Hand-shaking was not invented so that people could show friendship or to prove they are unarmed, but rather as a socially acceptable way of smelling each other, Israeli scientists have concluded.

A team at the Weizmann Institute filmed people shaking hands and found that they tended to smell their hands afterwards. People are "totally unaware" that they do this, and some even claimed that the videos had been doctored, said lead researcher Idan Frumin.

Mr Frumin said that hand-sniffing seemed to be a way for people to check out the functioning of each other's immune systems, their genetic make-up - "which is basically their essence" - and whether they are scared.

He said: "Our first finding was that people tend to bring their hands close to their faces and they do it as they sniff, taking in smells on their hands. We assume it is a way of conveying chemical signals between people."

Mr Frumin said that smell is "a non-verbal kind of communication which is very common in the animal kingdom, and we are no different". Asked what humans can learn from handshake smells about each other's immune systems, he said that this information can "tell you something about their suitability as a mate".

He said that the impact of the smelled person on the smeller may be so great that it could determine whether or not they like them.

So, if you find that people are not responding well to you after you shake hands, can you change your smell with perfume? Mr Frumin said not. "This is so subliminal and not prone to manipulation that you can't fake it."