Why can't we smell ourselves the way we smell others?

2023-10-30 2023-10-30T18:36:04Z

Arabia Weather - If you used public transportation after a long day at work or after visiting the gym, or were on an important date, you may have wondered if your body odor was noticeable to others. In fact, it is easy to notice when others recognize or have bad breath. However, it seems much more difficult to estimate our personal smell, so why can't we smell ourselves as strongly as we can smell others?

The human nose contains 400 odor receptors

Although our sense of smell is often compared unfavorably to that of super-olfactory organisms such as dogs and mice, humans are not poor at smelling and in some cases may even outperform these organisms.

Since our noses contain approximately 400 different smell receptors capable of registering 10 different types of smells and more than a trillion smells, it is believed that the sense of smell was one of the first senses to develop in humans. One study found that humans were better at detecting aromatic plant compounds than dogs, thanks to our evolutionary history as hunters and gatherers.

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A person gets used to his own smell with time

Although we can indeed smell our own scents — a quick sniff of our armpit can quickly confirm that — over time, we become accustomed to our own scents, noted Hiroaki Matsunami, a molecular neuroscience researcher at Duke University.

"The same is true for any smell we encounter regularly," such as perfume or inside our home, he added. This process is known as “olfactory fatigue,” and although the cause is not fully understood (it is thought it could be due to a change in smell receptors or in how the brain responds to smell), it can be reset by smelling areas that contain fewer odors. , such as the elbow or arm.

Our ability to detect our own scent also increases in some cases, according to Rachel Hertz, a neuroscientist at Brown University. “We have a unique body odor, so we are very sensitive to any changes in that,” she said.

A strange smell may be an indicator of an illness

For example, if you ate something with garlic or had a stressful day, you'll likely smell it in your sweat and saliva. Studies have also found a link between odor and more than a dozen diseases. Bad breath, like rotten fruit, can indicate untreated diabetes, while yellow fever makes sweat smell like fresh bread.

According to one woman who claimed to have noticed her husband's smell changing before he was diagnosed, Parkinson's disease gives off a "woody, musky smell." She later noted that she was able to detect the disease with approximate accuracy after smelling the shirts of six Parkinson's patients and six other people as a comparison group. Scientists are currently studying whether changes in skin oil, known as sebum, can be used to diagnose conditions before symptoms begin to appear.

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Our scents are linked to our social relationships

Besides health, our smell is also linked to our social relationships. In a famous 1995 study, scientists asked women to smell the shirts of men who avoided scented products. Both women had strong preferences, which the researchers linked to a group of genes called the major histocompatibility complex (MHC) that codes for peptides that the immune system uses to identify foreign invaders. There is something in our body odor that announces our unique MHC complex, and women preferred the scent of men who had MHC genes that were different from their own. The reason is still controversial, but it's possible that having children with someone who has a different set of major histocompatibility complex (MHC) genes may give those children immunity to more diseases, Matswamy said.

Although we seek a partner who is different from us, we use smell to judge how similar we are to others, and will often prefer those who smell similar to us by virtue of living in a similar environment.

"We use our sense of smell as a way to evaluate another, and we have different qualifications for the role we want that person to fill," Matsuami told Live Science.

The sense of smell is not given much attention

Because humans often rely on their visual senses, the sense of smell has not received the same attention as other senses, and thus, many aspects of it remain unknown. However, the COVID-19 pandemic has reignited interest in the sense of smell, because many people have lost the ability to smell in the days, weeks or years after their infection. The virus does not appear to destroy olfactory receptors or the neurons responsible for smell, so it's not clear exactly why this is, according to Hertz. But he hopes that this interest in the sense of smell will not go into oblivion, and that there is a continuing interest, awareness and recognition that smell is actually very important and connected to every aspect of our lives.