suggests which traits the females find most appealing.

Lea says “They tend to like longer calls. They also like lower-frequency calls. Then the other thing that’s a really big one for these gals is the ‘call rate.’ They love faster call rates. The faster a male can call the better.”

With some males making long whining noises and some making a lower-frequency whine with a “chuck” sound, the females were forced to make a decision.

“They have two traits to evaluate,” Lea dictates. “They have the call rate and they have the attractiveness of the call,” and she concludes, “They actually switch their preferences. So now call rate is no longer the most important thing.”

And what they found was that the túngara frog tends to be easily confused and frustrated, which further adds a notch to the unraveling fact that there are flukes in evolution. The question they will be forced to answer is if this means an eventual halt to evolution.