Scientists Recently Discovered That the Distinct Smell of Bananas Causes Male Mice to Become Stressed.
Researchers from McGill University in Montreal, Quebec, have uncovered an unusual aversion among male mice to this type of fruit while analyzing spikes in stress hormones when they are near pregnant or nursing females. The cause is a compound known as n-pentyl acetate found in the urine of female mice. This compound is also responsible for the characteristic aroma of bananas.
Exposure to n-pentyl acetate causes stress in male mice.
Jeffrey Mogil, the study’s author and a professor in the psychology department at McGill University, stated: “This entire finding was a surprise because we were not actively looking into it; we stumbled upon it. The pregnant female mice were in our lab for a different experiment, and one of the students noticed that the males started behaving strangely.”
In the paper, the researchers wrote: “Male mice, especially those that are virgin, often act aggressively to enhance their genetic fitness.” To protect themselves from these dangerous predators, pregnant and nursing females emit chemical signals through their bodies, warning males to stay away from their offspring.
Mogil explained: “Rodents and many other mammals rely heavily on their sense of smell. Mice also communicate with each other through olfaction. We have seen many olfactory messages sent from males to females, but rarely the other way around. Most of these messages relate to sexual behavior, but in this case, sex is irrelevant. This is a warning message from females to keep away from their young, or else a tense confrontation will occur.”
The pain relief due to stress is significantly higher in virgin male mice.
After observing increased stress levels in males in response to the chemical signals in female urine, Mogil and his team wondered if n-pentyl acetate from another source would elicit a similar reaction. They purchased banana oil from a local supermarket and added the liquid to cotton balls, placing them in the cages of male mice. The presence of this scent also heightened the stress levels of the males, and the researchers suspect that this hormonal increase is directly related to the stress experienced when facing a potential confrontation.
Additionally, exposure to urine or banana oil also had pain-relieving effects and reduced the sensitivity of male mice to pain.
The study’s authors also found that the pain relief caused by stress is significantly higher in virgin male mice, indicating that non-related males pose a greater threat to the survival of the offspring than the fathers.
Mogil shared that this discovery represents a breakthrough in the science of social signaling among mammals.
He said: “Mammalian species communicate with each other in ways that are richer than we initially thought.”
