People use handshakes to 'sniff' each other out

A new study has revealed that humans subconsciously sniff their hands following a handshake in order to interpret chemical information about those around them.

Study by Weizmann Institute found that people not only often sniff their own hands, but they do so for a much longer time after shaking someone else's hand.

The researchers found that after shaking hands with an experimenter of the same gender, subjects more than doubled the time they later spent sniffing their own right hand (the shaking one). In contrast, after shaking hands with an experimenter of the opposite gender, subjects increased the sniffing of their own left hand (the non-shaking one).

Individuals greeted with a handshake significantly increased the amount of time they touched their faces with the right hand. However, this only seemed to occur when someone was greeted by a person of the same gender.

In a further test, the scientists analysed sterile gloves used to shake the hands of volunteers. They found that two chemicals thought to be involved in social signalling in dogs and rats, squalene and hexadecanoic acid, were transferred on to the gloves.

The study is published in the journal eLife.