According to a new study, it is not just through language and visual cues that human beings can communicate, but also through the sense of smell.
The study, which was published in Psychological Science, found that the sweat of individuals displaying emotions of fear or disgust can trigger the same emotion in those who smell it. The study suggests that this system in all likelihood evolved as an unconscious form of communication, which humans could use to warn others of imminent danger.
For the study, a group of women were exposed to bottled sweat given off by men watching clips from the thriller The Shining (often voted as one of the scariest films ever made) and later sweat given off by men who were watching MTV’s Jackass, which features a number of stomach-churning stunts. The participants were not told where the samples came from.
According to the researchers, previous studies have shown how looking at a fearful expression leads us to breathe in more through our noses and accelerates eye movement, and how disgust signals cause us to wrinkle our noses and lower our eyebrows, in response to noxious chemicals. The researchers conducted this experiment hypothesising that the same would be found to be true in chemicals in bodily excretions such as sweat. According to them, “…people who inhaled chemosignals associated with fear would themselves make a fear expression and show signs of sensory acquisition, while people who inhaled chemosignals associated with disgust would make an expression of disgust and show signs of sensory rejection.”
The effect of men’s sweat on women was studied because men have been shown to release more chemical signals when they perspire, while women are more sensitive to such signals.
When the women were exposed to sweat of the ‘fear’ condition, they sniffed more deeply and scanned the room with their eyes more, which is considered an evolutionary response designed to help in detecting danger. When they were exposed to the ‘disgust’ scent, women wrinkled their noses and lowered their eyebrows, which is believed to be another evolutionary mechanism to help limit exposure to noxious chemicals.