Why your own scent becomes invisible to you over time
In short: You can easily detect a stranger's perfume or bad breath, yet your own body odor often escapes your notice. It isn't that we are blind to our own scent, but rather that our brains undergo a process of desensitization to the smells we encounter most frequently.
The phenomenon is known as odor fatigue, a process where we become habituated to scents we routinely encounter, such as the smell of our own homes or our personal body odor. While it is a misconception that we cannot smell ourselves at all—a quick sniff of an underarm can confirm our scent is present—we do become desensitized to it. Molecular neurobiologist Hiroaki Matsunami of Duke University notes that this occurs with any constant stimulus. The exact mechanism remains a subject of investigation, though scientists suspect it may involve changes in either our scent receptors or how the brain processes the olfactory signals.
Interestingly, our olfactory capabilities are more sophisticated than often assumed. While species like dogs, mice, and pigs are famous for their noses, humans can actually outsniff them in specific contexts. For instance, research suggests humans may be superior at detecting aromatic compounds from plants, a skill likely honed by our evolutionary history as hunter-gatherers. Our noses utilize roughly 400 different receptors, capable of registering 10 types of odors and over 1 trillion distinct scents.
Our sensitivity to smell is not static; it can fluctuate based on our physiological state. Neuroscientist Rachel Herz of Brown University explains that we are uniquely attuned to changes in our own body odor. For example, consuming garlic or experiencing stress can alter the scent of our sweat and saliva. This sensitivity is medically significant, as certain odors can signal health issues. Breath smelling of rotten fruit may indicate untreated diabetes, while typhoid can make sweat smell like freshly baked bread. Scientists are even investigating whether changes in skin oils, or sebum, could help diagnose diseases like Parkinson's before symptoms appear.
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Sources
- Summary by Intellect · source: Why Can't People Smell Themselves
- Also: Why can't we smell ourselves as well as we smell others? | Live Science
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