By Nick Fontaine
Smell has a strong connection to our emotions and memories. You have probably experienced an example of this with your grandmother’s cooking when you are suddenly transported back to your childhood. This is a result of smells being processed in the brain’s limbic system, which is where memories and emotions are also processed. The connection between smell and memory remains incompletely understood, but research by de Groot et al. reviews compelling evidence for the social importance of understanding odors. Olfaction has been overlooked by psychology and neuroscience compared to senses like vision and hearing. However, there is a growing field of study examining the communicative properties of smell – specifically body odor and what it tells people around us about us.
Research by de Groot et al. reviews how smelling someone’s body odor activates social information processing regions in the brain such as the fusiform face area and the mirror neuron systems. The fusiform face area aids recognition of familiar faces, and mirror neuron systems are best known for their involvement in empathy. It has also been shown that body odor is unique to each individual as your genes and environment interact to create your unique smell, or “odorprint” if you will.
Body odor may even have an effect on who you are attracted to, as BO may reveal compatible immune systems that would produce a child better equipped to fight disease. This is known to be the case in other animals, such as mice, but there is mixed evidence supporting it in humans – as it is not known if there is a real genetic relationship between immune system and body odor in humans. So take this aspect of communicative body odor with a grain of salt. Or pepper. Or another odiferous spice.
Body odor also has many basic evolutionary communicative functions. For example newborn babies can use their mother’s breast-specific body odor to orient to breastfeeding, and mothers can accurately identify their babies based on scent alone. Humans can also tell if a person is sick or not, better than if they were just guessing, based on body odor.
More characteristics can be told via smell, including sex, age, and emotion. When presented with the armpit section of a worn tee shirt, people could guess the former wearer’s sex, emotional state, and approximate age better than chance. Interestingly, it has been found that body odor is cultural. For example, Japanese elders express a different odor than American and European elderly people. Body odor also is representative of how a culture expresses emotion. De Groot et al. went as far as to document how tolerance of emotional expression is related to the intensity of body odor. Japanese and Chinese individuals coming from cultures with more emotionally restriction tend to have less intense smelling body odor compared to Americans and Europeans who come from cultures in which emotional expression is more accepted.
Despite all the social taboos surrounding body odor, scent has an evolutionary and communicative function that shows how complex the human cognitive experience truly is.
This research by de Groot et al. contributes to our growing understanding of smell as a meaningful social tool. Future research has the potential to explore more regions of the brain participating in olfactory recognition and encoding, and linking these sensory modalities to other groups.