‘Old Person Smell’ Is Real. So Real That Researchers Have Spent Years Trying to Understand How It Works

The nose knows many things—sometimes too many. According to research at the Monell Chemical Senses Center in Philadelphia, the average person can recognize between 10 billion and 100 billion different odors, including things we’d never suspect.

“Similar to other animals, humans can extract signals from body odors that allow us to identify biological age, avoid sick individuals, pick a suitable partner, and distinguish kin from non-kin,” Monell neuroscientist Johan Lundström stated.

And yes, Lundström said, “Identify biological age.” That means that “old person smell” is real, and we’re learning more about it.

It’s so real that the Japanese have a word for it: kareishu. Because of the Japanese devotion to old age, the locals traditionally consider this word a sign of respect. Laura López-Mascaraque, a Spanish National Research Council (CSIC) researcher, explained to local media that the idea that body odor changes with us is deeply rooted in Oriental culture.

Although each of us has a characteristic “chemical signature,” factors such as age, menstrual cycle, breastfeeding, eating habits, and stress change our scent. Indeed, the Japanese have a term for the “smell of stress”: sutoresushu.

How is a person’s scent made? This fact is interesting because, unlike other animals, humans “do not have specific scent-producing glands.” However, the skin’s three main glands contribute to creating this personal and inimitable scent.

The sebaceous glands produce an oily secretion over the entire surface of the body, the eccrine glands secrete sweat, and the apocrine glands produce a watery fluid in the scalp area. The secretions of these glands serve as food for the microbiota in our skin, and ultimately, it’s all of this metabolic activity that shapes our unique body odor.

And does this unique body odor change with age? Consuelo Borrás Blasco, a professor at the Faculty of Medicine at the University of Valencia, told the outlet La Voz de Galicia, “Hormonal changes, especially those associated with menopause and andropause, can affect body odor. The decrease in sex hormones can affect the production of sweat, oil, and alter the microbial environment of the skin. Finally, skin pH can change with age, affecting the skin microbiome and the types of odor-producing bacteria present.”

For example, the composition of the skin’s protective fatty acid layer changes after the age of 40, becoming five to six times more omega 7. Also, the deterioration of the skin favors the oxidation of these lipids. It produces things like 2-nonenal, an unsaturated aldehyde associated with what we know as “old person smell.”

Our smell actually changes a lot—or at least enough to easily identify it. In 2012, Lundström and his team tested how well humans can detect a person’s age just by their body odor. They found that while it was generally easy for evaluators to identify age by smell, the reliability skyrocketed for older people because of the presence of biomarkers associated with advanced age.

Underdeveloped research. As research into the digestive system’s microbiota becomes more popular, it becomes even more evident that we know very little about the human microbiota.

That is curious because, whether we like it or not, it’s involved in a multitude of health, beauty, and wellness processes. In this regard, the pharmaceutical industry has grown the most in recent years.

Fortunately, as we can see, this is beginning to change. Our knowledge of immunology, general medicine, and dermal ecology will give way to another of the tremendous medical revolutions of the decade.

This article was written by Javier Jiménez and originally published in Spanish on Xataka.

Image | Raychan

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