• Crannog Admin

Can humans and dogs smell emotions in humans?

By Alison Chenoweth

We have all heard the saying ‘he smells fear’, for many years we thought this was just a saying, although we kinda always knew it was absolutely true for dogs and other animals. Dogs possess olfactory superpowers that can detect a human’s emotional state by the scent that a human emits. Until recent times it was only a theory, but a study called Interspecies transmission of emotional information via chemosignals: from humans to dogs (Canis lupus familiaris)” (D'Aniello B, 2018) was able to prove that dogs can not only detect human odors produced under emotional conditions of happiness and fear but can respond accordingly.

How they did it

The team examined interspecies emotional transfer via body odors (chemosignals). The team’s main goal was to determine if emotional odors in humans are detectable by pet dogs (Labrador and Golden retrievers). (D'Aniello B, 2018)

The odor samples were collected from the axilla (armpit) of male human donors not involved in the main experiment. The experimental setup involved the co-presence of the dog’s owner, a stranger and the odor dispenser in a space where the dogs could move freely. (D'Aniello B, 2018)

There were three odor conditions or states [fear, happiness, and control (no sweat)] to which

the dogs were assigned randomly. The dependent variables were the relevant behaviors of the dogs (e.g., approaching, interacting and gazing) directed to the three targets (owner, stranger, sweat dispenser) aside from the dogs’ stress and heart rate indicators. (D'Aniello B, 2018)

Summary of Results

The results indicated with high accuracy that the dogs manifested the predicted behaviors in the three conditions. There were fewer and shorter owner directed behaviors and more stranger directed behaviors when they were in the “happy odor condition” compared to the fear odor and control conditions. (D'Aniello B, 2018)

In the fear odor condition, they displayed more stressful behaviors. The heart rate data in the control and happy conditions were significantly lower than in the fear condition. The findings suggest that interspecies emotional communication is facilitated by chemosignals. (D'Aniello B, 2018)

The above experiments conclude that dogs can anticipate and/or detect fear in humans through smell. So, can humans detect or perceive fear in other humans the same way? (Health 24, 2009)

In 2019 Dr Bettina Pause (right), a professor at the Heinrich-Heine-Universität Dusseldorf carried out extensive research to explore human communication and sensory perception on a cellular level. Her main focus was to find out how quickly and effectively humans convey emotional states such as aggression, anxiety without words. (Health 24, 2009)

It has long been thought that humans had lost their ability to sense or smell fear or other emotional states. The main reason that dogs are more effective at this and that we see it demonstrated in dogs, with various reactions, is that dogs possess up to 300 million olfactory receptors in their noses, compared to about six million in us. And the part of a dog's brain that is devoted to analyzing smells is about 40 times greater than humans. (Phoenix Veterinary Center, 2020) The Phoenix Veterinary Center comments:

“Dogs also have something called neophilia, which means they are attracted to new and interesting odors. Dogs possess a sense of smell many times more sensitive than even the most advanced man-made instrument. Powerful enough to detect substances at concentrations of one part per trillion—a single drop of liquid in 20 Olympic-size swimming pools. With training, dogs can sniff out bombs and drugs, pursue suspects, and find dead bodies.” (Phoenix Veterinary Center, 2020)

Dr Pause and her team primarily investigated the chemosensory communication of stress, anxiety, and aggression. To conduct the experiments they took the samples from other humans from the armpit (sweat), urine samples and blood samples. Dr Bettina Pause commented regarding her experiments (Scientia, 2019):

‘The investigation of chemical communication offers a unique way to understand human social relationships. Multimodal studies show that in humans, chemical social signals are processed preferentially, but without cognitive interference…The investigation of chemical communication offers a unique way to understand human social relationships.’’ (Scientia, 2019)

Dr Pause and her team have been investigating various ways the human brain responds to chemosensory signals since 2009. It is believed her observations will pave the way for further discoveries about chemosensory communication of emotions among humans, as well as the relationship between olfactory processing and mental health. (Scientia, 2019)