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Wildlife: Researchers solve mystery: Why do male mice hate the smell of banana peels?


Their stress hormones are rising, they just want to get away – but why do mouse men react so drastically when they smell banana peels? Researchers got to the bottom of the strange behavior.

It was one of those discoveries that left scientists stumped: Almost by accident, they found that male mice reacted with stress and rejection as soon as they caught the smell of banana peels. However, this only affected male animals. In fact, the researchers were even able to show in blood samples from the mouse men that their stress hormones jumped significantly after smelling banana peels or banana oil concentrate. An interesting and unexpected finding. Which, however, raised the question: Why is that so?

It is well known that many animal species are very sensitive to smells. Because they communicate via scents – for example, they mark their territories with urine or radiate a willingness to mate with a corresponding body odor. Scientists also began to research in this direction. But as they soon found out: The banana scent puzzle has nothing to do with sexual behavior. But very well with communication about fragrances.

Mice respond to banana peels with stress hormones

Female mice that are either heavily pregnant or actively breastfeeding exude a scent very similar to that of banana peels. During this time they smell of acetic acid n-pentyl ester – to warn males in their vicinity not to get too close to them and their young. Because mice can definitely become cannibals: Male animals are known to kill other baby mice because they want to pass on their own genes within the group. And mouse mothers are ready to defend their offspring by any means necessary. To prevent attacks from occurring in the first place, they exude acetic acid n-pentyl ester to make it clear to males that they are not to be trifled with.

And, as the scientists were able to determine: This method usually works. In either case, the scent elicits a measurable, drastic response in mouse-men. Their stress levels rise, they want to get away from the scent source as quickly as possible.

And the bananas? By coincidence, they exude a fragrance that is amazingly similar to n-pentyl acetate. It is called isoamyl acetate and is also found in other fruits. In banana peels, however, it appears to be particularly concentrated. If you want to keep mice out of your four walls, you could definitely think about distributing plenty of banana peels everywhere – but that would only deter the male animals. Bugs Bunny taught us that if we accidentally slip, then of course someone could.

Quellen:  “IFL Science”, “LiveScience”