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It has long been debated whether animals can smell fear in humans. Unfortunately, answering this age-old question isn’t as easy as pulling Fluffy or Fido aside and asking them what they’re feeling.
So what does the research say? Can animals actually smell fear? To get to the root of this question, researchers have largely taken humans out of the equation. Dogs are known to respond to our facial expressions and Position. Instead, the researchers are focusing on how animals such as horses and dogs respond to different odors emitted by humans watching happy and fear-inducing videos.
According to a horse study published in the journal 2023 scientific reportThe researchers had participants watch a comedy clip one day and a horror movie clip the next.
After participants watched each video, researchers used cotton pads to collect sweat samples from viewers’ armpits and had participants report the level of pleasure or fear they felt while watching each clip. asked to do so. The researchers then presented two swab samples taken from the same human to the assigned horses to see if they could distinguish between the scents of humans when they were happy and when they were in pain.
“Initially, we didn’t know whether horses could distinguish between odors,” says the study’s lead author. proteinine giardaa PhD student at France’s University of Tours told Live Science.
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However, the horses responded differently depending on the cotton pads they were given.
“When the horses sniffed the pleasure sample, they only used their left nostril,” Giardat said. “This shows us which parts of the brain horses use to analyze odors. In all mammals, the two brain hemispheres have different functions, and in emotional contexts, they can be used to detect odors. It appears that the odor from the sample was perceived as positive by the horses.” ”
However, when horses were given samples swiped during a horror movie screening, their reactions were very different, not only did they sniff the samples for longer, but they also used both nostrils to smell them. ” said Giardat.
But Giardat is quick to point out that this doesn’t necessarily mean the horse knows the meaning of fear. “It’s not like the word ‘fear’ that comes to mind when a horse smells another animal,” she says. “But now we know that [horses] It can distinguish odors from various human emotional states. ”
A question arises here. What specific compounds do humans produce in their sweat that cause changes in horse behavior?
Researchers have proposed that chemical signals – chemicals produced by animals that can influence the behavior of other animals – may be behind the horses’ reactions. Human sweat contains several compounds, including adrenaline and androstadienone (a pheromone-like protein), that can cause a change in smell at the moment of fear. These compounds may also convey “emotional information” from one species to another, the researchers said in the study.
In future studies, scientists will perform various tests after smelling the samples to determine whether smelling a fear odor triggers a fear response in horses and how it affects the horse’s emotions. We plan to investigate whether this may have a significant impact.
“We want to see if fear changes the response to testing,” Giardat said.
Meanwhile, a 2018 study published in the journal animal cognition, scientists asked Labrador retrievers to sniff a sample swiped from a male participant’s armpit after watching either a scary or happy video clip. The researchers placed the sample inside a box with an opening, and then placed the box in a closed room with the stranger and the stranger. dogI am the owner of
Similar to the horse study, the researchers found that dogs responded differently depending on whether they smelled a fearful or happy human.
“When dogs smelled the scent of a happy person, they had more interactions with strangers in the room,” study lead author Biagio DanielloFederico II, professor of zoology at the University of Naples in Italy, told Live Science.
But when the dogs smelled a sample of a scared person, they had a completely different reaction.
“When they smell fear, they either go to their owners or go to the door and try to leave the room,” said the study’s co-authors. Anna ScanduraFederico II, a postdoctoral researcher at the University of Naples, told Live Science.
Researchers reached similar conclusions to scientists in a study of horses. The dogs’ reactions are likely due to chemical signals, the authors write in their study, suggesting “interspecies emotional communication” is at work.
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