Can you smell when someone is aggressive?

Chemical signals in sweat can warn us about aggressive individuals. Researchers collected sweat samples from men who practiced boxing (an aggressive activity) or rode a bicycle. The sweat from the aggressive men triggered anxiety in volunteers who smelled it. The study suggests that people can subconsciously detect chemical signals of aggression.

The human nose senses aggression

Some animals are believed to be able to sense fear in humans. A recent discovery suggests that humans possess a similar ability—they can sense when someone is about to start a fight. The study's initiator, Dr. Smiljana Mutic from Aachen University Hospital, observed that the scent of human sweat can alert us to feelings of anger or aggression. Participants in the study who smelled the sweat of men engaged in an aggressive activity, such as boxing, reacted differently than when they smelled the body odor of individuals exercising on exercise bikes.

We detect chemical signals unconsciously

None of the volunteers consciously distinguished the scent samples. According to Dr. Smiljana, this is a remnant of our evolutionary past, when chemical signals were detected unconsciously . After all, humans acquire the vast majority of information through sight.

Smell warns against violence

To reach these conclusions, Dr. Smiljana initiated two experiments.

1. Sixteen healthy men boxed and rode exercise bikes. For two days before the tests, they were instructed to avoid strong-smelling foods and beverages, such as garlic, coffee, or curry. They were not allowed to use deodorant or perfume. Sweat samples were collected during the training sessions. The men also completed questionnaires regarding their motivation to commit harm and their level of anger.
2. The samples were demonstrated to 22 other people. They analyzed how exposure to the fragrance affected cognitive processing (e.g., emotion discrimination).

Volunteers showed increased anxiety levels when smelling samples from a boxing session . Cycling sweat, on the other hand, elicited no response. Scientists now need to agree on which odor components communicate aggression. For example, steroid hormones like testosterone and androstadienone have already been linked to aggression and natural body odor.