Maybe no one has noticed this, but just like all the other mammals in the world you sniff the people you meet. However, what differentiates us from animals is that we developed a very discreet way of doing it. We use handshakes.
Already studied for their subliminal social cues, handshakes also transmits chemical signals that could explain why the greeting evolved in the first place, according to Science Daily.
New research done at Israel’s Weizmann Institute of Science reveals that people use the touch of a handshake to sample and sniff signaling molecules. For this, scientists looked at 280 people who were greeted either with or without a handshake and observed to see how many times they touched their face. The results showed that people constantly sniff their own hands and keep a hand at the nose about 22% of the time, while subjects greeted with a handshake increased touching their faces with their right hand. However, this only seemed to be happen when the other subject was a person of the same gender.
To be sure about this, scientists gave the subjects nasal catheters to measure airflow and found that when it doubled when a hand was in close proximity to the nose. In other words, the subject was sniffing.
“It is well-known that we emit odors that influence the behavior and perception of others but, unlike other mammals, we don’t sample those odors from each other overtly,” says Professor Noam Sobel, Chair of Neurobiology at the Weizmann Institute of Science.
“Instead, our experiments reveal handshakes as a discreet way to actively search for social chemosignals,” he said.
Researchers also analyzed the content of sterile gloves used to shake the hands of the subjects to see if handshaking is effective at passing human chemosignals that play a role in mate selection, conveying fear, altering brain activity, and synchronizing women’s menstrual cycles. The results showed that squalene and hexadecanoic acid, both chemicals thought to play a part in social signaling in dogs and rats, were transferred onto the gloves.