Can Animals Really Smell Human Fear?

Many of you have probably heard that dogs or other animals can smell a person's fear, and this affects their behavior. For example, a pack of dogs, feeling fear, may allegedly begin to behave more aggressively and attack a person. But is there scientific evidence for this? In fact, scientists have been arguing about this for a long time, since there is no clear answer yet. It has long been known that the same dogs react to a person’s facial expression, his posture, etc. Therefore, perhaps they can determine fear by other signs. However, some scientific studies have brought some clarity to this issue.

Can animals really sense human fear by smell? Scientists argue about the ability of animals to sense human fear. Photo.

Human emotions are a psychophysiological process, that is, in addition to psychological experience, there is also a physiological process of the nervous, endocrine, respiratory and other systems, as a result of which certain chemical signals arise. As we have already said, certain chemical processes also occur during fear. At the same time, people begin to release adrenaline through sweat, which can cause a change in smell. Therefore, theoretically, animals with a good sense of smell may well feel these changes.

However, to confirm or refute this assumption, it is necessary to exclude the person. That is, the animal should react only to the smell, and not to human behavior. Therefore, different groups of scientists conducted research excluding the presence of humans. For example, one of these works was carried out in 2023. The authors had participants watch clips from comedy films on one day, and on another day — from horror films.

Does human fear have an odor? Horses are able to recognize changes in human odor that arise due to fear. Photo.

Horses are able to recognize changes in human odor that arise due to fear

While watching, scientists collected sweat samples from their armpits using a cotton swab. Moreover, all participants reported how strong their emotions were when watching certain videos. The horse was then given two swabs from the same person to sniff — one received when he was in a good mood, and the other — when he experienced great fear.

The researchers themselves doubted that the horse would react differently. However, as they reported in the journal Scientific Reports, when the horses sniffed the fun samples, they only used the left nostril. The choice of nostril, according to the researchers, indicates which part of the brain the animals used to analyze the smell. Let us recall that in mammals, different hemispheres are responsible for different functions. Based on which hemisphere was active, the scientists concluded that the horses perceived the smell positively.

But when the horses were given samples taken during a horror movie, they sniffed them more carefully, for a long time, and used both nostrils at once. True, this does not mean that horses have identified fear. However, it is safe to say that they sense the difference between the smells.

Does human fear have a smell? Dogs begin to behave restlessly when they smell human fear. Photo.

Can dogs smell fear

Another similar study was conducted in 2018, but instead of horses, scientists used Labrador retriever dogs. They placed the odor sample in a box with a hole, which they placed in a closed room. In addition to the dog, it contained its owner and a stranger.

As with horses, scientists found that dogs responded to odors differently. When they smelled a person in a good mood, they became more sociable towards the stranger, that is, they showed interest in him. But when they sniffed a sample obtained from a frightened person, they approached their owner or even the door and tried to leave the room. The authors of the work report this in the journal Animal Cognition.

Do dogs smell fear? Animals pick up chemical signals that arise in humans at the moment of fear. Photo.

Animals pick up chemical signals that arise in humans at the moment of fear

Scientists suggest that this reaction is associated with the above-mentioned chemical signals. It can be assumed that these signals carry “emotional information,” that is, they provide “interspecies emotional communication.” However, further research is needed to draw definitive conclusions. Therefore, scientists are going to find out whether the smell of fear can cause a response of fear in animals, and what kind of emotional impact it has in general.

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Finally, we note that not only animals, but also people can pick up chemical signals, and without even knowing it. We previously told you that the smell of women's tears changes the behavior of men. There is even an opinion that people choose their friends by smell. You can read more about this at the link.