I have a crazy idea there's a correlation between the rise of anxiety in a population and the decline in body odor due to deodorant and hygiene practices, as well as due to the increased availability of privacy, which is what I'll call the ability for each of us to have our own bedroom when growing up, or to live in an apartment alone as an adult, things that weren't available back in time because of financial constraints. That being said, the studies below do seem to suggest that smell has a stronger effect on our emotional states and our mental health status then we are aware of.
Research shows that sniffing women's tears reduces aggressive behavior in men
Dec 2023, phys.org
Science strikes again!
- They use the words "emotional tears" just to clarify. (not all tears are created equal)
- The men played a two-player game where they were allowed to get revenge on the opponent.
- Revenge-seeking aggressive behavior during the game dropped more than 40% after the men sniffed women's emotional tears.
via Weizmann Institute of Science: Agron S, de March CA, Weissgross R, Mishor E, Gorodisky L, Weiss T, et al. (2023) A chemical signal in human female tears lowers aggression in males. PLoS Biology (2023). DOI: 10.1371/journal.pbio.3002442
Scents might help depressed individuals, new study says
Feb 2024, phys.org
Scents are more effective than words at bringing back a memory of a specific event and could even be used in the clinical setting to help depressed individuals get out of the negative thought cycles and rewire thought patterns, aiding faster and smoother healing.
"It was surprising to me that nobody thought to look at memory recall in depressed individuals using odor cues before"
Professor Young presented study participants with a series of opaque glass vials containing potent familiar scents—from oranges and ground coffee to shoe polish, and even Vicks VapoRub. After asking participants to smell the vial, Young asked them to recall a specific memory, whether good or bad.
via University of Pittsburgh: Kymberly Young et al, Recall of Autobiographical Memories Following Odor vs Verbal Cues Among Adults With Major Depressive Disorder, JAMA Network Open (2024). DOI: 10.1001/jamanetworkopen.2023.55958
Study finds social interactions and olfactory cues prompt contagious itch in mice
Jun 2024, phys.org
Contagious itch only occurs in mice when they observe if a mouse that has been in their proximity is scratching.
Anosmic observer mice, whether itch-naïve or itch-experienced, displayed no contagious itch behavior.
via Tehran University of Medical Sciences: Shayan, M. et al. Social interactions and olfactory cues are required for contagious itch in mice. Scientific Reports(2024). DOI: 10.1038/s41598-024-61078-3.
Research shows young infants use their mother's scent to perceive faces
Jul 2024, phys.org
We tested 50 infants aged from 4 to 12 months, and found that the face-selective EEG response increases and complexified, indicative of improved face perception with development.
As expected, we also found that the benefit of adding the mother's body odor diminishes with age, confirming an inverse relation between the effectiveness of visual perception and its sensitivity to a concurrent odor.
Overall, this demonstrates that visual perception actively relies on odor cues in developing infants until the visual system becomes effective by itself.
What surprised me the most, not only in these studies but also in the previous studies we conducted, is the fact that the mother's odor has such a strong effect on the perception of various unfamiliar faces ... by showing reduced reactions to fearful faces, higher attention toward an unfamiliar woman, and increased interbrain synchrony between the infant and that woman.
Thus, it seems like the mother's body odor reassures the infant and promotes their interest when they encounter novel people. In other words, this primary social odor that infants learn already in the womb seems to encourage prosocial cognitions and behaviors.
via Society for Research in Child Development, Development of Olfactory Communication & Cognition Lab in the Center for Taste, Smell and Feeding Sciences at Université de Bourgogne, University of Hamburg, Université de Lyon, Institut Universitaire de France, Université de Lorraine, Centre Hospitalier de Nancy, and Centre National de la Recherche Scientifique CNRS: Olfactory-to-visual facilitation in the infant brain declines gradually from 4 to 12 months, Child Development (2024). DOI: 10.1111/cdev.14124
Smell of human stress can affect dogs' emotions, leading them to make more pessimistic choices
Jul 2024, phys.org
Dogs experience emotional contagion from the smell of human stress.
The researchers recruited 18 dog-owner partnerships to take part in a series of trials with different human smells present. During the trials, dogs were trained that when a food bowl was placed in one location, it contained a treat, but when placed in another location, it was empty. Once a dog learned the difference between these bowl locations, they were faster to approach the location with a treat, which reflected 'optimism', while a slow approach indicated 'pessimism'.
These trials were repeated while each dog was exposed to either no odor or the odors of sweat and breath samples from humans in either a stressed or relaxed state. The stress smell made dogs slower to approach the ambiguous bowl.
via University of Bristol Veterinary School: Parr-Cortes, Zoe ; Muller, Carsten T ; Talas, Laszlo et al, The odour of an unfamiliar stressed or relaxed person affects dogs' responses to a cognitive bias test, Scientific Reports (2024). DOI: 10.1038/s41598-024-66147-1
Emotional body odors may enhance the effect of mindfulness therapy
Nov 2024, phys.org
48 women with symptoms of social anxiety and 30 women with depression were divided into three different groups exposed to either happiness body odor, fear body odor, or clean air, then tasked with performing mindfulness exercises over two consecutive days.
"The results were quite surprising as we observed an enhanced symptom reduction for individuals with social anxiety that received chemosignals, regardless of whether they came from fear or happiness body odors. This may indicate that it is not the emotion itself that leads to the improved effect, but perhaps rather that chemosignals convey a kind of 'human presence.'"
Two nuanced results: 1. Exposure to fear body odor resulted in lower heart rate variability indicating a less relaxed state even though this was not reflected in the self-reported anxiety ratings, and 2. No differences were seen for the group with depressive symptoms, only anxiety.
via Karolinska Institutet and National Center for Suicide Research and Prevention: Cinzia Cecchetto et al, Sniffing out a solution: How emotional body odors can improve mindfulness therapy for social anxiety, Journal of Affective Disorders (2024). DOI: 10.1016/j.jad.2024.10.088
