Nice to…smell you?
Shaking hands dates back centuries, with many cultural explanations to back up the ancient customs. One study suggests that the true reason we shake hands is to find out what this new friend smells like. Why? Smell is a “socially significant chemical signal,” used by many other species in social interactions. The researchers conducting this Weizmann Institute study hypothesize that shaking hands is a subliminal way for us to register the smell of others, a primal social custom that survived evolution.
To begin the experiment, the researchers needed to determine if a handshake was enough to transfer detectable body odor. One subject wore a glove on their right hand and the other did not. When the glove was tested after the two subjects shook hands, odor residues containing “meaningful chemical signals” were found on the glove. The next step was to determine the amount of time (if any) spent sniffing the right hand after shaking hands. Around three hundred volunteers, unaware of the purpose of the experiment, were greeted by researchers via a handshake. Surveillance cameras in the room recorded the scene and showed how much time subjects spend sniffing their hands after the encounter. To ensure the subjects were actually subconsciously smelling their hands, nasal air flow was also recorded.
The results showed that subjects did indeed sniff their hands after handshakes and that several factors affected hand sniffing. Researchers observed that when the subjects and experimenters of the same gender shook hands, the subject smelled their hand for double the normal time. Interestingly enough, when shaking hands with someone of the opposite gender, sniffing of the left hand increased rather than the right hand. When experimenters wore a unisex perfume, the amount of time smelling the hand also increased, regardless of gender. But, when experimenters exuded odors derived from sex hormones, the overall amount of sniffing after a hand shake decreased.
While implications of this study are a little unclear, it does prove that chemosignaling is an important aspect of handshaking and social interaction, possible helping us to determine prejudgments. The researchers now hypothesize that social chemosignaling plays a larger role in human behavior than believed, at least at a subliminal level.
People Sniff Their Hands Twice as Much after a Handshake – Neuroscience News