For most of the animal kingdom, smell is a language. This is direct communication. Commonly used by bees, birds, rodents and fish. They send out scent and receive it. It is biology in its most primitive form.
human? The rules are not very clear.
The concept of human chemosignaling remains one of the hottest debates in modern science. It contains a pheromone which is said to be a chemical messenger. Scientists have wondered for years whether we really have them. Research from Israel’s Weizmann Institute of Science suggests the answer is yes. At least we use our noses for social checks more often than we care to admit.
This study highlights an often overlooked moment in one of our oldest social rituals: the handshake.
“Handshakes may serve functionally active but subconscious social chemosignaling,” the study concluded. This has nothing to do with conscious analysis. It plays an important role in ongoing human behavior and operates slightly below the level of consciousness.
Handshake study
The data comes from an experiment with 271 people. They participated in structured social activities. Some people shook hands. Some people did not. The researchers followed what happened next.
The result is simple. It is a normal human habit to smell one’s own hands. But after greeting, it goes up considerably.
But pattern of sniffing revealed surprising nuances. According to a study published in eLife in 2015, the hand you use is key.
When left alone in a room, volunteers who shook hands were more likely to touch their nose to their palm than those who didn’t say hello. However, the direction of the sniff changed depending on who you meet.
Participants spent more time smelling their right hand after shaking hands with someone of the same gender. This is usually the dominant hand used in a handshake.
When you shake hands with the opposite gender, the focus changes. Instead, they spent more time smelling their left hand.
Why does the brain prioritize different hands based on gender? This study does not provide a definitive answer to this question. It simply documents the behavior.
Evolution’s Subliminal Habit
The study’s lead author, Idan Frumin, provided the biological context. He noted that rodents, dogs and other mammals often sniff themselves and each other. This is a normal part of social interaction.
Humans seems to have preserved this custom. We just do it subliminally. We don’t openly raise our wrists to our faces. We don’t announce it. But the desire remains.
This chemosignaling is widely accepted in across species. Fathead minnows use urine to mark their territory. Ants, elephants, deer and bees use receptors to analyze the chemical composition of their peers. This is how they identify friends, foes, and mates.
The debate only starts when you look in the mirror.
The pheromone myth
To call human chemosignaling “sketchy” would be an understatement. In 2010, Richard L. Doty, director of the Center for Smell and Taste at the University of Pennsylvania, published “The Great Pheromone Myth.” His conclusion was blunt. He rejected the idea that a single chemical could passing messages between people.
Part of the problem is definition. Biology-online defines a pheromone as a substance secreted by an individual into the environment, which causes a specific reactions in other individuals of the same species. This also applies to multicellular organisms.
Doty thinks the bar for calling it a pheromone should be higher. In his book Neurobiology of Chemical Communication, he lists the following strict criteria:
- It must consist of one or only a few chemicals.
It must be species specific.
3. It must have well-defined behavioral or endocrine effects.
4. It must be little influenced by learning.
To date, no chemicals isolated in humans has met all of these criteria, Doty said.
Does this mean hand-sniffing study is nonsense? Not exactly.
This means that the terminology is messy.
Chemosignals vs. Pheromones
We know that scents can affect your mood. Perfume can be calming or energizing. The problem is pinpointing the specific agents responsible.
Some studies at the Weizmann Institute have shown that human tears contain chemosignal. This term has a broader than “pheromone”. The strict biological criteria required by Doty does not require It just recognizes that chemosignal from body fluids can influence others.
Does the handshake study prove we have pheromones? This provides evidence for possible social chemosignaling. This suggests that we checking each other’s chemical profiles after physical contact. Whether these cues are actual pheromones or just general olfactory cues interpreted by the brain is a distinction that has no clear boundaries.
Scientists continue to study this topic. The secret language of our fragrance is still being discovered. Until then, why don’t you check your hands?
